Host-dependent mutants of Sindbis virus whose growth is restricted in cultured Aedes albopictus cells produce normal yields of virus in intact mosquitoes.

Two host-dependent (hd), temperature-sensitive (ts) mutants of Sindbis virus (SV), clones 35 and 58, which are restricted in their ability to grow at 34 degrees in cultured Aedes albopictus cells [K.J. Kowal and V. Stollar (1981). Virology 114, 140-148] were not restricted in their ability to grow at 28-34 degrees after intrathoracic inoculation of Ae. albopictus, Ae. dorsalis, Ae. epactius, Anopheles freeborni, and Culex tarsalis mosquitoes. Compared to standard SV (SVSTD), the growth of SV clone 35 was somewhat restricted in parenterally infected C. pipiens females. Titers of SVSTD and the two mutants were modulated to relative low levels by some Ae. albopictus and Ae. dorsalis females after 192 hr incubation at 34 degrees but not at 28 degrees, suggesting that under some conditions mosquitoes have the ability to control the replication of SV. The hd and ts phenotypes of SV mutants were retained during growth at 31 degrees for 36 hr and 72 hr in Ae. epactius and Ae. dorsalis females, respectively, and at 28 degrees or 34 degrees for 192 hr in Ae. albopictus females. The demonstration that mutant viral clones, which are restricted in cultured mosquito cells, can produce normal yields of virus in intact mosquitoes indicates that considerable caution must be exercised in extrapolating results obtained with cultured cells to the level of the intact organism.