Case 1 - Fresher's Flu Flashcards
Brief Overview of Case:
Patient has: Coughing (flem) Lack of sleep Tired Sore throat
Cold VS Flu Symptoms:
Cold: More common to get a sore throat and stuffy nose, less likely to get aches or headaches. Symptoms arise more gradually
Flu: Cough / Chest discomfort more common, fatigue / lack of ability to carry out daily activities more common, muscle fatigue / aches, symptom onset more sudden
What type of virus in the influenza virus?
Air Borne - spreads through the air e.g. via coughing, sneezing etc.
Which type of cells does the influenza virus target?
Epithelial cells in the respiratory tract
What are the names of the 2 glycoproteins on the influenza virus and what are they responsible for?
HA— Haemagglutinin: Receptors on the influenza virus that attach to the sialic acid on the cell membrane of host cells, also causes haemagglutination, forming a network of RBCs and viral particles
NA — Neuraminidase: Glycoside hydrolase enzyme that cleaves sialic acid off the viral proteins, so the virus is released from the host cell and can continue to affect further cells
Influenza virus mechanism (6 steps):
- HA causes influenza virus to attach onto the sialic acid of the host cell membranes
- Influenza enters the cell by endocytosis, releases RNA into the cytoplasm
- The viral RNA is imported into the nucleus
- Viral RNA replicated using host cell machinery
- Viral RNA transported to cytoplasm, and uses host cells machinery to synthesis viral proteins
- Viral proteins and viral RNA assemble to form more influenza viruses, and are cleaved from the host cell by NA so they can further affect other host cells
What are the 2 mechanisms for the change in genetic material in viruses?
Antigenic drift and antigenic shift
Differences between antigenic drift and antigenic shift:
Antigenic drift occurs over a long period of time, gradually, whereas antigenic shift occurs abruptly, a major change in the genetic makeup causing a phenotypic change
Key features of Antigenic Drift:
Natural mutations overtime - small genetic changes
Initial small changes still result in same/similar antigenic properties so still recognised by immune system
Overtime, antigenic material will change and a new immune response will need to be formed
Occurs in all influenza types
Key Features of Antigenic Shift:
Sudden change in genetic conferring to a phenotypic change
Requires new immune response to new
/ changed antigenic material
Population at a risk of a pandemic (most have little to no protection)
Only occurs in Influenza A
How does antigenic shift arise?
From the combination of genetic information of 2 or more different strains of a virus that infect the same type of cell
Give an example of an animal in which antigenic shift is likely to arise and why?
Pigs - Depending on the HA, the virus can affect humans or birds. Pigs, however, can be affected by human and avian strains of influenza A. They act as a reservoir for genetic reassortment, and new strains of influenza capable of infecting humans arise from the assortment with avian genetic material
What is a Risk Factor?
Attribute/characteristic, or exposure to an individual that increases the chances of them contracting a particular disease
Risk factors for Fresher’s flu amongst freshers?
Lack of sleep
Poor diet
Close proximity (air borne, transmits more easily)
Poor hygiene
New people (e.g. internationals, exposed to pathogens never encountered before)
Risk factors for the general population contracting a respiratory viral illness?
Age (extremes i.e. infants and elderly - degenerating or developing immune system)
Respiratory conditions (e.g. cystic fibrosis, asthma, COPD etc)
Immunocompromised (e.g. chemotherapy, HIV, transplant patients)
Obesity
Pregnancy
Chronic stress
