TE/3’2J/B2 virus-associated mortality was infection route- and mosquito species independent: significantly more Ae. aegypti died when exposed to TE/3’2J/B2 virus either orally or via injection and Ae. albopictus and Cx. tritaeniorhynchus were susceptible to TE/3’2J/B2 virus following intrathoracic injection. We originally hypothesized that the observed mortality was caused by apoptotic death of a majority of infected cells in the mosquito. FHV has been shown to induce apoptosis in Drosophila cell culture through the depletion of an intracellular inhibitor of apoptosis
. Apoptosis in alphavirus-infected mosquito cell lines is dependent on the amount of viral RNA and SC79 infectious virus produced during infection [32–35]. We show that considerably more SINV subgenomic RNA and 100-fold more infectious virus are produced in mosquitoes when B2 protein is expressed during infection. However, apoptosis could not be detected within infected cells in sections of virus-infected mosquitoes (data not shown). It is possible that cell death caused by TE/3’2J/B2 virus is via a non-apoptotic this website mechanism. Necrosis has been observed in midgut epithelial cells of Culiseta
melanura mosquitoes orally-infected with eastern equine encephalitis virus at times corresponding to peak midgut virus titers . Electron microscopy of infected cell morphology and detailed analysis of infected mosquito gene expression using microarray analysis may help to more clearly define the mechanism of TE/3’2J/B2 virus-associated mortality. Behavioral changes have been suggested as a direct result of arbovirus infection . TE/3’2J/B2 virus infection of the brain and sensory organs may lead to changes in
mosquito behavior that could eventually lead to death such as decreased nutrient and water uptake or inability to oviposit. Although not examined here, quantitative observation of behaviors such as blood feeding and oviposition may provide evidence for neurological effects associated with virus infection . The salivary glands are an important organ for successful transmission of arboviruses. If TE/3’2J/B2 virus infection leads to cytopathology in the salivary glands, 17-DMAG (Alvespimycin) HCl transmission of the virus may be more efficient or could be hindered. It was suggested that SINV-associated pathology in Ae. albopictus midgut-associated musculature and salivary glands could lead to a decrease in feeding success . If this is true, then transmission of TE/3’2J/B2 virus could be more efficient as mosquitoes take a longer time to probe the skin prior to imbibing blood. However, if salivation were compromised by virus-induced cytopathology, transmission of virus from the salivary glands would be less efficient due to decreased saliva inoculation volumes. The B2 protein alone is likely not the mosquito mortality-associated factor.