Analytical Epidemiology of Genomic Variation among Pan Asia Strains of Foot-and-Mouth Disease Virus

Summary

Genetic data from field isolates of foot-and-mouth disease virus (FMDV) have been used to trace the source of recent outbreaks of FMD, to design better vaccines and diagnostic tests for FMDV, and to make conclusions regarding the general variability in the FMDV genome. Though epidemiologic data associated with FMDV isolates are available, these data have been used rarely to explore possible associations of epidemiologic factors with evolution or variation of the FMDV genome. In this study, factors associated with variation in the primary immunogenic peptide gene of FMDV (VP1), for a sample of 147 serotype O, Pan Asia strain sequences were explored using traditional analytical epidemiologic methods: logistic regression and multinomial-response logistic regression. Hypothesized factors included host type (bovine, ovine, buffalo, or porcine) and geographical region (Middle East, South Asia, East Asia, Southeast Asia, and Europe). Results of two regression analyses suggest that host type and region, considered to be possible surrogates for host management, may be associated with selection in the VP1 amino acid sequence in FMDV. For example, isolates from cattle and sheep in South Asia appear to converge with a proposed ancestor sequence, whereas isolates from the same species in the Middle East and Southeast Asia appear to diverge. The methods demonstrated here could be used on a more detailed dataset to explore the selective pressure of host immunity on the evolution of FMDV antigens in an endemic setting. More broadly, epidemiologic methods could be applied extensively to molecular data to explore the causes of genomic variation in disease-causing organisms.