C1 & 2

Question 1

Name the 5 routes of infection

Answer 1

1. Person to person
2. vector
3. fomite
4. Orally: food
5. contaminated water

Question 2

name 3 types of person to person transmission & examples

Answer 2

A. direct contact e.g. chicken pox/
B. contaminated body fluids e.g. Herpes simplex-2: increased chance HIV (females)
C. Vertical transmission e.g. Toxoplasma gondi (cat)

Question 3

Define viral infection

Answer 3

vector bone diseases are infected are infection transmitted by the bite of infected arthtopod species e.g. mosquitoes, ticks, triatomine bugs, sandflies, blackfiles

Question 4

Name examples of vector transmission

Answer 4

1. sandfly born disease: Leishmaniasis
   (protazoan parasite)
2. tick born encephalitis: flaviviridae: acts on receptors & reservoirs
3. Lyme Borreliosis: bacteria spirochete Borrelia burgorferi (lxodes genus)

Question 5

name a fever which can be caused by a tick

Answer 5

CCHF: crimean-congo pnemorrhagia fever
RNA virus of Bunyaviridae family
- transmitted: Hyalomma spp ticks from domestic animals (zoonosis)

Question 6

Name examples of fomite infection

Answer 6

non living objects. Bedding, toys, towels, flu on surfaces, athletes foot

Question 7

which immune components protect at each entry site?

Answer 7

1. Soluble mediators: anti-infectives e.g. desfensins, complement
2. tissue resident cells: eg. epithelial cells, alveolar macrophages
3. recruited cells: innate: neutrophils, NK. Specific: B/T
4. antibodies: different classes = diff functions

Question 8

C2.

Soluble blood components

Answer 8

complement, antimicrobial protein: lactoferrin/ bactericidal, permeability. a-defensins & B-defensins are cationic peptides: disrupt membranes
often present in an inactive form -> activated when immune response is taking place

Question 9

describe carbohydrate outer membrane

Answer 9

carbohydrate chain interlocked by short peptide strands

Question 10

describe function of lysosome

Answer 10

breaks down carbohydrate chains & damages structural integrity of bacterial outer membrane
(bacterial burst under own internal pressure)

Question 11

explain process defensins

Answer 11

Electrostatic attraction & transmembrane electric fields bring defensin into lipid bilayer
defensin peptides form a pore

Question 12

Cathelicidins

Answer 12

stored in granules & inactive precursors: released when cleaved by neutrophil elastase
LL37 - only CAMP gene in humans

Question 13

where is LL37 expressed

Answer 13

circulating neutrophils & myeloid BM cells, epithelial cells of the skin, GI, epididymis & lungs

Question 14

Function of CD3 T cells

Answer 14

co receptor helps to activate both cytotoxic CD8+ & CD4+

Question 15

what does a product mean

Answer 15

small product EXCEPT C2 (C2a=BIG): anaphylatoxins

may initiate localised inflammatory response by binding to receptors

Question 16

what does product b mean

Answer 16

BIG product - bind near activation sites

Question 17

what do all 3 pathways of complement generate

Answer 17

generate C3 convertase which cleaves C3, leaving C3b bound to the microbial surface & releasing C3a

Question 18

C3a & C5a recruit what cells to site of infection

Answer 18

phagocyte cells, also promote inflammation

Question 19

MAC leads to

Answer 19

disrupts cell membrane & causes cell lysis

1. recruits cells to site of infection (to kill infected cells)
2. reduces damage

Question 20

define alternative pathway

Answer 20

C3 undergoes spontaneous hydrolysis to C3(H20) to initiate eventual desposition of C3 convertase on microbial surfaces