Tuberculosis Research and Treatment

Tuberculosis Research and Treatment / 2015 / Article

Review Article | Open Access

Volume 2015 |Article ID 957519 | 11 pages | https://doi.org/10.1155/2015/957519

Evolution of M. bovis BCG Vaccine: Is Niacin Production Still a Valid Biomarker?

Academic Editor: Vincent Jarlier
Received16 Jul 2014
Revised15 Dec 2014
Accepted06 Jan 2015
Published28 Jan 2015

Abstract

BCG vaccine is usually considered to be safe though rarely serious complications have also been reported, often incriminating contamination of the seed strain with pathogenic Mycobacterium tuberculosis. In such circumstances, it becomes prudent to rule out the contamination of the vaccine seed. M. bovis BCG can be confirmed by the absence of nitrate reductase, negative niacin test, and resistance to pyrazinamide and cycloserine. Recently in India, some stocks were found to be niacin positive which led to a national controversy and closer of a vaccine production plant. This prompted us to write this review and the comparative biochemical and genotypic studies were carried out on the these contentious vaccine stocks at the Indian vaccine plant and other seeds and it was found that some BCG vaccine strains and even some strains of M. bovis with eugenic-growth characteristics mainly old laboratory strains may give a positive niacin reaction. Most probably, the repeated subcultures lead to undefined changes at the genetic level in these seed strains. These changing biological characteristics envisage reevaluation of biochemical characters of existing BCG vaccine seeds and framing of newer guidelines for manufacturing, production, safety, and effectiveness of BCG vaccine.

1. Introduction

BCG, an attenuated strain of Mycobacterium bovis (M. bovis), has been used in more than 182 countries or territories as a prophylactic vaccine against tuberculosis (TB), for more than 90 years, albeit amidst a considerable controversy related to its efficacy. The true efficacy of BCG has been difficult to understand due to many experimental variables [1]. M. bovis is the etiological agent of bovine tuberculosis and is closely related to Mycobacterium tuberculosis (M. tuberculosis) in the M. tuberculosis complex (MTBC), which consists of M. tuberculosis, M. bovis, M. bovis BCG, M. africanum, M. canettii, M. microti, M. caprae, and M. pinnipedii. The M. bovis mainly infects cattle (Bos taurus), but it can infect other mammalians including humans [2, 3]. The BCG vaccine undoubtedly provides protection against childhood disseminated form of TB including TB meningitis. However its efficacy against pulmonary TB in adults has been reported to give variable results [4]. In 2011, World Health Organization (WHO) monitored study revealed that protection levels ranged from 53% in Equatorial Guinea and 54% in Ethiopia to more than 99.5% in India and China [5]. Its efficacy in programmed mode is reported to be more than 80% [6]. So far more than 3 billion doses of BCG vaccine have been given since 1948, and by and large it is considered safe [7]. However localized abscess formation, disseminated disease, and regional lymphadenopathy, especially in immunocompromised hosts are rare but well-recognized complications [8].

An estimated 8.6 million new cases and 1.3 million deaths due to tuberculosis occur every year [9]. Almost all cases of tuberculosis are caused by M. tuberculosis, and share of M. bovis is less than 1.4 percent of all pulmonary tuberculosis cases outside of Africa. Though, in Africa, M. bovis accounts for approximately 2.8 percent of cases of pulmonary tuberculosis, for a crude incidence of 7 cases per 100,000 populations [10], the global proportion of M. bovis is higher among patients with extrapulmonary tuberculosis, since the pathogen is frequently acquired via oral ingestion and gastrointestinal disease is an important clinical manifestation [11].

2. Historical Aspect of BCG

The original BCG vaccine “strain” was derived from an isolate of M. bovis. Since 1900, Albert Calmette (1863–1933) began his research on the M. bovis strain, which had been isolated from the milk of an infected cow by veterinarian Jean-Marie Camille Guérin (1872–1961) in 1904. In addition, the “strain” was named Bacillus of Calmette and Guérin. They cultivated these bacilli in a medium containing glycerin and potato, but they found that there was difficulty in the production of homogenous suspension of the bacilli. To make the bacteria homogenous they added ox bile to the medium and to their revelation, they found that the additive has lowered the virulence of bacteria. This unexpected observation became source of vaccine production from the attenuated tubercle bacilli [12]. Benjamin Weill-Hall (1875–1958), a French pediatrician and bacteriologist, was the first to feed the vaccine to infants in Paris who were at a risk for the disease. However, in 1908, Camille Guérin and Benjamin Weill-Hall, both at the Institute Pasteur in Lille, France, began attenuating the M. bovis by passing it through a growth medium they had developed specifically for this purpose and an actual BCG vaccine was thus developed at the Pasteur Institute in Lille and was first given to humans in 1921. The first formal trial of BCG outside France was organized among the North American Indians in the 1930s [13]. By the late 1940s, several studies provided evidence favouring its utility in protection against tuberculosis. For this, the original culture was subcultured and distributed to several laboratories throughout the world, where the vaccine strain was called BCG and was maintained by continuous subcultures. After many years, the various strains maintained in different laboratories were found to be no longer identical to each other. In fact, it was likely that various strains maintained by continuous subculture continued to undergo undefined genetic changes. Indeed, even the “original” strain of BCG maintained at Paris also continued to change its characteristic during the subcultures. To limit the genetic changes the procedures needed to maintain the strain were modified time to time. Currently, the M. bovis BCG is maintained by using a “seed-lot” production technique to limit further genetic variations.

Presently, five main strains or seed-lots, accounting for more than 90% of the vaccine produced, are used worldwide with each strain possessing different biological characteristics. These strains are Pasteur 1173 P2, the DANISH 1331, the Glaxo 1077 (derived from the DANISH strain), the Russian BCG-I, the Tokyo 172-1, and the Moreau RDJ strains [24]. Confusions are generated by the vague terminologies used by individual stakeholders (e.g. “American” strain), varying nomenclature (e.g., BCG Brazil is the synonym of BCG Moreau, although Moreau was from Uruguay), and unusual corporate events (e.g., Pasteur-MeÂrieux-Connaught produces BCG- Glaxo except in Canada where BCG-Connaught is used) [25]. Articles on BCG molecular biology reflect this confusion, with studies employing different strains, attributed to different historical periods [26]. In the extent of different vaccine efficacy and safety in humans, it is not clear at present; but some differences in the molecular and genetic characteristics are known and each BCG has been called by the location where it is produced; for example, BCG (Paris), BCG (Copenhagen), BCG (Tice), and BCG (Montreal).

In India, the BCG vaccination programme was started in 1948 and BCG vaccine laboratory was established in Madanpalle (Tamil Nadu, India). By 1960, the first round of mass BCG vaccination was completed in all states with about 254 million persons having been vaccinated by 1979. Yet BCG is one of the most controversial vaccines till today [27]. Since the 1950s, the reason for the failure of BCG in some populations has been a subject of debate, and to explain the observed variation, different hypotheses have been suggested [28]. The differences in the strain of BCG, the age at vaccination, or methodological differences are important factors [29]. One exception from this general rule is the consistent high efficacy when BCG is used to vaccinate newborns. Neonatal vaccination with BCG reports protection against the childhood manifestations of TB, especially the meningitis [30], but the efficacy decreases over a period of times, and therefore in the adult population the third world vaccine does not prevent against the later breakdown with pulmonary TB [28].

3. Biochemical and Genotypic Characteristics of BCG

Phenotypic characteristics have been a contentious issue and some strains are considered inferior over the others. Not only allegations of contamination with M. tuberculosis have been made occasionally, but also recently one batch of the Indian BCG vaccine was found to give niacin positive reaction and this led to the closure of vaccine plant in India. A high-level technical committee was formed by Government of India and one coauthor was part of this committee. As described in Table 1, the diagnostic features of BCG include growth in Lowenstein-Jensen and 7H11 media and in the modified Dubos liquid medium at 37°C; inhibition of growth in the presence of thiophene-2-carboxylic acid hydrazide; negative tests for niacin, catalase production at 68°C, nitrate reduction, Tween 80 hydrolysis; and a positive urease test [31]. On the basis of secreted proteins, MPB64 and MPB70 substrains of M. bovis BCG have been divided in two major groups: high and low producers of these proteins [16]. Polymerase chain reaction (PCR) and hybridization experiments indicate that the MPB64 gene is absent in the BCG substrains Pasteur, Glaxo, Copenhagen, and Tice. The species specificity of MPB64 and its occurrence in both M. tuberculosis and virulent strains of M. bovis may create further confusion [32]. Biochemical tests are currently used for the identification of bacterial species, including the genus Mycobacterium [33]. Several enzymes such as NAD and NADH quinone reductases, mycobacterial phospholipase A (MPLA) which catalyses the hydrolysis of lipids including Tween 80, and others appear to contribute to survival of the mycobacteria [34, 35]. An important virulence factor for M. tuberculosis and M. bovis is the nitrate reductase system. Chemically, BCG can be distinguished from M. tuberculosis by its weakly positive nitrate reduction ability. While the amidase test gives a strongly positive reaction to carbamide, whereas other amidases give negative results in Bônicke series [36].


Tests strain M. bovis BCG P3M. tuberculosis H37RvRemarks

Nitrate reductionNegativePositive¥
NiacinPositivePositive
CatalaseNegativeNegative
hsp65-PCRPositivePositive
esat6-PCRNegativePositive
Mac-PCRNegativeNegative
MPT64 antigenNegativePositive
MPT63 antigenPositivePositive
Binary spoligotyping■■□■■■■■□■■■■■■□■■■■■■■■■■■■■■■■■■■■■■□□□□□■■■■■■■■■■■■■■■■■■■□□■■■■■■■■■■■□□□□■■■■■■■
Octal number676773777777600777777477760771
Shared type482451
Lineage/sublineagesBovis1_BCGH37Rv

Guinea pig virulenceNon-virulentVirulentΨ

M. bovis BCG (Tokyo)M. tuberculosis H37Ra

Nitrate reductionPositivePositive [14]
NiacinPositivPositive
CatalaseNegativePositiv

M. bovis BCG (ATCC 19274), M. bovis BCG (Biken)M. tuberculosis H37Rv (TMC102), H37Rv (Biken), H37Ra (Biken)

Niacin testWeakly PositivePos [15]

BCG Copenhagen, BCG Glaxo, BCG Pasteur, BCG TiceM. tuberculosis H37Rv, M. tuberculosis H37Ra

MPB64NegativePositive [15]
MPB70PositivePositive
16SrRNAPositivePositive

BCG Tokyo, BCG Moreau, BCG Russia, BCG Sweden.  M. bovis AN5

MPB64Positive [16]
MPB70Positive
16SrRNAPositive

M. bovis BCG (Glaxo, Pasteur, Tice)M. tuberculosis (H37Rv)

MPB64NegativePositive [16]
IS6110 copy number1

M. bovis BCG (Brazilian, Japanese, Russian, Swedish)

MPB64Positive [16]
IS6110 copy number2

M. bovis BCG M. tuberculosis (classical)

Nitrate reduction PositivePositive [17]
NiacinNegativePositive

M. bovis BCG M. tuberculosis (classical)

Nitrate reductionNegativePositive [18]
NiacinNegativePositive
MPB70PositivePositive
Mtp40NegativePositiv (very occasionally)

M. bovis BCGM. tuberculosis

Nitrate reductionNegativePositive [19]
NiacinNegativePositive
MPB70PositiveNegative
Mtp40NegativePositive
Spoligotyping spacer 39–43NegativePositive

M. bovis M. tuberculosis

Nitrate reductionNegativePositive [20]
Niacin accumulationNegativePositive
Presence of mtp40NegativePositive
Spoligotype
(characteristic features)
At least one of spacers 39–43 presentSpacers 39–43 absent

M. bovis BCG M. tuberculosis (H37Rv)

Binary spoligotyping■■□□□■■■□■■■■■■□■■■■□■■■■■■■■■■■■■■■■■□□□□□■■■■■■■■■■■■■■■■■■■□□■■■■■■■■■■■□□□□■■■■■■■ [21]
Octal number616773677777600777777477760771
Shared type663451
BOVIS1H37Rv

M. bovis M. tuberculosis

Spacers 33 to 36
(derived from BCG)
M. tuberculosis does not hybridize to the spacers [22]
Spacers 39 to 43
(derived from M. tuberculosis)
M. bovis and BCG do not hybridize to the spacers

M. bovis M. tuberculosis (H37Rv)

Capilia TB-NeoPositivePositive [23]
SD MPT64PositivePositive
TbcIDPositivePositive

M. bovis BCG TokyoM. bovis BCG Connaught

Capilia TB-NeoPositiveNegative [23]

Our analysis on the Indian seed-lot; personal communication with the Director of the BCG vaccine producing laboratory; very occasionally positive; Weak Positive.

Niacin production during the adaptation to hosts of several strains of biovars 1 to 4 can more readily switch on and switch off the genes. It is reported that M. bovis strains of the “European” type (which possess a single IS6110 fragment and which lack DR spacer sequences 39 to 43) branched off at an earlier stage than the other M. bovis strains. The M. bovis BCG has been reported as niacin test negative, nitrate reductase negative, and pyrazinamide and cycloserine resistance [37].

The elevated levels of nitrate reductase activity increase the virulence and consequently the success of some lineages of M. tuberculosis [38]. However, nitrite production has also been reported in some strains of M. bovis under different conditions such as longer incubation period and anaerobic conditions [39]. Both M. tuberculosis and M. bovis BCG express an anaerobic nitrate reductase (NarGHJI) activity and a narG M. bovis BCG mutant lacks the ability to reduce nitrate under anaerobic conditions [40]. A narG knockout mutant of BCG showed reduced virulence and reduced lung damage in severe combined immunodeficiency (SCID) mice. Thus M. bovis BCG, like M. tuberculosis, can form granulomas in different body sites and abscesses in various human tissues [41]. In MTB granuloma formation hypoxia plays an important role and this pathology is mediated by several enzymes including nitrate reductase [42, 43]. However, the role of hypoxia is not well defined in vaccine strain M. bovis BCG [44].

The human tubercle bacilli (M. tuberculosis) produce more niacin than other mycobacteria, and the detection of niacin production has been widely used for differentiating MTBC species from M. bovis which are usually niacin negative [4547]. Recently, this biomarker created a huge crisis in Indian Government system, because the in-use lots of BCG vaccine were found to be niacin positive. Other manufacturers of the BCG vaccine alleged that the Indian seed-lot was contaminated with M. tuberculosis. Besides closing the vaccine production plant, the Government of India set up a technical committee to examine the controversy. Several seed-lots along with the alleged Indian lots were analyzed in Table 1. These results indicated that besides Indian seed-lot (BCG-P3) several other strains have also become niacin positive, without any evidence. The strain BCG-P3 has been found to lack genes normally present in M. tuberculosis but absent in BCG and was nonvirulent for Guinea pigs, ruling out contamination by M. tuberculosis, important fact. All vaccine producers are required to follow standard vaccine virulence testing guidelines as per WHO guidelines [45]. The literature also indicates that some bovine strains with eugenic-growth characteristic, mainly old laboratory strains, and some BCG vaccine strains may give a positive niacin reaction; on the other hand, certain M. tuberculosis strains with dysgenic-growth characteristics, such as isoniazid-resistant strains, may give a niacin negative reaction [48, 49].

4. M. bovis Genome and Biological Lifestyle

At genetic level also heterogeneity of niacin accumulation has been observed among BCG substrains. The M. bovis cell wall contains phenolic glycolipids that are absent in M. tuberculosis. A family of membrane-spanning proteins involved in the export of the phenolic cell wall glycolipids in the M. bovis genome (TbD1 locus) consists of the mmp genes [50]. A group of antigens of ESAT-6 family such as CPF-7 and CPF-10 which were originally described as T-cell antigens are secreted by M. tuberculosis [51], but these are also encoded by the genome of M. bovis. Other members of the family act in match-up; possibly in a mix-and-match array the interaction between ESAT-6 and CPF-10 is exhibited, whereas in M. tuberculosis the six members of the ESAT-6 familyare absent from the genome of M. bovis [52, 53].

5. M. bovis BCG Infection

BCG infections are infrequent, but rarely some children can develop localized or disseminated BCG infections. To differentiate these manifestations from other conditions recovery of the BCG strain of M. bovis from the pretentious focus is mandatory. The identification process of M. bovis is not simple as it relies on the isolation of the bacteria from the site of localized infection, usually the injection site, or from other tissues including the blood such as in case of disseminated infection. In adults, when BCG vaccine is used in bladder cancer therapy, dissemination can lead to fatal infection. Recently, molecular techniques have been frequently used to identify the true pathogens even when it is not culturable. The commonest molecular methods used to identify and confirm the diagnosis of BCG vaccine infections are PCR followed by single stranded conformation polymorphism (SSCP). The pncA gene is the most specific target due to the fact that polymorphic site at the 169 position of this gene, M. bovis BCG vaccine can be differentiated from M. tuberculosis using PCR-RFLP [54]. The standard mycobacterial culture techniques currently used in clinical microbiology laboratories are capable of identifying mycobacteria to the level of the M. tuberculosis complex. On the basis of morphology and biochemical criteria, it is difficult to differentiate between virulent M. bovis and M. bovis BCG. More sophisticated methods are probably needed to confirm a diagnosis of M. bovis BCG. Complications after BCG vaccination and the intrinsic resistance of M. bovis BCG to pyrazinamide, as well as knowledge on BCG infection, would be of particular interest to the clinician responsible for guiding therapy. After PCR-based diagnosis, therapy is based on drug susceptibility with BCG sensitive regimens, that is, isoniazid, rifampin, and ethambutol. However, the prevalence of BCG infection is not known, mainly because most laboratories cannot quickly differentiate between BCG and other members of the M. tuberculosis complex. Utilization of an allele-specific PCR combined with a multiplex PCR was found to be a sensitive and rapid test for the detection of M. bovis BCG in clinical specimens [37].

6. Complications of BCG Vaccination

BCG vaccine has been given to more than a billion people, but the protective efficacy is reported to vary in various human trials and the utility is further limited by their propensity to induce tuberculin reactivity [55, 56]. The current global threat of tuberculosis and the emergence of drug-resistant strains are compelling the scientific community to improve BCG vaccine or develop an entirely new vaccine against tuberculosis [57]. BCG vaccine has been considered to be safe, and although complications are rare after vaccination and the outcome is usually favourable, serious BCG infections can occur. Localized abscesses, regional lymphadenopathy, and disseminated disease in immunocompromised hosts are uncommon but well-recognized complications [58]. The retrospective review identified 60 cases of dissemination for which the mortality rate was 50%. BCG vaccine has been administered per cutaneous in Brazil since 1968 using the multiple puncture method. More than 1,000 publications made between 1921 and 1982 reported approximately 10,000 complications of BCG vaccination [58]. Recent molecular work has demonstrated differences between BCG and M. tuberculosis as well as within the BCG strains [59, 60]. Since BCG strains vary in protein expression [61], lipid composition [62], pathobiology in laboratory animals [63, 64] and humans, an understanding of genetic differences may provide insights into the determinants of protective immunity and vaccine associated complications [6567].

The mild adverse reaction is characterized by a papule at an injection site, which may progress to become ulcerated. This may heal after 2–5 months leaving a superficial scar, and swelling of the epilateral regional lymph nodes may also occur. Multiple cutaneous lesions may signal disseminated BCG disease usually in an immunocompromised host [24]. Severe adverse events include subcutaneous abscess and keloids at the injection site and occurrence of a number of cutaneous lesions (such as TB chancre, lupus vulgaris, scrofuloderma, papulonecrotic, and disseminated tuberculosis) at the sites distinct from the vaccination site [68]. The incidence of local complications depends on the age of the recipient and the dose of vaccine. In newborn, BCG administration as an intradermal injection at any age is not easy; the commonest error is to inject the vaccine too deep. This deep injection can cause injection abscesses (2% cases). In more serious injection related complications, deep ulcers, osteomyelitis (0.04%), and lymphadenopathy (1%), especially in younger infants under one year, may occur. The immune dysfunction is directly related to disseminated disease, in the order of 1/1,000,000 doses, but is thought to be rare [69].

7. BCG Complications in HIV Infected Hosts

Following M. bovis BCG vaccination, development of disseminated disease in immune-compromised individuals has been reported which can be fatal in several cases [70]. The significantly high risk of disseminated BCG (dBCG) disease is reported in HIV-positive infants, with rates approaching 1% in South Africa [71]. Immune reconstitution inflammatory syndrome (IRIS) has recently been identified as a BCG vaccine-related adverse event in immunocompromised individuals after antiretroviral therapy (ART) [72]. The cellular primary immunodeficiency predisposes to the condition [73, 74]. The place of BCG vaccination in TB control programs is being carefully assessed as of the considerable risk of human to human transmission in immune-compromised patients, particularly in TB nonendemic countries [7577].

8. BCG Vaccine and Tuberculin Skin Test (TST)

BCG-induced tuberculin reactivity is identical with reactivity induced by M. tuberculosis infection and the increased degree has been found in BCG revaccination in school children. The influence of BCG vaccination in past has been reported on tuberculin skin test (TST) surveys used as an auxiliary tool to estimate latent or active tuberculosis [78, 79].

9. Current Understanding of BCG Vaccination

The production of M. bovis BCG from different strains and by different manufacturers resulted in variable quality of vaccine and viabilities per dose of vaccine, as discussed in the previous paragraphs [80, 81]. Therefore, the World Health Organization is contemplating the revision in vaccine production guidelines, scope, terminology, and requirement of BCG vaccines. To discuss issues regarding the standardization, characterization of live and attenuated BCG vaccines, and evaluation of these vaccines, a consultative meeting of regulators, BCG vaccine manufacturers, researchers, and program managers was organized in 2010. The development of live attenuated TB vaccines, new recombinant BCG, and the characterization of different BCG sub-strains were also reviewed using state-of-the-art technologies to revise and update the various important issues related to current recommendations focused on the scope, terminology, manufacturing issues, and the incorporation of new reference reagents and new quality control test [82]. Interestingly, recent studies have shown that the combination of priming with recombinant BCG such as ΔureC hly+ rBCG and boosting it with most efficacious subunit vaccine would provide more powerful intervention measure against tuberculosis [83, 84]. The results of a long-term controlled trial of a BCG vaccine provides supports to investigators aspiring to produce vaccine with similar or improved characteristics as trial of a BCG vaccine found to have good protective efficacy against TB that extended up to 60 years after vaccination except some cases of pulmonary and extrapulmonary TB [85, 86].

10. Guidelines on Administration of BCG Vaccine

Tuberculosis emerged as a major concern in the aftermath of World War II, and subsequently, the use of BCG was encouraged in many countries, particularly by UNICEF and by Scandinavian Red Cross Societies and then by the WHO. Major trials were set up by the British Medical Research Council (BMRC) and by the United States Public Health Service (USPHS) in the early 1950s. The procedure employed by the BMRC provided high efficacy against tuberculosis [86, 87]. In contrast, BCG used by the USPHS (Park or Tice strains given to tuberculin-negatives of various ages) provided very little protection [55]. Respective public health agencies reported that BCG was recommended as a routine for tuberculin-negative adolescents in the UK, whereas in USA, BCG was restricted to certain high-risk populations but was not recommended for routine use [88]. Following major policy changes in the field of infectious disease control and immunization programs, and the amendment of the Immunization Law in 2001 BCG vaccination campaign was introduced [83, 89] according to various schedules (e.g., at birth, school entry, or school leaving) in the majority of countries [82].

11. Molecular Biology of BCG

11.1. Genetic Evolution

BCG is a derivative of M. bovis after the loss of the region of deletion 1 (RD1) that encodes the ESX-1 secretion system [90]. During the first half of the 20th century BCG was maintained by serial passage throughout the world, as mentioned in the history section. Over the decades, multiple BCG daughter strains were produced which resulted in several regions of genomic deletions as well as regions of genomic duplication and other mutations [8386]. A tremendous opportunity is provided by the complete genome sequence of M. tuberculosis for investigating molecular mechanisms of overlapping disease manifestations produced by M. bovis BCG and M. tuberculosis and it is now evident that both share 99.9% of their DNA. It also shows that the BCG strain retained at least some of its original virulence characters [9193]. The attenuation of BCG due to the loss of RD1 region from M. bovis and reintroduction of RD1 into BCG increased virulence significantly. Because of complementation neither BCG Pasteur nor the least passaged strain, BCG Russia, with RD1 resulted in the restoration of virulence to levels characteristic of M. tuberculosis or M. bovis. The reported genetic studies weaken the theory that the RD3, RD4, RD5, RD7, and RD9 loci are responsible for virulence among the tubercle bacilli [90]. The immune suppressive capacity of BCG is perhaps the most apparent feature in-vivo [8791].

Some of the M. bovis BCG isolates that are reported to be sensitive to ethambutol, streptomycin, and p-nitrobenzoic acid reacted positively to cycloserine, but they are found to be resistant to isoniazid, rifampicin, pyrazinamide, and thiophen-2-carbonic acid hydrazide. However, lately, the cloning of pyrazinamidase gene (pncA) shows a single point mutation in the gene which is unique to M. bovis [9498]. Therefore, to differentiate M. tuberculosis and M. bovis polymorphism, this gene could be a good option for diagnosis methods.

The standard mycobacterial culture techniques currently used in clinical microbiology laboratories are capable of identifying mycobacteria to the level of the M. tuberculosis complex.

It has been reported that most of M. bovis strainscontainspacers 40 to 43, whereas they lacks spacer 39 [36]. In 1993, Hoffner studied a high degree of biochemical heterogeneity within strains of the M. tuberculosis complex isolated [98], when subtyped by DNA fingerprinting using the insertion element IS6110 and spoligotyping [92]. Variable-number tandem repeats (VNTRs) occur throughout the chromosome of M. tuberculosis. Mycobacterial interspersed repetitive units (MIRUs) are polymorphic VNTRs and also have proved to be useful tools in molecular epidemiology; their biological significance is less well understood. The copy number of VNTR 3690 varies among Indian clinical isolates of M. tuberculosis (one to twelve copies), M. tuberculosis H37Rv TMC102 (four copies), M. tuberculosis H37Ra (two to four copies), and M. bovis BCG (one copy) [99]. A detailed comparison among virulent M. tuberculosis, M. bovis, and M. bovis BCG based on published literature [14, 15, 1723] and on our own work is summarized in Table 1.

12. Conclusion

M. bovis strains are more virulent for cattle, while classical M. tuberculosis strains are thought to be more virulent for humans. The benefit of BCG immunization against M. tuberculosis infection has been the subject of much controversy. It is of uncertain efficacy and is associated with significant safety concerns in untreated HIV-infected infants and in those on ART.

The diagnosis and management of BCG disease are complex, leading to under recognition and suboptimal care in resource-limited settings often due to misdiagnosis. Better safety and efficacy profiles under investigations are highly needed for the new BCG vaccines. Vaccination policy attempt to balance risk and benefit needs to be revived. Various biochemical tests currently being used are useful methods for identifying M. bovis BCG virulence pathology, especially niacin positivity, which differs in the results of these tests among BCG substrains. The differences observed in different parts of the world could be attributed to the long passages of the BCG strains that have been subcultured in different laboratories leading to the divergence of M. bovis BCG strains in due course of time.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Acknowledgments

The authors acknowledge the Indian BCG Special Investigation Committee Members Dr. Kiran Katoch and Dr. DS Chauhan of National Jalma Institute of Leprosy and other Mycobacterial Diseases, Agra; Dr. Vanaja Kumar and Dr. Aleyamma Thomas of National Institute of Research in Tuberculosis, Chennai, for the experiments carried out on the Indian seed-lot of BCG vaccine under question; and Dr. Surinder Singh, Drug Controller General of India and Dr. RK Srivastava, Director General of Health Services, India, for their regulatory and administrative comments. The authors specially thank Dr. VM Katoch, Director General of Indian Council of Medical Research and Secretary to Government of India, Ministry of Health & Family welfare and Chairman of this committee for his technical inputs and encouragement to write this review.

References

  1. J. F. T. Griffin, D. N. Chinn, C. R. Rodgers, and C. G. Mackintosh, “Optimal models to evaluate the protective efficacy of tuberculosis vaccines,” Tuberculosis, vol. 81, no. 1-2, pp. 133–139, 2001. View at: Publisher Site | Google Scholar
  2. P. H. Lagrange, B. Hurtrel, and J. L. Stach, “Vaccines against mycobacteria and other intracellular multiplying bacteria,” Annales de l'Institut Pasteur D—Immunology, vol. 136, no. 2, pp. 151–162, 1985. View at: Google Scholar
  3. B. M. Buddle, N. A. Parlane, D. L. Keen et al., “Differentiation between Mycobacterium bovis BCG-vaccinated and M. bovis-infected cattle by using recombinant mycobacterial antigens,” Clinical and Diagnostic Laboratory Immunology, vol. 6, no. 1, pp. 1–5, 1999. View at: Google Scholar
  4. World Health Organization, “Tuberculosis,” WHO, Geneva, Switzerland, 2014, http://www.who.int/topics/tuberculosis/en/. View at: Google Scholar
  5. World Health Organization, “BCG Vaccines,” WHO, Geneva, Switzerland, 2014, http://www.who.int/biologicals/areas/vaccines/en/. View at: Google Scholar
  6. World Health Organization, BCG Vaccine: Safety, WHO, Geneva, Switzerland, 2014, http://www.who.int/vaccine_safety/committee/topics/bcg/en/.
  7. E. A. Talbot, M. D. Perkins, S. F. M. Suva, and R. Frothingham, “Disseminated bacille Calmette-Guerin disease after vaccination: case report and review,” Clinical Infectious Diseases, vol. 24, no. 6, pp. 1139–1146, 1997. View at: Publisher Site | Google Scholar
  8. I. S. Aljada, J. K. Crane, N. Corriere, D. G. Wagle, and D. Amsterdam, “Mycobacterium bovis BCG causing vertebral osteomyelitis (Pott’s disease) following intravesical BCG therapy,” Journal of Clinical Microbiology, vol. 37, no. 6, pp. 2106–2108, 1999. View at: Google Scholar
  9. WHO, WHO Global Tuberculosis Report 2013, WHO, 2014, http://www.who.int/tb/publications/global_report/en/.
  10. B. Müller, S. Dürr, S. Alonso et al., “Zoonotic Mycobacterium bovis-induced tuberculosis in humans,” Emerging Infectious Diseases, vol. 19, no. 6, pp. 899–908, 2013. View at: Publisher Site | Google Scholar
  11. L. M. O'Reilly and C. J. Daborn, “The epidemiology of Mycobacterium bovis infections in animals and man: a review,” Tubercle and Lung Disease, vol. 76, supplement 1, pp. 1–46, 1995. View at: Google Scholar
  12. M. Gheorghiu, J. Augier, and P. H. Lagrange, “Maintenance and control of the French BCG strain 1173p2 (primary and secondary seed-lots),” Bulletin de l'Institut Pasteur, vol. 81, pp. 281–288, 1983. View at: Google Scholar
  13. J. D. Aronson, “Protective vaccination against tuberculosis with special reference to BCG vaccination,” The American Review of Tuberculosis, vol. 58, pp. 255–281, 1948. View at: Google Scholar
  14. T. Udou, “Adaptation of mycobacteria on solid, egg-based media to anaerobic conditions and characterization of their diagnostic phenotypes,” Journal of UOEH, vol. 35, no. 2, pp. 109–117, 2013. View at: Publisher Site | Google Scholar
  15. T. Hirai, “Distribution of η precipitinogen in mycobacteria,” International Journal of Systematic Bacteriology, vol. 34, no. 4, pp. 401–404, 1984. View at: Publisher Site | Google Scholar
  16. H. Li, J. C. Ulstrup, T. O. Jonassen, K. Melby, S. Nagai, and M. Harboe, “Evidence for absence of the MPB64 gene in some substrains of Mycobacterium bovis BCG,” Infection and Immunity, vol. 61, no. 5, pp. 1730–1734, 1993. View at: Google Scholar
  17. L. M. Parsons, R. Brosch, S. T. Cole et al., “Rapid and simple approach for identification of Mycobacterium tuberculosis complex isolates by PCR-based genomic deletion analysis,” Journal of Clinical Microbiology, vol. 40, no. 7, pp. 2339–2345, 2002. View at: Publisher Site | Google Scholar
  18. A. Aranaz, E. Liébana, E. Gómez-Mampaso et al., “Mycobacterium tuberculosis subsp. caprae subsp. nov.: a taxonomic study of a new member of the Mycobacterium tuberculosis complex isolated from goats in Spain,” International Journal of Systematic Bacteriology, vol. 49, no. 3, pp. 1263–1273, 1999. View at: Publisher Site | Google Scholar
  19. R. K. Tenguria, F. N. Khan, S. Quereshi, and A. Pandey, “Epidemiological study of zoonotic tuberculosis complex ( Ztbc ),” World Journal of Science and Technology, vol. 1, pp. 31–56, 2011. View at: Publisher Site | Google Scholar
  20. S. Niemann, E. Richter, and S. Rüsch-Gerdes, “Biochemical and genetic evidence for the transfer of Mycobacterium tuberculosis subsp. caprae Aranaz et al. 1999 to the species Mycobacterium bovis Karlson and Lessel 1970 (approved list 1980) as Mycobacterium bovis subsp. caprae comb. nov.,” International Journal of Systematic and Evolutionary Microbiology, vol. 52, no. 2, pp. 433–436, 2002. View at: Google Scholar
  21. P. Brodin, K. Eiglmeier, M. Marmiesse et al., “Bacterial artificial chromosome-based comparative genomic analysis identifies Mycobacterium microti as a natural ESAT-6 deletion mutant,” Infection and Immunity, vol. 70, no. 10, pp. 5568–5578, 2002. View at: Publisher Site | Google Scholar
  22. J. Kamerbeek, L. Schouls, A. Kolk et al., “Simultaneous detection and strain differentiation of Mycobacterium tuberculosis for diagnosis and epidemiology,” Journal of Clinical Microbiology, vol. 35, no. 4, pp. 907–914, 1997. View at: Google Scholar
  23. K. Chikamatsu, A. Aono, H. Yamada et al., “Comparative evaluation of three immunochromatographic identification tests for culture confirmation of Mycobacterium tuberculosis complex,” BMC Infectious Diseases, vol. 14, article 54, 2014. View at: Publisher Site | Google Scholar
  24. World Health Organization, Information Sheet-Observed Rate of Vaccine Reactions Bacille Calmette-Guérin (Bcg) Vaccine Global Vaccine Safety, Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland, 2012, http://www.who.int/vaccine_safety/initiative/tools/BCG_Vaccine_rates_information_sheet.pdf.
  25. F. T. Perkins, Analysis of the Replies to a Questionnaire, vol. 17 of Series in Immunobiology Stand, 1971.
  26. E. A. Talbot, D. L. Williams, and R. Frothingham, “PCR identification of Mycobacterium bovis BCG,” Journal of Clinical Microbiology, vol. 35, no. 3, pp. 566–569, 1997. View at: Google Scholar
  27. V. Seth, S. Kabra, Y. Jain, and O. P. Semwal, “BCG revisited,” Indian Pediatrics, vol. 31, no. 12, pp. 1585–1593, 1994. View at: Google Scholar
  28. L. Brandt, J. F. Cunha, A. W. Olsen et al., “Failure of the Mycobacterium bovis BCG vaccine: some species of environmental mycobacteria block multiplication of BCG and induction of protective immunity to tuberculosis,” Infection and Immunity, vol. 70, no. 2, pp. 672–678, 2002. View at: Publisher Site | Google Scholar
  29. J. D. Clemens, J. J. H. Chuong, and A. R. Feinstein, “The BCG controversy. A methodological and statistical reappraisal,” The Journal of the American Medical Association, vol. 249, no. 17, pp. 2362–2369, 1983. View at: Publisher Site | Google Scholar
  30. G. A. Colditz, C. S. Berkey, F. Mosteller et al., “The efficacy of bacillus Calmette-Guerin vaccination of newborns and infants in the prevention of tuberculosis: meta-analyses of the published literature,” Pediatrics, vol. 96, no. 1, pp. 29–35, 1995. View at: Google Scholar
  31. H. C. Engbaek, B. Vergmann, and K. Bunch-Christensen, “Pulmonary tuberculosis due to BCG in a technician employed in a BCG laboratory,” Bulletin of the World Health Organization, vol. 55, no. 4, pp. 517–520, 1977. View at: Google Scholar
  32. D. Thierry, A. Brisson-Noel, V. Vincent-Lévy-Frébault, S. Nguyen, J.-L. Guesdon, and B. Gicquel, “Characterization of a Mycobacterium tuberculosis insertion sequence, IS6110, and its application in diagnosis,” Journal of Clinical Microbiology, vol. 28, no. 12, pp. 2668–2673, 1990. View at: Google Scholar
  33. D. Hayashi, T. Takii, T. Mukai et al., “Biochemical characteristics among Mycobacterium bovis BCG substrains,” FEMS Microbiology Letters, vol. 306, no. 2, pp. 103–109, 2010. View at: Publisher Site | Google Scholar
  34. H. I. M. Boshoff, X. Xu, K. Tahlan et al., “Biosynthesis and recycling of nicotinamide cofactors in Mycobacterium tuberculosis: an essential role for NAD in nonreplicating bacilli,” Journal of Biological Chemistry, vol. 283, no. 28, pp. 19329–19341, 2008. View at: Publisher Site | Google Scholar
  35. C. D. Sohaskey and L. Modesti, “Differences in nitrate reduction between Mycobacterium tuberculosis and Mycobacterium bovis are due to differential expression of both narGHJI and narK2,” FEMS Microbiology Letters, vol. 290, no. 2, pp. 129–134, 2009. View at: Publisher Site | Google Scholar
  36. G. Källenius, T. Koivula, S. Ghebremichael et al., “Evolution and clonal traits of Mycobacterium tuberculosis complex in Guinea-Bissau,” Journal of Clinical Microbiology, vol. 37, no. 12, pp. 3872–3878, 1999. View at: Google Scholar
  37. W.-J. Su, C.-Y. Huang, and R.-P. Perng, “Utility of PCR assays for rapid diagnosis of BCG infection in children,” International Journal of Tuberculosis and Lung Disease, vol. 5, no. 4, pp. 380–384, 2001. View at: Google Scholar
  38. K. S. Goh, N. Rastogi, M. Berchel, R. C. Huard, and C. Sola, “Molecular evolutionary history of tubercle bacilli assessed by study of the polymorphic nucleotide within the nitrate reductase (narghji) operon promoter,” Journal of Clinical Microbiology, vol. 43, no. 8, pp. 4010–4014, 2005. View at: Publisher Site | Google Scholar
  39. M. Stermann, A. Bohrssen, C. Diephaus, S. Maass, and F.-C. Bange, “Polymorphic nucleotide within the promoter of nitrate reductase (NarGHJI) is specific for Mycobacterium tuberculosis,” Journal of Clinical Microbiology, vol. 41, no. 7, pp. 3252–3259, 2003. View at: Publisher Site | Google Scholar
  40. R. J. North and A. A. Izzo, “Mycobacterial virulence. Virulent strains of Mycobacteria tuberculosis have faster in vivo doubling times and are better equipped to resist growth-inhibiting functions of macrophages in the presence and absence of specific immunity,” The Journal of Experimental Medicine, vol. 177, no. 6, pp. 1723–1733, 1993. View at: Publisher Site | Google Scholar
  41. C. Fritz, S. Maass, A. Kreft, and F.-C. Bange, “Dependence of Mycobacterium bovis BCG on anaerobic nitrate reductase for persistence is tissue specific,” Infection and Immunity, vol. 70, no. 1, pp. 286–291, 2002. View at: Publisher Site | Google Scholar
  42. D. R. Sherman, M. Voskuil, D. Schnappinger, R. Liao, M. I. Harrell, and G. K. Schoolnik, “Regulation of the Mycobacterium tuberculosis hypoxic response gene encoding alpha-crystallin,” Proceedings of the National Academy of Sciences of the United States of America, vol. 98, no. 13, pp. 7534–7539, 2001. View at: Publisher Site | Google Scholar
  43. C. D. Sohaskey and L. G. Wayne, “Role of narK2X and narGHJI in hypoxic upregulation of nitrate reduction by Mycobacterium tuberculosis,” Journal of Bacteriology, vol. 185, no. 24, pp. 7247–7256, 2003. View at: Publisher Site | Google Scholar
  44. S. Virtanen, “A study of nitrate reduction by mycobacteria,” Acta Tuberculosea Scandinavica, vol. 48, pp. 1–119, 1960. View at: Google Scholar
  45. World Health Organization, Recommendations to Assure the Quality, Safety and Efficacy of BCG Vaccines Replacement of: WHO Technical Report Series, no. 745, Annex 2 and Amendment to WHO Technical Report Series, no. 771, Annex 12, World Health Organization, Geneva, Switzerland, 2012, http://www.who.int/biologicals/BCG_DB_HK_23_April_2012.pdf.
  46. T. P. Kent and G. P. Kubica, Public Health Mycobacteriology. A Guide for Level III Laboratory, vol. 30, United States Department of Health and Human Services, Centre for Disease Control, Atlanta, Ga, USA, 1985.
  47. K. S. Goh and N. Rastogi, “Simple and rapid method for detection of nitrate reductase activity of Mycobacterium tuberculosis and Mycobacterium canettii grown in the Bactec MGIT960 system,” Journal of Microbiological Methods, vol. 81, no. 2, pp. 208–210, 2010. View at: Publisher Site | Google Scholar
  48. L. Sula and M. Langerova, “Drug sensitivity-resistance determination and simple enzymatic tests for the differentiation of Mycobacteria,” Bulletin of the World Health Organization, vol. 29, pp. 579–588, 1963. View at: Google Scholar
  49. G. P. Kubica, P. P. Gontijo Filho, and T. Kim, “Preservation of mycobacteria at −70°C: persistence of key differential features,” Journal of Clinical Microbiology, vol. 6, no. 2, pp. 149–153, 1977. View at: Google Scholar
  50. M. Ventura, C. Canchaya, A. Tauch et al., “Genomics of Actinobacteria: tracing the evolutionary history of an ancient phylum,” Microbiology and Molecular Biology Reviews, vol. 71, no. 3, pp. 495–548, 2007. View at: Publisher Site | Google Scholar
  51. A. L. Sørensen, S. Nagai, G. Houen, P. Andersen, and A. B. Andersen, “Purification and characterization of a low-molecular-mass T-Cell antigen secreted by Mycobacterium tuberculosis,” Infection and Immunity, vol. 63, no. 5, pp. 1710–1717, 1995. View at: Google Scholar
  52. P. S. Renshaw, P. Panagiotidou, A. Whelan et al., “Conclusive evidence that the major T-cell antigens of the Mycobacterium tuberculosis complex ESAT-6 and CFP-10 form a tight, 1:1 complex and characterization of the structural properties of ESAT-6, CFP-10, and the ESAT-6·CFP-10 complex. Implications for pathogenesis and virulence,” The Journal of Biological Chemistry, vol. 277, no. 24, pp. 21598–21603, 2002. View at: Publisher Site | Google Scholar
  53. P. Akhtar, S. Srivastava, A. Srivastava, M. Srivastava, B. S. Srivastava, and R. Srivastava, “Rv3303c of Mycobacterium tuberculosis protects tubercle bacilli against oxidative stress in vivo and contributes to virulence in mice,” Microbes and Infection, vol. 8, no. 14-15, pp. 2855–2862, 2006. View at: Publisher Site | Google Scholar
  54. A. S. Barouni, C. Augusto, M. V. N. P. Queiroz, M. T. P. Lopes, M. S. Zanini, and C. E. Salas, “BCG lymphadenopathy detected in a BCG-vaccinated infant,” Brazilian Journal of Medical and Biological Research, vol. 37, no. 5, pp. 697–700, 2004. View at: Publisher Site | Google Scholar
  55. G. W. Comstock and C. E. Palmer, “Long-term results of BCG vaccination in the Southern United States,” The American Review of Respiratory Disease, vol. 93, no. 2, pp. 171–183, 1966. View at: Google Scholar
  56. P. E. M. Fine, “Bacille Calmette-Guérin vaccines: a rough guide,” Clinical Infectious Diseases, vol. 20, no. 1, pp. 11–14, 1995. View at: Publisher Site | Google Scholar
  57. A. S. Malin and D. B. Young, “Designing a vaccine for tuberculosis,” British Medical Journal, vol. 312, no. 7045, p. 1495, 1996. View at: Publisher Site | Google Scholar
  58. A. Lotte, O. Wasz-Höckert, N. Poisson, N. Dumitrescu, M. Verron, and E. Couvet, “BCG complications. Estimates of the risks among vaccinated subjects and statistical analysis of their main characteristics,” Advances in Tuberculosis Research. Fortschritte der Tuberkuloseforschung. Progres de la exploration de la tuberculose, vol. 21, pp. 107–193, 1984. View at: Google Scholar
  59. G. G. Mahairas, P. J. Sabo, M. J. Hickey, D. C. Singh, and C. K. Stover, “Molecular analysis of genetic differences between Mycobacterium bovis BCG and virulent M. bovis,” Journal of Bacteriology, vol. 178, no. 5, pp. 1274–1282, 1996. View at: Google Scholar
  60. N. G. Fomukong, J. W. Dale, T. W. Osborn, and J. M. Grange, “Use of gene probes based on the insertion sequence IS986 to differentiate between BCG vaccine strains,” Journal of Applied Bacteriology, vol. 72, no. 2, pp. 126–133, 1992. View at: Publisher Site | Google Scholar
  61. M. Harboe and S. Nagai, “MPB70, a unique antigen of Mycobacterium bovis BCG,” The American Review of Respiratory Disease, vol. 129, no. 3, pp. 444–452, 1984. View at: Google Scholar
  62. D. E. Minnikin, J. H. Parlett, M. Magnusson, M. Ridell, and A. Lind, “Mycolic acid patterns of representatives of Mycobacterium bovis BCG,” Journal of General Microbiology, vol. 130, no. 10, pp. 2733–2736, 1984. View at: Google Scholar
  63. J. Bøe, “Variations in the virulence of BCG,” Acta Tuberculosea Scandinavica, vol. 22, no. 1, pp. 125–133, 1948. View at: Google Scholar
  64. M. R. R. Lagranderie, A.-M. Balazuc, E. Deriaud, C. D. Leclerc, and M. Gheorghiu, “Comparison of immune responses of mice immunized with five different Mycobacterium bovis BCG vaccine strains,” Infection and Immunity, vol. 64, no. 1, pp. 1–9, 1996. View at: Google Scholar
  65. K. M. Edwards, M. H. Cynamon, R. K. Voladri et al., “Iron-co-factored superoxide dismutase inhibits host responses to Mycobacterium tuberculosis,” The American Journal of Respiratory and Critical Care Medicine, vol. 164, pp. 2213–2219, 2001. View at: Google Scholar
  66. J. A. Tree, A. Williams, S. Clark, G. Hall, P. D. Marsh, and J. Ivanyi, “Intranasal bacille Calmette-Guérin (BCG) vaccine dosage needs balancing between protection and lung pathology,” Clinical and Experimental Immunology, vol. 138, no. 3, pp. 405–409, 2004. View at: Publisher Site | Google Scholar
  67. K. Bunch-Christensen, A. Ladefoged, and J. Guld, “The virulence of some strains of BCG for golden hamsters. Further studies,” Bulletin of the World Health Organization, vol. 43, no. 1, pp. 65–70, 1970. View at: Google Scholar
  68. J. S. Bellet and N. S. Prose, “Skin complications of Bacillus Calmette-Guérin immunization,” Current Opinion in Infectious Diseases, vol. 18, no. 2, pp. 97–100, 2005. View at: Publisher Site | Google Scholar
  69. F. M. Turnbull, P. B. McIntyre, H. M. Achat et al., “National study of adverse reactions after vaccination with bacille Calmette-Guérin,” Clinical Infectious Diseases, vol. 34, no. 4, pp. 447–453, 2002. View at: Publisher Site | Google Scholar
  70. F. Altare, D. Lammas, P. Revy et al., “Inherited interleukin 12 deficiency in a child with bacille Calmette-Guérin and Salmonella enteritidis disseminated infection,” The Journal of Clinical Investigation, vol. 102, no. 12, pp. 2035–2040, 1998. View at: Publisher Site | Google Scholar
  71. J. J. C. Nuttall and B. S. Eley, “BCG vaccination in HIV-infected children,” Tuberculosis Research and Treatment, vol. 2011, Article ID 712736, pp. 1–6, 2011. View at: Publisher Site | Google Scholar
  72. J. A. DeSimone, R. J. Pomerantz, and T. J. Babinchak, “Inflammatory reactions in HIV-1-infected persons after initiation of highly active antiretroviral therapy,” Annals of Internal Medicine, vol. 133, no. 6, pp. 447–454, 2000. View at: Publisher Site | Google Scholar
  73. G. Aslan, N. Kuyucu, E. Aydin, S. Günal, and G. Emekdaş, “A case of fatal disseminated infection caused by Mycobacterium bovis BCG strain and the identification of the isolate by spoligotyping,” Mikrobiyoloji Bulteni, vol. 44, no. 2, pp. 297–302, 2010. View at: Google Scholar
  74. A. Lotte, O. Wasz-Hockert, N. Poisson et al., “Second IUATLD study on complications induced by intradermal BCG-vaccination,” Bulletin of the International Union Against Tuberculosis and Lung Disease, vol. 63, no. 2, pp. 47–59, 1988. View at: Google Scholar
  75. M. J. Cayabyab, L. Macovei, and A. Campos-Neto, “Current and novel approaches to vaccine development against tuberculosis,” Frontiers in Cellular and Infection Microbiology, vol. 2, no. 154, pp. 1–16, 2012. View at: Google Scholar
  76. P. E. Fine, “BCG vaccines and vaccination,” in Tuberculosis: A Comprehensive International Approach, L. B. Reichman and E. S. Hershfield, Eds., pp. 503–522, Marcel Dekker, New York, NY, USA, 2nd edition, 2001. View at: Google Scholar
  77. V. Romanus, H. O. Hallander, P. Wåhlén, A. M. Olinder-Nielsen, P. H. W. Magnusson, and I. Juhlin, “Atypical mycobacteria in extrapulmonary disease among children. Incidence in Sweden from 1969 to 1990, related to changing BCG-vaccination coverage,” Tubercle and Lung Disease, vol. 76, no. 4, pp. 300–310, 1995. View at: Publisher Site | Google Scholar
  78. J. Singh, M. M. Sankar, S. Kumar et al., “Incidence and prevalence of tuberculosis among household contacts of pulmonary tuberculosis patients in a peri-urban population of South Delhi, India,” PLoS ONE, vol. 8, no. 7, Article ID e69730, 2013. View at: Publisher Site | Google Scholar
  79. M. O. C. Ota, R. H. Brookes, P. C. Hill et al., “The effect of tuberculin skin test and BCG vaccination on the expansion of PPD-specific IFN-γ producing cells ex vivo,” Vaccine, vol. 25, no. 52, pp. 8861–8867, 2007. View at: Publisher Site | Google Scholar
  80. J. B. Milstien and J. J. Gibson, “Quality control of BCG vaccine by WHO: a review of factors that may influence vaccine effectiveness and safety,” Bulletin of the World Health Organization, vol. 68, no. 1, pp. 93–108, 1990. View at: Google Scholar
  81. S. Luca and T. Mihaescu, “History of BCG vaccine,” Mædica, vol. 8, no. 1, pp. 53–58, 2013. View at: Google Scholar
  82. M. M. Ho, J. Southern, H.-N. Kang, and I. Knezevic, “WHO Informal Consultation on standardization and evaluation of BCG vaccines Geneva, Switzerland 22-23 September 2009,” Vaccine, vol. 28, no. 43, pp. 6945–6950, 2010. View at: Publisher Site | Google Scholar
  83. A. L. Bierrenbach, S. S. Cunha, M. L. Barreto et al., “Tuberculin reactivity in a population of schoolchildren with high BCG vaccination coverage,” Pan American Journal of Public Health, vol. 13, no. 3, pp. 285–286, 2003. View at: Publisher Site | Google Scholar
  84. L. Grode, P. Seiler, S. Baumann et al., “Increased vaccine efficacy against tuberculosis of recombinant Mycobacterium bovis bacille Calmette-Guérin mutants that secrete listeriolysin,” The Journal of Clinical Investigation, vol. 115, no. 9, pp. 2472–2479, 2005. View at: Publisher Site | Google Scholar
  85. N. E. Aronson, M. Santosham, G. W. Comstock et al., “Long-term efficacy of BCG vaccine in American Indians and Alaska natives: a 60-year follow-up study,” The Journal of the American Medical Association, vol. 291, no. 17, pp. 2086–2091, 2004. View at: Publisher Site | Google Scholar
  86. P. D. Hart and I. Sutherland, “BCG and vole bacillus vaccines in the prevention of tuberculosis in adolescence and early adult life. Final report to the Medical Research Council,” British Medical Journal, vol. 2, no. 6082, pp. 293–295, 1977. View at: Publisher Site | Google Scholar
  87. C. E. Palmer, L. W. Shaw, and G. W. Comstock, “Community trials of BCG vaccination,” American Review of Tuberculosis, vol. 77, no. 6, pp. 877–907, 1958. View at: Google Scholar
  88. P. E. M. Fine, I. A. M. Carneiro, and C. J. Clements, Issues Relating to the Use of BCG in Immunization Programmes, World Health Organization, Geneva, Switzerland, 1999.
  89. H. Nakatani, T. Sano, and T. Iuchi, “Development of vaccination policy in Japan: current issues and policy directions,” Japanese Journal of Infectious Diseases, vol. 55, no. 4, pp. 101–111, 2002. View at: Google Scholar
  90. A. S. Pym, P. Brodin, R. Brosch, M. Huerre, and S. T. Cole, “Loss of RD1 contributed to the attenuation of the live tuberculosis vaccines Mycobacterium bovis BCG and Mycobacterium microti,” Molecular Microbiology, vol. 46, no. 3, pp. 709–717, 2002. View at: Publisher Site | Google Scholar
  91. R. Brosch, S. V. Gordon, C. Buchrieser, A. S. Pym, T. Gamier, and S. T. Cole, “Comparative genomics uncovers large tandem chromosomal duplications in Mycobacterium bovis BCG Pasteur,” Yeast, vol. 17, no. 2, pp. 111–123, 2000. View at: Google Scholar
  92. R. Brosch, S. V. Gordon, T. Garnier et al., “Genome plasticity of BCG and impact on vaccine efficacy,” Proceedings of the National Academy of Sciences of the United States of America, vol. 104, no. 13, pp. 5596–5601, 2007. View at: Publisher Site | Google Scholar
  93. M. A. Behr, M. A. Wilson, W. P. Gill et al., “Comparative genomics of BCG vaccines by whole-genome DNA microarray,” Science, vol. 284, no. 5419, pp. 1520–1523, 1999. View at: Publisher Site | Google Scholar
  94. D. M. Collins, R. P. Kawakami, G. W. de Lisle, L. Pascopella, B. R. Bloom, and W. R. Jacobs Jr., “Mutation of the principal sigma factor causes loss of virulence in a strain of the Mycobacterium tuberculosis complex,” Proceedings of the National Academy of Sciences of the United States of America, vol. 92, no. 17, pp. 8036–8040, 1995. View at: Publisher Site | Google Scholar
  95. I. Weber, C. Fritz, S. Ruttkowski, A. Kreft, and F.-C. Bange, “Anaerobic nitrate reductase (narGHJI) activity of Mycobacterium bovis BCG in vitro and its contribution to virulence in immunodeficient mice,” Molecular Microbiology, vol. 35, no. 5, pp. 1017–1025, 2000. View at: Publisher Site | Google Scholar
  96. S. Sadagopal, M. Braunstein, C. C. Hager et al., “Reducing the activity and secretion of microbial antioxidants enhances the immunogenicity of BCG,” PLoS ONE, vol. 4, no. 5, Article ID e5531, 2009. View at: Publisher Site | Google Scholar
  97. A. Scorpio and Y. Zhang, “Mutations in pncA, a gene encoding pyrazinamidase/nicotinamidase, cause resistance to the antituberculous drug pyrazinamide in tubercle bacillus,” Nature Medicine, vol. 2, no. 6, pp. 662–667, 1996. View at: Publisher Site | Google Scholar
  98. S. E. Hoffner, S. B. Svenson, R. Norberg, F. Dias, S. Ghebremichael, and G. Kallenius, “Biochemical heterogeneity of Mycobacterium tuberculosis complex isolates in Guinea-Bissau,” Journal of Clinical Microbiology, vol. 31, no. 8, pp. 2215–2217, 1993. View at: Google Scholar
  99. P. Akhtar, S. Singh, P. Bifani, S. Kaur, B. S. Srivastava, and R. Srivastava, “Variable-number tandem repeat 3690 polymorphism in Indian clinical isolates of Mycobacterium tuberculosis and its influence on transcription,” Journal of Medical Microbiology, vol. 58, no. 6, pp. 798–805, 2009. View at: Publisher Site | Google Scholar

Copyright © 2015 Sarman Singh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

3324 Views | 956 Downloads | 3 Citations
 PDF  Download Citation  Citation
 Download other formatsMore
 Order printed copiesOrder

We are committed to sharing findings related to COVID-19 as quickly and safely as possible. Any author submitting a COVID-19 paper should notify us at help@hindawi.com to ensure their research is fast-tracked and made available on a preprint server as soon as possible. We will be providing unlimited waivers of publication charges for accepted articles related to COVID-19.