MinakshiGupta, Om Narayan2017-08-162017-08-162008http://krishikosh.egranth.ac.in/handle/1/5810028719Avian adenoviruses (AAV) are diverse group of pathogens causing variety of problems for poultry production. Most of them are regarded as complicating organisms in diseases primarily induced by other agents or as component of multifactorial problems. However A few AAVs are considered exceptionally highly pathogenic for chickens such as fowl adenovirus (FAV) causing hydropericardium syndrome (HPS) and inclusion body hepatitis (IBH). These diseases have posed a serious threat to poultry industry by causing severe economic losses through out the country in recent year. Antigenically, FAV is very complex and is reflected by the presence of 12 different serotypes. The major virus surface protein of adenovirus is the “hexon protein” on which, type, group and subgroup antigenic determinants are located. With a need for more rapid, sensitive and specific detection procedures, PCR assays of variable region of hexon gene combined with restriction endonuclease analysis have been proved to be very suitable. PCR-RFLP and nucleotide sequencing of locally prevalent AAV strains circulating in poultry population would eventually help in formulation of comprehensive disease diagnosis and control strategies. To address these concerns, the present study was undertaken to characterize AAVs circulating in this area. A total of 245 tissue samples from, chickens were screened 31 (12.4%) were found positive by PCR. Twenty-nine Positive samples were from 100 liver tissues suspected for IBH (29%). One tissue from trachea of chicken diagnosed with respiratory disease, and one from intestine of apparently healthy chicken was found positive. PCR-RFLP of hypervariable region hexon gene revealed presence of three FAV serotypes (FAV-4, FAV-9, and FAV-12) in Haryana state. Based on RFLP pattern, Out of 31 positive samples 25 (80%) were found to be FAV-12 indicating it as a major cause of IBH in this state. Representative of all three serotypes were also isolated in CEL cell culture and tested by PCR. Amplified partial length hexon gene hypervariable region were cloned and screened by touch PCR. The positive recombinant bacterial colonies were subjected to sequencing. The sequences were analysed using BlastN and aligned by Clustal X. The percent identity and distance matrices of the partial hexon gene sequences of Haryana isolates with representatives of all FAV serotypes from other countries were generated by MEGA version 4. Phylogenetic trees were constructed by analyzing nucleotide sequences by MEGA 4 software. Sequence comparision studies revealed that Indian sequences might have originated from Canada, U.S.A. or Belgium. Hence, it can be concluded that hypervariable L1 loop region of hexon gene of FAV might be useful in determining the evolution of virus. In conclusion, the vaccine strain used in Haryana is specific for HPS but not effective against various other serotypes associated with IBH cases in this region. Since incidence of IBH is several times more than HPS and so are the economic losses pertaining to it, hence there is strict need to formulate a vaccine which takes in to account multiple serotypes circulating in this region.enThesis