Preadsorption of boar semen with kaolin: increased efficiency of foot-and-mouth disease virus detection.

The boar semen-associated cytotoxic factor(s), but not the antiviral activity, were removed by adsorption with kaolin. Although foot-and-mouth disease virus was efficiently removed from medium by kaolin or kieselguhr, the virus was not removed from semen-virus mixtures. Because the cytotoxicity induced by boar semen apparently altered the ability of tissue culture cells to support virus replication, preadsorption with kaolin increased the probability of detecting this virus in semen samples.