Aedes aegypti transducing densovirus pathogenesis and expression in Aedes aegypti and Anopheles gambiae larvae

Aedes aegypti densovirus (AeDNV) is a small DNA virus that has been develop ed into an expression and transducing vector for mosquitoes [Afanasiev et a l. (1994) Exp Parasitol 79: 322-339; Afanasiev et al. (1999) Virology 257: 62-72; Carlson et al. (2000) Insect Transgenesis: Methods and Applications (Handier, A.M. & James, A.A., eds), pp. 139-159. CRC Press, Boca Raton]. Vi rions carrying a recombinant genome expressing the GFP gene were used to ch aracterize the pathogenesis of the virus in 255 individual Aedes aegypti la rvae. The anal papillae of the larvae were the primary site of infection co nfirming previous observations (Afanasiev et al, 1999; Allen-Muira et al. ( 1999) Virology 257:54-61). GFP expression was observed in most cases to spr ead from the anal papillae to cells of the fat body, and subsequently to ma ny other tissues including muscle fibers and nerves. Infected anal papillae were also observed to shrink, or melanize and subsequently fall off in a v irus dependent manner. Three to four day-old larvae were less susceptible t o viral infection and, if infected, were more likely to survive into adulth ood, with 14% of them still expressing GFP as adults. Higher salt concentra tions of 0.10-0.15 M inhibited viral infection, Anopheles gambiae larvae al so showed infection of the anal papillae (17%) but subsequent viral dissemi nation did not occur. The persistence of the reporter gene expression into adulthood of Aedes aegypti indicates that transduction of mosquito larvae w ith recombinant AeDNV may be a means of introducing a gene of interest into a mosquito population for transient expression.