Bacteria

Question 1

Gram positive bacteria

Answer 1

Characterized by a thick cell wall composed of peptidoglycans - sugar chains crosslink linked with proteins. Antibiotics can penetrate.

Without the wall, bacteria burst due to high osmotic pressure.

Question 2

Gam negative bacteria

Answer 2

Contains a lipopolysaccharide outer membrane with small water pores. Antibiotics must be very lipophilic, or small and water soluble to gain access.

Question 3

Viruses

Answer 3

Contain genetic information (DNA or RNA) in the form of nucleic acids. But they lack the genetic information for protein synthesis and metabolism. So they replicate in the host cell by coopting its machinery.

Influenza, Smallpox, HIV, West nile, HPV,

Question 4

Stages in Viral binding

Answer 4

binding
fusion/penetration
uncoating
translation
replication
assembly (RER)
budding and release (GA)

Question 5

How does bacteria resist antibiotics?

Answer 5

degrading enzymes
mutation in target
reduced permeability
Efflux pumps.

Question 6

Where do bacteria multiply in the body?

Answer 6

Some are extracellular, others are intracellular. Need different treatments.

Question 7

Effective response extracellular infection?

Answer 7

• Drive inflammation, complement
• Neutrophils and phagocytes for clearance.
• Antibodies will neutralize, agglutinate, opsonisation.

Question 8

Effective response extracellular infection?

Answer 8

Activate cytotoxic T cells.

Question 9

How do Th cells know how to differentiate?

Answer 9

Cells that first recognize an antigen secrete different cytokines, depending on the type of receptor that to which the antigen bound. Viruses and gram +/- will bind to different receptors.

The cytokines help Th cells differentiate to their different types, to either drive antibody production, promote inflammation, or activate cytotoxic T cells.

Question 10

What are the targets for different Th cells (Th1, Th2, Th17)?

Answer 10

-Th1 -> IFNgamma for intracellular bacterial infections.
Th2 -> IL4/5. Drive production of IgE from B cells, activates mast cells.
Th17 -> produces IL17, which promotes inflammation, neutrophil recruitment, IgG production, and bacterial clearance. Has role, however, in asthma, MS, Crone’s, Psoriasis.

Question 11

Cell-mediated immunity

Answer 11

Required to defeat intracellular pathogens, which are hidden from the effects of antibody and complement.

Immunity comes from cytotoxic T cells and Helper cell-mediation of macrophage activation.