Lecture 24

Question 1

Describe TB

Answer 1

• Common form is pulmonary
• Infects intracellularly
• Slow growing
• Most infections are dormant, long antibiotic course

Question 2

Describe M.TB host range

Answer 2

Narrow, specialised human pathogen

Question 3

Describe the reductive evolution difference between M.TB and M.M

Answer 3

• Genome size = smaller
• IS elements = has more
• PE/PPE genes = has less than M.M
• Metabolism = M.M has greater metabolic flexibility

Question 4

What is the closest relative of the M.T complex?

Answer 4

M.Marinum

Question 5

Describe the relative number of transporters between M.M and M.T

Answer 5

M.M. has more transporters meaning it has more metabolic frequency that M.TB
-T.B gets everything from the host therefore can survive without these genes

Question 6

Describe Leprosy

Answer 6

• Disease of peripheral nerves
• Skin lesions
• Still very prominent

Question 7

Describe M.Leprae

Answer 7

• Unculturable slow grower
• Obligate intracellular parasite (only grows inside our cells)
• Infects Schwann cells of nerves causing decrease firing

Question 8

Describe the M.Leprae genome in terms of reductive evolution

Answer 8

• Lost 2000+ genes since diverging
• 1/3 genome is pseudogenes
• Almost 1/2 non-coding

Question 9

Describe the possible mechanisms of Genomic Reduction

Answer 9

1. Extensive pseudogene formation
   - M.L lacks DNA proofreading activities in DNA Pol3 which could account for mutations
2. Genomic reduction
   - Short repeat elements in the genome, unknown if these were previously IS elements
   - >repetitive nature has promoted recombination = deletions/reductions

Question 10

Does M.Leprae require large use of PE/PPE?

Answer 10

No because M.leprae co-evolves with us