NEUTRALIZING EPITOPE ON PENETRATION PROTEIN OF VACCINIA VIRUS

The monoclonal antibody 2D5 neutralized vaccinia virus by preventing p enetration of the virus and reacting with VP23-29K. The conformation o f the VP23-29K was maintained by a disulfide bond(s), and the 2D5mAb r eacted stronger with the nonreduced 23-kDa form than with the reduced 29-kDa form. We selected several escape mutants. Sequences of the A17L genes, which were thought to encode the VP23-29K, did not show cognat e mutation. Genomic DNA of a 2D5mAb-resistant mutant (M4) was cleaved with Hindlll, and all the fragments were introduced in to parental IHD -J strain vaccinia virus by transfection. Only the L fragment produced a 2D5mAb-resistant virus. Dissection of the L fragment and subsequent transfection revealed that the L1R gene induced the 2D5mAb-resistant virus. The 2D5mAb-resistant mutants showed a consensus G to A conversi on at nucleotide 101 of their LIRs which would replace asparatic acid 35 with asparagine. Ishibashi-111 strain mousepox virus spontaneously resistant to 2D5mAb also had the same sequence at this region. Moreove r, the VP23-29K was myristoylated as predicted by the L1R gene. The co ding gene of the VP23-29K was L1R. (C) 1996 Academic Press, Inc.