The Research Of Biologic Characteristics Of Thermostable Nature Avirulent Newcastle Disease Virus Strain B95

Newcastle Disease Virus(NDV) Strain B95 is a thermostable nature avirulent strain .The aim of our experiments is to study the immunolgic and molecular biologic?characteristics of B95 strain.I In our experiments, 1 day and 8 days old chickens were immunized with B95,Clone30, LaSota and V4 respectively. The sera HI antibodies liters demonstrate that B95 and Clone30 may not be interfered by maternal antibodies, The chickens which immunized with LaSota vaccine have been developped mild respiratory disease. The immunization effects of V4 were not as good as B95 . Iday chickens immunized with B95 have higher HI antibodies titers than 8 days old ones. Heamagglutination tests were applied to detect virus in allantoic fluid of chicken embryos which were infected by B95 gathered from the vaccinated chickens' cloacal and oral cavity.The results show that the virus may be detected from 2 days to 11 days after the chicken being vaccinated .The HI antibodies were measured by Heamagglutination inhibition tests.There is no significant difference between the immunized and the control chickens which were fed in one case.Chickens were immunized with B95 by different immunization meathods or with different vaccines by the same meathod.lt is demonstrated that eyedrop, drinking water,spray or muscle injection all can stimulate good effects,but eyedrop and spray seem to be the best meathods.B95 immunized chicken have relatively higher HI titers and it also can last for a longer time than others.The immunization effects of B95 can be disturbed by HI20 if the immunized ? interval less than 10 days with the normal dose. However, the B95 antibody level? appears to be unaffected by HI20 if there is an higher B95 immune dose or an\ immunized interval more than 10 days.In order to study the B95 virus' molecular biologic characteristics and its homology relationship with other NDV strains the follwing experiments have been done . The NDV strain B95 were replicated in embryonated chicken eggs and its RNA was extracted from allantoic fluid. Using a pair of special primers, whole sequence of M gene of B95 were amplified by RT-PCR and be sequenced after being directly inserted in plasmid vector pBluescript SK. The length of B95 M gene is 1232 bp. The sequence56analysis shows that there is a long open reading frame in it which encode a protein of 364 animo acid residues. The M protein include 47 basic amino acid ,30 acidic amino acid,Which cause a basic estimated PI of 9.7 . Phylogenetic tree based on NDV Matrix protein gene shows that the B95 and V4 has the most close relationship than other NDV strain.