Monoclonal and polyclonal antibody studies of VSV(hrMMTV) pseudotypes

Abstract By phenotypic mixing between the host range (hr) variant of mouse mammary tumor virus (MMTV) and the is-045 mutant of vesicular stomatitis virus (VSV), we were able to produce high titers of “complete” pseudotypes bearing the VSV genome and hrMMTV envelope. Four “strains” of pseudotypes designated VSV(C 3 H), VSV(GR), VSV(RIII), and VSV(C 3 Hf) were generated. To find out whether group-specific and type-specific neutralizing antigenic determinants (epitopes) were expressed on some of these pseudotypes, we utilized several monoclonal antibodies to MMTV-gp52 and sera from mammary tumor-bearing C 3 H/HeN mice in neutralization assays. Four monoclonal antibodies to MMTV-gp52, which were group specific in solid-phase MMTV binding assays, were found to neutralize the infectivity of VSV(C 3 H), VSV(GR), VSV(RIII), and VSV(C 3 Hf), indicating the expression of group-specific “neutralizing epitopes” on these pseudotypes. One monoclonal antibody to MMTV-gp52 that was C3Hf type specific in MMTV binding assays was found to neutralize only the infectivity of VSV(C 3 Hf) and not VSV(C 3 H), VSV(GR), or VSV(RIII). In addition, polyclonal antibodies were found in sera of mammary tumor-bearing C 3 H/HeN mice which neutralized specifically the infectivity of VSV(C 3 H). Such antibodies were not found in the sera of normal C 3 H/HeN mice or normal BALB/c mice. These results indicate that group-specific “neutralizing epitopes” were expressed on VSV(C 3 H), VSV(GR), VSV(RIII), and VSV(C 3 Hf). Furthermore, they suggest that type-specific “neutralizing epitopes” were expressed on VSV(C 3 H) and VSV(C 3 Hf) pseudotypes.