BALB/ Mtv -Null Mice Responding to Strong Mouse Mammary Tumor Virus Superantigens Restrict Mammary Tumorigenesis

Abstract

The absence of endogenous mouse mammary tumor viruses (MMTVs) in the congenic mouse strain, BALB/ Mtv -null, restricts the early steps of exogenous C3H MMTV infection, preventing the superantigen (Sag) response and mammary tumorigenesis. Here we demonstrate that BALB/ Mtv -null mice also resist tumor induction by FM MMTV, which encodes a stronger Sag compared to C3H MMTV. In contrast to infections with C3H MMTV, Mtv -null mice show FM-MMTV Sag-specific responses comparable to those observed in susceptible BALB/c mice. Neither virus shows significant replication in the spleen or mammary gland. Thus, Mtv -null mice restrict MMTV replication and mammary tumorigenesis even after a robust Sag response.