Flashcards in Viral and Bacterial Infections Deck (43):
What is a a) pneumotropic b) lymphotropic c) enterotropic and d) neurotropic infection?
a) One via the lungs: upper and lower respiratory tract epithelial cells
b) lymphatic cells
c) gut epithelial and liver cells
d) neuronal cells
What are viruses?
Small infectious agents that can replicate only inside the living called of a host. Depend on a host cells machinery to enter, replicate, and assemble new viruses.
What is the term given to a cell in which a virus can enter?
What do susceptible cells often require?
A specific receptor which can bind a viral attachment protein
What are the three types of infections?
Acute, latent or persistent and slow
Which (acute, latent or slow) can the immune system contain and clear?
Which (acute, latent or slow) has frequent reactivation?
Latent and slow
Which (acute, latent or slow) has the slowest onset of symptoms?
What does HIV stand for?
Human immunodeficiency virus
Do a) 10 million, b) 3300 or c) 3.3 million die annually from HIV?
What does HIV cause?
AIDS- acquired immunodeficiency syndrome
What does AIDS target and why?
T helper cells to make them into factories in order to produce thousand of copies of the virus.
Why is AIDS so destructive?
Leads to low levels of T helper cells and a loss of cell mediated immunity which highly increases susceptibility to infections
How is HIV transmitted?
Unprotected sex, sharing needles, mother to foetus and blood products
How many classes of anti-HIV are there today and how to they work?
5 and they target different stages of the viruses life cycle
What 5 stages do anti-HIV drugs target?
Entry, integration, transcription, assembly and release/budding.
How are anti-HIV drugs takes?
Different classed drugs are combined to act on different points, this is called highly active antiretroviral therapy (HAART)
Why is one class of drug not sufficient?
As resistance is common in HIV due to mutations
Why are respiratory viruses common?
As the lungs have a very large surface area and come into contact with huge volumes of air every minute.
How are respiratory viruses transmitted?
Droplet inhalation, airborne and direct, or exhaled breathe, within close proximity.
The deeper you get into the lungs via the respiratory tract the ? Does the infection get?
What does infection cause and how?
General cell destruction, via virus-mediated death and immune mediated death
Why is influenza a devil?
Mutates into new strains very easily and frequently
What is antigenic shift in viruses?
When 2 virus infect the same cell and a new virus emerges
Describe influenzas external morphology?
Polymorphic particles and 3 membrane proteins ( NA, M2 and HA)
Describe influenzas interior morphology?
Sheath of matrix beneath membrane and 8 RNA segments encode the viral genes
What two steps in influenzas life cycle can be targeted by drugs?
Segment release into the cytoplasm (endoscope release) and general release
What drugs are influenza anti viruses?
What two properties do antibiotics have?
To kill (bactericidal) or to inhibit (bacteriostatic)
Define the term antibiotics?
A group of drugs that kill or inhibit the growth of pathogens without causing serious damage to the host.
Natural products isolated from bacteria, fungi etc. Semi-synthetic
How do bactericidal and bacteriostatic antibiotics work?
Bactericidal disrupt cell wall syntheses and bacteriostatic interfere with DNA/protein synthesis
What level of activity do antibiotics have?
Some have very broad and some narrow, a large spectrum
How are antibiotics classified?
What do sulphonamides or trimethoprim do?
Prevent nucleotide syntheses by inhibiting folate synthesis
What do ß-lactams do?
In bacteria and plants they prevent cell wall synthesis
What feature do ß-lactam antibiotics have?
A ß-lactam ring
What antibiotics inhibit protein syntheses?
Tetracycline (inhibits tRNA binding)
Aminoglycosides (miss read)
Chloroamphenicol (inhibits peptide bond formation)
Pyromycin (causes premature termination)
Enthrythromycin (prevents translocation)
What antibiotics inhibit RNA transcription?
How are trimethoprim and sulphonamide given?
Orally. Both absorbed in GI tract
What's the difference between a gram negative and a gram positive bacteria?
Gram negative have an outer membrane which creates a peri plastic space, this is not present in gram positive bacteria
What is the structure of peptodoglycan?
N-acetyl glucosamine is linked to N-acetyl muramic acid and chains are cross linked by oligopeptides
Is it only ß-lactams that prevent cell wall synthesis?