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Micro lec 13 Flashcards

Viral Respiratory Tract Infections (67 cards)

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1
Q

What is the most cause of illness in otherwise healthy adults

A

acute respiratory viruses

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2
Q

SLIDE

A

4-7

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3
Q

When does teh common cold onset and how long does it lasts

A

1-3 days after viral infection, 1 week

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4
Q

What happens during the common cold

A

inflammation of teh nasal passages

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5
Q

What are the possible complications of the common cold

A

otitis media and sinusitis

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6
Q

who are susceptible to severe infection of the common cold

A

Elderly
Immunocompromised
Asthma, COPD, CF

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7
Q

List the possible viral causes of the common cold

A

Rhinovirus
Isolated in 1950s
Picornaviridae family
Now three species
RV-A, RV-B and RV-C
RV-C discovered in 2006
>100 types

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8
Q

Outline the features of rhinoviruses

A

Belong to the picornavirus family
+ssRNA
acid-labile
at least 100 serotypes are known
Capsid Ø25-30nm
Capsid consists of 60copies of each of the 4 capsid genes (VP1-4)

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9
Q

Outline the features of coronaviruses

A

+ssRNA Virus
Enveloped, pleomorphic morphology
Largest RNA viruses in terms of genome- 26-32kb
Virion size 80-100nm

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10
Q

Where is RNA packaged

A

with the nucleocapsid protein, several membrane proteins and the spike protein

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11
Q

What is the cell protein

A

reversible for cell attachment

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12
Q

What do ORF1 and 1b produce

A

2 large poly proteins needed for replication

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13
Q

slide

A

12

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14
Q

What are the symptoms associated with pharyngitis

A

Sore throat, fever and pharyngeal inflammation
Other symptoms include:
Coryza, hoarseness, cough

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15
Q

What are the possible viral pathogens of pharyngitis

A

Adenovirus (up to 25% cases)
Rhinovirus
Influenza
Parainfluenza
Enterovirus
-Herpangia
-HFMD

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16
Q

Outline the features of adenoviruses

A

ds DNA virus
non-enveloped
At least >60 serotypes are known
classified into 7 subgenera: A to G

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17
Q

When does croup peak

A

age 2 years (range 3months to 3 years)

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18
Q

How does croup present itself

A

Prodrome
- Fever, rhinorrhoea, cough, sore throat
Nonproductive harsh seal-like cough
Inspiratory stridor
Tachypnoea
Subglottic obstruction

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19
Q

What are the possible complications of croup

A

intubation

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20
Q

what viruses are associated with croup

A

parainfluenza viruses 1-4

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21
Q

Outline the features of parainfluenza virus

A

neg ssRNA virus
Paramyxovirus
enveloped, pleomorphic morphology
5 serotypes: 1, 2, 3, 4a and 4b
No common group antigen
Closely related to Mumps virus

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22
Q

What is bronchiolitis also known as

A

respiratory syncytial virus (RSV)

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23
Q

What is the incubation period of RSV

A

3 to 5 days

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24
Q

How does RSV present itself

A

inflammation and narrowing of small airways
Attaches to the airway epithelial cells (AECs)
AECs are shed, mucous production and oedema

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25
What is RSV
Low-grade fever, wheezing, increased respiratory effort (chest wall retraction, tachypnoea, nasal flare), reduced oral intake Apnoea in <6 weeks of age
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When are most children infceted with RSV by
2 years of age, reinfection. common but less severe
27
Whatd oes RSV have association with
development of asthma
28
What is a treatment for RSV
ribavirin, there is also a vaccine called ISV available, very effective and is encouraged for pregnant women
29
Why is RSV a major nosocominal hazard to at risk patients
Can survive on surfaces for 4 to 7 hours Cohort, PPE, hand washing
30
What can be given monthly to treat RSV
A prophylatic monocloncal antibody is available (Palivizumab/Synagis) Given IM monthly
31
Outline the features of influenza virus
Orthomyxovirus Segmented genome 4 types of influenza virus
32
What are the 4 types of influenza virus
Influenza type A - Subtyped based on surface glycoprotein H and N - A/H1N1 and A/H3N2 Influenza type B - Circulating variants belong to Yamagata or Victoria lineage Influenza type C Influenza type D
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How are influenza A viruses classified
by their antigenic composition. Usually on the basis of the 2 envelope proteins Hemaggluitinin (H) and Neuraminidase (N). Hemagglutinin has 15 subtypes and Neuraminidase has 9.
35
What is antigenetic drift and what does it occur as a result of
occurs as a result of the mutation in the H or N proteins. RNA polymerases have no proof reading mechanism so the mutation rate is high. A mutation resulting in evading protective immunity is advantageous to the virus.
36
What does antigenic shift occur as a result of
results from the exchange of genome segments by different virus types called reassortment.
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What are the risk factors for complicated influenza patient
Neurological Hepatic Renal Pulmonary Chronic cardiac Diabetes mellitus Severe immunosuppression Age >65 years Children <6 months Pregnancy (inc. up to 2 weeks post partum) Morbid obesity (BMI≥40)
39
What are influenza pandemics
worldwide epidemics of a newly emerged strain of influenza
40
Who has immunity to the new influenza
few, if any people
41
What occurs during influenza pandemic
virus spreads widely easily and antigenic shift occurs
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What type of influenza causes influenza pandemic
influenza A
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What is avian influenza
Natural reservoir influenza A viruses aquatic birds
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How does avian influenza pass
Can pass to domestic poultry Sporadic zoonotic infections
46
How is avian influenza transmitted to humans
Close contact infected bird - Respiratory droplets or faeces Household contact HCWs
47
What is the incubation period for SARs-Cov2
around 5-6 days, transmission 1-2 days before symptoms onset
48
How does SARs-Cov2 present itself
Wide clinical presentation Fever, cough, headache, sore throat, anosmia, agesuia, myalgia, fatigue, SOB, GI symptoms, nasal obstruction
49
What are the risk factors of SARs-Cov 2
Chronic conditions associated with lungs, heart, kidney, liver, neurological diseases and diabetes, endocrine disorders, immunosuppressed, BMI≥40, severe mental impairment, pregnancy (all stages)
50
How does SARs-Cov2 begin to show clinical deterioration
in 2nd week with pneumonia, acute respiratory distress, septic shock, multi-organ failure
51
How does SARs-Cov 2 present in children
Mild symptoms Rare: Paediatric multisystem inflammatory temporally associated with SARS-COV-2 infection (PIMS-TS)
52
What are the treatment options for SARs-Cov2
Glucocorticoids Dexamethasone Modulate inflammation-mediated lung damage RECOVERY Trial (177 hospitals in the UK) 6mg once daily dose for up to 10 days reduces mortality in those receiving respiratory support Not beneficial in those who do not required oxygen support IL-6 inhibitors Interleukin 6 part of the immune response COVID-19 can cause hyperinflammatory response IL-6 involved Tocilizumab and sarilumab are IL-6 inhibitors
53
List more examples of treatment options for SARs-Cov2
Antiviral Remdesivir Pre-clinical trial for ebola virus Nucleoside analogue Administered as IV only Molnupiravir Pre-clinical trial for influenza Nucleoside analogue Reduces hospital admissions and mortality in those at risk of severe illness Paxlovid Viral protease inhibitor Combination of PF-07321332 and ritonavir Reduces hospital admissions and mortality rates in those at risk of severe illness Antibody Ronapreve Antibody combination casirivimab and imdevimab Monoclonal antibodies Each target separate region of viral spike protein Prevents viral spike protein from attaching to cell receptor Sotrovimab Monoclonal IgG antibody Targets the viral spike protein Prevents viral spike protein attaching to cell receptor Decrease in vitro neutralisation against Omicron BA.2
54
What is the main target for neutralising antibodies
SARS-CoV-2 spike protein
55
What are the different types of SARS-CoV-2 vaccines and what do they target
Vaccines target the S protein Two mRNA vaccines Pfizer BioNTech COVID-19 mRNA vaccine BNT162b2 (Comirnaty) Moderna mRNA-1273 COVID-10 vaccine (Spikevac) Modified mRNA Viral S-protein genetic code Host cells translate the code to make spike protein Adenovirus vector vaccine AstraZeneca COVID-19 vaccine (Vaxzervia) Vector is a replicon deficient chimpanzee adenovirus containing full length SARS-CoV-2 spike protein Recombinant S protein- vaccine Novavax COVID-19 vaccine (Nuvaxovid) Baculovirus containing modified spike protein infects moth cells and spike protein is then harvested Adjuvant added
56
How can SARS-CoV-2 be diagnosed
electron microscopy respiratory viruses almost all qPCR Respiratory test include: Nasal pharyngeal swab Throat swab Throat/nose combined swab Gargle Sputum ETA BAL
57
What does qPCR tend to be
multiplex qPCR assays and screen for a panel of viruses referred to as syndromic testing
57
What are the benefits of molecular testing
Improves the diagnosis of previously under diagnosed infections Rapid detection Reduces unnecessary antibiotic treatment Isolation or cohort groups according to result Can be developed to detect new pathogens Cause of Covid-19 isolated on 7th January Public Health England test available on 20th January for labs to send samples for testing Laboratories in Glasgow and Edinburgh started testing for SARS-CoV2 on 10th March 2020 Better understanding of respiratory illness Informs public health E.g. Containment and isolation of infected individuals New treatments
57
What are the negatives of molecular testing
Rapidly changing viruses can lead to false negative PCR test if primers/probes designed in region experiencing genetic drift E.g. commercial influenza tests Low level positive PCR results are these real? Immunocompomised can still shed virus for long periods of time Cannot determine if detecting viable virus Cell culture can be used for SARS-CoV2 patients False positive degradation of probe Contamination e.g. patient swabbed in area where live influenza vaccine is administered
58
What is a disadvantage of point of care testing (POCT)
Less sensitive and the range of pathogen testing is limited
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What are the 2 main types of POCT
Antigen testing (using lateral flow devices) Nucleic acid amplification
61
What are lateral flows used for
influenza, RSV and covid 19
62
What do some POCT lateral flows test for
multiple pathogens simultaneously
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How does nucleic acid amplification work
Samples are added to cartridges and loaded onto the corresponding device. The nucleic acid extraction, qPCR reaction and analysis is carried out by the device with all reactions contained in the cartridge
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