Possibility of a DNA-containing Mammary Tumour Virus in Red Blood Cells of Mouse

Abstract

THE classical mammary tumour virus (MTV), also referred to as the Bittner virus, is transmitted in milk from mother to offspring. Studies1–4 of the fate and biological behaviour of MTV in BALB/cfC3H (C+) mice suggested to us that MTV goes through a cycle in the infected host. Milk-borne MTV (M-MTV), assumed to be B particles, is abundantly present in milk and mammary tissues of infected mice. It seems likely that, on entering the host, M-MTV first infects the erythropoietic cells; subsequently the virus is carried into the general circulation chiefly inside the reticulocyte fraction2 of red blood cells (RBC) in a form which we have called R-MTV4. We have also suggested4 that, in the MTV cycle, R-MTV functions in the infection of mammary tissues, which are the primary sites of production of M-MTV (or B particles). The latter form of the virus, in turn, is involved in the transport of the viral genome to the young through milk.