[The prevalence of antibodies to influenza virus and respiratory coronavirus in fattening pigs in Spain].

The presence of antibodies to two influenza viruses of the type A (H1N1 and H3N2) and to a porcine respiratory coronavirus was investigated in a study lasting a year. 735 blood serum samples were collected from 79 closed pig fattening farms in the province Segovia (Spain). Hemagglutination inhibition was used with influenza viruses. The percentage of positive results was 78.5% and 62.5% respectively for the serotypes H1N1 and H3N2. A clear reduction in the spread of antibodies was observed in the autumn. The ELISA technique was used with the porcine respiratory coronavirus. As antigen we used the antigenically related transmissible porcine gastroenteritis virus. Using this technique 87% of the sera were positive. Some of these sera with representative ELISA values were confirmed by means of serum neutralisation and radioimmune precipitation of the viral proteins. The incidence of these antibodies remained unchanged over the whole year of the investigation.