influenza virus

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 2

3. Classification Group: Group V ((-)ssRNA Family: Orthomyxoviridae Genus: Influenza virus Species: Influenza A, Influenza B, Influenza C 3

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 4

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 5

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 6

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 7

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 8

9. Lifecycle 10

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 9

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 11

12. Cont… Indirect transmission : Transfer through contaminated objects called fomite, such as toys, doorknobs, light switches etc 12

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 14

15. Diagnosis Viral culture Serology Rapid antigen testing RT-PCR Immunofluorescence assays Rapid molecular assays 15

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 16

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 17

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 18

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 19

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 20

21. THANK YOU 1