Assessing the Roles of Endogenous Retrovirus EAV-HP in Avian Leukosis Virus Subgroup J Emergence and Tolerance
AUTOR(ES)
Sacco, Melanie A.
FONTE
American Society for Microbiology
RESUMO
Avian leukosis virus (ALV) subgroup J is thought to have emerged through a recombination event between an unknown exogenous ALV and the endogenous retrovirus elements designated EAV-HP. All EAV-HP elements identified to date in the chicken genome show large deletions, including that of the entire pol gene. Here we report the identification of four segregating chicken EAV-HP proviruses with complete pol genes, one of which shows exceptionally high sequence identity and a close phylogenetic relationship with ALV-J with respect to the env gene. Embryonic expression of EAV-HP env has been suggested as a factor associated with immunological tolerance induction in a proportion of ALV-J-infected meat-type chickens. In support of this, env gene transcripts expressed from two of the four newly identified EAV-HP proviruses were demonstrated in chicken embryos. However, when ALV-J-infected outbred meat-type chickens were assessed, the presence of intact EAV-HP proviruses failed to directly correlate with ALV-J tolerance. This association was further examined using F2 progeny of two inbred lines of layer chicken that differed in EAV-HP status and immunological responses to ALV-J. Immunological tolerance developed in a small proportion of F2 progeny birds, reflecting the expected phenotypic ratio for inheritance of a double-recessive genotype; however, the status of tolerance did not show any direct correlation with the presence of the intact EAV-HP sequence. Nevertheless, identification of an intact chicken EAV-HP locus showing a uniquely close relationship to the ALV-J prototype clone HPRS-103 in the env region provides the strongest evidence of its contribution to the emergence of ALV-J by recombination.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=516401Documentos Relacionados
- Avian Endogenous Retrovirus EAV-HP Shares Regions of Identity with Avian Leukosis Virus Subgroup J and the Avian Retrotransposon ART-CH
- Intact EAV-HP Endogenous Retrovirus in Sonnerat's Jungle Fowl
- Segregation of EAV-HP Ancient Endogenous Retroviruses within the Chicken Population
- The Unique Envelope Gene of the Subgroup J Avian Leukosis Virus Derives from ev/J Proviruses, a Novel Family of Avian Endogenous Viruses
- HPRS-103 (exogenous avian leukosis virus, subgroup J) has an env gene related to those of endogenous elements EAV-0 and E51 and an E element found previously only in sarcoma viruses.