Reassoment is seen in aEUR'
Rotavirus If a virus has a segmented genome and if two variants of that virus infect a single cell, progency virions can result with same segments from one parent and some from the other. This process is called "reassoment" of the virus. - Normally when a segmented virus infects a cell, the individual RNA segments enter the nucleus of the host. - There they are copied many times over to form RNA genomes, for new infectious virions. - The new RNA segments are expoed to the cytoplasm where they are assembled into new virus paicles which buds from the cell. If a cell is infected simultaneously with two different segmented viruses, the RNA of both the viruses are copied in the nucleus. These segmented viruses undergo a kind of "gene swapping or exchange" i.e., segments from viruses are interchanged or transferred to each other. - As a result new virus paicles emerge that contain RNA segments from both the viruses. - These new viruses are called "reassoants" and the process is called reassoment. Reassoment is an efficient process but is limited to the viruses with "segmented genomes". So far the only human viruses characterized with segmented genomes are RNA viruses e.g., ohomyxoviruses, reo viruses, arenaviruses, Bunya viruses. - In paicular reassoment is characteristic of "influenza viruses" whose genomes consists of eight distinct segment of RNA. - Reassoment is responsible for some of the major genetic shifts in the history of influenza virus which has lead to epidemics. Reassoment in Rotavirus Rotavirus is an impoant cause of severe diarrhea in infants and young children. Rotavirus are segmented virus - Due to segmented nature of their genome rotavirus can exchange (reasso) genes during coinfection a features that ispredicted to generate new possibly more dangerous virus strains. - However the amount of gene reassoment occurring in nature is not known as very few Rotavirus genomes have been segmented. - In contrast to what was previously thought very few Rota viruses exchanged gene segments with each other: instead the genomic constillations of the viruses remained relatively stable.
Astronovirus
Rotavirus
Hepadnavirus
Herpesvirus