Cell-mediated immune responses in children towards secreted proteins of Mycobacterium bovis BCG.
BACKGROUND
There is a need to develop an improved anti-TB vaccine for adequate control and elimination of tuberculosis, to control the spread of MDR-TB and TB/HIV co-infection. Studies in children have indicated that BCG vaccination has certain beneficial effects, especially against miliary TB and TB meningitis, but needs to be improved for protection against pulmonary tuberculosis.


OBJECTIVE
The aim of the present study was to identify the immunogenic proteins in the culture filtrate (CF) of Mycobacterium bovis BCG by studying the effector mechanism of protection in children, which may help in the formulation of an effective vaccine against tuberculosis.


METHODS
Lymphoproliferative responses (LTT) and the levels of IL-2 and IFN-gamma (Th1 cytokines) released into the culture supernatants were estimated (by ELISA) in short-term cultures of PBMC of BCG vaccinated (n=25) and unvaccinated (n=15) children and children with tuberculosis (n=15) against 10 different fractions of CF (mol.wt > or = 90-<14 kDa).


RESULTS
The mean stimulation indices (SI) in LTT against all the (10) fractions in vaccinated children were high when compared to the unvaccinated and diseased groups; however, of the 10 fractions, F3, F4, F6, F8 and F9 elicited significantly higher SIs than the other fractions (p<0.05). In the vaccinated children, the SI (5.58+/-1.57), levels of IL-2 (381.66+/-16.40 pg/ml) and IFN-gamma (732+/-62.36 pg/ml) in the cultures stimulated by fraction 8 (34-30k Da) were significantly higher (p<0.001), than responses to the other fractions and also to those of other groups of children.


CONCLUSIONS
Thus, the peptides within the cluster 34-30 kDa appear to be promising vaccine candidates by virtue of their immunodominant nature specifically priming Th1 cells in normal, BCG-vaccinated children.
Surekha Rani
H
H
Bhagawan Mahavir Medical Research Centre, Mahavir Marg, Hyderabad 500 004, AP, India.
Vijaya Lakshmi
V
V
Sumanlatha
G
G
Murthy
K J R
KJ
D001500:BCG Vaccine / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D003470:Culture Media; D006801:Humans; D007111:Immunity, Cellular / Q000276:immunology; D007371:Interferon-gamma / Q000032:analysis; D007376:Interleukin-2 / Q000032:analysis; D008213:Lymphocyte Activation / Q000276:immunology; D009163:Mycobacterium bovis / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D014376:Tuberculosis / Q000276:immunology*; D014611:Vaccination / Q000379:methods
D001500:BCG Vaccine; D001426:Bacterial Proteins; D003470:Culture Media; D007376:Interleukin-2; D007371:Interferon-gamma