The Complete Sequence of a Reticuloendotheliosis Virus Isolated from Chickens

Abstract

Reticuloendotheliosis virus (REV) causes runting, immunosuppression, and chronic neoplasia in a variety of birds, including chickens. Its serological prevalence reaches 95% in adult chickens in Taiwan. A REV from blood samples in a male 32-week-old broiler breeder farm in Changhua was isolated in July, 2005. The complete proviral sequence of this isolate was determined. Its proviral genome is 8,238 nucleotides in length and exhibits a genetic organization characteristic of replication-competent Gammaretroviruses. The provirus contains two identical long terminal repeats (LTR) and a complete set of genes including gag, poi and env. Alignments with other REV sequences showed high similarity. The whole gene of the present REV gene showed high nucleotide sequence identity with REV sequences inserted in fowl poxvirus (98.7%). Sequences coding for a previously reported immunosuppressive peptide contained in the transmembrane region of the env gene were well conserved in this REV. Comparing with reference REV strains, the LTR was the most divergent region, which could be use for epidemiological investigation.