Physiology and pathology of host immune responses to exogenous and endogenous murine retroviruses--from gene fragments to epitopes.

Abstract

Spontaneous and induced immunity against exogenous Friend murine leukemia retrovirus infection is controlled by four H-2-linked host genes and a single non-H-2 gene. Recognition of the envelope glycoprotein gp70 of Friend virus by helper T cells is restricted by Ab and hybrid Eb/k(d) class II MHC molecules. By expressing portions of the env gene and by utilizing synthetic oligopeptides, an Ab-restricted and a hybrid Eb/d-restricted helper T cell epitopes were identified in the N-and C-terminal portions of gp70, respectively. These epitopes differ in their amino acid sequences from the previously reported endogenous retroviral peptides naturally presented by mouse MHC class II molecules. Possible roles of recombinant polytropic viruses in the induction of autoimmune responses against endogenous retroviral antigens are also discussed.