Oral transmission of human T-cell leukemia virus type-I into a common marmoset (Callithrix jacchus) as an experimental model for milk-borne transmission.

To obtain experimental support for possible milk-borne infection of human T-cell leukemia virus type-I (HTLV-I), short-term-cultured viral antigen-positive lymphocytes obtained from peripheral blood of adult T-cell leukemia lymphoma complex (ATLL) patients were inoculated into the oral cavity of two adult common marmosets (Callithrix jacchus) in amounts comparable to those of HTLV-I-carrying cells fed to a baby in the milk of seropositive mothers. One of the animals seroconverted 2.5 months after the first inoculation. Cultures of peripheral blood mononuclear leukocytes of the marmoset revealed HTLV-I antigen expression in cells, indicating the establishment of oral infection of HTLV-I in an adult marmoset. The cell number deduced to be responsible for the infection was 5.6 X 10(7) cells (used in the first 2 inoculations). The results suggest that the concept of milk-borne infection of HTLV-I from a seropositive mother to her child is plausible.