Reassortment

Under reassortment or reassortment is understood in virology mixing or redistribution of genetic information between two similar viruses. Most of them are variants or subtypes of a virus species or closely related species within a genus virus. A reassortment is only possible under natural conditions if:

The first condition is satisfied only if both viruses also can infect the same host, as only then can find their genomes in a cell. The reassortierenden viruses are therefore usually not fixed to a single host, so have a low host specificity or can often adapt by variants to a new host.

The second condition is only met in some virus families, which are characterized by a segmented genome. For viruses that infect vertebrates, these are exclusively RNA viruses, namely 10-12 Reoviridae segments ( for example, the genus Rotavirus ), the 3 segments Bunyaviridae (e.g. Hantavirus genus ), the Arenaviridae 2 segments, and the Orthomyxoviridae ( 6-8 sections) with the best known example, in the genus influenza virus A.

Result of a reassortment

The result of a reassortment is the sudden emergence of a genetically very divergent variant that contains segments of two mixed viral genomes. If the segments have reassortment mixes the capsid proteins of a virus for the surface proteins, or (for non-enveloped viruses), the result is a sudden change of the epitopes on the viral surface. This phenomenon as a result of reassortment is called antigenic shift (English antigenic shift ).

Reassortment are rare because of the necessary infection of a host with two viruses in natural habitats. Also the result of a reassortment in most cases, viruses that are not or only partially capable of reproduction or the progeny virus is produced, the target cell can no longer recognize with their new surface proteins. The probability of reassortment then increases significantly when two populations ( eg, humans and pigs or chickens birds) with different viral variants in large numbers and density have the possibility of mutual infection.

Reassortment with non- the animal viruses

In addition to the virus families mentioned above, there are other families or genera with a segmented genome, but only infect bacteria, plants, fungi or insects. Even with these reassortment has been described. These are:

• Genus Nano Virus ( plant virus ): 6-9 segments ssDNA
• Family Cystoviridae ( bacteriophages ): 3 dsRNA segments
• Family Chrysoviridae ( fungal viruses): 4 dsRNA segments
• Genus Varicosavirus ( plant viruses ): 2 segments ssRNA
• Genus Tenuivirus ( plant and insect viruses): 3-4 segments ssRNA
• Genera Sadwavirus and Cheravirus ( plant viruses ): 2 segments ssRNA
• Family Comoviridae ( plant viruses ): 2 segments ssRNA
• Genera Tobravirus and Furovirus ( plant viruses ): 2 segments ssRNA
• Genera Hordeivirus and Pomovirus ( plant viruses ): 3 segments ssRNA
• Family Bromoviridae ( plant viruses ): 3 segments of ssRNA