Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2005
Publication Date: 4/11/2005
Citation: Becnel, J.J., White, S.E. 2005. Transmission of viruses to mosquito larvae mediated by divalent cations. Society for Invertebrate Pathology Annual Meeting. Interpretive Summary: None.
Technical Abstract: The most common occluded viruses of mosquitoes are baculoviruses (nucleopolyhedro viruses, NPV) and cypoviruses (CPV). Mosquito NPV’s have a circular, double-stranded DNA genome packaged into rod-shaped enveloped capsids embedded in a protein matrix. Mosquito cypoviruses are RNA viruses with a 10 segmented genome packaged into an icosahedral virion. Replication, assembly and occlusion of CPV’s occurs in the cytoplasm of midgut epithelial cells. Historically, both mosquito NPV’s and CPV’s have been difficult to transmit to the larval host. Studies on an NPV from Culex nigripalpus (CuniNPV) revealed that transmission is mediated by divalent cations: magnesium is essential, whereas the presence of calcium inhibits the activity of magnesium. Transmission of a second baculovirus (UrsaNPV) is also enhanced by the presence of magnesium. Transmission studies with a CPV from Uranotaenia sapphirina (UsCPV) have shown a 30 fold increase in infectivity when magnesium is present. Calcium inhibits the activity of magnesium to facilitate transmission of UsCPV. The role these divalent ions play in either enhancing or inhibiting transmission is unknown. It is interesting that two distantly related virus groups have similar transmission requirements suggesting that the divalent ions interact with components of the mosquito midgut rather than directly with virions of the virus.