Replication of Dengue Virus in Cultured Mosquito Cells at Suboptimal Temperature

Abstract

Cultured Aedes albopictus mosquito cells were infected at optimal (28.degree. C) and suboptimal (20.degree. C) temperatures with dengue virus type-3 at multiplicities of infection (m.o.i.) of 2.0 and 0.01. Extracellular and intracellular virus titers were determined over an interval of 6 wk by fluorescent focus assay using hyperimmune mouse ascites fluid as a source of antibody. Upon infection at a multiplicity of 2.0, cultures at 28.degree. C reached peak virus titers in 3 days, while cultures at 20.degree. C required 14 days. At a lower m.o.i. of 0.01, peak titers were reached in 5 days at 28.degree. C but required 3 wk at 20.degree. C. Viral titers maintained after the peak was reached were the same at both m.o.i. and temperatures tested. At both 28.degree. C and 20.degree. C A. albopictus cultures became persistenly infected with 20-30% of the cells containing immunofluorescent cell-associated viral antigen. The time required to reach peak infectious virus titers for dengue-3-infected A. albopictus cell cultures apparently is temperature-dependent. The viral titers maintained after the peak was reached, the release of virus from infected cells and the establishment of persistent infection were the same at both 28.degree. and 20.degree. C.