Molecular Properties and Evolutionary Origins of a Parvovirus-Derived Myosin Fusion Gene in Guinea Pigs.

Sequences derived from parvoviruses (family ) are relatively common in animal genomes, but the functional significance of these endogenous parvoviral element (EPV) sequences remains unclear. In this study, we used a combination of and molecular biological approaches to investigate a fusion gene carried by guinea pigs (genus ) that is partially derived from an EPV. This gene, named , encodes a predicted polypeptide gene product comprising a partial 9-like () gene fused to a 3' truncated, EPV-encoded replicase. We examined the genomic and phylogenetic characteristics of the EPV locus () that encodes the viral portions of , revealing that it derives from an ancient dependoparvovirus (genus ) that was incorporated into the guinea pig germ line between approximately 22 and 35 million years ago (MYA). Despite these ancient origins, the regions of the locus that are expressed in the gene are conserved across multiple species in the family Caviidae (guinea pigs and cavies), consistent with a potential function at the amino acid level. Using molecular biological approaches, we further demonstrated that (i) mRNA is broadly transcribed in guinea pig cells, (ii) the cloned transcript can express a protein of the expected size in guinea pig cells , and (iii) the expressed protein localizes to the cytosol. Our findings demonstrate that, consistent with a functional role, the fusion gene is evolutionarily conserved, broadly transcribed, and capable of expressing protein. DNA from viruses has been "horizontally transferred" to mammalian genomes during evolution, but the impact of this process on mammalian biology remains poorly understood. The findings of our study indicate that a novel gene has evolved in guinea pigs through fusion of host and virus genes.