Comparative tests on safety and potency of IBA vaccines
Vielitz, E.; Landgraf, H.
Developments in Biological Standardization 33: 332-339
1976
ISSN/ISBN: 0301-5149 PMID: 182590 Document Number: 105832
During a comparative test on the pathogenicity and immunogenicity of a non-adapted and an embryo-adapted infectious bursitis virus, the following observations were made. The non-adapted virus remained pathogenic as determined by weight loss and bursal lesions. Clinical signs and mortality did not occur. A change in the virulence did not occur during back passage. The immunosuppressive effect of the non-adapted virus was diminished by maternal antibodies. The embryo-adapted virus was diminished by maternal antibodies. The embryo-adapted virus produced little pathogenicity as demonstrated by minor weight depressions. The vaccinated birds had no recognizable pathological lesions in the bursae. Immunosuppression with this virus was not observed. The embryo adapted strain was able to induce neutralizing antibodies in birds with or without maternal antibodies. However, precipitins were not detected. Immunization with the embryo-adapted strain after 8 days of age was protective whereas prior to that age it was not, confirming the age susceptibility factor reported by Hitchner [see VB 42, abst. 4627]. No change in virulence occurred during back passages with both test materials.