The EAV-HP group of chicken endogenous retrovirus elements was previously shown to be defective, with large deletions of the pol gene. In this report, we demonstrate that genomes of other Gallus species also maintain EAV-HP elements with similar deletions. The chicken EAV-HP1 locus was detected in both red (Gallus gallus gallus) and Sonnerat's (Gallus sonneratii) jungle fowl with identical integration sites, indicating that these elements had integrated before separation of the Gallus species. Furthermore, we demonstrate for the first time that the G. sonneratii genome carries EAV-HP elements with intact pol regions.The EAV-HP (also designated ev/J), the most recently identified members of the endogenous avian retrovirus (EAV) family, are present in Gallus species as 10 to 15 copies per genome (12). Four different structures of EAV-HP proviruses have been identified in the chicken genome. Three of these 4-kbplong provirus structures, designated types I, II, and III, show large deletions spanning the entire pol gene and parts of the gag and env regions. Each structure has a different gag-env deletion junction, with the type II and III provirus deletions extending an additional 57 and 86 bp, respectively, than the smallest (type I) provirus deletion size (9, 10). These proviruses are found at multiple loci, with the type I provirus appearing to be the most abundant, based on its frequency in clones randomly screened from separate chicken genomic DNA libraries (9, 10). A single clone, designated ev/J clone 4-1, forms the fourth type of proviral structure, comprising a cDNA of the env subgenomic transcript bounded by long terminal repeats (LTRs) (9). The EAV-HP proviruses are more than 97% identical to the newly emerged subgroup J avian leukosis virus (ALV-J) env gene and demonstrate Ͼ96% sequence identity to other EAV family members in the R and U5 regions, the 5Ј untranslated region, and portions of the gag gene (6, 9, 10).Because of their distribution in several Gallus species, the EAV family is considered an ancient group of retroviruses that integrated into a common ancestor. The genus Gallus is composed of four species: the Sonnerat's or grey jungle fowl (SJF; G. sonneratii), the green jungle fowl (GJF; G. varius), the Ceylonese jungle fowl (CJF; G. lafayettei), and the red jungle fowl (RJF; G. gallus), of which domesticated chickens are a subspecies (G. gallus domesticus) (4). EAV-HP proviruses have also been detected in both RJF and SJF by hybridization of env and LTR sequences and PCR amplification of the env region (10, 12). In this study, we have used a PCR approach to examine whether (i) the EAV-HP proviruses in RJF and SJF have the same pol region deletions as in chickens, (ii) the EAV-HP1 and EAV-HP2 loci, present in chickens, could be detected in the jungle fowls, and (iii) the genomic deletion and integration events occurred before or after the separation of Gallus species.The EMBL accession numbers for the sequences described here are AJ292966 for clone EAV-JF1 and AJ292967 for EAV-JF2, which includ...