Avian endogenous retrovirus EAV-HP shares regions of identity with avian leukosis virus subgroup J and the avian retrotransposon ART-CH.
نویسندگان
چکیده
The existence of novel endogenous retrovirus elements in the chicken genome, designated EAV-HP, with close sequence identity to the env gene of avian leukosis virus (ALV) subgroup J has been reported (L. M. Smith, A. A. Toye, K. Howes, N. Bumstead, L. N. Payne, and K. Venugopal, J. Gen. Virol. 80:261-268, 1999). To resolve the genome structure of these retroviral elements, we have determined the complete sequence of two proviral clones of EAV-HP from a line N chicken genomic DNA yeast artificial chromosome library and from a meat-type chicken line 21 lambda library. The EAV-HP sequences from the two lines were 98% identical and had a typical provirus structure. The two EAV-HP clones showed identical large deletions spanning part of the gag, the entire pol, and part of the env genes. The env region of the EAV-HP clones was 97% identical to the env sequence of HPRS-103, the prototype subgroup J ALV. The 5' region of EAV-HP comprising the R and U5 regions of the long terminal repeat (LTR), the untranslated leader, and the 5' end of the putative gag region were 97% identical to the avian retrotransposon sequence, ART-CH. The remaining gag sequence shared less than 60% identity with other ALV sequences. The U3 region of the LTR was distinct from those of other retroviruses but contained some of the conserved motifs required for functioning as a promoter. To examine the ability of this endogenous retroviral LTR to function as a transcriptional promoter, the EAV-HP and HPRS-103 LTR U3 regions were compared in a luciferase reporter gene assay. The low luciferase activity detected with the EAV-HP LTR U3 constructs, at levels close to those observed for a control vector lacking the promoter or enhancer elements, suggested that these elements function as a weak promoter, possibly accounting for their low expression levels in chicken embryos.
منابع مشابه
Segregation of EAV-HP ancient endogenous retroviruses within the chicken population.
Avian leukosis virus subgroup J (ALV-J), an exogenous avian retrovirus, is thought to have evolved by recombination with the highly identical env gene of the endogenous avian retrovirus EAV-HP. Embryonic expression of EAV-HP env has been suggested to be associated with the induction of immunological tolerance, a feature observed in a significant proportion of meat-type chickens infected with AL...
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ورودعنوان ژورنال:
- Journal of virology
دوره 74 3 شماره
صفحات -
تاریخ انتشار 2000