Horizontal transmission of the mouse mammary tumor virus in cage mates of the same and opposite sex of low and high mammary cancer strain mice.

Horizontal transmission of mouse mammary tumor virus (MTV) was investigated in cage mates of the same and opposite sex of low (BALB/c) and high mammary cancer strains (DD/Tbr, SHN and GR). By MTVp27 and MTVgp52 radioimmunoassay, MTV antigen expression was found in the salivary glands, mammary glands and secondary male genital organs of the MTV-free BALB/c strain. Infectivity and oncogenicity were also found in DDf or BALB/c mice by inoculating extracts of salivary gland and/or seminal vesicle in high mammary cancer strains. It is suggested that the primary source of the infectious agent in cases of caged animals of the same sex is saliva, while the primary source in cases of caged animals of the opposite sex is the seminal fluid, although additional infection through saliva cannot be ruled out in the latter case.