Introduction, Classification,Epidemiology, Morphology, Life cycle, Antigenic shift, Transmission, Pathophysiology, Symptoms, Diagnosis, Treatment, Prevention

1. INFLUENZA VIRUS
PRESENTED BY
NAVEED UR REHMAN
BS, MICROBIOLOGY

2. – Influenza virus is an infectious agent that causes a respiratory tract
infection
– It cause diseases in vertebrates
– It is an antisense single stranded RNA virus
– Influenza virus has three main types i.e. Influenza A, Influenza B,
influenza C
INTRODUCTION
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3. Classification
– Group: Group V ((-)ssRNA
– Family: Orthomyxoviridae
– Genus: Influenza virus
– Species: Influenza A, Influenza B, Influenza C
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4. Epidemiology
– The epidemiology of influenza although unpredictable
– Influenza outbreaks are known to occur in three patterns:
– Pandemic every 30 to 40 years, with high mortality
– Epidemics much more frequently, with lower mortality
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5. Morphology
– Influenza type A, B and C
are similar in structure
– These are roughly spherical
of 80-120nm in dimeter
– Type C may occur as
filamentous
– Outer layer is lipid membrane
Morphology of influenza virus
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6. Cont…
– There are two types of projections: hemagglutinin (HA) spikes and
neuraminidase (NA) spikes
– The HA spikes, of which there are about 500 on each virus present
– The NA spikes, of which there are about 100 per virus
– These spikes are composed of glycoproteins
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7. Cont…
– NA differs from the HA spikes in appearance and function
– Viral strains are identified by variation in the HA and NA antigens
– The different forms of the antigens are assigned numbers
– For example HI, H2, H3, N1, and N2
– There are 16 subtypes of HA and 9 of NA
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8. Cont…
– Complete genome of influenza is segmented into 8
fragments
– Influenza C has 7 fragments of genome
– Genomic size is about 13.5 bp
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9. Lifecycle
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10. Antigenic shift
– Caused by exchange of genetic materials(RNA)
– New strains generate
– Results in pandemics
– For example, Asian flu by H2N2 subtype in 1958-1959
– Only occur in influenza type A
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11. Transmission
– Influenza can spread in three main ways
– Direct transmission: An infected person frequently touch their nose,
mouth and conjunctiva
– Virus aerosols: Sneezing, coughing and speaking all produce aerosols
– A good sneeze can generate up to 20,000 aerosols
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12. Cont…
– Indirect transmission: Transfer through contaminated objects
called fomite, such as toys, doorknobs, light switches etc
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13. Pathophysiology
– Influenza virus infect both upper and lower respiratory tracts
– Sialic acid on epithelial cells are the receptors
– Typically incubation period of influenza is 24 hours to 4 days
– Children are more affected than adults
13 Influenza infected lungs

14. Symptoms
– Fever may be 100°F to 104°F
– Headache
– Dry nose
– Runny nose
– Sore throat
– Fatigue(tiredness)
– Body aches
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15. Diagnosis
– Viral culture
– Serology
– Rapid antigen testing
– RT-PCR
– Immunofluorescence assays
– Rapid molecular assays
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16. Treatment
– It includes a range of medications and therapies:
Antiviral drugs
– 1) Oseltamivir: Serve as competitive inhibitor of the activity of
viral neuraminidase enzyme in sialic acid
– 2) Zanamivir: it binds to the active site of the neuraminidase
proteins, make the influenza virus unable to escape its host cell
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17. Cont…
– 3) M2 inhibitor: the antiviral drug such as Amantadine and
Rimantadine block a viral ion channel(M2 protein)
– Prevent the virus from infecting cells
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18. Prevention
– Get vaccinated each year
– Washing hands
– Covering nose and mouth while coughing or sneezing
– Avoid touching nose, mouth and eyes
– Limited contact with sick people
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19. Vaccination
– Annual vaccination for a given year
– Each seasonal vaccine contains three or four viral-strain antigens:
• Type A H1N1
• Type B H3N2
• Type B strains
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20. Cont…
– CDC said that flu vaccine is 61 effective and recommends flu
vaccination for all over 6 months
– Side effect:
– No severe side-effect of influenza vaccine
– Sometimes allergic reaction and increased cough, runny nose,
asthma are identified in children
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21. THANK YOU
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