Paper II — 2017 February (2010 Scheme) — Q10

Paper II

2017 February (2010 Scheme) · 40 marks · 120 min

Question

Antigenic shift

Q102 marksShort Notes★✓

Answer

Antigenic shift is a major, abrupt structural change in the surface antigens (haemagglutinin, HA, and/or neuraminidase, NA) of influenza A virus, occurring through genetic reassortment — distinct from the gradual point-mutation-driven “antigenic drift” seen in both influenza A and B.

Mechanism: influenza A’s segmented RNA genome (8 gene segments) allows two different strains (e.g., human and avian/swine strains) to co-infect the same host cell (a “mixing vessel,” classically pigs) and exchange whole gene segments, producing a novel reassortant virus with an entirely new HA/NA combination.

Consequence: since this new combination is completely novel to the human population, there is little/no pre-existing immunity, potentially resulting in a pandemic with rapid spread and high morbidity/mortality.

Restriction to Influenza A only: requires an animal reservoir for reassortment — influenza B and C lack this and undergo only antigenic drift.

Historical examples: 1918 “Spanish flu” (H1N1), 1957 “Asian flu” (H2N2), 1968 “Hong Kong flu” (H3N2), 2009 “swine flu” (H1N1).

Related Concepts

1. 1Influenza

Other Years Asked

1. 1o high grade fever, head ache, nasal discharge and cough and breathing difficulty. Answer the following.2017 August (Supplementary) (2010 Scheme)Essay · 10 marks
2. 2Read the following clinical history and answer the following questions A 45 years old diabetic male was hospitalized in ICU isolation ward for the following complaints. High fever for two days, rapidly progressive sore throat, cough, dyspnoea and headache of one day duration. He gave history of returning from a country which was notified for the presence of a pandemic flu like disease.  What is the most probable diagnosis.  What specimen do you collect from the patient  How do you transport it to laboratory  How will you proceed with the specimen in the microbiology lab for the proper lab diagnosis.  What is the role of vaccine in preventing this disease (1+1+2+4+2)2022 May (Supplementary) (2010 Scheme)Essay · 10 marks
3. 3What is antigenic shift and drift in influenza virus. What are the implications. What are the risk factors for complications following influenza infection2022 February (2019 Scheme)Short Essay · 8 marks
4. 4Antigenic variations of influenza virus2024 March (Supplementary) (2019 Scheme)Short Answer · 4 marks
5. 5Antigenic variations in influenza virus2024 June (Supplementary) (2019 Scheme)Short Answer · 4 marks
6. 6Differentiate between antigenic shift and antigenic drift2023 July (Supplementary) (2019 Scheme)Short Answer · 4 marks
7. 7Antigenic shift in influenza virus.2013 September (Supplementary) (2010 Scheme)Short Note · 2 marks
8. 8Antigenic variation in influenza virus2021 May (Supplementary) (2010 Scheme)Short Note · 2 marks
9. 9Draw the morphological structure of influenza virus2018 February (2010 Scheme)Short Note · 2 marks
10. 10Avian influenza2018 July (Supplementary) (2010 Scheme)Short Note · 2 marks
11. 11Antigenic variations of influenza virus2025 August (Supplementary) (2010 Scheme)Short Note · 2 marks
12. 12Morphology of influenza virus2014 September (Supplementary) (2010 Scheme)Short Note · 2 marks
13. 13Antigenic drift.2023 March (Supplementary) (2010 Scheme)Short Note · 2 marks
14. 14A: Influenza viruses are responsible for pandemics over the years R: Antigenic shift is common is these viruses2025 March (Supplementary (SAY)) (2019 Scheme)MCQ (Multi) · 1.8 marks
15. 15Name an antiviral drug used for the treatment of influenza.2023 July (Supplementary) (2019 Scheme)1 mark
16. 16List TWO common viral causes of community acquired pneumonia.2022 February (2019 Scheme)1 mark
17. 17Name ONE antiviral drug used for treatment of influenza2024 March (Supplementary) (2019 Scheme)1 mark