[Hemagglutination inhibition test for the diagnosis of coronavirus infection in cattle].

The main aim of the work was to obtain a viral corpuscle suspension with high hemagglutinating activity to be used as an antigen in HAI tests. The bovine coronavirus SC-1 strain was cultivated on ovine foetal renal cells and gave a suspension with a hemagglutinating titer of 1:64-1:128. A monospecific anti-coronavirus immune serum to be used in the HAI test, too, was prepared by hyperimmunization of a gnotobiotic calf. Its hemagglutinating and neutralizing titers were of 1:2560 and, respectively, 8.5 log. The HAI test was performed using the following reagents: the coronavirus suspension as a hemagglutinating antigen, a 1% suspension of mouse red blood corpuscles, the monospecific anti-coronavirus immune serum as a positive control, and a negative serum. 265 serum samples were investigated, collected from cows and calves in 18 farms where neonatal gastroenteritis was diagnosed. In 72.4% out of these samples there were positive results in the IHA test.