A Viral Biorealm page on the Rudiviridae
Higher order taxa
Viruses; dsDNA viruses, no RNA stage; Rudiviridae
Description and Significance
Rudiviridae is a family of recently discovered viruses which infect crenarchaeota. Rudiviruses were first isolated from acidic hot springs in Iceland. Not much is known about crenarchaeal viruses due to their recent discovery, but they are a growning area of interest due to the fact that they are good models for understanding the biochemistry and molecular biology required for life at high temperatures. (sources: Ortmann et al., Rice et al.)
The Rudivirus genome is non-segmented and contains a molecule of linear, double-stranded DNA. The genome is 32,312- 35,502 nucleotides long. The DNA forms a superhelix with a single basic 15.8-kD binding protein. The two strands of DNA are covalently linked to form a continuous polynucleotide chain. The DNA has three tail fibers at the end. (sources: ICTVdB, Prangishvili et al., Peng et al.)
Virion Structure of a Rudivirus
Rudivirus virions consist of a capsid. The capsid is a non-enveloped, elongated, rigid rod shape which exhibits icosahedral symmetry. The virion particles are 600-900 nm in length and 23 nm in width. Rudivirus virions resemble some RNA plant virus virions. (sources: ICTVdB, Ortmann et al.)
Reproduction Cycle of a Rudivirus in a Host Cell
The basic replication cycle of crenarchaeal viruses, including Rudiviruses, has yet to be determined. There are, however, some trends which have been reported. It is thought that members of the Rudiviridae family, as well as members of the Fuselloviridae, Lipothrixviridae, and Guttaviridae families, associate with host cells by tail fibers which are present on one or both ends of the virion. Some viruses integrate their genome into the host cell's chromosome, while others maintain their genomes as extrachromosomal elements. The DNA replication of Rudiviruses are thought to be similar to that of the eukaryal poxviruses.
Assembly and release of Rudiviruses, as well as most known crenarchaeal viruses, do not require cell lysis. Most crenarchaeal viruses, the Rudiviridae included, appear to set up chronic infections, either continually producing virus particles or doing so in short events resulting in growth inhibition. These long-term chronic infections are thought to be an adaptation to the extremely hot and acidic environments crenarchaeal viruses inhabit. (source: Ortmann et al.)
Viral Ecology & Pathology
Rudiviruses infect only Sulfolobus and Acidianus species. As mentioned above, Rudiviruses set up chronic infections in their hosts, neither lysing nor killing the host cells. (sources: Ortmann et al., Prangishvili et al.)
Ortmann et al. "Hot crenarchaeal viruses reveal deep evolutionary connections." Nature Reviews Microbiology 4 (2006): 520-528.
Peng et al. "Sequences and Replication of Genomes of the Archaeal Rudiviruses SIRV1 and SIRV2: Relationships to the Archaeal Lipothrixvirus SIFV and Some Eukaryal Viruses." Virology 29.2 (2001): 226-234.