Infectivity of Drosophila C virus following oral delivery in Drosophila larvae.

The route of pathogen entry can have a major effect on the ability of a virus to induce a prolific infection, but it can also affect the ability of the host organism to induce an immune response to fight the infection. Transmission of arboviruses that cause serious diseases in humans often begin by an insect ingesting a virus, which then disseminates through the internal organs and tissues and ultimately culminates in virus transmission to a human host. Understanding the effect of a natural route of infection on the host-pathogen interaction may facilitate development of approaches to prevent viral dissemination. Drosophila has been a useful model organism for understanding host-virus interactions; however, most studies have achieved infection by artificially injecting the virus into the host. Here, we developed a single-stranded quantitative PCR able to detect only actively replicating Drosophila C virus (DCV) to study the effect of viral feeding at the early stages of larval development. Exposure of newly hatched larvae to DCV led to 20 % of larvae becoming infected within 12 h post-contamination, and caused a 14 % egg-to-adult mortality. This is the first time, to the best of our knowledge, that it has been shown experimentally that DCV is able to establish a prolific infection following larval feeding. Using these newly developed tools, the results suggest that larvae that become infected die before adult eclosion.