Growth of Epizootic Hemorrhagic Disease, Akabane, and Ephemeral Fever Viruses in Aedes albopictus Cells Maintained at Various Temperatures

Abstract

The growth curves of one epizootic hemorrhagic disease (EHD) virus serotype (Reoviridae), two Akabane virus strains (Bunyaviridae) and three bovine ephemeral fever (BEF) group viruses (Rhabdoviridae) were determined in Aedes albopictus cells maintained at IS, 20, 28 and 33�e. Ae albopictus cells supported the growth of all the viruses although not necessarily at all temperatures. Because none of the viruses exhibited cytopathic effect in Ae albopictus cells, growth was assayed in baby hamster kidney 21 (BHK21) cells maintained at 37�e. The temperature at which the Ae albopictus cells were maintained had a marked effect on the growth and yield for each virus studied. EHD virus was heat-stable and grew after 4 days at 28 and 33�C, and after 8 days at 20�e. No growth was recorded up to 12 days at 15OC. The two Akabane viruses were heat-sensitive and exhibited different growth patterns. One strain (B8935) showed no growth at 15�C and only minimal growth at 20, 28 and 33�e. The other strain (CSIRO 16) showed growth after 1-2 days at all temperatures with higher titres reached at 15 and 200C than at 28 and 33OC. The BEF group viruses grew to approximately the same titres at all temperatures. At the higher temperatures (28 and 33�C) most of BEF group viruses had disappeared within 9 days. In contrast at the lower temperatures (15 and 20�C), there was still virus present 18 days after inoculation. BEF virus grew at 280C after being maintained in Ae albopictus cells held at 4�C for 14 and 42 days.