Interfere of maternal derived antibodies in early age of chicks with the efficacy of vaccination against Avian Influenza viruse.

Avian Influenza virus is an Orthomyxovirus mainly infecting the upper respiratory tract, in numerous bird species. AIV vaccines are commonly used. . In Egypt vaccination based on commercial H5 vaccines .. This work was planned to explain that vaccination against AIV in differen stages of age could interfere with MDA. we studied the efficacy of available commercial Inactivated H5N1 vaccine (batchnumber:1901230101)againstH5N2(A/chicken/EG/16194V/2016),andH5N8(A/greenwingedteal/Egypt/871/2016(H5N8)(871/H5N8)) our experiment was achieved using commercial chicken groups which were vaccinated at one ,five ,ten and twelve day old, the chicken groups were tested every week post vaccination for the first month then follow immunity every month till the 6th month using HI test, then challenge test were conducted at 2nd ,3rd and 4th weeks PV using the recently isolated H5N2 and H5N8 field isolate strains challenge virus, tracheal and cloacal swabs were collected for detection of virus shedding which was calculated according to Spearman-Karber method (1961).Our results recorded that HI test against H5N1 , H5N2 and H5N8 viruses had no great significant difference between groups . Results of the challenge test against H5N2 virus revealed 0%, 0%, 60 % 20 %, 30%, 40% ,40 ,%50%,70% ,40% ,60%, and 80% of protection in gps .E1,E3,E5,F1,F3,F5,H1,H3,H5,I1,I3 and I5 respectively . while chllange against H5N8 virus revealed 0%, 10%, 10 % 10 %, 20%, 30% ,30 ,%40%,50% ,30% ,40%, and 70% of protection in gps .E2,E4,E6,F2,F4,F6,H2,H4,H6,I2,I4 and I6 respectively . Our study proved that maternal antibodies interfere with vaccination at one and five days of chicken age.