Sequences derived from parvoviruses (family Parvoviridae) are relatively common in animal genomes, but the functional significance of these endogenous parvoviral element (EPV) sequences remains unclear. In this study we use a combination of in silico and molecular biological approaches to investigate a fusion gene encoded by guinea pigs (genus Cavia) that is partially derived from an EPV. This gene, named enRep-Myo9, encodes a predicted polypeptide gene product comprising a partial myosin9 (Myo9)-like gene fused to a 3′ truncated, EPV-encoded replicase. We first examined the genomic and phylogenetic characteristics of the EPV locus that encodes the viral portions of enRep-Myo9. We show that this locus, named enRep, is specific to guinea pigs and derives from an ancient representative of the parvoviral genus Dependoparvovirus that integrated into the guinea pig germline 22-35 million years ago. Despite these ancient origins, however, the regions of enRep that are incorporated into the coding sequence of the enRep-Myo9 gene are conserved across multiple species in the family Caviidae (guinea pigs and cavies) consistent with purifying selection. Using molecular biological approaches, we further demonstrate that: (i) enRep-Myo9 mRNA is broadly transcribed in guinea pig cells; (ii) the cloned enRep-Myo9 transcript can express a protein of the expected size in guinea pig cells in vitro, and; (iii) the expressed protein localizes to the cytosol. Our findings demonstrate that, consistent with a functional role, the enRep-Myo9 fusion gene is evolutionarily conserved, broadly transcribed, and capable of expressing protein.

Molecular properties and evolutionary origins of a parvovirus-derived myosin fusion gene in guinea pigs