Picornaviruses: Structure and Genomic Information

What is the size of the diameter of picornaviruses?

Which viral proteins form the capsid shell in a mature picornavirus?

What is the function of the internal ribosome entry site (IRES) in picornaviruses?

What is covalently bound to the 5’ end of the RNA in picornaviruses?

What is the mechanism by which most cellular RNAs initiate translation near their 5' end?

What is the consequence of Picornavirus infection on host cell cap-dependent translation?

What role do host cell proteins play in Picornavirus translation process?

What is the fate of the precursor polyprotein made during Picornavirus protein synthesis?

What initiates the replication of Picornavirus RNAs in host cells?

What is the major conformational change in poliovirus that facilitates its entry into the cytoplasm?

What is the function of VP0 during poliovirus assembly?

What are the consequences of Picornavirus infection on host cell macromolecular functions?

Picornaviruses Overview

Diameter of picornaviruses is approximately 22-30 nanometers.
Capsid shell in mature picornaviruses is formed by viral proteins VP1, VP2, VP3, and VP4.
Internal ribosome entry site (IRES) facilitates direct binding of ribosomes to RNA, enabling translation independent of the 5' cap structure.

RNA Properties

The 5' end of picornavirus RNA has a covalently attached viral protein, known as VPg.
Most cellular RNAs utilize the cap-dependent translation initiation mechanism, where ribosomes recognize and bind to the 5' cap before scanning for the start codon.

Host Cell Interaction

Picornavirus infection leads to the inhibition of host cell cap-dependent translation by disrupting the cellular translation machinery.
Host cell proteins, such as eIFs, are hijacked by picornaviruses to facilitate their translation, often shifting the host's translational program in favor of viral proteins.

Protein Synthesis and Replication

The precursor polyprotein synthesized during picornavirus protein synthesis is subsequently cleaved into functional viral proteins by viral proteases.
Replication of picornavirus RNAs in host cells is initiated by the viral RNA-dependent RNA polymerase after the viral genome is released into the cytoplasm.

Viral Entry Mechanism

A significant conformational change in poliovirus occurs upon receptor binding, allowing the viral genome to be released into the cytoplasm for replication.
VP0 plays a crucial role during poliovirus assembly, later being cleaved into VP2 and VP4, which are important for viral stability and entry.

Impact on Host Functions

Picornavirus infections disrupt host cell macromolecular functions, including protein synthesis and cellular signaling, favoring viral replication and spread.

Test your knowledge of the structure and genomic features of picornaviruses with this quiz. Learn about their small RNA genome, icosahedral capsid, binding to cellular receptors, and more.