The cell biology of receptor-mediated virus entry

Grove, Joe; Marsh, Mark

exquisite example of how sequential receptor engagement and receptor-induced signaling are coupled to facilitate virion translocation and entry. Recent findings indicate that a related picornavirus, echovirus 11, also undergoes DAF-dependent transport to the tight junctions, although a junctional coreceptor has yet to be identified (Sobo et al., 2011) . Like coxsackievirus B, hepatitis A virus is a fecal orally transmitted picornavirus; however, its principal site of replication is the liver, and it must therefore have developed mechanisms to cross the gut epithelium. In vitro studies suggest that hepatitis A virus-specific IgA facilitates transcytosis of virus particles through polarized epithelial cells via the polymeric immunoglobulin receptor (Dotzauer et al., 2005) . Critically, complexed IgA can subsequently mediate hepatitis A virus entry to hepatocytes via asialoglycoprotein receptors (Dotzauer et al., 2000) . Thus, IgA acts as a bridging component for sequential receptor-mediated hepatitis A virus transit and infection. This process appears to be independent of the standard hepatitis A virus receptor T cell immunoglobulin and mucin domain 1 (TIM-1; Kaplan et al., 1996) .