Trypsin-induced haemagglutination assay for the detection of infectious bronchitis virus
2004
Mahmood, M.S. | Siddique, M. | Hussain, I. (University of Agriculture, Faisalabad (Pakistan). Dept. of Microbiology) | Khan, A.
A trypsin-induced haemagglutination (THA) assay was standardized to detect infectious bronchitis virus (IBV) in allantoic fluid (AF) of embryonated eggs. The test was used in 20 samples, each collected from 5 different layer farms suspected for IBV. Allantoic fluid from inoculated embryos was harvested and treated with reagent grade trypsin at the percentages of 0.25, 0.50, 1.0 and 2.0 for 30 minutes to 3 hours at pH 7.2. The IBV in trypsinized AF was identified by clear and consistent agglutination of chicken red blood cells within 5 minutes of incubation at 37øC. The results indicated that AF treated with equal volume of 1.0% reagent grade trypsin elicited the haemagglutinating (HA) activity in 3.0 hours whereas 2.0% reagent grade trypsin elicited the HA activity only after 30 minutes incubation at 37øC. Sensitivity of THA was 92% as compared with 76% for agar gel precipitation test. Gross pathological lesions (curling and dwarfing) in chick embryo, intracereberal inoculation of un-weaned mice and pathogenicity test in one-day-old broiler chicks showed 79, 84 and 77% sensitivity, respectively.
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