Effect of Lymphoproliferative Disease Virus and of Niridazole on the in vitro Blastogenic Response of Peripheral Blood Lymphocytes of Turkeys

Abstract

Turkeys inoculated at 5 weeks of age with lymphoproliferative disease (LPD) virus developed typical lesions in the spleen, thymus, and pancreas. The in vitro blastogenic response of peripheral blood lymphocytes to the mitogens phytohemagglutinin and concanavalin A was drastically (up to 90%) suppressed in the inoculated turkeys 1 to 4 weeks postinoculation compared with uninoculated controls, and even at 11 weeks the response was about 50% inhibited. A lethal (about LD33) dose of antihelminthic drug niridazole, 100 mg/kg given each day for 3 days to 4-week-old turkeys, caused a transient inhibition of the blastogenic response within 32 days of treatment, which was less pronounced than that observed in turkeys inoculated with LPD virus, whether pretreated with niridazole or not. Virus-associated reverse transcriptase activity in the plasma was significantly higher in the turkeys pretreated with niridazole, and LPD lesions developed to the same extent in the untreated and treated groups, as determined 9 weeks post virus inoculation. A sublethal dose of niridazole, 50 mg/kg given each day for 4 days, did not suppress the blastogenic response to mitogens at any time determined (starting 10 days post-treatment) and did not affect the pathogenesis of LPD and the viremia. Body weights were significantly decreased by virus infection and by treatment with lethal doses of niridazole.