Myxoma virus

Myxoma virus
Virus classification
Group:	Group I (dsDNA)
Family:	Poxviridae
Genus:	Leporipoxvirus
Species:	Myxoma virus

The Myxoma virus causes Myxomatosis in rabbits and was used as a pest control in Australia.

Structure

Virions are enveloped, have a surface membrane with lateral bodies. The envelope contains host-derived lipids and self-synthesized glycolipids. They are brick shaped and are about 250 nm in diameter, 300 nm in length and 200 nm in height. The middle contains a bi-concave core which appears to be characteristic to many poxviruses.

The genome encodes 171 open reading frames.

Genome

The genome is non-segmented and contains a single molecule of linear double-stranded DNA, 160000 nucleotides in length. The genome has a G-C content of ~40% with terminally redundant sequences which is repeated at both ends^[1].

Infection and Pathology

During their normal life cycle, virions produce extracellular and intracellular proteins. The extracellular proteins are used primarily for suppressing or circumventing the host immune responses, and hence are non-essential. Infection is also initiated by extracellular virions. The Myxoma virus mature naturally by budding through the surface membrane of the host cell^[2].

Pathology in rabbits

Most other rabbit and hare hosts are susceptible to the virus. This means that many species of rabbits and hares have the receptor with which the virus is able to get into the cell. However, susceptibility is not the primary indicator for symptomatic infection or pathology. A distinction must be made between susceptibility and permissibility, in which only the latter must be true before the virus is able to replicate in the cell and cause pathologies. This is the reason that Myxoma virus is very species specific; it is able to circumvent a certain species of rabbit's immune response, but is unable to do so for any other species. However, the virus is able to get into the cells of many different species of rabbits and hares, which is generally useless if it is unable to replicate and avoid the immune system.

Literature

1. ^ Cheryl Cameron et al. "The Complete DNA Sequence of Myxoma Virus." Virology, Volume 264, Issue 2, 25 November 1999, Pages 298-318.
2. ^ ICTVdB Management (2006). 00.058.1.05.001. Myxoma virus. In: ICTVdB - The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA.