Analysis of two monoclonal antibodies reactive with envelope proteins of murine retroviruses: One pan specific antibody and one specific for Moloney leukemia virus

• We describe two monoclonal antibodies to murine leukemia virus (MuLV) env proteins.
• One of the antibodies reacts with all MuLVs tested including amphotropic MuLVs.
• Another antibody reacts with the proline-rich region of the Moloney MuLV SU protein.
• The Moloney MuLV-specific antibody is useful for immunoblotting procedures.
• Both antibodies are capable of neutralizing virion infectivity.

Many monoclonal antibodies (MAbs) reactive with various proteins of murine leukemia viruses (MuLVs) have been developed. In this report two additional MAbs with differing and unusual specificities are described. MAb 573 is reactive with the envelope protein of all MuLVs tested including viruses in the ecotropic, xenotropic, polytropic and amphotropic classes. Notably, MAb 573 is one of only two reported MAbs that react with the envelope protein of amphotropic MuLVs. This MAb appears to recognize a conformational epitope within the envelope protein, as it reacts strongly with live virus and live infected cells, but does not react with formalin-fixed or alcohol-fixed infected cells or denatured viral envelope protein in immunoblots. In contrast, Mab 538 reacts only with an epitope unique to the envelope protein of the Moloney (Mo-) strain of MuLV, a prototypic ecotropic MuLV that is the basis for many retroviral tools used in molecular biology. MAb 538 can react with live cells and viruses, or detergent denatured or fixed envelope protein. The derivation of these antibodies as well as their characterization with regard to their isotype, range of reactivity with different MuLVs and utility in different immunological procedures are described in this study.