Sindbis virus infection of a Chinese hamster ovary cell mutant defective in the acidification of endosomes.

Sindbis virus infection of a Chinese hamster ovary temperature-sensitive mutant cell line defective in its ability to acidify endosomes was examined to evaluate the importance of this step in the process of alphavirus penetration of host cells by measuring the time at which viral RNA synthesis was initiated. We found that RNA synthesis was initiated in these mutant cells at the same time after addition of virus at either permissive or nonpermissive temperature. We conclude that exposure to the acidic environment of an endosome is not a prerequisite for alphavirus infection.