Ecological factors rather than temporal factors dominate the evolution of vesicular stomatitis virus

Ecological factors rather than temporal factors dominate the evolution of vesicular stomatitis virus

^*Tropical Disease Research Program, School of Veterinary Medicine, Universidad Nacional, P.O. Box 304-3000, Heredia, Costa Rica; ^‡Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92717; and ^§Cell and Molecular Biology Program and Department of Biochemistry, University of Nevada, Reno, NV 89557

Abstract

Vesicular stomatitis New Jersey virus (VSV-NJ) is a rhabdovirus that causes economically important disease in cattle and other domestic animals in endemic areas from southeastern United States to northern South America. Its negatively stranded RNA genome is capable of undergoing rapid evolution, which allows phylogenetic analysis and molecular epidemiology studies to be performed. Previous epidemiological studies in Costa Rica showed the existence of at least two distinct ecological zones of high VSV-NJ activity, one located in the highlands (premontane tropical moist forest) and the other in the lowlands (tropical dry forest). We wanted to test the hypothesis that the viruses circulating in these ecological zones were genetically distinct. For this purpose, we sequenced the hypervariable region of the phosphoprotein gene for 50 VSV-NJ isolates from these areas. Phylogenetic analysis showed that viruses from each ecological zone had distinct genotypes. These genotypes were maintained in each area for periods of up to 8 years. This evolutionary pattern of VSV-NJ suggests an adaptation to ecological factors that could exert selective pressure on the virus. As previous data indicated an absence of virus adaptation to factors related to the bovine host (including immunological pressure), it appears that VSV genetic divergence represents positive selection to adapt to specific vectors and/or reservoirs at each ecological zone.

Footnotes

↵ † Present address: Special Pathogens Branch, Centers for Disease Control and Prevention, Mailstop G-14, 1600 Clifton Road NE, Atlanta, GA 30333.
↵ ¶ To whom reprint requests should be sent at the present address.
Walter M. Fitch
Abbreviations: VSV, vesicular stomatitis virus; VSV-NJ, VSV New Jersey; VSV-IN, VSV Indiana.

Data deposition: The sequences reported in this paper have been deposited in the GenBank data base (accession nos. U39202–U39225U39202 U39203 U39204 U39205 U39206 U39207 U39208 U39209 U39210 U39211 U39212 U39213 U39214 U39215 U39216 U39217 U39218 U39219 U39220 U39221 U39222 U39223 U39224 U39225).