Histamine and Eicosanoid Levels in Plasma and Peripheral Blood Leucocyte Cultures During Experimental Infection of Cattle with Bluetongue Virus Serotype 11

Abstract

Three calves were sensitized with three doses of inactivated B T V l l UC8 strain and then experimentally infected with the homologous virus. In addition, four BTV-seronegative heifers were also experimentally infected with BTV-11. Granulocyte rich fractions of peripheral blood leucocyte CpBL-GRF) cultures from BTV-sensitized/infected calves and from control unexposed cattle were exposed in uitm with BTV-11. Histamine, leukotriene (Lp C, and prostaglandin (PG) D, were assayed in supernatant fluids. Plasma histamine levels increased in BTV-infected heifers from 10.1 f 2 ng/ml at Day 0 to 23.1 f 6.6ng/ml at Day 12 following virus exposure. In addition, in this experimental group the concentration of PGF,, (mean 551.97 f 243.54pg/ml) increased significantly (P < 0.05) compared with control cattle (mean 467.3 f 73.9 pg/ml). Bluetongue virus induced hlstamine and I,TC, release after in vitm infection of PBL-GRF. Release of LTC, was sigruficantly ( I ' < 0.05) higher in PBL-GRF cultures from sensitized and control animals than in unexposed PBL-GRF cultures. In contrast to these results, PGDz was not released after BTV infection of PBL-GRF in vitro. The histamine release caused by BTV was virus-specific and mainly mediated by an immunological reaction, since the rclease was significantly reduced by removal of cell surface immunoglobuhns.