Transboundary and Emerging Diseases

Equine hepacivirus (EqHV), also known as Hepacivirus A, represents the most closely related genetic homologue of human hepatitis C virus (HCV). Although detected worldwide, limited information on the clinical features of this infection is available and on the mechanisms by which EqHV is transmitted. In this study, we describe a spread of infection of EqHV that occurred in a small stable of horses in southern Italy. The RNA of EqHV was detected in 6/13 (46.2%) sera of the horses introduced into the herd, at different times, over a period of approximately one year. Based on the sequencing analyses of genomic portions located in the NS5B, 5′UTR, and NS3 genes, the viruses detected in the animals were genetically highly related (100% nt identity) to each other. The nearly full-length genome of the virus identified from two horses was generated. For one animal with a profile of chronic infection, the genome sequence was determined with a 7-month interval, revealing 26nt changes resulting in 11 nonsynonymous intrahost nucleotide variations. Overall, based on the epidemiological information, we support the hypothesis that horizontal transmission occurred in the herd.

Chytridiomycosis is an infectious disease in amphibians caused by two chytrid fungi, Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal), and is the worst infectious disease known in wildlife so far. Worldwide spread of the disease has caused unprecedented loss of global amphibian diversity. Although some lineages of Bd are enzootic and are not as deadly as the pandemic lineage, nearly 40% of amphibian species are still declining globally due to chytridiomycosis. Efficient surveillance and monitoring of chytridiomycosis are the immediate safeguard against rapid declines or extinctions of amphibian populations. Previous studies showed that existing diagnostic assays were not sensitive to certain Bd haplotypes like those from Korea, China, India, Japan, and Brazil and thereby, there is a need for a universal, sensitive, specific, reproducible, and affordable diagnostic assay. We designed a one-step SYBR green-based quantitative polymerase chain reaction (nSYBR qPCR) for robust detection of Bd. It amplifies an 82 base-pair segment between the 5.8S rRNA and ITS2 of the Bd genome. The primer pair was tested in-silico on 40 isolates from four known Bd lineages. Using skin swab samples of wild amphibians and cultured zoospores from Australia and Panama, we compared the clinical specificity and sensitivity of the newly described primers to the existing TaqMan-based qPCR assay. From India, we used samples which had been previously tested with Nested PCR to validate the new primer pairs. The newly described primer pair was then tested on swab samples from Anura, Caudata and Gymnophiona from India. We report widespread chytridiomycosis with varying infection loads on them. The new assay showed comparable efficiency to the TaqMan-based qPCR assay. This diagnostic assay can facilitate widespread surveillance of chytridiomycosis where it has been previously absent, which may reveal several reservoirs of the pathogen and can improve our understanding of this important wildlife disease.

A cluster of vultures, artificially bred in a zoo in Shandong Province, China, displayed signs of emaciation and some even died, which raised the suspicion of an immunosuppressive pathogen. Upon conducting nucleic acid testing on the clinical samples, it was found that the CIAV was present in the tissue of dead vulture. In this study, samples of dead vulture tissue were used to isolate a chicken infectious anemia virus (CIAV) via the MDCC-MSB1 cell line, which was designated the SDTY2021-TJ strain. The full-length genomic sequence of SDTY2021-TJ was determined and analyzed in detail. The full genomic DNA of SDTY2021-TJ was found to be 2298 bp, with no omissions or additions in the coding region. The homology between the full-length genomic sequence of SDTY2021-TJ and the reference strain ranged from 95.5% (Del-Ros) to 98.7% (YN04). In comparison with the reference strain, the VP1 protein of SDTY2021-TJ contained a number of mutations. To assess the virulence of SDTY2021-TJ, one-day-old SPF chickens were inoculated with both high and low doses of the pathogen. The results demonstrated that SDTY2021-TJ had a considerable pathogenicity to SPF chickens, as the high-dose group caused a 50% mortality rate, and even the low-dose group caused a 30% mortality rate. The chickens infected with the disease exhibited paleness in the cockscomb and stunted growth, as well as a compromised response to NDV and AIV-H9 inactivated vaccine. Furthermore, histological observation revealed an atrophy and degeneration of the thymus. To the best of our knowledge, this is the first instance of CIAV being isolated from artificially bred Aegypius monachus, implying that wild birds may be involved in the transmission and spread of CIAV.

Porcine sapelovirus (PSV) is an emerging swine enteric virus that can cause various disorders including acute diarrhea, respiratory distress, reproductive failure, and polioencephalomyelitis in pigs. In this study, we isolated a PSV strain HNHB-01 from a clinical porcine deltacoronavirus- (PDCoV-) positive intestinal content of a diarrheic piglet. PSV was first identified using the small RNA deep sequencing and assembly, and further identified by the electron microscopic observation and the immunofluorescence assay. Subsequently, this virus was serially passaged in swine testis (ST) cells, and the complete genomics of PSV HNHB-01 passage 5 (P5), P30, P60, and P100 were sequenced and analyzed. 9 nucleotide mutations and 7 amino acid changes occurred in the PSV HNHB-01 P100 strain when compared with the PSV HNHB-01 P5. Pathogenicity investigation showed that orally inoculation of PSV HNHB-01 P30 could cause obvious clinical symptoms and had broad tissue tropism in 5-day-old piglets. Epidemiological investigation revealed that PSV infections and the coinfections of diarrhea coronaviruses were highly prevalent in swine herds. The complete genomes of 8 representative PSV epidemic strains were sequenced and analyzed. Phylogenetic analysis revealed that the PSV epidemic strains were closely related to other PSV reference strains that located in the Chinese clade. Furthermore, recombination analysis revealed that the recombination events were occurred in downstream of the 2C region in our sequenced PSV HNNY-02/CHN/2018 strain. Our results provided theoretical basis for future research studies of the pathogenic mechanism, evolutionary characteristics, and the development of vaccines against PSV.

Ebola virus disease (EVD) is an acute viral hemorrhagic fever disease causing thousands of deaths. The large Ebola outbreak in 2014–2016 posed significant threats to global public health, requiring the development of multiple medical measures for disease control. Sudan virus (SUDV) and Zaire virus (EBOV) are responsible for severe disease and occasional deadly outbreaks in West Africa and Middle Africa. This study shows that bivalent bacterium-like particles (BLPs)-based vaccine, SUDV-EBOV BLPs (S/ZBLP + 2 + P), generated by mixing SUDV-BLPs and EBOV-BLPs at a 1 : 1 ratio, is immunogenic in mice. The SUDV-EBOV BLPs induced potent immune responses against SUDV and EBOV and elicited both T-helper 1 (Th1) and T-helper 2 (Th2) immune responses. The results indicated that SUDV-EBOV BLPs-based vaccine has the potential to be a promising candidate against SUDV and EBOV infections and provide a strategy to develop universal vaccines for EVD.

Goose astrovirus genotype 2 (GoAstV2), as a contagious pathogen of fatal visceral gout in goslings, has been widely distributed in major goose-producing regions in China since 2017, leading to significant economic losses to the Chinese goose industry. In this study, a novel goose astrovirus (GoAstV-SDHZ) was isolated and identified from laying hens with nephritis for the first time. Phylogenetic analysis of the sequenced genome of ORF2 gene revealed that the GoAstV-SDHZ strain clustered into Group 2 GoAstVs and shared the highest identity with the other representative GoAstV2 in the nucleotide (ORF1a: 97.2–99.7%; ORF1b: 98.4–99.8%; ORF2: 97.2–99.9%) and amino acid sequence (ORF1a: 98.2–100%; ORF1b: 98.8–99.6%; ORF2: 97.4–99.6%). In summary, this study provides the first evidence of the GoAstV2 infection in Chinese laying hens, which raises potential threat to the poultry industry in China.