A group of researchers found a unique viral genome that has
never before been reported - a circular, single-stranded DNA
virus encoding a major capsid protein seen previously only in
RNA viruses. This unusual genome provides proof that integration
of an RNA virus into a DNA virus may have occurred between two
unrelated virus groups at some point in evolution - something
that has not been observed before. Moreover, this suggests that
entirely new virus types may emerge via recombination of
functional and structural modules between vastly different
viruses, using mechanisms that are as-yet unknown. The team
observed that the Boiling Springs Lake RNA-DNA hybrid virus (BSL
RDHV) genome is circular, but its size is roughly double that of
typical circoviruses, with the ORFs arranged in an uncommon
orientation. They compared the BSL RDHV genome to other
metagenomic DNA sequences from the Global Ocean Survey, and
found strong evidence to conclude that previously undetected BSL
RDHV-like viruses could be widespread in