Prior to budding, the virus may put its own receptor onto the surface of the cell in preparation for the virus to bud through, forming an envelope with the viral receptors already on it. These include enveloped viruses such as HSV, SARS, or smallpox. “Budding” through the cell envelope, in effect using the cell’s membrane for the virus itself is most effective for viruses that need an envelope in the first place. It also depends on where the virus ‘bud’ off from the host.īudding is a method which viruses use to exit the cell. The viral envelope is the typical lipid bilayer, derived from the host cell itself and sources usually come from the nuclear membrane, endoplasmic reticulum, Golgi apparatus/body, and plasma membrane. However, they require an envelope to enclose the DNA as well as to bind with the other healthy cells so that they can infect. When the virus has replicated and multiplied, they would want to leave the infected cell and infect other cells. Aside from this, assembly also occurs in the viroplasm which is an inclusion body in a cell. Virus assembly depends on the site of synthesis and such sites are the nucleus, endoplasmic reticulum, and the Golgi apparatus aka Golgi body. For example, synthesis and replication for DNA viruses occur in the cell’s nucleus while it is usually the cytoplasm for RNA viruses. Once replication has been completed and the host cell is exhausted of all resources in making viral progeny, the viruses may begin to leave the cell by several methods.ĭifferent types of virus have varying sites of synthesis and replication. Viral shedding refers to the successful reproduction, expulsion, and host-cell infection caused by virus progeny. During this process the virus acquires its envelope, which is a modified piece of the host’s plasma or other, internal membrane. Enveloped viruses (e.g., HIV) typically are released from the host cell by budding. However, at some point, the provirus or prophage may give rise to active virus, which may lyse the host cells. The viral genome is mostly silent within the host. ” Whenever the host divides, the viral genome is also replicated. The viral genome is then known as a ” provirus ” or, in the case of bacteriophages a “prophage. Some viruses undergo a lysogenic cycle where the viral genome is incorporated by genetic recombination into a specific place in the host’s chromosome. This is a feature of many bacterial and some animal viruses. Viruses can be released from the host cell by lysis, a process that kills the cell by bursting its membrane and cell wall if present. The life cycle of viruses differs between species, but follows the same basic stages. Instead, they use the machinery and metabolism of a host cell to produce multiple copies of themselves, and they assemble in the cell. Viral populations do not grow through cell division because they are acellular.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |