Iridoviridae

Electron micrograph of an Iridovirus

Iridoviridae is a family of viruses that primarily infect invertebrates and cold-blooded vertebrates, such as fish, amphibians, and reptiles. Members of this family are known for their large, icosahedral virions and double-stranded DNA genomes.

Structure

Iridoviruses are characterized by their large, icosahedral capsids, which can range from 120 to 350 nm in diameter. The capsid is composed of multiple protein subunits that form a protective shell around the viral genome. The genome itself is a linear, double-stranded DNA molecule, which can vary in size from 140 to 303 kilobase pairs, depending on the specific virus.

Genome

The genome of iridoviruses is composed of double-stranded DNA, which encodes a variety of proteins necessary for viral replication and infection. These proteins include enzymes involved in DNA replication, transcription, and modification, as well as structural proteins that form the viral capsid.

Replication

Iridoviruses replicate within the cytoplasm of the host cell. The replication cycle begins with the attachment of the virus to the host cell surface, followed by entry into the cell. Once inside, the viral DNA is released into the cytoplasm, where it is transcribed and replicated. New virions are assembled in the cytoplasm and are eventually released from the host cell, often causing cell lysis.

Pathogenesis

Iridoviruses can cause a range of diseases in their hosts, from mild infections to severe, systemic diseases. In fish, iridoviruses are responsible for diseases such as lymphocystis and epizootic haematopoietic necrosis. In amphibians, they can cause ranavirus infections, which have been associated with significant declines in amphibian populations worldwide.

Ecological Impact

Iridoviruses play a significant role in the ecology of aquatic environments. They can affect the population dynamics of their host species, particularly in cases where they cause high mortality rates. This can have cascading effects on the ecosystem, influencing predator-prey relationships and the overall biodiversity of the environment.

Research and Applications

Research on iridoviruses has provided insights into viral evolution, host-virus interactions, and the mechanisms of viral pathogenesis. Understanding these viruses is important for the development of strategies to manage and control viral diseases in aquaculture and wild populations.

Related pages

• Virus
• DNA virus
• Icosahedral virus
• Ranavirus