6.2.9 - Evolutionary Race Between Pathogens & Hosts

Question 1

What Is The Evolutionary Race?

Answer 1

When host and pathogen, develop new ways to have an advantage over the other. (Evolutionary Arms Race).

Question 2

What Are The 2 Pieces Of Evidence, Which Supports The ‘Evolutionary Arms Race’ Theory?

Answer 2

~ HIV evasion mechanisms.

~ TB evasion mechanisms.

Question 3

Describe ‘HIVs Evasion Mechanisms’
(3 Points)

Answer 3

~ HIV kills T helper cells, reducing their numbers.

~ HIV shows antigenic variation, due to high levels of mutations, forming new strains requiring a new primary response.

~ HIV disrupts APCs, preventing the immune system from recognising foreign antigens.

Question 4

Describe ‘TBs Evasion Mechanisms’
(3 Points)

Answer 4

~ Once engulfed by phagocytes, TB produces substances preventing a lysosomes from fusing with the phagocytic vacuole.

~ Allowing bacteria to multiply undetected, within the phagocyte.

~ The bacteria also disrupts APCs, preventing the immune system from recognising the foreign antigens.