SUPERINFECTION EXCLUSION OF ALPHAVIRUSES IN 3 MOSQUITO CELL-LINES PERSISTENTLY INFECTED WITH SINDBIS VIRUS

Three Aedes albopictus (mosquito) cell lines persistently infected wit h Sindbis virus excluded the replication of both homologous (various s trains of Sindbis) and heterologous (Aura, Semliki Forest, and Ross Ri ver) alphaviruses. In contrast, an unrelated flavivirus, yellow fever virus, replicated equally well in uninfected and persistently infected cells of each line. Sindbis virus and Semliki Forest virus are among the most distantly related alphaviruses, and our results thus indicate that mosquito cells persistently infected with Sindbis virus are broa dly able to exclude other alphaviruses but that exclusion is restricte d to members of the alphavirus genus. Superinfection exclusion occurre d to the same extent in three biologically distinct cell clones, indic ating that the expression of superinfection exclusion is conserved amo ng A. albopictus cell types. Superinfection of persistently infected C 7-10 cells, which show a severe cytopathic effect during primary Sindb is virus infection, by homologous virus does not produce cytopathology , consistent with the idea that cytopathology requires significant lev els of viral replication. A possible model. for the molecular basis of superinfection exclusion, which suggests a central role for the alpha virus trans-acting protease that processes the nonstructural proteins, is discussed in light of these results.