TB Today: Baggage from a long standing relationship

1
TB Today Baggage from a long standing
relationship

• Peter M. Small, MD
• February 26, 2004

2
Overview

• Beyond Molecular Epidemiology
• Molecular Evolution
• Genus
• Species
• Of vaccines
• Of bacilli
• Insights Gained
• And your program?

3
Conventional Molecular Epidemiology

• Conventional
• Epidemiology

Molecular Markers
Disease Control
4

A New Paradigm
Molecular Epidemiology
Molecular Epidemiology
Molecular Microbiology
Comparative Genomics
Fundamental Biology-- Evolution
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Evolution
Getting out of the Primordial Muck
Isolationist Only vertical gene
transmission Evolve by gene change and
loss e.g. Mycobacteria
Constructive engagement Promiscuous sexual gene
exchange Evolve by gene change, lose and
gain e.g. Intestinal organisms
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Evolution of The Genus
?
Environmental Organism
Environmental Pathogen
Pathogen
Symbiont
M. marinum
M. tuberculosis Complex (4.4Mb)
M. smegmatis (?7Mb)
M. ulcerans
M. leprae (3.3Mb)
MAC
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Evolution of the M. tuberculosis Complex
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TB Vaccine A Brief History of BCG

• Calmette Guerin attenuated M. bovis
• 240 serial passages between 1908 1921
• Currently the most widely used vaccine
• Efficacy controversial

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Historical genealogy of BCG strains
(240 passages)
Up to 1500 passages
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BCG Efficacy vs. Passage Number
100
80
Pasteur
Denmark
60
Tice
Efficacy
40
Frappier
Phipps
20
0
0
500
1000
1500
Passage
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DNA Microarrays
DNA
DNA 1
DNA 2
label
label
label
Hybridization
laser scanner
Analysis
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Evolution of the BCG family
1908
1921
1931
1961
Japan
Glaxo
Tice
Frappier
Pasteur
Russia
Birkhaug
Phipps
Moreau
Prague
Denmark
Connaught
Sweden
Behr et al, Science 284, 1520-3, 1999
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Genomic Deletions Among 100 Isolates
STRAINS
68 regions deleted 224 genes (5.5) Median 19
genes _at_
Genomic Location
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The Worlds TB Tree
M. africanum M. microti M. bovis
M. canetti
Beijing
Manila
Rest of the World
M. bovis
BCG
classical
1
4 6
M. caprae
M. pinnipedii
701 702
M. microti
12 13
236a
224c
142
150
s
m
oryx
181
198a
236
121
711 713
145 178 182
CDC1551
7 8 10
198c
174b
183 252
H37Rv
147c 239
231
167
219
193
188
122
213
115
174
105 207
9
888
M. canetti
891
RDcan
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A Paradigm Shift?
Microbial virulence factors
An ongoing dialogue
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The Central Question

• How does the macrophage respond to MTB?
• How does MTB subsequently adapt to this response?

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Two Routes to Bacterial Survival

• Marines
• Invade
• Incapacitate
• Fight on (and on)

• al Qaeda
• Feel the heat
• Hunker down
• Await opportunity

Which strategy does MTB pursues?
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al Qaeda
Toxic Anerobic Reduced Carbs Iron
Schoolniks group, PNAS 2003
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Two Routes to Bacterial Survival

• Marines
• Invade
• Incapacitate
• Prevail

• al Qaeda
• Feel the heat
• Hunker down
• Await opportunity

Pheonolic glycolipids
Immunosuppressing components of the bacterial
cell wall
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Value of Specimen Banks

• Can a phylogenetic perspective help explain the
  role of PGL?
• Stratified random sample from SF bank
• Selection from SF collection (1802 cases 91-99)
• Generate phylogeny
• Which have mutation?

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M. africanum M. microti M. bovis
M. canetti
Beijing
Manila
Rest of the World
M. bovis
BCG
PGL mutation
classical
1
4 6
M. caprae
M. pinnipedii
701 702
M. microti
12 13
236a
224c
142
150
s
m
oryx
181
198a
236
121
711 713
145 178 182
CDC1551
7 8 10
198c
174b
183 252
H37Rv
147c 239
231
167
219
193
188
122
213
115
174
105 207
9
888
M. canetti
891
RDcan
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Conclusion

• Evolution provides a perspective for
• Understanding species
• BCG failure
• Strain to strain differences in MTB
• Resulting insights
• Are cool
• And may provide new tools for TB control
• E.g marker of strains that rapidly progress to
  disease

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Art is I, Science is We
Peter Small Roxanna Aga Melissa Wong Antonio
Enciso Margaret Hannan Kathy DeRiemer Midori
Kato-Maeda Neil Abernathy Hugh Salamon
Gary Schoolnik Dimitri Petrov Brendan
Bohannan Cliff Barry
Affymetrix, Santa Clara, CA Tom Gingeras Jorg
Drenkow
Marc Feldman Aaron Hirsh