title: Enhanced and enduring protection against tuberculosis by recombinant BCG-Ag85C and its association with modulation of cytokine profile in lung.
abstract: BACKGROUND
  The variable efficacy (0-80%) of Mycobacterium bovis Bacille Calmette Guréin (BCG) vaccine against adult tuberculosis (TB) necessitates development of alternative vaccine candidates. Development of recombinant BCG (rBCG) over-expressing promising immunodominant antigens of M. tuberculosis represents one of the potential approaches for the development of vaccines against TB.
  
  
  RESULTS
  A recombinant strain of BCG - rBCG85C, over expressing the antigen 85C, a secretory immuno-dominant protein of M. tuberculosis, was evaluated for its protective efficacy in guinea pigs against M. tuberculosis challenge by aerosol route. Immunization with rBCG85C resulted in a substantial reduction in the lung (1.87 log(10), p<0.01) and spleen (2.36 log(10), p<0.001) bacillary load with a commensurate reduction in pathological damage, when compared to the animals immunized with the parent BCG strain at 10 weeks post-infection. rBCG85C continued to provide superior protection over BCG even when post-challenge period was prolonged to 16 weeks. The cytokine profile of pulmonary granulomas revealed that the superior protection imparted by rBCG85C was associated with the reduced levels of pro-inflammatory cytokines - interleukin (IL)-12, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, moderate levels of anti-inflammatory cytokine - transforming growth factor (TGF)-beta along with up-regulation of inducible nitric oxide synthase (iNOS). In addition, the rBCG85C vaccine induced modulation of the cytokine levels was found to be associated with reduced fibrosis and antigen load accompanied by the restoration of normal lung architecture.
  
  
  CONCLUSIONS
  These results clearly indicate the superiority of rBCG85C over BCG as a promising prophylactic vaccine against TB. The enduring protection observed in this study gives enough reason to postulate that if an open-ended study is carried out with low dose of infection, rBCG85C vaccine in all likelihood would show enhanced survival of guinea pigs.
authors.affiliation: Department of Biochemistry, University of Delhi South Campus, New Delhi, India.
authors.forename: Ruchi
authors.initials: R
authors.lastname: Jain
authors.forename: Bappaditya
authors.initials: B
authors.lastname: Dey
authors.forename: Neeraj
authors.initials: N
authors.lastname: Dhar
authors.forename: Vivek
authors.initials: V
authors.lastname: Rao
authors.forename: Ramandeep
authors.initials: R
authors.lastname: Singh
authors.forename: Umesh D
authors.initials: UD
authors.lastname: Gupta
authors.forename: V M
authors.initials: VM
authors.lastname: Katoch
authors.forename: V D
authors.initials: VD
authors.lastname: Ramanathan
authors.forename: Anil K
authors.initials: AK
authors.lastname: Tyagi
mesh_terms: D000818:Animals; D001500:BCG Vaccine / Q000235:genetics / Q000276:immunology; D016207:Cytokines / Q000378:metabolism*; D005260:Female; D006168:Guinea Pigs; D007150:Immunohistochemistry; D008168:Lung / Q000276:immunology* / Q000382:microbiology; D009163:Mycobacterium bovis / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D014376:Tuberculosis / Q000276:immunology / Q000517:prevention & control*
chemical_list: D001500:BCG Vaccine; D016207:Cytokines; D011993:Recombinant Fusion Proteins; C534913:rBCG85C vaccine