Virology Ch 16

1. What are some diseases caused by picornaviruses?

Zika virus infection

Hepatitismyocardidtispoliofoot-and-mouth disease

Malaria

Influenza

Picornaviruses are a group of viruses that can cause a variety of diseases in humans and animals. The diseases mentioned in the correct answer are known to be caused by picornaviruses, while the incorrect answers do not belong to this viral group.

Explanation

Picornaviruses are a group of viruses that can cause a variety of diseases in humans and animals. The diseases mentioned in the correct answer are known to be caused by picornaviruses, while the incorrect answers do not belong to this viral group.

2. What are the four proteins that make up the capsid of a virus and how many copies of each are there?

VP1, VP2, VP3, VP4 60 copies of each

VP2, VP3, VP4 40 copies of each

VP1, VP2, VP4 60 copies of each

VP1, VP2, VP3 40 copies of each

The correct answer includes all four proteins – VP1, VP2, VP3, and VP4, with 60 copies of each protein making up the capsid structure of the virus.

Explanation

The correct answer includes all four proteins – VP1, VP2, VP3, and VP4, with 60 copies of each protein making up the capsid structure of the virus.

3. What distinguishes picornaviruses capsid from other viruses?

There are no receptors on the capsid surface only depressions called "canyons" or "pits"

They have a lipid bilayer membrane surrounding their capsid.

Picornaviruses capsid is much larger in size compared to other viruses.

The capsid is made up of a double-layered protein shell.

Picornaviruses capsid lacks receptors which are commonly found on the surface of other viruses' capsids. Instead, they have depressions like 'canyons' or 'pits', providing a unique structural feature.

Explanation

Picornaviruses capsid lacks receptors which are commonly found on the surface of other viruses' capsids. Instead, they have depressions like 'canyons' or 'pits', providing a unique structural feature.

4. How do Rhinoviruses and Foot-and-mouth disease gain entry to the cell?

Via phagocytosis

Via receptor-mediated endocytosis

Via exocytosis

Via passive diffusion

Rhinoviruses and Foot-and-mouth disease gain entry to the cell specifically through the process of receptor-mediated endocytosis, where the virus attaches to specific cell surface receptors and is engulfed into the cell for further infection.

Explanation

Rhinoviruses and Foot-and-mouth disease gain entry to the cell specifically through the process of receptor-mediated endocytosis, where the virus attaches to specific cell surface receptors and is engulfed into the cell for further infection.

5. How does the poliovirus attach and gain entry into host cell?

Poliovirus enters host cells by forming pili-like structures that physically penetrate the cell membrane.

Attachment is via poliovirus receptor VP2 and VP3, which bind to host cell receptors and mediate entry through endocytosis.

Attachment is via poliovirus receptorVP4, N-term of VP1 and RNA genome (bound to VPg at 5' end) are inside (a) a conformation change causes VP4 to become externalized and the N-term of all 5 VP1 molceules are inserted into the membrane to form a channel for the RNA to pass into the cytoplasm of the host cell

The poliovirus gains entry into host cells through direct fusion of its envelope with the host cell membrane.

The correct answer explains the specific mechanisms by which the poliovirus attaches and gains entry into host cells. The incorrect answers propose alternative but inaccurate methods of entry.

Explanation

The correct answer explains the specific mechanisms by which the poliovirus attaches and gains entry into host cells. The incorrect answers propose alternative but inaccurate methods of entry.

6. What is the mechanism of cap-dependent initiation of protein synthesis?

A) mRNA use eIF-2 complex for initiation of translation

MRNA use this to initiate translation near their 5' end eIF-4F complex (eIF-4A, eIF-4E, eIF-4G) recruit a 40S ribosomal subunit to the capped 5' end of mRNA40S will scan mRNA in search of proper AUG codon. 60S ribosomal subunit joins to form an 80S complex and protein synthesis begins

C) 40S ribosomal subunit scans mRNA for the 3' UTR before initiating translation

B) Ribosomal subunits directly bind to the 3' end of mRNA to start translation

Cap-dependent initiation of protein synthesis involves the recruitment of ribosomal subunits to the capped 5' end of mRNA using the eIF-4F complex. The ribosomal subunits then scan the mRNA for the proper AUG codon before forming the 80S complex and starting protein synthesis.

Explanation

Cap-dependent initiation of protein synthesis involves the recruitment of ribosomal subunits to the capped 5' end of mRNA using the eIF-4F complex. The ribosomal subunits then scan the mRNA for the proper AUG codon before forming the 80S complex and starting protein synthesis.

7. Is the poly A tract at the 3' end of picornaviruses added?

No it is part of the genome sequence

Yes, it is a post-translational modification after virus assembly.

Yes, it is artificially synthesized and added during replication.

No, it is only present in certain strains of picornaviruses.

The poly A tract at the 3' end of picornaviruses is actually part of the genome sequence and not added during replication or assembly.

Explanation

The poly A tract at the 3' end of picornaviruses is actually part of the genome sequence and not added during replication or assembly.

8. Describe cap-independent initiation of protein synthesis.

Ribosomes are directed to the initiator 5' AUG sequence via an Internal Ribosome Entry Site (IRES) that lies within the highly structured 5' noncoding region. the host cell proteins bind to the IRES and help to dock the 40S onto the RNA. Translocation occurs until initiator AUG is met. the 60S ribosomal subunit will combine to form an 80S and synthesis will occur.

Host cell proteins are not involved in the cap-independent initiation of protein synthesis.

During cap-independent initiation, ribosomes directly bind to the 3' end of mRNA for translation to begin.

Protein synthesis is solely dependent on the presence of a 5' cap structure on mRNA.

Cap-independent initiation of protein synthesis involves a unique mechanism where ribosomes are guided to the initiator AUG sequence by an IRES within the noncoding region of mRNA. Host cell proteins play a crucial role in this process by assisting in the docking of the ribosomes, leading to successful protein synthesis without the need for a 5' cap structure.

Explanation

Cap-independent initiation of protein synthesis involves a unique mechanism where ribosomes are guided to the initiator AUG sequence by an IRES within the noncoding region of mRNA. Host cell proteins play a crucial role in this process by assisting in the docking of the ribosomes, leading to successful protein synthesis without the need for a 5' cap structure.

9. What are the essential features of IRES?

IRES translation is enhanced if larger than 30nt

EIF-3,eIF-4G and eIF-4a promote IRES assembly. A host factor X is alsorequired.contain a pyrimidine-rich tract 20-25 nt from a conserved AUG codoninitiation of translation is reduced if smaller or larger than 20-25ntGNRA sequence is conserved in specific loop regions of stem-loop structures

IRES require eIF-2, eIF-5 and eIF-6 for assembly

IRES always contain a purine-rich tract 20-25 nt from a conserved AUG codon

IRES require eIF-3, eIF-4G, and eIF-4a, not eIF-2, eIF-5, and eIF-6. IRES contain a pyrimidine-rich tract, not purine-rich. Initiation of translation is reduced if smaller or larger than 20-25nt, not enhanced if larger than 30nt.

Explanation

IRES require eIF-3, eIF-4G, and eIF-4a, not eIF-2, eIF-5, and eIF-6. IRES contain a pyrimidine-rich tract, not purine-rich. Initiation of translation is reduced if smaller or larger than 20-25nt, not enhanced if larger than 30nt.

10. How do picornavirus genome RNAs engineer their translation in host cells?

By relying on the host cell's translation machinery to initiate translation.

By using a cap-dependent translation mechanism.

By undergoing reverse transcription before translation in host cells.

Translation occurs cap-independently.genomes has a 743nt long UTR untraslated leader seq contains 8 AUG codons prior to initiation siteInternal ribosomal binding occurs at the IRES

Picornavirus genome RNAs utilize a cap-independent translation mechanism where internal ribosomal binding occurs at the IRES, allowing translation to initiate without the need for a 5' cap structure. This unique process enables efficient translation of picornavirus RNAs in host cells.

Explanation

Picornavirus genome RNAs utilize a cap-independent translation mechanism where internal ribosomal binding occurs at the IRES, allowing translation to initiate without the need for a 5' cap structure. This unique process enables efficient translation of picornavirus RNAs in host cells.

11. What are the IRES ribosomal subunits?

ElF-4A- helicase

ElF-4G (component in eIF4F) cellular initiation factorelF-3Elf-4A- helicase40S ribosomal subunitX (a host factor)

40S ribosomal subunit

ElF-3

The correct answer is elF-4G, which is a component in the eIF4F cellular initiation factor. The incorrect answers include elF-3, elF-4A- helicase, and 40S ribosomal subunit.

Explanation

The correct answer is elF-4G, which is a component in the eIF4F cellular initiation factor. The incorrect answers include elF-3, elF-4A- helicase, and 40S ribosomal subunit.

12. What are the key molecules and their specific functions of picornaviruses during translation?

2D protein-functions as a viral capsid protein

2A proteinase-cleaves N-term immediately after translation3C Proteinase+precurser 3CD- carry out remaining polyprotein cleavages2B protein-host range determinant involved in RNA synthesis2C protein- highly conserved; involved in RNA synthesis3D- RNA dependend RNA polymerase; has GDD plymerase motif3B = VPg at the 5' end

1A proteinase-involved in RNA translation process

4C Proteinase-responsible for viral attachment to host cells

The correct answer provides detailed information about the key molecules and their specific functions of picornaviruses during translation, while the incorrect answers are not consistent with the roles of the specific proteins mentioned.

Explanation

The correct answer provides detailed information about the key molecules and their specific functions of picornaviruses during translation, while the incorrect answers are not consistent with the roles of the specific proteins mentioned.

13. Which genera in the Picornaviridae family lack an L protein?

Enterovirusesrhinoviruses

Hapatoviruses

Teschoviruses

Kobuviruses

Enteroviruses and rhinoviruses are the only genera within the Picornaviridae family that do not possess an L protein, which plays a role in RNA synthesis and replication.

Explanation

Enteroviruses and rhinoviruses are the only genera within the Picornaviridae family that do not possess an L protein, which plays a role in RNA synthesis and replication.

14. How does picornavirus infection affect host cell macromolecular functions?

4. Activation of host cell apoptosis pathways

5. Increased expression of host genes involved in immune response

1a. shut off cap-dependent translation host can no longer recognize 5' mRNA allowing cap- independent translation of viral RNA to occur1b. some inhibit cap-dependent translation by binding and sequestration of the eIF-4E protein that binds directly to the 5' cap of eukaryotic mRNAs.2. Shut off host cell RNA synthesis 3C proteases cleave RNA Pol I, II, II and histone H33. induction of cytoplasmic vesicles causes alteration in intracellulart transport b/t E.R. and Golgi; 2B and 3A block membrane traffickng; 3C brings genome RNAs in contact w/ vesicle

6. Stimulation of host cell proliferation

15. What is a cis-acting replication element (cre)?

Proteins that facilitate the replication of host cell RNA.

Binding sites on the surface of a virus that allow it to attach to host cells.

Sequence elements located in viral RNA that are required for initiation of viral RNA replication. cre probably interact w/ specific viral proteins

Sequence elements located in bacterial DNA that regulate DNA replication.

A cis-acting replication element (cre) specifically refers to sequence elements located in viral RNA that play a crucial role in initiating viral RNA replication. These elements are essential for the virus to replicate its RNA and are believed to interact with specific viral proteins for this process.

Explanation

A cis-acting replication element (cre) specifically refers to sequence elements located in viral RNA that play a crucial role in initiating viral RNA replication. These elements are essential for the virus to replicate its RNA and are believed to interact with specific viral proteins for this process.

16. What is a jell roll B-barrel?

Folding of a polypeptide chain into a number of parallel B strands, usually as two sheets, found in many virion capsid proteins

A cylindrical container used for storing jellied substances.

A type of pastry filled with jelly and rolled up.

A dance move involving twisting and turning in a barrel-like motion.

A jell roll B-barrel refers to the folding of a polypeptide chain into a specific structure, not related to pastries, containers, or dance moves.

Explanation

A jell roll B-barrel refers to the folding of a polypeptide chain into a specific structure, not related to pastries, containers, or dance moves.

17. What is receptor-mediated endocytosis?

Endocytotic uptake of molecules from the extracellular space involving their specific binding to plasma membrane receptors

The movement of molecules across the cell membrane without the need for receptors.

The breakdown of molecules within the cell for energy production.

A process where cells release molecules into the extracellular space.

Receptor-mediated endocytosis is a specific process where molecules are taken up into the cell through binding to specific membrane receptors, distinguishing it from other cellular processes mentioned in the incorrect answers.

Explanation

Receptor-mediated endocytosis is a specific process where molecules are taken up into the cell through binding to specific membrane receptors, distinguishing it from other cellular processes mentioned in the incorrect answers.

18. What does CD 155 stand for?

Immunoglobulin superfamilythe poliovirus receptor stabilized by disulphide bondsPvr is an equivalent

Chemical Dependency 155

Cytokine Domain 155

Cell Division 155

CD155 is a protein also known as Poliovirus Receptor (PVR) that belongs to the immunoglobulin superfamily and is stabilized by disulphide bonds.

Explanation

CD155 is a protein also known as Poliovirus Receptor (PVR) that belongs to the immunoglobulin superfamily and is stabilized by disulphide bonds.

19. What is the function of ICAM-1?

Integral membrane proteinInterCellular Adhesion Molecule 1receptor for human Rhinovirusesimmunoglobulin superfamilyfound of hte surface of many tissues (nose and lungs)normal function is to bind a ligand on the surface of lymphocytes and promote immunological and inflammatory functions

A type of neurotransmitter involved in muscle contraction

A genetic disorder affecting red blood cells

A cell organelle responsible for energy production

ICAM-1 is not a cell organelle, neurotransmitter, or genetic disorder. It is an integral membrane protein found on the surface of tissues that plays a role in immune responses.

Explanation

ICAM-1 is not a cell organelle, neurotransmitter, or genetic disorder. It is an integral membrane protein found on the surface of tissues that plays a role in immune responses.

20. What is Heparan Sulfate?

A rare type of infectious disease caused by bacteria.

A type of mineral found in the Earth's crust.

An enzyme responsible for breaking down protein in the stomach.

A sulfated polysaccharide made from repeating disaccharides. these are covalently attached to core proteins to form proteoglycans found on the cell surface.

Heparan Sulfate is a specific type of molecule composed of repeating disaccharides that play a crucial role in cell surface interactions. Proteins attached to heparan sulfate help regulate various cellular processes.

Explanation

Heparan Sulfate is a specific type of molecule composed of repeating disaccharides that play a crucial role in cell surface interactions. Proteins attached to heparan sulfate help regulate various cellular processes.