Virology

Question 1

define and explain the following terms

1. virus
2. viroids
3. virusoids
4. prions

Answer 1

1. virus
   
   1. ribosomal parasite
2. viroids
   
   1. naked RNA that infect plants
3. virusoids
   
   1. RNA, coated with protein, from a neighboring plant
      
      1. the RNA does not encode for any protein
4. prions
   
   1. infectious proteins
   2. misfolded, very protease resistant proteins
   3. mediate the misfolding of other host proteins

Question 2

what are the types of interferon? 1, 2,3

purpose?

Answer 2

1. IFN
   
   1. alpha-all cells, triggered by dsRNA
   2. beta-all cells, triggered by dsRNA
2. IFN gamma
   
   1. Tcells, NK cells-triggered by antigen, mitogen, IL-2,12
3. IFN lambda
   
   1. 1,2,3 = IL-29/28a/28b
   2. coexpressed with type 1 IFN, sounds like these are required
   3. signal independent of Type1-a/b

IFN are not expressed regularly, they are usually repressed via repressor

• purpose
  
  • a/b- go to neighboring cells and tell them to prepare for viral invasion
    *

Question 3

what is the reason that 70% of viral infections are subclinical?

Answer 3

Type 1 (A/B) IFN

-go to neighboring cells and allow themto prepare defenses

Question 4

what is the goal of IFN expression?

what targets dsRNA

Answer 4

shut down the cell translation machinery- no virus replication

dsRNA is targeted by PKR, which increases in expression

Question 5

what is the function of PKR

Answer 5

PKR monomers bind to dsRNA.

when bound, the domains of PKR conform and the catlytic domains can be phosphorylated.

cross phosporylation leads to the ability to phosphorylate and shut down other substrates:elongation factor 2 (eLF2)

Question 6

WHICH interfeon stimulates the adaptive immune system?

Answer 6

Type 1 IFN stimulates the adaptive immune system

Type2 is the most important in stimulating the lymphocytes.

Question 7

what are common side effects of interferon?

Answer 7

fever, malaise, fatigue, muscle pains,

toxicity to: kidney, liver, bone marrow, heart

Question 8

describe the pathway for interferon activation

Answer 8

Type 1 and 3 interferons initiate the same intracellular response through two different receptors:

Type1: a/b,

Type3:lambda

Question 9

what are the cytopathic effect that are associated with different virus infections

Answer 9

cell death: apoptosis, pyroptosis, necrosis, syntia formatiton, inclusiong bodies

syncytia- multinucleated cells. formed when cells fuse together

Question 10

explain when can Cytopathic effects be seen in a culture

Answer 10

cpe in cultured cells between 5-15 days

Question 11

what are direct test(6)? Indirect tests(4)?

Answer 11

• direct-presence of virions, virus proteins or virus genomes
  
  • CPE
  • PCR
  • RT-PCR
  • Fluorescence assay- detects the virus in infected cells
  • snadwich ELISA
  • Hemagglutination assay
• indirect- presence of Ab
  
  • Western blot (HIV)
  • indirect ELISA
  • Heamagglutination inhibition assa
  • virus neutralization assy

Question 12

explain how to read and inerpret the hemagglutination assay and hemagglutination inhibition assay

Answer 12

the top is hemagglutination assay, bottom is hemagglutination inhibition assay

• reading
  
  • HA- virus of various dilutions are mixed with consistent sample sizes of chicken blood.
    
    • sample A causes hemagglutination up to a dilution of 1:256 dilution;HA titer causes hemagglutination up to a certain dilution and the last reading = the virus stock
      
      • sample A
        
        • dilution up to 1:256= titer of this virus stock = 256
      • sample b and c
        
        • dilution up to 1:128= titer of the virus stock = 128
  • HI- dilutions of patients serum are performed and added to consistent samples of virus in blood.
    
    • there is enough Ab in the patients serum to keep the virus from causing hemagglutination.
      
      • sample shows a dilution of 1:160 allows for viral hemagglutination.
        
        • dilution up to 1:80=titer of Ab is 80

Question 13

The hemagglutination inhibition assay was performed on serum sample. what are the patients titers the first and second time.

Answer 13

<10 on 1/12; 80 on 2/15

Question 14

list the DNA viruses and their disesaes

Answer 14

1. PPPAHHP
   
   1. Parvo-ss(+/-)
      
      1. linear
      2. disease
         
         1. parvo
         2. erychrovirus
   2. polyma -DS
      
      1. cicular
      2. disease
         
         1. BK virus-kidney disease
         2. JC virus-progressive brain disorder
   3. Papilla-DS
      
      1. circular
      2. disease
         
         1. HPV
            
            1. warts
            2. cancer
   4. adeno-DS
      
      1. linear
      2. disease
         
         1. serotype- dependent (GI, respiritory, conjuctiva)
   5. Hepadna-DS
      
      1. circular-gapped
      2. disease
         
         1. Hepatitis B
   6. herpes-DS
      
      1. linear
      2. disease
         
         1. alpha
            
            1. HSV1-cold sores
            2. HSV2-genittal herpes
            3. VZV-chicken pox
         2. beta
            
            1. HCMV/HHV6/HHV7
         3. gamma
            
            1. EBV
            2. HHV8/KSHV
   7. pox-DS
      
      1. covanalent
      2. disease
         
         1. small pox
         2. money pox
         3. molluskum contagiosum

Question 15

what type of viruses have a necleocapsid?

Answer 15

all helical viruses

RNA only

1. Corona, Filo, Rhabdo, Arena, Bunya, Peramyxo, Orthomyxo

Question 16

Diagram the replication cycle of the adenovirus

Answer 16

Question 17

A patient was exposed to the chicken pox and never experienced and episode. Diagram the two cycles and explain this patients current state.

Answer 17

VZV is part of the herpes family wich is known for lysogenic and lytic cycles.

lysogenic (left) The Latency Associate Transcript is transcribed and forms a lariat, stopping the continuation of immediate early and early transcription.

Lytic (Right) similar to the adeno virus, only the last step would be for several cycles of golgi/ER to collect all the necessary proteins in the tegument.

Question 18

list the RNA viruses, and relevant information

Answer 18

RNA

1. Rheo
   
   1. DS-
   2. disease
      
      1. Rotavirus
         
         1. gastroenteritis
2. hepe/cilici
   
   1. SS
   2. disease
      
      1. hepetitis E
      2. noro virus-gastroenteritis
3. Pico
   
   1. SS
   2. disease
      
      1. hepatits A
      2. Entero virus
         
         1. polio
         2. echovirus
         3. coxsackivirus- hand/foot virus
4. Flavi
   
   1. SS
   2. disease
      
      1. Hep C
      2. yellowfever
      3. dengue virus
      4. west nile
      5. Zika
5. Toga
   
   1. SS
   2. disease
      
      1. rubella
      2. alpha virus-mosquito
      3. chikungunya
         
         1. very old and young
6. Retro
   
   1. SS-2 copies
   2. disease
      
      1. HIV
7. corona
   
   1. SS
   2. disease
      
      1. corona- cold, SARS, MERS
8. filo
   
   1. SS
      ​disease
      
      1. ebola
9. Rhabdo
   
   1. ss
   2. disease
      
      1. rabies
10. arena
    
    1. ss-2seg
    2. disease
       
       1. alot
11. Bunya
    
    1. ss-3 seg
    2. disease
       
       1. hanta
12. paramyxo
    
    1. ss
    2. disease
       
       1. measles
       2. mumps
       3. paramyxo
       4. RSV
13. orthormyxo
    
    1. ss-8seg
    2. disease
       
       1. influenza

Question 19

what the the following receptor correspond with?

1. CAR
2. HVR
3. CD4/CCR5/CXCR4
   4.

Answer 19

1. adenovirus-
2. Heparin-sulfate, herpes virus receptor- herpes
   3.

Question 20

describd the cycle of polio

Answer 20

1. attachment/entry
2. uncoating
3. translation of mRNA to poly protein
4. polyprotein cleavage
5. RNA amplification
6. virus assembly and release

Question 21

of the following which can use host cell machinary and which need to generate their own polymerases? explain

1. adenovirus
2. Herpes simplex virus
3. Polio
4. Rabies
5. HIV

Answer 21

1. adenovirus
   
   1. go into the nucleaus and use host cell machinary for transcription and translation
2. herpes simplex virus
   
   1. go into the nucleus and use host cell machinery for transcription and translation- lytic
   2. lysogenic, LAT-lariat is formed and DNA circularizes, suppressing transcription
3. polio
   
   1. +SS, can use host cell machinary upon entry in to host cell
4. rabies
   
   1. -SS, but is introduced with viron polymerases assembeled.
   2. once the +mRNA is transcribed, by the viron polymerase, then host cell machinary translates the +mRNA
5. HIV
   
   1. the virus has in intorduced to the cell with reverse transcriptase in tacked.
      2.

Question 22

describe the HIV infection cycle

Answer 22

1. atttachment to cells andbinding to receptors:
   
   1. CD4
   2. CXCR4
   3. CCR5
2. MEMBRANE fusion and capsid and nucleocapsid release
3. reverse transcription, nuclear import and proviral DNA integration
4. Transcription and translation of viral genes and replication of the genome
5. assembly of progeny virions
6. budding of progeny virions

Question 23

Describe the rhabdovirus replication cycle

Answer 23

1. attachment/entry
2. uncoating
3. transcription
4. translation
5. tranlsation of viral envelope glycoprotein
6. genome amplification
7. envelope glycoprotein glycosylation, maturation
8. envelop glycoprotein trafficking to cell membrane
9. virus assembly and release

Question 24

an increase in temperature of the host, is to combat what viral replication cycle? explain

Answer 24

Viral assembly will be affected, as the heat makes the stochastic assembly of the structures more difficult.

The capsid will undergo regular generation at optimal temperatures.

Question 25

describe, in general, viral egress for evneloped vs naked

Answer 25

1. enveloped 1. must bud off from the cytoplasmic membrane 2. naked 1. leave tthe host cell through lysis, usually

Question 26

explain how vaccinia virus is transferred to other cells, compared to naked and enveloped viruses

Answer 26

part of the pox family - vaccinia virus induces the host cell to generate actin tails that allow the virus to travel to the tip of the tails and attach to another cell

Question 27

What is the infection outcome when the host cell produces so many cells that the host cell usually dies.

Answer 27

a productive or lytic infection = acute infection

Question 28

infection outcome when the cell survives and becomes a source of constant exposure of virus to the host.

Answer 28

persistent infection = virus production and chronic infection 1. may be ***_asymptomatic_*** *or* **_chronic disease state_** *or* **_latent_** this contrasts to acute, where you get the disease and then its gone, chronic and latent stick around = persistnet

Question 29

types of infections

Answer 29

1. subclinical infections(asymptomatic)-most common 2. acute 1. localized infections 2. generalized infections 3. persistent infections

Question 30

a virus enters the body and spreads to lymphnodes in the reagion and NO FURTHER. What type of infection is this? Could

Answer 30

acute, localized infections

Question 32

common cold (picorna/corona), rotavirus, influenza (para/ortho), RSV, HPV-warts/cervical cancer. These all fall under what category of infection?

Answer 32

acute localized infection

Question 33

HSV 1/2 and EBV fall under what categories

Answer 33

Acute localized, latent and persistent.

Question 34

describe the acute generalized infection. there are viremic stages before the end organ is reached.

Answer 34

1. enters body 2. replicates at site 3. spreads 4. replicates 5. spreads to blood stream-***_primary viremia_*** 6. central focus 1. location that the virus can spread to- usually an organ (muscle, liver, spleen, blood vessel) 7. secondary viremia- virus gets back into the blood circulation from the central focus 8. target organ 1. the virus hasa preferred organ to live in (skin, mucous, lung, kidney, GI, brain) 2. once here, the disease becomes apparent.