Currently there are three major classes of known viruses: exclusively RNA viruses, which do not require a DNA intermediate in their replication and propagation; DNA viruses, which use DNA dependent processes to perform their genome replication; so-called retroviruses, which go through both an RNA and a DNA phase with the help of a reverse transcriptase enzyme. Until very recently there was no evidence that there was genetic exchange between these distinct virus classes. However, a single stranded DNA (ssDNA) virus genome, recently found using metagenomics in Boiling Springs Lake in Lassen Volcanic National Park, USA (BSL) contains elements homologous to both ssRNA and ssDNA viruses. The genome of this RNA-DNA hybrid virus (BSL-RDHV) contains a gene similar to that of ssDNA circoviruses that infect animals and a capsid protein (CP) gene similar to that of the ssRNA tombusviruses that infect plants. It is currently unclear how the RNA virus capsid gene integrated into the DNA virus genome and what, if any, evolutionary impacts are associated with this recombination. My current work focuses on the characterization of the BSL-RDHV CP using recombinantly expressed protein. The CP gene will be amplified from the BSL viral metagenome using Polymerase Chain Reaction and expressed in bacterial cells. The long term goal is to determine the structure of this protein using X-ray crystallography and use the protein for in vitro assembly reactions. Successful completion of this work will be an important step towards understanding virus evolution and possibly the emergence of novel virus disease.