[Virus neutralization microreaction to determine antibodies against the infectious bovine rhinotracheitis virus].

Comparative studies were carried out with a total of 170 serum samples from cattle with the use of the virus-neutralization test and the virus-neutralization microreaction to demonstrate the presence of antibodies against the IBR virus. It was found that the two reactions were equally effective in terms of specificity. The coincidence of the results obtained with regard to the positive and negative tests was 97 per cent with variant alfa and 98 per cent with variant beta. Comparatively higher sensitivity was demonstrated with variant beta. It was established that the virus-neutralization microreaction was not influenced by the presence of antibodies against the virus in the initial cell cultures, it producing a well marked border line when reading the results. It was concluded that the virus-neutralization microreaction could in all cases be used instead of the virus-neutralization test as it is economical and is readily performed.