The Van Etten Lab studies a wide range of topics associated with the molecular biology, biochemistry, genetics, bioinformatics and ecology of viruses that infect certain unicellular, eukaryotic chlorella-like green algae. Chloroviruses are found in freshwater all over the world and have many interesting and unexpected properties. Currently, researchers are studying four host virus systems. All viruses are evolutionarily related. One interesting property of the chloroviruses is that they are among the largest viruses known, and their genomes contain as many as 16 tRNA genes and 400 protein-encoding genes. These include many genes not previously found in viruses, such as genes encoding DNA restriction and modification enzymes, hyaluronan biosynthetic enzymes, polyamine biosynthetic enzymes, and ion channels and ion transporters. The proteins encoded by many of these viruses are either the smallest or among the smallest proteins of their class. Consequently, several of the viral proteins are the subject of intensive biochemical and structural investigation.