Myco tuberculosis

April 2, 2005

Heres an interesting exploration of TB at the cell/tissue level. This

illustrates a number of interesting pitfalls in studying infection. It

says the processes in the mouse are pretty different from those in the

human. Also, the processes in the human change very signficantly over

time, in more ways than one.

Interestingly, the authors say the bulk of the biomass is

extracellular in established disease (is this also true of the bulk of

biomass growth?). They say M. leprae is obligate intracellular - not

sure but I think the same may be true of M. avium in the human.

It looks like maybe the most crucial virulence factor of Mtb for

humans is the Esat6/CF-10 operon product, a secreted factor that lyses

host cells. Deletion of this operon has been discovered to be the

basis of the attenuation of the M bovis BCG vaccine strains, and it is

consitutively lacking in M microti which fails to infect humans.

Esat6/CF-10 knockout Mtb penetrate tissue poorly when introduced to

the alveolar epithelium.

I wonder how this squares with the virulence correlation for Mtb that

I posted about before, having to do with apoptosis of infected cells,

and NO production. And how it all compares to whatever M. leprae is doing.

Recommended Posts