CSIM 1.71 Respiratory Viruses Flashcards
Describe rhinovirus virology:
1) Envelope
2) Genetic material
3) Incubation period
- Non-enveloped
- Positive sense ssRNA
- Incubation 2-3 days (cold)
Why do rhinoviruses affect the nasal cavity?
Their optimum growth temperature is 33ºC, the temperature of the nasal cavity
How is rhinovirus transmitted?
- Respiratory
* Hand to mouth
Describe adenovirus virology
• Envelope
• Genetic material
- Non enveloped
* dsDNA
How many adenovirus species are there?
Which causes gastroenteritis?
7 (A-G)
Adenovirus F
Describe the external structure of an adenovirus
External hexon capsid with penton bases at each vertex, and a fibre protruding from each (IMG 175)
What structure of the virus binds to human cells? What specifically does it bind to?
The fibres protruding from the penton bases bind to “Coxsackie B virus and adenovirus receptor” (CAR)
What pathologies and symptoms can adenovirus cause?
- Cold and fever
- Conjunctivitis
- Tonsillitis
- Bronchiolitis and pneumonia (atypical)
- Diarrhoea
How can a cold caused by adenovirus and rhinovirus be differentiated?
Adenovirus colds will cause a fever, rhinovirus colds will not
Describe the transmission of adenoviruses
- Respiratory
- Hand to mouth
- Faecal/oral
How can adenovirus be diagnosed (in severe cases)?
- PCR
- Antigen tests
- Culture
- Serology (antibodies)
Describe the virology of coronaviruses
• Envelope
• Genetic information
Coronaviruses
• Non-enveloped
• positive sense ssRNA
How are coronaviruses diagnosed
- RT-PCR (RT = reverse transcriptase, because the RNA needs to be made into DNA before PCR can occur)
- Serology
- Culture
What pathologies does coronavirus cause?
- SARS!!!!!
* MERS
Describe the symptoms of SARS
Describe the transmission of SARS
10 to 20 days after exposure: • High fever • Cough • Diarrhoea 20 to 30 days after exposure: • Pneumonia
7 to 30 days after exposure: • Nasopharynx virus secretion 14 to 30 days after exposure: • Faecal viral excretion 20 to 30 days after excretion: • Viruria
What are the symptoms of MERS?
- Fever
- Cough
- Shortness of breath
- Death (30%)
Which virus is the most common causative agent of bronchiolitis? What family is it a part of? Describe the following virology:
• Envelope
• Genetic information
Respiratory syncytial virus (a paramyxovirus)
• Enveloped
• Negative sense ssRNA
What are the symptoms of a respiratory syncytial virus infection
Bronchiolitis:
• Cough
• Wheezing
• Sneezing
How is RSV diagnosed in severe cases?
- RT-PCR
- Culture
- Antigen tests
What drug can be given to treat RSV in episodes of severe bronchiolitis?
Palivizumab - a monoclonal antibody.
Describe the main epidemiological characteristics of RSV
- Peaks in winter
- Majority of infections under 1 year old
- Incidence rates are unstabe between years
What family of viruses is the influenza virus a member of?
Describe the virology of this family:
• Envelope
• Genetic information
• Number of chromosomes/RNA segments
Orthomyxoviruses
• Enveloped
• Negative sense ssRNA
• 8 RNA segments
Describe the transmission and incubation period of influenza virus
- Respiratory transmission
* 2-3 days incubation
What are the symptoms of influenza virus?
- Vomiting
- Muscular tiredness/aches
- Coughing
- Sore throat
- Running nose
- Headache
- Fever
When is influenza defined as an ‘epidemic’?
When there are more than 200 recorded infections in a geographic area per 100,000 (do not confuse with pandemic which is worldwide)
What are the serotypes of influenza?
1) Which of these undergo antigenic shift and drift?
2) Which of these are the most severe?
3) Which animals have each?
4) What are the subtypes of each?
Influenza A, B and C
1) Only A undergoes antigenic shift, all undergo drift
2) A is the most severe (pandemics), followed by B (epidemics) then C (sporadic)
3) A: humans, pigs, birds, horses, marine mammals
B: Humans
C: Humans and pigs
4) A, subtypes are dependent on HA and NA (e.g. H1N1). B & C have no subtypes
From which day does the following occur (after infection)?
1) Virus in respiratory secretions
2) Interferon induction/cytokine storm
3) Clinical symptoms
4) Respiratory pathological changes
5) Rise in virus specific antibody
1) 1 day
2) 3 days
3) 4-5 days
4) 5-6 days
5) 6 days
Decribe the structure of influenza virus:
1) envelope
2) Protein core
3) Antigens
1) Matrix-protein, surrounded in a lipid bilayer
Matrix bilayer links the viral core to the lipid bilayer
2) Nucleo-protein (NP) which links the genetic material together into a structure
3) Neuraminidase and (NA) haemagglutinin (HA) present
(IMG 176)
What is the function of neuraminidase?
Antigen which aids viral release from infected cells
What is the function of haemagglutinin?
Antigen which binds to target cell surfaces (to allow entry)
How many types of HA and NA are there?
NA: N1 - N10
HA: H1 - H17
Recall the difference between antigenic drift and antigenic shift
DRIFT:
• Accumulation of point mutations over time
• Results in a new strain ever 4 years
• Causes epidemics
SHIFT: (INFLUENZA A ONLY)
• Recombination/reassortment of coinfecting viruses
• Creates a novel virus every 10-20 years
• Causes pandemics
IMG 177
What is the treatment for influenza?
Neuraminidase inhibitors (therefore prevents viral release)
• Tamiflu
• Relenza
Describe the vaccines for influenza
Inactivated vaccines containing purified HA and NA subunits
