ABSTRACT
Fowl adenovirus serotype 4 (FAdV-4) strain SD1511 was isolated from chickens with severe inclusion body hepatitis and hydropericardium syndrome in Shandong Province, China. The isolate was cultured in primary chicken embryo kidney cells. A study of pathogenicity indicated that SD1511 readily infected 7-35-d-old chickens by intramuscular injection and intranasal and oral routes, causing 50%-100% mortality. The 35-d-old chickens suffered more severe infection than 7- and 21-d-old chickens with mortality highest in the intramuscular injection group. The serum from surviving chickens showed potent viral neutralizing capability. The complete genome of SD1511 was sequenced and analyzed. The strain was found to belong to the FAdV-4 cluster with more than 99% identity with the virulent FAdV-4 strains isolated in China in recent years except for some distinct variations, including deletions of open reading frame 27 (ORF27), ORF48, and part of ORF19. Our findings suggest that SD1511 might be used as a prototype strain for the study of pathogenesis and vaccine development.
Subject(s)
Animals , Antibodies, Neutralizing , Aviadenovirus/pathogenicity , Cell Line , Chick Embryo/virology , Chickens/virology , China , Gene Deletion , Genetic Variation , Genome , Genome, Viral , Genomics , Kidney/virology , Liver/virology , Open Reading Frames , Poultry Diseases/virology , Serogroup , Viral Load , Virulence , Virus Diseases/virologyABSTRACT
Two-day-old specific pathogen-free (SPF) chickens were divided into two groups. Group I was inoculated orally with fowl adenovirus VIII (FAV-VIII). Group II served as a negative control. Chickens were investigated at various days post-inoculation (dpi) by flow cytometric analysis for changes in T lymphocyte subpopulations in immune system and blood. In the thymus, CD3+ T lymphocytes were increased at 25 dpi, with significant increases in the FAV infected noted at 1, 12, 20dpi (p<0.05). This was accompanied by a corresponding increase of CD4+ and CD8+ T lymphocytes. In the spleen, CD3+ and CD4+ T lymphocytes were increased significantly at 30 dpi (p<0.01) whereas CD8+ and TCR γ δ+ T lymphocytes were decreased at 1 (p<0.05), 30 dpi (p<0.01). An increase of CD3+, CD4+ and CD8+ T lymphocytes was noticed in peripheral blood, and accompanied by a decrease of TCR γ δ+ T lymphocytes. These results demonstrated that infection with FAV-VIII causes significant fluctuations in T lymphocyte subpopulations in thymus, blood and spleen. It can be concluded that an infection with FAV-VIII has profound effects on the immune system, especially on cell mediated immune competency.