Biomarkers
The identification of biomarkers for mycobacterial
diseases either disease state or with predictive values has
lagged behind cancer until recently. It has been pointed
out (Biomarkers Definitions Working Group, 2001) that
identification of TB biomarkers of protection against active
TB be as immunological markers or molecular markers
would facilitate a new TB vaccine development or efficacy
of new antibiotics.
TBBiomarkers will have a potential in many aspects ofthe
disease, can provide information about disease status, risk of
progression, likelihood of response to therapeutics or of drug
toxicity and protective immunity. Biomarkers of protection
could determine which vaccines in clinical trials are the most
efficacious; which vaccine candidates and strategies are the
most promising in early stagesin the preclinical development
pipeline (including relevant antigens, antigen delivery, live
vaccines); and which combination vaccines (prime/boost)
would be the most effective [55]. Tissue destruction islargely
involved during active TB disease. From the basis of involvement
of tissue damage, M. tuberculosis should influence the
metabolism of affected tissues. It is quite likely that lung
containing dormant bacteria during latent infection vs. lung
associated with progressive disease with excessive tissue
damage will produce different metabolites. Similarly, there
could be differential expression of host metabolites during
the stages (acute and chronic stages) of the disease. This is
the basis for metabolite biomarker studies in TB [56].