Comparative tests on safety and potency of IBA vaccines.
During a comparative test on the pathogenicity and immunogenicity of a non-adapted and an embryo-adapted IDA virus, following observations were made: 1) 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 passages; 2) the immunosuppressive effect of the non-adapted virus was diminished by maternal antibodies; 3) 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; 4) the embryo-adapted strain was able to induce neutralizing antibodies in birds with or without maternal antibodies. However, precipitins were not detected; 5) 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 (1971); 6) no change in virulence occurred during back passages with both test materials.
D000284:Administration, Oral; D000818:Animals; D000914:Antibodies, Viral; D001835:Body Weight; D002060:Bursa of Fabricius / Q000033:anatomy & histology / Q000473:pathology; D002645:Chickens; D004326:Drinking; D005123:Eye; D007109:Immunity; D001351:Infectious bronchitis virus / Q000276:immunology; D007243:Infectious bursal disease virus / Q000276:immunology*; D009522:Newcastle disease virus / Q000276:immunology; D009929:Organ Size; D011201:Poultry Diseases / Q000517:prevention & control*; D011234:Precipitins / Q000032:analysis; D012087:Reoviridae / Q000276:immunology*; D012088:Reoviridae Infections / Q000517:prevention & control / Q000662:veterinary*; D014613:Vaccines, Attenuated / Q000009:adverse effects; D014765:Viral Vaccines / Q000008:administration & dosage / Q000009:adverse effects
D000914:Antibodies, Viral; D011234:Precipitins; D014613:Vaccines, Attenuated; D014765:Viral Vaccines