Experimental infection of bulls and cows with bluetongue virus serotype 20

Abstract

Bluetongue virus serotype 20 (BTV20) was inoculated intradermally and subcutaneously in 4 bulls and by the intrauterine route in 8 nulliparous cows after insemination at oestrus. Viraemia was detected intermittently between 8 and 21 days after inoculation. Virus was isolated from tissue samples of 2 cows and a bull after slaughter at 14 days and from one bull at 28 days. Group reactive and type specific antibodies to BTV20 were demonstrated from 17 to 27 days after infection. No antibodies were detected in the animals slaughtered at 14 days. No clinical signs of disease were seen during the experiment and no gross or histopathological changes referable to BTV20 infection were observed post-mortem. Because of the viraemia and the production of detectable serum antibodies, gametes from these cattle would be excluded from export.

Experimental Infection of Pregnant Cattle with Bluetongue Virus Serotype 11 between Postbreeding Days 21 and 48

“…The coexistence of virus and neutralizing antibodies in the blood of BTV-infected animals has been previously reported, 13,27 suggesting that once an animal becomes infected, BTV is inaccessible to subsequent neutral- izing antibodies. However, the 2 animals that already had neutralizing antibodies against the same serotype failed to become viremic, confirming previous results that neutralizing antibodies may be protective against reinfection by the same serotype.…”

“…A similar situation may occur with BTV infection. Isolation of BTV from bovine ovaries has been reported, 27 but ovarian lesions due to BTV infection have not been described, possibly because in most experiments on BTV pathogenesis, the virus strains used for inoculation have not been characterized. We used a well-characterized virulent strain of BTV-11/UC-8; [33][34][35] therefore, the ovarian changes may have been associated to BTV infection.…”

Evaluation of a Monoclonal Antibody Blocking ELISA for the Detection of Group-specific Antibodies to Bluetongue Virus in Experimental and Field Sera

“…Post-infection (p.i.) serial bleeds of bovine and ovine antisera to Australian BTV serotypes resulted from earlier studies (Parsonson et al, 1987;Della-Porta et al, 1983a). Inactivated ovine and guinea-pig antisera to South African BTV serotypes were obtained from the Commonwealth Serum Laboratories, ParkviUe, Australia.…”

Flow cytometric analysis of in vitro bluetongue virus infection of bovine blood mononuclear cells

“…BTV infection of cattle typically is subclinical and is characterized by prolonged viraemia (Du Toit, 1962;Luedke et al, 1969;MacLachlan & Fuller, 1986;MacLachlan et al, 1987;Richards et al, 1988), during which the virus invariably is cell-associated (Luedke, 1970;Collisson & Barber, 1983;Morrill & McConnell, 1985;Parsonson et al, 1987). Recent studies have established that mononuclear inflammatory cells might be important to the pathogenesis of bluetongue in cattle.…”