E (XSR) element contributes to the oncogenicity of Avian leukosis virus (subgroup J).
Among the six subgroups of Avian leukosis virus (ALV) that infect chickens, subgroup J (ALV-J) was isolated from meat-type chickens where it predominantly induces myeloid leukosis (ML) and erythroblastosis (EB). The sequence of HPRS-103, the ALV-J prototype virus, shows several distinct features, one of which is the presence of a distinct hairpin stem-loop structure called the E (also called XSR) element in the 3' untranslated region. In order to determine the role of the E element in ALV-induced pathogenicity, a comparison was made of the oncogenicity of viruses derived from the provirus clones of parental and E element-deleted HPRS-103 viruses in two genetically distinct lines of birds. In line 15I birds, deletion of the E element had profound effects on virus replication in vivo, as only 55 % of birds showed evidence of infection, compared with 100 % infection by the parental virus. Furthermore, none of the line 15I birds infected with this virus developed tumours, indicating that the E element does contribute to the oncogenicity of the virus. On the other hand, deletion of the E element had only a marginal effect on the incidence of tumours in line 0 birds. These results indicate that, although the E element per se is not absolutely essential for tumour induction by this subgroup of viruses, it does contribute to oncogenicity in certain genetic lines of chicken.
Chesters
Peter M
PM
Viral Oncogenesis Group, Division of Microbiology, Institute for Animal Health, Compton, Berkshire RG20 7NN, UK.
Smith
Lorraine P
LP
Viral Oncogenesis Group, Division of Microbiology, Institute for Animal Health, Compton, Berkshire RG20 7NN, UK.
Nair
Venugopal
V
Viral Oncogenesis Group, Division of Microbiology, Institute for Animal Health, Compton, Berkshire RG20 7NN, UK.
D020413:3' Untranslated Regions; D000818:Animals; D001353:Avian Leukosis / Q000209:etiology* / Q000473:pathology / Q000821:virology; D001354:Avian Leukosis Virus / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D001483:Base Sequence; D002642:Chick Embryo; D002645:Chickens; D004279:DNA, Viral / Q000737:chemistry* / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017384:Sequence Deletion; D014774:Virulence / Q000235:genetics
D020413:3' Untranslated Regions; D004279:DNA, Viral