Abstract
Leukocyte suspensions from the lymph nodes, spleen and blood of cottontail rabbits experimentally infected with Herpesvirus sylvilagus were examined as fresh cell preparations and after in vitro cultivation for (1) the presence of virus, virus replication and release; (2) activation of virus by arginine deprivation or BUdR treatment and (3) the ability of such cell suspensions to give rise to actively replicating lymphoblastoid cell lines. Virus recovery was accomplished most consistently by co‐cultivation of viable cells on permissive DRK cell monolayers. The percentage of virus‐yielding cells, measured by formation of infectious centers when plated under agar on permissive monolayers, was generally less than 0.1%. Most cells yielding virus by this method showed no detectable intracellular virus in the sonically ruptured cell extracts. In vitro cultivation did not stimulate increased intracellular virus replication. It did, however, result in a 400‐ to 500‐fold increase in the number of cells capable of forming infectious centers in cultures of blood lymphocytes from two of 11 animals examined in this manner. Arginine deprivation of BUdR treatment also failed to activate productive infection. Maintenance of infected lymphoid cell cultures for 6 months did not result in establishment of actively replicating lymphoblastoid cell lines.