Pathways of viral antigen processing and presentation to CTL: defined by the mode of virus entry?

Processing requirements for antigen presentation to cytotoxic T lymphocytes (CTL) vary among viruses and between major histocompatibility complex (MHC) class I- and class II-restricted responses to the same virus. In this article, Eric Long and Steven Jacobson argue that the mode of virus entry may define processing pathways and that the invariant chain associated with MHC class II molecules may account for the distinct processing requirements for MHC class I- and class II-restricted CTL.