EN
Virologic examinations to detect the BHV 1 and serological studies to determine the titre of anti BHV 1 antibodies and the content of serum immunoglobulins were lone on bulls aging 2—4 and 6—10 months naturally .nfected with BHV 1 and showing clinical symptoms of ;he respiratory tract inflammation. For control healthy mimals uninfected were included. It was found that bulls nfected with BHV 1 excrete the virus for a relatively ong time (42—56 days). In some animals the SN titres 1:2—1:8 were noted only in some periods of studies, irrespectively of the age of bulls serum content of IgG, md IgG increased and IgG, decreased. The level of IgM ind IgA was stable and it was not related to the age of tnimals.