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Abstract
The aim of the present work is toevaluate the immunological response of the imported and local inactivated H5N1 and H5N2 AI vaccines.
from this study, it was found that:
1. The results of HI test for the inactivated imported H5N1 vaccine revealed that there was highlydifference between the titer of the control group and all the vaccinated groups. Also, differences were noted between the vaccination of chicken with one dose, two homologous doses and two heterologous doses either as primer and booster vaccine to the imported H5N2. It was found that chickens vaccinated with two homologous doses of the imported H5N1 vaccine produced the higher and protective antibody titers. The protection in the groups vaccinated with the imported H5N1 vaccine as one dose, two doses, H5N1+H5N2 and H5N2+H5N1 were 85.7 %, 100 %, 93.3 % and 93.3 % respectively. The results of viral shedding reduction through oro-pharyngeal swabs treatment were 2.9, 4.5, 3.5 and 3.5 corresponding for groups of chicken vaccinated with one dose and two doses of H5N1, H5N1+H5N2 and H5N2+H5N1 respectively. While, the reduction degrees in viral shedding from intestinal tract for each the previous vaccines were 3.3, 5.1, 4.1 and 4.1 EID50 respectively.
2. The results of HI test for measuring anti-inactivated imported H5N2 vaccine revealed that there was highly difference between the vaccination of chickens with one dose, two homologous doses and two heterlogous doses either as primer and booster vaccine to the imported H5N1 vaccines. Chickens vaccinated with two homologous doses of the imported H5N2 vaccine produced the higher and protective antibody titers. The protection percentages, after challenging the immunity of the various vaccinated chickens with local virulent HPAI virus, were 80 %, 93.3 %, 93.3 % and 93.3 % in the groups vaccinated with the imported H5N2 vaccine as one dose, two doses, H5N2+H5N1, H5N1+H5N2 respectively. The reduction in viral shedding from respiratory tract were 3, 3.9, 3.5 and 3.5 in groups of chicken vaccinated with one dose and two doses of H5N2, H5N1+H5N2 and H5N2+H5N1 respectively. While, the reduction degrees in viral shedding from intestinal tract for each the previous vaccines were 2.8, 5.1, 4.1and 4.1 EID50 respectively.
3. It was observed that HI antibody levels of local inactivated H5N1 and H5N2 AI vaccines either one and two doses did not reach the recommended HI titer (7 log2) authorized by the Egyptian standard regulation at any week post vaccination. Also, the local inactivated AI vaccines both H5N1 and H5N2 did not give a high percentage of protection (26.7% and 20% in case of one dose, 28.6% and 26.7% in case of two doses) to the chicken after challenge with the local HPAI virus and showed high percentage of mortalities. One dose from the local inactivated AI vaccines both H5N1 and H5N2 produced very poor reduction in the titer of challenge virus. Meanwhile, the degree of viral shedding reduction from respiratory or intestinal tracts in case of two doses of local H5N1 (100.7 and 101.3) and local H5N2 (100.5 and 101.5) was very low.
4. It could be deduced that the vaccination of chicken with two homologous doses of inactivated vaccines gave highly acceptable antibody titer, good protection levels and high reduction degrees in the challenge virus replication and shedding from respiratory and intestinal tracts in comparison either with one dose or two heterologous doses. Also, the imported inactivated vaccines gave an acceptable result than local and recombinant vaccines.