Slide 1
A package that needs a cell
A virus contains genetic material in a protective package. It cannot reproduce independently and must use a suitable host cell.
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Viral genomes can be DNA or RNA. Some viruses also have an outer membrane envelope, so viruses share dependence on cells without sharing one identical physical design.
Slide 2
Entry requires a match
Viral attachment depends on interactions with the host-cell surface. A virus cannot necessarily enter every cell it encounters.
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Receptors help determine which hosts and tissues a virus can infect. Successful attachment is only an early requirement; conditions inside the cell must also support later stages.
Slide 3
The cell makes components
After entry, viral instructions direct production of new genetic material and proteins. The exact route depends on the kind of virus.
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Viruses rely on host machinery such as ribosomes to make proteins, while some supply specialized enzymes for copying their genomes. Dependence does not mean every copying step is performed by a normal host enzyme.
Slide 4
New particles are assembled
Viral components come together into new particles. Release may damage the cell or occur by budding through a membrane.
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Budding can give an enveloped virus its outer covering. The exit route is therefore connected to particle structure, rather than being a separate detail with no effect on the next infection.
Slide 5
Infection has different courses
Some infections produce new virus rapidly; others include periods of persistence or latency. Infection does not always cause immediate noticeable illness.
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An asymptomatic infection can still be biologically active. Distinguishing symptoms, replication and persistence helps explain why the presence of a virus and the experience of disease are related but separate observations.
Sources
- Virus
NHGRI, NIH
- Virus Infections and Hosts
OpenStax, Rice University