In a new paper in Virology Journal, Ogata et al. describe the PolB gene of a marine giant virus (AKA "girus") that infects a dinoflagellate. Dinoflagellates can poison fish and other marine critters when they bloom, but the dinoflagellate Heterocapsa circularisquama can be killed by Heterocapsa circularisquama DNA virus (HcDNAV). HcDNAV is a "giant virus" because it's giant, around 200 nm with a 356,000 nucleotide genome. Compared to the usual viruses that we're familiar with, that's quite big, actually approaching the size of the smallest bacteria.
Ogata et al.'s results indicate that the PolB gene of HcDNAV is surprisingly similar to the PolB gene from African Swine Fever Virus (ASFV). ASFV is a completely terrestrial virus that lives in wild pigs and ticks, where it causes no disease. In domestic pigs, it can cause a hemorrhagic infection with very high mortality rates. Ogata et al. present further phylogenetic evidence from environmental sampling that indicate that ASFV is related to a variety of unknown marine viruses.
I wish creationist virology was advanced enough to be able to say definitively whether ASFV is really derived from a marine ancestor or whether it was created to serve some purpose for wild pigs and ticks. Whatever the creationist interpretation, giant virus research will be an interesting subject to study.
Ogata et al. 2009. Remarkable sequence similarity between the dinoflagellate-infecting marine girus and the terrestrial pathogen African swine fever virus. Virology Journal 6:178 doi:10.1186/1743-422X-6-178.