Respiratory Viruses Flashcards

Question

Antigenic Drift

Answer 1

Genetic mutations HA gene changes -> antigen it encodes changes shape -> antibodies that normally bind to it no longer can RNA polymerase = error prone :( Exposed to new strains - virus more fit to replicate => endemic

Answer 2

Genetic change - reassortment +/- genetic mutations - that enables flu strain to jump from one animal specifies to another => Pandemic

Answer 3

1) Aquatic bird passes strain to intermediate host, human passes strain of same virus to pig. Genes from both strains mix and form new strain which can spread from intermediate host (like shuffling a deck of card). Genome segments mix 2) Bird strain can jump directly to human without undergoing genetic change 3) Bird strain can jump directly to intermediate host to human without undergoing genetic change

Answer 4

1997 - avian influenza passed directly from birds to humans Hong Kong 1997 variant - avian H5N1 virus - infected 18 people, killed 6 (high mortality rate) ~ 30% Virus was poorly transmissible between humans

Answer 5

Fever Cough Pulmonary infiltrates Exposure to ill poultry Shortness of breath Diarrhoea Headache Myalgia

Answer 6

Sentinel diagnostic labs worldwide Anti-viral stockpiling - Oseltamivir, Zanamivir (limited supplies) Vaccine stockpiling - Only 8 countries with manufacturing facilities

Answer 7

Unusual cocktail of avian, swine and human viruses Pigs harbour several flu viruses, they act to form new strain. Transmission via inhaling **viral particles**

Answer 8

High fever Cough Breathing difficulties Loss of appetite

Answer 9

2 or more WHO regions affected (Spread not severity is decisional criterion) **Government must respond**

Answer 10

chronic lung, heart, kidney, liver, neurological disease immunosuppression diabetes mellitus patients who have had drug treatment for past three years pregnant women people aged 65 and older

Answer 11

Epidemic - disease that affects a large number of people within a community, population, or region Pandemic - disease that's spread over multiple countries or continents

Answer 12

Virus attacks cilia in LRT Innate response Interferon response Virus eliminated 6-10 days Antibody response Antibodies prepare body for re infection of same strain

Answer 13

Can affect many organs Enzyme found on all cells High pathology

Answer 14

Affects local organs e.g respiratory and GI in birds Enzyme only in cells of the lungs and GI tract Low pathology

Answer 15

Cellular protease

Answer 16

**Envelope virus** - derived from infected cell membrane **Surface glycoproteins** - **Neurominidase** (tetramer), **HA** (homotrimer) **Negative strand RNA** **M2 protein** - forms pore between cell membrane and viral envelope **8 genomic segments** - replication and survival **Matrix protein** - gives morphology/shape **RNA dependent RNA polymerase complex** made up of PB1, PB2 and PA **HA** is surface cell receptor; 18 types **NA** cleaves terminal sal acid; 11 types Influenza is endocytosed -> reduces pH -> change in HA -> movement to juxtaposition of endosomal membrane -> Viral envelope able to fuse with cell membrane - M2

Answer 17

No prior antibodies = surge = pandemic People build resistance but virus may mutate Epidemics occur Pandemic again

Answer 18

Time between 2 pandemics

Answer 19

Infection is constantly present or maintained at baseline

Answer 20

Period between infection and display of symptoms, in which the virus is replicating.

Answer 21

Implementation of masks, social distancing and lockdown led to a dramatic decrease n cases of influenza.

Answer 22

Indicates the level of incidence above which a disease requires an urgent response.

Answer 23

Reye’s syndrome, a complication of influenza in children <16 years, however its neurological and thought to be associated with high-dose aspirin