Immunogenicity and protective efficacy of DNA vaccines encoding secreted and non-secreted forms of Mycobacterium tuberculosis Ag85A.
OBJECTIVE
To determine the efficacy of Ag85A-DNA against challenge with a highly virulent human clinical isolate of Mycobacterium tuberculosis (CSU37) and to compare the potencies of two types of Ag85A-DNA vaccines; those expressing secreted and non-secreted forms of the protein.


METHODS
Ag85A-DNA vaccinated mice were challenged with a highly virulent clinical isolate of M. tuberculosis (CSU37) in order to compare the efficacy of these vaccines. In vitro studies were also performed.


RESULTS
Enhanced humoral and cellular responses were induced in mice vaccinated with the secreted Ag85A-DNA compared to the non-secreted Ag85A-DNA. In addition, secreted Ag85A-DNA conferred protective immunity against infection with M. tuberculosis (CSU37).


CONCLUSIONS
DNA vaccines encoding M. tuberculosis Ag85A have been shown to induce potent humoral and cellular immune responses leading to protection from M. tuberculosis (Erdman) challenge in mouse models. In this study we demonstrate that Ag85A can confer protection in a rigorous challenge model using a highly virulent human clinical isolate of M. tuberculosis (CSU37). This challenge model appears able to discriminate between DNA vaccines of differing potencies, as the more immunogenic DNA construct encoding a secreted form of Ag85A was protective, whereas the less immunogenic DNA construct encoding a non-secreted form of Ag85A was not.
Baldwin
S L
SL
Department of Microbiology, Colorado State University, Fort Collins 80523, USA. susanb@lamar.colostate.edu
D'Souza
C D
CD
Orme
I M
IM
Liu
M A
MA
Huygen
K
K
Denis
O
O
Tang
A
A
Zhu
L
L
Montgomery
D
D
Ulmer
J B
JB
D000217:Acyltransferases; D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D001500:BCG Vaccine / Q000235:genetics / Q000276:immunology*; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D014376:Tuberculosis / Q000235:genetics / Q000276:immunology / Q000517:prevention & control; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*
D000942:Antigens, Bacterial; D001500:BCG Vaccine; D019444:Vaccines, DNA; D000217:Acyltransferases; C112580:antigen 85A, Mycobacterium tuberculosis