EFFECTS OF TEMPERATURE ON VIROGENESIS OF BLUETONGUE VIRUS SEROTYPE-11 IN CULICOIDES-VARIIPENNIS-SONORENSIS

Culicoides variipennis sonorensis females were fed bluetongue virus serotype 11 mixed in sheep blood and were held at constant temperatures of 32, 27, 21 and 15-degrees-C. Virogenesis, as measured by enzyme-linked immunosorbent assay (ELISA), proceeded significantly faster at higher temperatures. Based on ELISA absorbance greater-than-or-equal-to 0.2, some flies first were categorized as infected after 1 day, 2 days and 4 days at 32, 27 and 21-degrees-C, respectively. Peak levels of virus antigen were seen after 5-7, 7-13 and 18-22 days for flies held at 32, 27 and 21-degrees-C, respectively. There was no significant virus replication in flies held at 15-degrees-C for 22 days, but latent virus replicated and was detected easily (44% infection) 4-10 days after these flies were transferred to 27-degrees-C. The implications for temperature effects on bluetongue epizootiology are discussed.