Lecture 17- Influenza Flashcards
Viral structure?
Delivery system with internal payload that contains genome and enzymes necessarily for first few steps of viral replication
What is flu?
Acute viral infection of respiratory tract including throat, mouth, nose, bronchial tubes and lungs
What type of virus is influenza?
Orthomyxovirus which is a spherical, enveloped virus containing a segmented, negative strand RNA genome
What is significant about influenza RNA polymerase?
Have high error rates leading to antigenic drift
What are the two significant surface antigens of influenza?
Haemagglutinin which helps attach to cell and neuraminidase which helps replicated viruses leave cell
Why is influenza A most significant
Seen in many species which means it can cause huge pandemics. Also unlike influenza B it can undergo antigenic shift as well as drift and can cause pandemics
What causes RNA replication in viruses?
RNA- dependent RNA polymerase
How is RNA replicated in viruses?
Negative single strand RNA converted to positive strand and mRNA which goes to form protein and negative single stranded RNA to make new viruses
How I’d flu spread?
Small particles aerosols stay in air
Larger droplets coughed onto someone within 3m
Cough onto surface
Barriers to virus?
Ciliaa
Mucus
Immunogenicity defence like natural killer cells and macrophages
Influenza symptoms?
Headache, fever , dry cough, sore throat, nausea, diarrhoea, fatigue etc but up to 75% have no symptoms
Influence incubation?
1-5 days and with no symptoms can still infect others
Risk people with influenza
Children under 6 months Over 65 Immunocompromised Pregnant women High BMI over 40
How to diagnose influenza?
Range of diagnostic tests but usually use clinical assessment and history. Use tests if admitted to hospital etc
Influenza treatments.
Antivirals not used m,ugh due to resistance
Neuramidase inhibitirs like tamiflu
Prevention through vaccination
Influenza vaccinations?
I activated vaccine and attenuated vaccin. Attenuated usually given to children.
I activated can be quad rivals to or trivalent depending on how many strains it works against
What is antigenic drift?
Small mutations in haemagluttinin and neuraminidase that occur gradually over time due to error prone rna polymerase
Antigenic shift?
Only influenza type A and only occurs every 10-20 years and can cause pandemics.
Two or more different strains combine to give a different sub type of flu. Occurs when influenza viruses from several different species occur in the same host
How does reassortement occur in antigenic shift?
Environments where pigs, birds humans etc live close together a pig can be simultaneously infected with multiple influenza subtypes and a new subtype can arise which can spread to humans and birds etc
How does flu kill?
Causes immune response that triggers antibodies and immune cells which move to infection site and release cytokines leading to inflammation.
Immune system can overreact and damage lung tissue and cause secondary opportunistic inf3ction fr9mvorganisms like streptococcus or staphylococcus
Who should get flu vaccine?
The old, the young
Health care workers
Chronic medical conditions
Pregnant women
Effects of flu with pregnancy?
Lower birth rate
Increased maternal complications
Increased risk of prematurity
Increased risk of perinatal mortality
