Iridoviridae

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Iridoviridae
Kingdom:	Varidnaviria
Phylum:	Nucleocytoviricota
Class:	Megaviricetes
Order:	Iridescentvirales
Family:	Iridoviridae

Iridoviridae is a family of viruses that primarily infects invertebrates and ectothermic vertebrates, such as fish, amphibians, and reptiles. Members of this family are known for their large, icosahedral virions and their ability to cause significant disease in their hosts. The family Iridoviridae is part of the order Iridescentvirales and is classified within the class Megaviricetes.

Structure

Iridoviruses are characterized by their large, icosahedral capsids, which can range from 120 to 350 nm in diameter. The virions have a complex structure with a lipid membrane surrounding the capsid. The genome of iridoviruses is composed of a single molecule of double-stranded DNA, which can be as large as 280 kilobase pairs, encoding approximately 100 to 200 proteins.

Genome and Replication

The genome of iridoviruses is linear and double-stranded, with terminally redundant sequences. Replication occurs in the cytoplasm of the host cell, although some early transcription events may occur in the nucleus. The replication cycle involves the synthesis of viral mRNA, which is translated into viral proteins that assist in the replication of the viral DNA and the assembly of new virions.

Pathogenesis

Iridoviruses are known to cause a range of diseases in their hosts, often leading to high mortality rates. In fish, they can cause systemic infections that result in symptoms such as hemorrhaging, necrosis, and organ failure. In amphibians, iridoviruses are associated with mass die-offs and have been implicated in the global decline of amphibian populations. The pathogenesis of iridoviruses involves the evasion of host immune responses and the induction of apoptosis in host cells.

Ecological and Economic Impact

Iridoviruses have significant ecological and economic impacts, particularly in aquaculture and wildlife conservation. In aquaculture, iridovirus outbreaks can lead to substantial economic losses due to the high mortality rates in fish populations. In natural ecosystems, iridoviruses can affect biodiversity by causing declines in amphibian and reptile populations.

Research and Control

Research on iridoviruses focuses on understanding their molecular biology, pathogenesis, and host interactions. Efforts to control iridovirus infections include the development of vaccines and the implementation of biosecurity measures in aquaculture facilities. Understanding the mechanisms of iridovirus transmission and infection is crucial for developing effective control strategies.

Also see

• Virus classification
• Viral replication
• Fish virology
• Amphibian diseases
• Reptile diseases