T-cell hybridomas recognizing the envelope proteins of Semliki forest virus: their sensitivity to endo/lysosomal protease and the antigenicity.

Abstract

Eight T-cell hybridomas were established from the draining lymph node of C3H mice immunized with Semliki forest virus (SFV). Six of them showed specificity toward viral-structure protein E2, while the remaining two clones included one with specificity to an other structural protein E1 and the other with specificity to C. The production of IL-2 by the E2 protein-specific T-cell hybridomas in the presence of SFV was suppressed by treating the antigen-presenting cells (APC) with ammonium chloride raising pH of the acidic compartments. It was found also that treatment of APC with a thiol protease inhibitor, leupeptin or E64, resulted in a reduced response of some of the E2-specific T-cell hybridomas. The E2 protein of SFV proved to be resistant at pH 7.0, and sensitive at pH 5.0 to in vitro cathepsin B treatment. In contrast, the E1 and C proteins proved to be resistant to both pH values. These results indicate that the thiol protease, probably cathepsin B, works as one of the enzymes group involved in antigen processing.