| Affect on preparation of IBV HI antigen of different stemed enzyme filtered cultivating liquid from clostricdium perfringens A. crude extract phospholipase C(PLC),phospholipase C type I,(PLC|),neuraminida -se) different density and serotype of IBV strains,different temperature and time of allanto-amnionic fluid(AAF) and so on were compared.According to the best prepared condition IBV HI Antigen was prepared by the mix of rude extract PLC whose protein density was 2.798mg/ml with equal volum fresh AAF of M41, Y strains by incubating under 37℃ for two hours with continuing shaking.This antigen did not react to serum of AiV H3, AIV H9, NDV, EDS-76, SPF chicken, habbit and cow but only react to IBV serum,which indicate high specifity and it's titre didn't change at 4℃ for three months.This antigen can be used in HI similar to commercial PLC1 whith can be prepared easily and cheepely.After some factors which affect IBV HI were studied.the HI test was established to detect the antibody of IBV.with 0.5% red blood cell density.the dilute liquid of PH7.4 0.01M PBS.Antigen and antibody worked under room temperature for 30min.the result was read after red blood cell added and work at 4℃ for 50min.After the detection of 25 negative serum and challenge test boundary line of HI titre was defined as 41og2.HI titre abover 41og2 is equal to ELISA(P/N) above 2.1 of, 1:20 of neutralization titre and 10/11 of challege test(P/C);HI titre below 4log2 is equivalent to P/N of ELISA below 2.1 > neutualization titre below 1:20, 3/9 of challege test (P/C) 3/9.These results were obviously interrelated .In order to reduce the affect of kinds of factors and enhance the comparablity among the results under different condition the positive serum was used in HI test which has the best specifity, repeation and stable titre under-20癈 for five months.Serotype was classified by established HI test according to the result of HI test using six Mab and fifteen IBV antigen. Fifteen IBV isolates were divided into three groups:one group which didn't react to Mab C2 but Mab Jj,one group which did't react to Mab but Mab C2,another group reacted to neither of the Mab.Similariy,fifteen IBV strain can also be divided into three groups:one group which had high relation to M4] but low relation to Y,one group which had ligh relation toY but low relation to M4it another group which have medium relation to the both.There are multiple serotypes of IBV in our country.But serotype M is primary (50%), Y strain has a certain proportion(30%).We can select M+Y or M+field isolate strain, to produce IB vaccine.IBVHI has high specifity.We should select the same serotype with vaccine strain to produce antigen in primary vaccination but select the mixed serotype strains to produce antigen in the second vaccination. Epidemic investigation of IB serum is done by IBV HI.Original antibody of chichen would drop to boundary line(41og2) between five to ten days posthatch.The HI litre of different age adult hen was low (4log2)before vaccinating and raised to 8-121og2.HI titre of 25-day-age chicken reached the climax at 21 day postvaccination and maitain one month and dropped to the boundary line.HI titre of 70-day vacunated hen also reached the climax 21 days postvaccination .HI titre of adult hen will enhance with their age and maitain more term.It conform to the immunology regulation.Practice proved that IBV HI had simple quick accurate and filed for field application It can also be used in diaganose,detection affect of vaccination and serurn epidemic investigation of IB and provided theory reference for selection of vaccine strain.formulation of vaccinating program,prevention of IB.
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