Screening chickens for endogenous virus ev21 viral element by the polymerase chain reaction.

The molecular architecture of the sex-linked late-feathering region of the chicken genome is still poorly defined. Current evidence points to a strong association between the presence of the endogenous viral element ev21 and the late-feathering phenotype. However, analysis at the molecular level has demonstrated that this is not a simple case of insertional mutagenesis. Instead, the structure of the region of the chicken genome containing the feathering locus is complex and variable between and within lines of chickens. Significant clues to the molecular structure of this genomic region can be obtained by analyzing rare and revertant genotypes. However, searching for rare genotypes can only be carried out effectively using quick screen methodology. This paper describes a quick, polymerase chain reaction-based test for ev21 that facilities the search for rare genotypes.