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How do viruses reproduce inside host cells?
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infectious disease
Birds are the primary reservoirs of West Nile virus. The virus is transmitted to humans and horses by mosquitoes that have bitten infected birds.
Viruses are obligate parasites that cannot reproduce independently; they must hijack a host cell to manufacture their components. The reproductive process generally follows a series of steps known as the cycle of infection:123
- Adsorption and Penetration: The virus attaches to the surface of a host cell and enters it, either by injecting its genetic material or by entering the cell intact. In animal cells, this often occurs via endocytosis, where the cell membrane engulfs the virus.3
- Uncoating: If the virus entered intact, the protein capsid is degraded to release the viral DNA or RNA into the cell.32
- Synthesis: The viral genetic material instructs the host cell to produce viral components. The virus uses the host’s ribosomes, amino acids, and energy sources to synthesize viral proteins and replicate the viral genome.231
- Assembly: Newly replicated genomes and structural proteins are assembled into complete progeny virions.32
- Release: The new viruses are released from the host cell, often resulting in the death of the cell through lysis or by budding off the cell membrane.32
Some viruses, known as temperate or latent viruses, may integrate their DNA into the host genome and remain dormant, replicating only when the host cell divides.34