Small-and large-plaque variants of chikungunya virus in two vertebrate and seven invertebrate cell lines.

Nine cells lines--BHK-21, Vero, Aedes albopictus, A. aegypti (monolayer and howwow vesicles), A. w-albus, A. vittatus, Anopheles stephensi and Culex quinquefasciatus--were infected with small- and large-plaque (SP, LP) variants of chikungunya virus. Ross strain, and incubated at different temperatures. In the Aedes (29 plus or minus 1 degrees C) and the vertebrate cell lines (36 degrees C), infectivity titers of extracellular virus rapidly reached a peak; cytopathic effect (CPE) occurred only in the latter. In Anopheles cells (29 plus or minus 1 degrees C), infectivity titers increased very slowly to a peak at 10 days post-inoculation (p.i.); in Culex cells (29 plus or minus 1 degrees C or room temperature), persistence of virus only or no multiplication was observed. In infected A. albopictus, A. aegypti and A. w-albus carrier cultures, the SP variant continued to resemble the original stock virus in terms of mouse pathogenicity and plaque morphology in Vero cells, but the LP variant tended to modify toward the SP variant.