New, closely related haloarchaeal viral elements with different nucleic Acid types.
During the search for haloarchaeal viruses, we isolated and characterized a new pleomorphic lipid-containing virus, Haloarcula hispanica pleomorphic virus 1 (HHPV-1), that infects the halophilic archaeon Haloarcula hispanica. The virus contains a circular double-stranded DNA genome of 8,082 bp in size. The organization of the genome shows remarkable synteny and amino acid sequence similarity to the genome and predicted proteins of the halovirus HRPV-1, a pleomorphic single-stranded DNA virus that infects a halophilic archaeon Halorubrum sp. Analysis of the two halovirus sequences, as well as the entire nucleotide sequence of the 10.8-kb pHK2-plasmid and a 12.6-kb chromosomal region in Haloferax volcanii, allows us to suggest a new group of closely related viruses with genomes of either single-stranded or double-stranded DNA. Currently, closely related viruses are considered to have the same genome type. Our observation clearly contradicts this categorization and indicates that we should reconsider the way we classify viruses. Our results also provide a new example of related viruses where the viral structural proteins have not diverged as much as the proteins associated with genome replication. This result further strengthens the proposal for higher-order classification to be based on virion architecture rather than on genome type or replication mechanism.
Roine
Elina
E
Department of Biosciences and Institute of Biotechnology, P.O. Box 56 (Viikinkaari 5), University of Helsinki, FIN-00014 Helsinki, Finland. elina.roine@helsinki.fi
Kukkaro
Petra
P
Paulin
Lars
L
Laurinavicius
Simonas
S
Domanska
Ausra
A
Somerharju
Pentti
P
Bamford
Dennis H
DH
D023641:Archaeal Viruses / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D004279:DNA, Viral / Q000032:analysis*; D016679:Genome, Viral; D019613:Haloarcula / Q000821:virology*; D016366:Open Reading Frames; D010743:Phospholipids / Q000032:analysis; D010957:Plasmids; D014764:Viral Proteins / Q000032:analysis
D004279:DNA, Viral; D010743:Phospholipids; D014764:Viral Proteins