Session Speaker: Dr. Helen Piontkivska Ph.D., School of Biomedical Sciences, Kent State University

Title: "Patterns of sequence changes at epitopes and adaptive evolution of host-pathogen interactions"

Abstract: During the course of long-term viral infections (e.g., HIV, SIV), selection exerted by the host immune system on the virus is critical and can lead to the escape of host defenses. Molecular sequence analysis can provide insights into the patterns of adaptive evolution at particular regions of viral genomes, such as CTL epitopes and neutralizing antibody epitopes. The higher rate of nonsynonymous substitutions than synonymous substitutions (dN > dS pattern) may serve as an indicator of positive selection, while the opposite pattern of dS > dN indicates purifying selection. Analyses of substitution patterns in viral genomes shows existence of heterogeneity among epitope regions potentially related to
functional constraints.

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