Myxoma virus
Encyclopedia
The Myxoma virus causes Myxomatosis
in rabbits and was used as a pest control in Australia
.
, 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.
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.
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.
Myxomatosis
Myxomatosis is a disease that affects rabbits and is caused by the Myxoma virus. It was first observed in Uruguay in laboratory rabbits in the late 19th century. It was introduced into Australia in 1950 in an attempt to control the rabbit population...
in rabbits and was used as a pest control in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
Structure
Virions are envelopedCell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
, have a surface membrane with lateral bodies. The envelope contains host-derived lipids and self-synthesized
Biosynthesis
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
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.Infection and Pathology
During their normal life cycle, virions produce extracellularExtracellular
In cell biology, molecular biology and related fields, the word extracellular means "outside the cell". This space is usually taken to be outside the plasma membranes, and occupied by fluid...
and intracellular
Intracellular
Not to be confused with intercellular, meaning "between cells".In cell biology, molecular biology and related fields, the word intracellular means "inside the cell".It is used in contrast to extracellular...
proteins. The extracellular proteins are used primarily for suppressing or circumventing the host immune responses
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
, 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.
Pathology in rabbits
Most other rabbitRabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
and hare
Hare
Hares and jackrabbits are leporids belonging to the genus Lepus. Hares less than one year old are called leverets. Four species commonly known as types of hare are classified outside of Lepus: the hispid hare , and three species known as red rock hares .Hares are very fast-moving...
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
Permissive
When a cell or host is defined as permissive in virology, it refers to the fact that the virus is able to circumvent host defenses and is able to replicate. Usually this occurs when the virus has modulated one or several of the host cellular intrinsic defenses, and the host immune system...
, 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
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
of many different species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of rabbits and hares, which is generally useless if it is unable to replicate and avoid the immune system.