Diversity and transboundary mobility of serotype O foot-and-mouth disease virus in East Africa: Implications for vaccination policies
Loading...
Date
2010
Journal Title
Journal ISSN
Volume Title
Publisher
Infection, Genetics and Evolution
Abstract
Foot-and-mouth disease (FMD) virus serotype O has been responsible for most reported outbreaks of the
disease in East Africa. A sustained campaign for the past 40 years to control FMD mainly by vaccination,
combined with quarantine and zoosanitary measures has been undertaken with limited success. We
investigated the genetic relationships among serotype O strains in eastern Africa using complete VP1
coding region sequences obtained from 46 FMD virus isolates collected in Kenya in the years 1964–2008
and 8 Ugandan isolates collected between 1999 and 2006. In addition, 21 selected FMDV sequences from
Genbank representing reference strains from eastern Africa and elsewhere were included in the Bayesian
inference analyses and the detection of selection forces. The results confirmed previous observations
that eastern Africa harbours four distinct topotypes (clades with >15% sequence divergence). All but one
strain isolated post-2000 belonged to topotypes EA-2, EA-3 and EA-4, while all three vaccines have been
based on strains in the EA-1 topotype. The estimated dN/dS ratios across the individual codons of the
entire VP1 coding region revealed that purifying (negative) selection constituted the dominant
evolutionary force. Cross-border disease transmission within the region has been suggested with
probable incursions of topotypes EA-3 and EA-4 into Kenya and Uganda from neighboring Ethiopia and
Sudan. Weconclude that the vaccines have probably been effective in controlling EA-1, but less so for the
other topotypes and propose a more comprehensive representation of topotypes in the development of
new vaccines in recognition of the considerable diversity and transboundary nature of serotype O.
Description
Keywords
FMDV, Topotype, Selection East Africa
Citation
Balinda, S. N., Sangula, A. K., Heller, R., Muwanika, V. B., Belsham, G. J., Masembe, C., & Siegismund, H. R. (2010). Diversity and transboundary mobility of serotype O foot-and-mouth disease virus in East Africa: implications for vaccination policies. Infection, Genetics and Evolution, 10(7), 1058-1065.