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Advances in Bioinformatics
Volume 2010 (2010), Article ID 178069, 6 pages
Research Article

Algorithmic Assessment of Vaccine-Induced Selective Pressure and Its Implications on Future Vaccine Candidates

1Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
2Laboratory of Methods Development, Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD 20852, USA
3Department of Physiology and Biophysics, School of Medicine, Georgetown University, Washington, DC 20007, USA

Received 21 August 2009; Accepted 4 November 2009

Academic Editor: Wojciech Makalowski

Copyright © 2010 Mones S. Abu-Asab 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.


Posttrial assessment of a vaccine's selective pressure on infecting strains may be realized through a bioinformatic tool such as parsimony phylogenetic analysis. Following a failed gonococcal pilus vaccine trial of Neisseria gonorrhoeae, we conducted a phylogenetic analysis of pilin DNA and predicted peptide sequences from clinical isolates to assess the extent of the vaccine's effect on the type of field strains that the volunteers contracted. Amplified pilin DNA sequences from infected vaccinees, placebo recipients, and vaccine specimens were phylogenetically analyzed. Cladograms show that the vaccine peptides have diverged substantially from their paternal isolate by clustering distantly from each other. Pilin genes of the field clinical isolates were heterogeneous, and their peptides produced clades comprised of vaccinated and placebo recipients' strains indicating that the pilus vaccine did not exert any significant selective pressure on gonorrhea field strains. Furthermore, sequences of the semivariable and hypervariable regions pointed out heterotachous rates of mutation and substitution.