Protection against tuberculosis induced by oral prime with Mycobacterium bovis BCG and intranasal subunit boost based on the vaccine candidate Ag85B-ESAT-6 does not correlate with circulating IFN-gamma producing T-cells.
The potent IFN-gamma inducing fusion antigen Ag85B-ESAT-6 (85B6) is a lead subunit candidate to improve current vaccination against Mycobacterium tuberculosis (Mtb). The recombinant M. bovis BCG strain Myc3504 was constructed to secrete 85B6. It was based on commercial BCG strain Moreau Rio de Janeiro (BCG(MoWT)) which remains available for human oral administration. Myc 3504 induced higher levels of 85B6-specific IFN-gamma circulating T-cells as compared to BCG(MoWT). A novel needle-free mucosal immunization regimen combining oral prime with Myc3504 or BCG(MoWT) with intranasal boost with LTK-63-adjuvanted 85B6 was compared to subcutaneous prime-boost immunization. Strikingly whereas parenteral immunization induced sustained levels of 85B6-specific IFN-gamma secretion by circulating T-cells, mucosal regimens induced barely detectable IFN-gamma. Despite this, mice and guinea pigs immunized with the mucosal regimens were as efficiently protected against aerosol Mtb challenge as parenterally immunized animals. After Mtb challenge, anti-ESAT-6 IFN-gamma responses sharply increased in non-vaccinated mice as a hallmark of infection. Parenterally immunized mice that controlled Mtb infection, displayed anti-ESAT-6 IFN-gamma responses as high as non-immunized infected mice, compromising the possible use of ESAT-6 as a diagnostic tool. Interestingly, in mucosally immunized mice that were equally protected, post-challenge ESAT-6-specific IFN-gamma T-cell response remained low.
Badell
Edgar
E
Institut Pasteur, Unité de Génétique Mycobactérienne, 25-28 rue du Docteur Roux, 75724 Paris Cedex 15, France.
Nicolle
Fabienne
F
Clark
Simon
S
Majlessi
Laleh
L
Boudou
Frédéric
F
Martino
Angelo
A
Castello-Branco
Luiz
L
Leclerc
Claude
C
Lewis
David J M
DJ
Marsh
Philip D
PD
Gicquel
Brigitte
B
Winter
Nathalie
N
D000217:Acyltransferases / Q000276:immunology*; D000281:Administration, Intranasal; D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D001500:BCG Vaccine / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology*; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D007117:Immunization, Secondary; D007371:Interferon-gamma / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009163:Mycobacterium bovis / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology*; D014376:Tuberculosis / Q000276:immunology / Q000517:prevention & control*
D000942:Antigens, Bacterial; D001500:BCG Vaccine; D001426:Bacterial Proteins; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D007371:Interferon-gamma; D000217:Acyltransferases; C121433:antigen 85B, Mycobacterium tuberculosis