Host alternation of chikungunya virus increases fitness while restricting population diversity and adaptability to novel selective pressures.
The mechanisms by which RNA arboviruses, including chikungunya virus (CHIKV), evolve and maintain the ability to infect vertebrate and invertebrate hosts are poorly understood. To understand how host specificity shapes arbovirus populations, we studied CHIKV populations passaged alternately between invertebrate and vertebrate cells (invertebrate ↔ vertebrate) to simulate natural alternation and contrasted the results with those for populations that were artificially released from cycling by passage in single cell types. These CHIKV populations were characterized by measuring genetic diversity, changes in fitness, and adaptability to novel selective pressures. The greatest fitness increases were observed in alternately passaged CHIKV, without drastic changes in population diversity. The greatest increases in genetic diversity were observed after serial passage and correlated with greater adaptability. These results suggest an evolutionary trade-off between maintaining fitness for invertebrate ↔ vertebrate cell cycling, where maximum adaptability is possible only via enhanced population diversity and extensive exploration of sequence space.
Institut Pasteur, Viral Populations and Pathogenesis, CNRS URA 3015, 28 rue du Dr Roux, 75724 Paris Cedex 15, France.
Lark L
LL
Coffey
Marco
M
Vignuzzi
D000818:Animals; D002460:Cell Line; D002646:Chikungunya virus / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D002522:Chlorocebus aethiops; D006224:Cricetinae; D014644:Genetic Variation; D058507:Host Specificity; D006801:Humans; D019562:Viral Load; D014774:Virulence