Virus Structure/ Function

Question 1

• Virus definition? Needs what of host? Break Koch postulate how? Genetic material directs what?
• Survival strategy? (3)
• Class schemes: System named based on physical properties? 4 characteristics? (4)
• Seven classes of viral genomes? (7)
• What is created in host? (2)
• RNA viruses need to bring or translate what?
• RDRP then generates what? (2)
• mRNA then what?
• (+) strand vs. (-) strand?
• • strand still has to convert to dsDNA why?
• What strand has many deadly viruses?

Answer 1

• Submicroscopic (filterable, infectious, obligate intracellular parasite; machinery; can’t grow in vitro; production of new particles
• House their genetic material in capsids, genome contains info to initiate and complete infectious cycle; establish a relationship with host
• Classical; nature DNA/RNA, symmetry of capsid, naked or envelope, dimensions of virion
• dsDNA, gapped circular DNA with reverse trans., ssDNA, dsRNA, (+) RNA, (-) RNA, (+) RNA with DNA intermediate
• Proteins and genetic material
• RdRP
• RNA genome and mRNA for next virus
• • can be translated directly
• Replicate genetic info
• (-) RNA

Question 2

• Baltimore class system based on? Grouped how?
• Studying viruses: Egg system? Microscope type? 3 cell culture systems? (2) Plaque assay has serial dilutions that what? Immune response with?
• Capsids: Made of? Shapes? (2) Genome wrapped how?
• Enevelope: Lipid with? Helps with? (3)
• Growth chart: 1.) Eclipse phase: Hours? Replication? 2.) Latency: Hours? Rep? Then?

Answer 2

• Central dogma; seven groups and how they turn genetic material to mRNA
• Place in eggs; electron microscope; primary (directly from tissue) short lifespan; cell from tumors which may have infinite lifespan; then plated; Western or ELISA
• protein; helical or icosohedral; inside or out
• glycoprotiens; entry, assembly, evasion
  1. ) 0-12 hours; no 2.) 0-16 hours; yes 3.) Release virus

Question 3

• Attachment: Suseptible host? Resistant? Permissive? Need what to replicate? Receptors per virus?
• Types of entry? (2)
• Gene expression: All viruses encode? 5 ways they maximize space?
• Replication: Steps? (3)
• Assembly: Helical: genomic RNA coated when? Icosohedral coated when? (2)
• Eggress: NAked capsids? Enveloped?

Answer 3

• Has a receptor (may or may not replicate); no receptor; capacity to replicate (may not have receptor); Sus and permiss; usually >1
• Fusion or endocytosis
• RDRP; splicing, ambiescence (code both ways), RNA editing, poly proteins, suppressed stop codons
• decode genome to make mRNA and protein, make copies of genome, assemble the two
• Synthesis; around genome of fed in
• Cells lyse; go through membranes (could be ER or golgi)

Question 4

Viral pathogenesis:

• Tropism? Many start with? Ex?
• Virulance?
• Pathogenicity?
• Iceberg concept?
• Common initial sites? (4)
• Incubation period? Varies? Ex?
• Factors that influence virulence: genes that effect? (4)
• Host factors? (6)
• Virus induced immunopathology? Dengue virus example? Another example?
• Typical 3 steps of acute, primary virus?

Answer 4

• Cells or tissue of a host that support a particular virus; epithelium; HIV with CD4 cells
• Degree to which virus can cause disease
• Ability to cause disease
• Only a few viruses under right conditions lyse and kill host
• skin, mucus membranes, GI tract, urinary tract
• Time b/n when virus gets in and start of infection; yes; flu = short; Hep = long
• ability to replicate, modify host defense, facilitate spread, directly toxic to host
• Receptors, cell type, age, genetics, exposure hostory, immune status
• Immune response causes virulance; increases risk of future infections, complex formation
• Uninfected –> Infected –> Approp immune reposponse or not

Question 5

• 4 viruses related to cancer?
• 3 outcomes with virus?
• Acute local vs acute systemic: First viral spot? Viremia (spread to other spots)? Incubation time?Immunity? Ab?
• Persistant vs. Latent: Ex?
• Example of acute local? (2) Acute systemic? (2) Chronic? Latent? Slow? (2)
• More serotypes means?
• What type of deficiency is more dangerous with viruses?

Answer 5

• EBV, HIV, Hep C, Papilloma
• Acute infection, persistant, latent
• Acute local: Epi; no; short; short; IgA
• Acute systemic: Epi; primary and secondary by entering blood; Longer; Life long; IgG/IgA
• Persistant = ongoing virus production = Hep B
• Latent = Has true dormant periods = HSV, EBV HPV
• Less AB’s to recognize it and greater virulence
• T cell

Question 6

• What is cytopathic effects? Direct? Indirect?
• Synctia?
• Growth?
• Apoptosis?
• Other effects of viruses? (3)
• Typical host response? (3) Ex: APOBEC3G does what? But what?
• IFN response: Released by? Helps who? Type 1? Released by who? Type 2? Released by who? Made in response to? Antiviral state due to? Altering TF’s blocks what? Often triggered by? (2)
• Innate responses: OASa degrades? PKR decreases what? Increase what presentation?

Answer 6

• Not in interest of virus to kill host but damage is ok; lyse cells; integrate, cause inflamm
• Virus mediated fusion to cells
• Turn cells into replication machines
• Inhibit it
• Nuclear alteration, break chrom., add inc. bodies
• Release INF, apoptose, restrction factors; integrates with HIV genome to kill it; HIV mutates
• Infected cell; adjacent cells; alpha and beta; infected cells; gamma; NK cells and T cells; finding antigen; Type 1 mostly; Cell prolif; dsRNA or abnormal nucleic acids; MRNA, translation, MHC to T cells

Question 7

• Innate response: Specific? TLRs identify what? (2) TLR7? TLR9? Recognize factors such as APOBEC? INFa from? INFB from? JAK/STAT signalling? PKR/Oasa? INF prepares what?
• Adaptive response: Humoral: Group specific? Type specific?
• Cell mediated primarily? Problem with hepatocytes? Th1 release? (3) Type response? Th2 release? (3) Type response?
• Innate job? Adaptive job?
• Virus evasion tactics? (5)

Answer 7

• No; viral nucleic acid, dsRNA; viral RNA; unmethylated CpG; yes; leukocytes; epithelia; yes; play big role; Capsase system for dsRNA
• bind common viral epitope; bind epitope of virus subtype
• CD8; not APC’s; INFgamma, IL2, IL12 proinflammatory; IL4, IL5, IL10 –> Ab response
• Containment; Destroy
• Drift/shift; Inhibit INF; Mimicry, Downreg. MHC, Infect immune system