HISTAMINE AND EICOSANOID LEVELS IN PLASMA AND PERIPHERAL-BLOOD LEUKOCYTE-CULTURES DURING EXPERIMENTAL-INFECTION OF CATTLE WITH BLUETONGUE VIRUS SEROTYPE-11

Three calves were sensitized with three doses of inactivated BTV-11 UC 8 strain and then experimentally infected with the homologous virus. I n addition, four BTV-seronegative heifers were also experimentally inf ected with BTV-11. Granulocyte rich fractions of peripheral blood leuc ocyte (PBL-GRF) cultures from BTV-sensitized/infected calves and from control unexposed cattle were exposed in vitro with BTV-11. Histamine, leukotriene (LT) C-4 and prostaglandin (PG) D-2 were assayed in super natant fluids. Plasma histamine levels increased in BTV-infected heife rs from 10.1 +/- 2 ng/ml at Day 0 to 23.1 +/- 6.6 ng/ml at Day 12 foll owing virus exposure. In addition, in this experimental group the conc entration of PGF(2 alpha) (mean 551.97 +/- 243.54 pg/ml) increased sig nificantly (P less than or equal to 0.05) compared with control cattle (mean 467.3 +/- 73.9 pg/ml). Bluetongue virus induced histamine and L TC4 release after in vitro infection of PBL-GRF. Release of LTC4 has s ignificantly (P less than or equal to 0.05) higher in PBL-GRF cultures from sensitized and control animals than in unexposed PBL-GRF culture s. In contrast to these results, PGD, was not released after BTV infec tion of PBL-GRF in vitro. The histamine release caused by BTV was viru s-specific and mainly mediated by an immunological reaction, since the release was significantly reduced by removal of cell surface immunogl obulins.