Densovirus crosses the insect midgut by transcytosis and disturbs the epithelial barrier function

Densoviruses are parvoviruses that can be lethal for insects of different orders at larval stages. Although the horizontal transmission mechanisms are poorly known, densoviral pathogenesis usually starts with the ingestion of contaminated food by the host. Depending on the virus, this leads to replication restricted to the midgut or excluding it. In both cases the success of infection depends on the virus capacity to enter the intestinal epithelium. Using the Junonia coenia densovirus (JcDNV) as the prototype virus and the lepidopteran host Spodoptera frugiperda as an interaction model, we focused on the early mechanisms of infection during which JcDNV crosses the intestinal epithelium to reach and replicate in underlying target tissues. We studied the kinetics of interaction of JcDNV with the midgut epithelium and the transport mechanisms involved. Using several approaches, in vivo, ex vivo, and in vitro, at molecular and cellular levels, we show that JcDNV is specifically internalized by endocytosis in absorptive cells and then crosses the epithelium by transcytosis. As a consequence, viral entry disturbs the midgut function. Finally, we showed that four mutations on the capsid of JcDNV affect specific recognition by the epithelial cells but not their binding.