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📘 How does a virus enter a cell?

A virus is a package of genetic material surrounded by proteins, and sometimes by a lipid envelope. It cannot usually cross a cell membrane by simply drifting through it.

5
lessons
~25 min
to learn
Adults
level
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What you’ll learn

  1. A virus must find a compatible cellExplain how receptor binding and coreceptor use begin productive viral entry.Viruses exploit ordinary cell-surface molecules, but attachment is only the first checkpoint.
  2. The membrane offers more than one routeCompare direct membrane fusion, endocytosis followed by escape, and nonenveloped genome delivery.Viral structure and cellular compartments determine how a genome crosses a membrane.
  3. Entry is a sequence of checkpointsConnect uptake, fusion or penetration, uncoating, and delivery to the correct intracellular compartment.A particle is inside only when its genome is released where the next infection step can use it.
  4. Host range depends on more than one lockExplain why receptors, tissue distribution, host factors, and later permissiveness shape host specificity.Host range emerges from several molecular filters rather than one receptor alone.
  5. So how does a virus enter a cell?Synthesize receptor binding, entry routes, genome release, and host specificity into one explanation.Successful infection is a chain from molecular recognition to usable genome release.

Questions this course answers

What does a viral receptor primarily provide?

A receptor lets the virus bind a cell and can activate the next entry step, but later checkpoints still determine whether infection succeeds.

Put these early entry events in order

Entry begins with contact and receptor binding, then uses a membrane or injection route before the genome becomes available.

What happens during receptor-mediated endocytosis?

The cell takes the bound particle into an endosomal compartment, where the virus must later escape.

Why can influenza need an acidic endosome?

The acidic compartment supplies a trigger that activates fusion after uptake rather than at the cell surface.

What is uncoating?

Uncoating removes or rearranges the capsid or nucleocapsid so the genome can reach the machinery it needs.

Match each virus feature to its entry problem

Structure and compartment determine how the virus must cross the membrane and avoid destruction.

Grounded in trusted sources

  • Hunter E, Viral Entry and Receptors, Retroviruses, NCBI Bookshelf, https://www.ncbi.nlm.nih.gov/books/NBK19440/
  • Molecular Biology of the Cell, Cell Biology of Infection, NCBI Bookshelf, https://www.ncbi.nlm.nih.gov/books/NBK26833/
  • Marsh M and Helenius A, Virus entry: open sesame, Cell, https://pubmed.ncbi.nlm.nih.gov/16125548/
  • Yin W et al., Virus entry: molecular mechanisms and biomedical applications, Signal Transduction and Targeted Therapy, https://pmc.ncbi.nlm.nih.gov/articles/PMC7097642/
  • Wang H et al., Mechanisms of SARS-CoV-2 entry into cells, Cell, https://pubmed.ncbi.nlm.nih.gov/34611326/
  • Wikimedia Commons MediaWiki API, image metadata and 960px thumbnails, https://commons.wikimedia.org/w/api.php

Every Wunder lesson is built from real, reputable sources — never invented.

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