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To enter the cells, proteins on the surface of the virus interact with proteins of the cell. Attachment, or adsorption, occurs between the viral particle and the host cell membrane. A hole forms in the cell membrane, then the virus particle or its genetic contents are released into the host cell, where replication of the viral genome may commence.
Viruses may undergo two types of life cycles: the lytic cycle and the lysogenic cycle. In the lytic cycle, the virus introduces its genome into a host cell and initiates replication by hijacking the host's cellular machinery to make new copies of the virus. [12] In the lysogenic life cycle, the viral genome is incorporated into the host genome.
Virus latency (or viral latency) is the ability of a pathogenic virus to lie dormant within a cell, denoted as the lysogenic part of the viral life cycle. [1] A latent viral infection is a type of persistent viral infection which is distinguished from a chronic viral infection. Latency is the phase in certain viruses' life cycles in which ...
In the lytic cycle, the viral DNA exists as a separate free floating molecule within the bacterial cell, and replicates separately from the host bacterial DNA, whereas in the lysogenic cycle, the viral DNA is integrated into the host genome. This is the key difference between the lytic and lysogenic cycles.
An example would include the ability of the herpes simplex virus, which causes cold sores, to remain in a dormant state within the human body. This is called latency [ 110 ] and is a characteristic of the herpes viruses, including Epstein–Barr virus, which causes glandular fever, and varicella zoster virus , which causes chickenpox and shingles .
The most important aspect of a virus is not whether it’s technically new or simply a variant. It’s the danger that virus poses. Body work: When does a virus grow so much that it gets a new name?
The herpes virus can then exit this dormant stage and re-enter the lytic cycle, causing disease symptoms. Thus, while herpes viruses can enter both the lytic and lysogenic cycles, latency allows the virus to survive and evade detection by the immune system due to low viral gene expression. The model organism for studying lysogeny is the lambda ...
Life-cycle of a typical virus (left to right); following infection of a cell by a single virus, hundreds of offspring are released. When a virus infects a cell, the virus forces it to make thousands more viruses. It does this by making the cell copy the virus's DNA or RNA, making viral proteins, which all assemble to form new virus particles. [37]