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Structure
Structure
RNA: It is a single-stranded positive-sense RNA that is enclosed in a protein capsid. Do to it being positive-sense this means that it can be directly used as mRNA (messenger RNA) once it enters a host cell. Since there is direct translation of the RNA this allows the viral proteins to be made rapidly in the host (Poliovirus Structure: Genome, Capsid, and Function, 2025).
Icosahedral Protein Capsid: Is composed of VP1, VP2, VP3, and VP4 capsid proteins that are Structural Proteins. The VP1, VP2, and VP3 proteins are in the outer surface of the capsid. These are meant to give the virus its shape and also help mediate the interactions with host cells. The VP4's function is to provide a stable structure for the internal surface of the capsid. It gives it a protection for the virus internal structures in addition to the structure that the other three VP provide for the virus (Poliovirus Structure: Genome, Capsid, and Function, 2025).
Non-Structural Protein: The 2A protease, 2B and 2C protein, 3A protein, 3B, 3C protease, 3D RNA-dependent RNA polymerase, and 3CD precursor. These proteins are used for replication, polyprotein processing and host cell manipulation. The 2A protease's purpose is to help with assembly and function of the vital capsid. Both 2B and 2C proteins are important for the uncoating of the viral capsid as well as the replication of RNA. The 3A and 3B proteins are involved in cleaving the viral RNA and to regulate the immune response of the host. As for the enzyme 3D it is used for transcription of viral RNA genome (Yuan et al., 2018). The 3C protease inhibits the host cell's ability to transcribe by cleaving the TATA-binding proteins (Wikipedia Contributors, 2023).
*Help me evade the host's immune system* 😉
Non-Enveloped: It helps the virus be resistant to many disinfectants. Since it does not have this lipid envelope it makes it resistant to environmental condition and organic solvents like disinfectants (Poliovirus Structure: Genome, Capsid, and Function, 2025). This lack of an envelope helps the virus survive outside of a host for longer than enveloped viruses. The absent lipid envelope makes the virus more virulent and usually indicates that the host cell will be lysed when exiting the host cell (Virology Research services, 2022).
3 Genotypes: PV1, PV2, and PV3
PV1: This is the most common and most virulent strain.
PV2: It is vaccine derived and less common than PV1.
PV3: This is less virulent than PV1 and not found in the wild.
Enter Cell
Enter Cell
The virus attaches to the CD155 protein receptor it is the brown hairpin structure on host cell (Shown on Step 1 Fig. from Book Vol. 1). "This receptor is a glycoprotein that extends from the surface of certain human cells, acting as a docking station for the virus". Once the virus attaches to the receptor it is enclosed in an endosome into the cell's cytoplasm. The CD155 receptor is actually there to be used by the host but it is hijacked by the virus for its own use. It being used by the virus also weakens the hosts immune system since it is one its normal functions (Poliovirus Receptor: From Viral Entry to Cancer Treatment, 2025).
Leave Cell
Leave Cell
The host cell is lysed to release the virions (Shown on Step 14 Fig. from Book Vol. 1). This action by the virus causes the damage to the hosts cell membrane. In addition to leading to cell death and at times damage to the tissue of the host (Virology Research services, 2022). When the cell is lysed, this can cause an inflammatory response from host. This can be an issue due to there being a coordinated lyse of cells. Meaning that there is a widespread throughout the host release of virions that lead to inflammation (Fiveable, 2025).
Transmission
Transmission
Poliovirus is transmitted only Human-to-human. It is highly contagious and possess a greater risk to children and immunocompromised people. Found in contaminated water and food mainly under unsanitary conditions. If there are poor sanitation and hygiene conditions this can increase the risk of contracting and spreading Poliovirus. Contact with feces of an infected person and droplets from a sneeze or cough are the most common form of transmission. This can occur mainly to people that are caring for people infected with Poliovirus. (CDC, 2024)
Entry To Host Immune System
Entry To Host Immune System
Enters through the mouth:
Once it enters it starts to replicate in the hosts throat (Oropharynx) and gut (Gastrointestinal tract). After replication it spreads and targets the lymphoid tissues. It spreads by using the hosts bloodstream to get around. In rare cases it can even spread to the central nervous system where it targets motor neurons that can lead to paralysis (What Happens to a Cell Infected by Poliovirus?, 2025).
How does it evade the immune system:
Once way that it evades the immune system is by being resistant to the gut's acid, bile and IgA. The virus is encased in acid-resistant capsid and replicates rapidly. Another form of evasion is by blocking interferon responses. The viral protease blocks the interferon signaling of the host. It can also evade mucosal antibodies such as IgA and IgG evasion
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