11a: Infection routes

Question 1

Survival of viruses =

Answer 1

successful infection

Question 2

Extent of virus propagation in the host organism:

Answer 2

• Localized infection: papillomatosis, rabies

- Generalized infection: viraemia

Question 3

What are the different infection routes?

Answer 3

• transcutaneous
• airborne
• oral
• veneral
• transplacental
• germinative
• iatrogenic

Question 4

Transcutaneous infection:

Answer 4

via the skin

• keratinized cells on the surface - NO VIRUS INFECTION
• injuries: papilloma, rabies (bite)
• arthropod vector
• special: conjunctiva (herpes)

Question 5

What is an arthropod vector?

Answer 5

arthorpod vector: arthropod-borne: arbovirus

• mosquito, tick, fly, louse
• mechanic vector - biological vector
• orbi-, toga-, flavi-, bunyaviruses

Question 6

Airborne infection:

Answer 6

via the respiratory tract

• droplet infection
• aerosol particles between 5 and 0.5 um
• UV light, drying out
• defense systems:
• -> mucosal immunity (IgA, lymphoid cells, alv. macrophage)
• -> temperature: 33*C - polymerase activity low
• -> microvilli
• respiratory diseases (paramyxo, rhinovirus)

Question 7

Oral infection:

Answer 7

via the enteric system

• Oral cavity - lysozyme
• stomach: acidic pH, proteolytic enzymes
• small intestines: digestive enzymes, bile (detergent)
• -> resistant viruses (mainly non-enveloped): adeno-, reo-, picorna-, calici-, astroviruses-, corona-, orthomyxoviruses.
• -> proteolytic enzymes sometimes activate virus receptors

Question 8

Veneral infection:

Answer 8

via the urogenital tract

• sexual intercourses
• sensitive viruses too
• often cell-associated transmission
• hepers-, papilloma-, hepadna-, arteri-, retroviruses

Question 9

Transplacental- or intrauterine infection:

Answer 9

via the placenta

• different placenta structures; barriers
• age/development of the embryo; resorption, tolerance, abortion, mummification
• herpes-, parvo-, flaviviruses

Question 10

germinative infection:

Answer 10

via the egg (birds)

• on the surface of the egg - at hatching (i.e herpes)
• inside the egg (circo-, adeno-, picorna-, retroviruses)
• yolk immunity!

Question 11

Latrogenic infection:

Answer 11

by veterinarians

• non-sterile equipment (papilloma-, flaviviruses)
• needle, syringe (flavi-, arteri-, retroviruses)

Question 12

Mixed forms:

Answer 12

OroNasal - influenza

Question 13

Factors influencing the result of infection:

Answer 13

• susceptibility
• infectivity
• amount of viruses
• pathogenicity
• virulence

Question 14

Factors influencing the result of infection, Susceptibility:

Answer 14

abortive infection - non pathogenic, not suitable route

• -> host spectrum
• stenoxen
• euryxen

Question 15

Factors influencing the result of infection, Infectivity:

Answer 15

viral receptors, nucleic acid

Question 16

Factors influencing the result of infection, amount of viruses:

Answer 16

• changes of successful infection

- capacity of the immune system

Question 17

Factors influencing the result of infection, pathogenicity:

Answer 17

overt disease adaptation

Question 18

Factors influencing the result of infection, Virulence:

Answer 18

degree of expression (pathogenicity)