T-CELL HYBRIDOMAS RECOGNIZING THE ENVELOPE PROTEINS OF SEMLIKI FOREST VIRUS: THEIR SENSITIVITY TO ENDO/LYSOSOMAL PROTEASE AND THE ANTIGENICITY

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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 antigenpresenting 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 pH7.0, and sensitive at pH5.0 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.