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WEEK 12 SEM 4 > Morphology and Biology of Viruses > Flashcards

Morphology and Biology of Viruses Flashcards

(61 cards)

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1
Q

List Human viruses and what they cause?

A 
Herpes simplex type 1 - cold sores (around mouth)
Herpes simplex type 2- genital warts
Varicella zoster- chicken pox and shingles
Epstein Barr Virus- glandular fever
Rubella 
Measles 
Mumps 
Adenovirus - fever, coughs, sore throats, diarrhea, and pink eye
Rabies 
HIV 
Poxvirus 
Influenza 
Rhinovirus- common cold
Rotavirus - affect bowel
Papillomavirus
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2
Q

How do we classify viruses?

A
  • type and organization of genome (rna,dna, double/single stranded)
  • how virus replicates
  • virus has envelope
  • virus size
  • how it affects the host (tissue tropism, pathogenecity)
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3
Q

What does the herpesviridae virus consist of?

A 
varicella zoster
herpes simplex type 1
herpes simplex type 2
EBV
CMV (cytomegalovirus)
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4
Q

What do all herpesviridae viruses look like?

A

icosahedral nucleocapsid
double stranded DNA
enveloped
can remain latent and then reactivate

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5
Q

What kind of virus is HIV?

A

ENVELOPED

RNA (2 copies)

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6
Q

What important proteins does HIV have on its surface?

A

GP120
GP41
they infect T helper cells

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7
Q

What enzymes does HIV have?

A

integrase

protease

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8
Q

What family does hepatitis A come from?

A

picornaviridae

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9
Q

What kind of bacteria is Hep A?

A

naked RNA

no envelope

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10
Q

What is the shape of Hep A?

A

icosahedral

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11
Q

Is Hep A positive sense?

A

YES

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12
Q

What is positive sense?

A

viral RNA can be translated by ribosomes (they dont need to become mRNA first)

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13
Q

What is the incubation period for Hep A?

A

15-45 days (mean= 25 days)

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14
Q

How is Hep A transmitted?

A

faecal oral

sexually

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15
Q

What kind of bacteria is Hep B?

A

enveloped DNA

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16
Q

What family is Hep B part of?

A

hepadnaviridae family

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17
Q

What is the shape of Hep B?

A

icosahedral

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18
Q

How can Hep B exist?

A
  • can exist as complete virus or incomplete particles
  • incomplete particles= tubular filaments of the virus surface antigens
  • diverts immune system away from real virus
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19
Q

What is the incubation time for Hep B?

A

30-150 days (mean=75 days)

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20
Q

Who does Hep B mainly affect?

A

young adults
babies
toddlers

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21
Q

How is Hep B transmitted?

A

percutaneous (sharing needles)
perinatal
sexual

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22
Q

What kind of bacteria is Hep C?

A

enveloped RNA (single stranded)

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23
Q

What 2 important proteins does Hep C have?

A
  • NS1 = non-structural protein 1 = evades from host immune system
  • E protein = glycoprotein on the envelope
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24
Q

What is the incubation period of Hep C?

A

15-120 days (mean= 50 days)

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25
What is the transmission of Hep C?
percutaneous (through needles), but sexual and perinatal transmission is possible
26
What can Hep C cause?
chronic and can cause cancer (hepatocellular carcinoma and liver cirrhosis)
27
What are the risk factors for contraction of Hep C?
- people who use IV drugs - needle stick injuries - hemodialysis patients - vertical transmission (mother to baby) and sexual transmission - blood transfusions before 1992 - people who have haemophilia (a disease where the blood doesn’t coagulate)
28
What are 2 gastrointestinal infections?
- noravirus | - rotavirus
29
Talk about Noravirus:
- calciviridae family (bc nora is classy) - non-enveloped - RNA virus - icosahedral shape
30
What does noravirus cause?
- diarrhoea
31
What is rotavirus look like?
- non-enveloped - RNA - Triple capsid (3 layers) - affects interstium epithelial cells
32
What are the symptoms of rotavirus?
- fever - vomiting - diarrhoea - abdominal pain
33
What is the treatment for rotavirus?
there is non but can get prophylaxis oral vaccines
34
What is the cycle of rotavirus?
1. virus binds and enters cell- endocytosis 2. VP7 and VP4 help with this 3. outermost layer lost 4. its can replicate its double stranded RNA within the structure irself - VP6 helps by acting as channel and allowing RNA to move 5. VP1, 2, 3, 4 transcribe double stranded RNA to mRNA 6. single and double shelled particles assemble in the cytoplasm 7. double shelled particles enter the ER and get a 3rd shell 8. virus leaves cell
35
Talk about measles:
- enveloped - single stranded RNA - negative sense (RNA cant be directly translated by host ribosomes) - pleomorphic - paramyxoviridae family - highly contagious - present in mucus of nose and throat of infected individual
36
How is measles transmitted?
- transmit: sneeze/cough droplets
37
What are the symptoms of measles?
- fever, cough, runny nose, red eyes, and sore throat - after 2-3 days white spots appear in the mouth - after 3-5 days, rash appears on the face and spreads down to the feet - when the rash appears, the fever may spike
38
Talk about mumps:
- enveloped - ssRNA - paramyxoviridae family - helical nucleocapsid shape
39
What are the symptoms of mumps?
- fever, headache, muscle ache, tiredness, loss of appetite and swollen and tender salivary glands under the ears on both or one side (parotitis) - usually appear 16-18 days after infection - transmission is via droplets, similar to measles
40
Talk about rubella:
- enveloped - ssRNA - togavirus family - icosahedral - fever and rash for 2-3 days - spread- droplets
41
What happens if rubella is spread from the mother to the child (congenital)?
``` - congenital rubella Birth defects: - deafness - cataracts - heart defects - damage to the foetal brain and liver - spleen damage ```
42
Talk about adenovirus:
- non enveloped - double stranded DNA virus - adenoviridae family
43
What does adenovirus cause?
- resp illness - gastroenteritis - conjunctivitis - cystitis
44
Talk about papillomavirus:
- non enveloped - double stranded DNA virus - papovavridae
45
What does papillomavirus cause?
- genital tract infection | - cervical cancer
46
What is parvovirus?
- non enveloped - single stranded DNA virus - icosahedral
47
What does parvovirus cause?
- It has a receptor that allows it to attach to erythrocyte progenitor cells - so parvovirus B19 causes inhibition of erythropoiesis - results in shortened lifespan of RBCs
48
Normally parvovirus is asymptomatic. But what symptoms can it cause?
- slapped-cheek appearance - red rash on the trunk and limbs - rash can be itchy - low grade fever - malaise - normally resolves in 7-10 days - gloves and socks syndrome - arthropathy - transient aplastic crisis - chronic red cell aplasia - neutropenia - thrombocytopenia - pancytopenia
49
If you have parvovirus during pregnancy what can happen?
miscarriage or intrauterine foetal death
50
How is parvovirus transmitted?
- respiratory route (droplets) | - mother to foetus
51
What is influenza virus?
- RNA - lipid envelope - orthomixoviridae family - has hemagglutinin and neuraminidase proteins and M2 (matrix protein 2) channel protein
52
What are the types of influenza?
A B C
53
What happens in type A influenza?
- most serious type - affects mammals and birds - cross over between different strains- PANDEMIC
54
What happens in type B influenza?
- affect humans only | - minor outbreaks
55
What happens in type C influenza?
- mild - only affect humans - endemic - similar to normal cold
56
What is the replication cycle of influenza virus?
1. virus attach to cell using hemagglutinin to attach to sialic acid on host surface 2. endocytosis 3. virus now in endosome 4. endosome has low pH 5. virus envelope fuses with endosome membrane 6. triggers uncoating of virus 7. viral nucleocapsid released into cytoplasm 8. viral RNA (negative sense) copied to nucleus to become positive sense 9. mRNA made 10. mRNA translated in cytoplasm 11. viral proteins made 12. RNA segments assembled within nucleocapsid 13. budding off of viral particles at plasma membrane
57
Why do the surface proteins of Influenza virus mutate rapidly?
- because the RNA polymerase involved in its replication has a low selectivity and has no proof reading mechanism, and so mistakes are made and not corrected
58
What is an antigenic drift?
- continued viral mutation that goes on in the viruses - minor mutations - no major effects - new drifted strains - occurs every 2-8 years
59
What is antigenic shift?
- only in TYPE A INFLUENZA VIRUSES - genetic reassortment - different strains mix - everyone lacks immunity
60
What does the Global Influenza Network (GIN) do?
- estimate strain of virus for next season and recommend vaccines - aim to prevent mass illness
61
What are the limitations of GIN?
- estimate errors - manufacturing difficulties - short amount of time - developing countries lack resources

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