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Infection and Immunity, May 2006, p. 2751-2759, Vol. 74, No. 5
0019-9567/06/$08.00+0 doi:10.1128/IAI.74.5.2751-2759.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
Laboratory of Mycobacterial Immunology,1 Biochemistry of Macromolecules, Scientific Institute for Public HealthPasteur Institute of Brussels, 642 Engelandstraat, 1180 Brussels, Belgium2
Received 21 November 2005/ Returned for modification 29 December 2005/ Accepted 7 February 2006
Reactivation tuberculosis (TB) is a serious problem in immunocompromised individuals, especially those with human immunodeficiency virus (HIV) coinfection. The adaptive immune response mediated by CD4+ and CD8+ T cells is known to confer protection against TB. Hence, vaccines against TB are designed to activate these two components of the immune system. Anti-TB DNA vaccines encoding the immunodominant proteins Ag85A, Ag85B, and PstS-3 from Mycobacterium tuberculosis are ineffective in mice lacking CD4+ T cells (CD4/ mice). In this study, we demonstrate that reconstitution of the T-cell compartment in CD4/ mice restores vaccine-specific antibody and gamma interferon (IFN-
) responses to these DNA vaccines. The magnitude of the immune responses correlated with the extent of reconstitution of the CD4+-T-cell compartment. Reconstituted mice vaccinated with DNA encoding PstS-3, known to encode a dominant Db-restricted CD8+-T-cell epitope, displayed CD8+-T-cell responses not observed in CD4/ mice. M. tuberculosis challenge in reconstituted mice led to the extravasation of IFN-
-producing CD4+ and CD8+ T cells into lungs, the primary site of bacterial replication. Importantly, a reconstitution of 12 to 15% of the CD4+-T-cell compartment resulted in Ag85B plasmid DNA-mediated protection against a challenge M. tuberculosis infection. Our findings provide evidence that anti-TB DNA vaccines could be effective in immunodeficient individuals after CD4+-T-lymphocyte reconstitution, as may occur following antiretroviral therapy in HIV+ patients.
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