Persistent infection of rabbits with HTLV-1: Patterns of anti-viral antibody reactivity and detection of virus by gene amplification

Two groups of rabbits were inoculated on the day of birth or at 4 weeks of age with a human T-cell leukemia virus type-I (HTLV-I)-infected and transformed rabbit cell line (Ra-I). Rabbits seroconverted to HTLV-I, as determined by indirect immunofluorescence, by 3 weeks after inoculation and remained persistently seropositive during a 22-month period of observation. Seroconversion did not occur in saline-inoculated controls. Using Western immunoblotting and radio-immunoprecipitation, persistent seroconversion occurred against viral antigens p24, p55 and gp68, while reactivity to p19 was variable between rabbits. Using the polymerase chain reaction (PCR) with HTLV-I gag and pol primer pairs, HTLV-I sequences were demonstrable in peripheral blood mononuclear cells and other tissues collected at 70 and 90 weeks after inoculation. DNA extracts from normal rabbit tissue remained negative under the same conditions. No qualitative or quantitative changes in leukocytes or erythrocytes were detected in the infected rabbits and no clinical signs could be directly attributed to infection with HTLV-I.