The detection of the herpesvirus of bovine malignant catarrhal fever in rabbit lymphocytes in vivo and in vitro.

The herpesvirus of bovine malignant catarrhal fever (MCFV, alcelaphine herpes-virus I) causes an acute, fatal lymphoproliferative disorder in rabbits. In dying rabbits, virus antigen and infectivity were associated with medium sized lymphocytes and not with theproliferative lymphoblastoid cells. Virus antigen was found diffusely in the cytoplasm and as diffuse or particulate areas in the nucleus of infected cells. Fresh suspensions of the lymphoid tissues from rabbits killed 1 to 3 days after the onset of pyrexia contained 1 to 4 of both infective and fluorescent antigen positive cells per 10(6) cells. After 2 to 3 days of culture there was a 50- to 1000-fold increase in their concentration when a similar concentration of cells also contained herpesvirus type particles, both in the cytoplasm and the nucleus. About 40- to 100-fold more antigen-positive cells developed in cultures of lymphoid tissues from rabbits killed on the 2nd or 3rd day of pyrexia compared with the cultures from rabbits killed on the first day of pyrexia. Both cytosine arabinoside and 5-iododeoxyuridine inhibited the development of the infected cells upon culture. The findings are discussed in relation to lymphoproliferative disorders caused by other herpesviruses.