Novel avian leukosis virus-related endogenous proviruses from layer chickens: characterization and development of locus-specific assays.
During the course of evolution, vertebrate genomes have been invaded and colonized by retroviruses. In humans, for example, endogenous retroviruses (long terminal repeat elements) occupy roughly twice as much sequence space as essential genes. There are numerous reports in the literature implicating endogenous proviruses in the modulation of host physiology. The fact that many of these host-virus interactions take place in a proviral locus-specific manner speaks to the need for rapid assays for element profiling. This report deals with the identification of novel elements belonging to a family of endogenous retroviruses, designated ALVE, that reside in the genome of the chicken and that are closely related to exogenous avian leukosis viruses. The study of ALVE elements in the chicken genome serves as a model system for understanding the interplay between endogenous viruses and their vertebrate hosts in general, including humans. In this report, we present locus-specific, diagnostic PCR-based assays for 2 novel ALVE elements. In addition, we characterize the proviral structures and examine the genomic environments of both novel elements along with a previously described element known as ALVE-NSAC-3.