Foetal infections with bovine viral diarrhoea virus in Argentina.

The frequency of isolation of bovine viral diarrhoea virus (BVDV) from primary tissue cultures and organs from bovine foetuses was studied between 1992 and 1994. Around 25% of primary tissue cultures were BVDV positive. Primary testis cultures were inoculated with homogenates of spleen, kidney, lung and liver from 52 foetuses. Cells were passaged twice and BVDV antigen investigated by indirect immunofluorescence. Non-cytopathic BVDV was detected in at least one organ in 11/52 foetuses (21.2%): 6/10 spleens, 4/7 kidneys, 7/9 lungs and 3/5 livers. Cytopathic BVDV was detected in lung and kidney from two foetuses. Since only gamma-irradiated sera are used in the laboratory and only inactivated BVDV vaccines are applied in Argentina, it was concluded that these isolations represented field infections. In addition to the 11 virus positive foetuses, two foetuses were positive for BVDV antibodies, which suggested a 25% prevalence of infection. These results stress the need for disease control on a herd basis and the requirement for biological reagents of bovine origin for the detection of BVDV.