RT Journal Article SR Electronic(1) A1 Le Goff, Frédérick A1 Méderlé-Mangeot, Isabelle A1 Jestin, André A1 Langlois, PatrickYR 2005 T1 Deletion of open reading frames 9, 10 and 11 from the avian adenovirus CELO genome: effect on biodistribution and humoral responses JF Journal of General Virology, VO 86 IS 7 SP 2019 OP 2027 DO https://doi.org/10.1099/vir.0.80879-0 PB Microbiology Society, SN 1465-2099, AB In this study, the in vivo effect of the 3·6 kbp deletion of the three open reading frames (ORF) 9, 10 and 11 found at the right end of the CELO genome was examined. Groups of chickens were inoculated oronasally with 105–107 p.f.u. per animal of wild-type virus and two recombinant CELO strains (rCELO) expressing luciferase and secreted alkaline phosphatase (SEAP). The tissue biodistribution, assessed by PCR, was similar for both wild-type and recombinant viruses. The infectious viral particle titre was determined by a p.f.u. counting method and the antibody responses to the CELO vector and the SEAP antigen were evaluated by ELISA. Infectious particle titres in tissues from chickens inoculated with the wild-type CELO virus increased up to 6 days post-inoculation, and declined until 11 days while titres in organs from chickens inoculated with the rCELO strain were low and only detectable at 4 days post-inoculation. Moreover, although anti-CELO antibody levels were three times lower in sera from chickens inoculated with rCELO, antibodies directed to the heterologous SEAP antigen were detected. Based on these results, no differences in tropism were observed, but the level of production of viral particles and the humoral responses appeared to decrease. Viruses replicate less efficiently with a deletion performed at the right end of the CELO genome. Nevertheless, the presence of antibodies directed to heterologous antigens makes the CELO virus an advantageous candidate for avian vaccination., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.80879-0