title: Mycobacterial growth inhibition in murine splenocytes as a surrogate for protection against Mycobacterium tuberculosis (M. tb).
abstract: Development of an improved vaccine against tuberculosis (TB) is hindered by the lack of a surrogate of protection. Efficacy of new TB vaccines in humans can only be evaluated by expensive and time consuming efficacy trials within TB endemic areas. It is critical that vaccines with the greatest potential to protect are selected for these trials. Mycobacterial growth inhibition assays (MGIAs) have been developed with the hope that these in-vitro functional assays will correlate with protection, which could aid in the selection of the best vaccine candidates. The present study describes the use of the BACTEC system to perform MGIAs in mice. We demonstrate reproducible mycobacterial growth inhibition in splenocytes from BCG immunised mice compared with unimmunised mice (P < 0.023), which corresponded with in-vivo efficacy against Mycobacterium tuberculosis (M. tb) challenge. Microarray data showed extensive differential gene expression in splenocyte responses to ex-vivo BCG stimulation between unimmunised and BCG-immunised mice. TH1 responses, including IFN-γ, nitric oxide synthase (NOS2) and Interleukin -17 (IL-17) expression were enhanced in BCG immunised mice, indicating a possible mechanism for mycobacterial growth inhibition. Further investigation into whether the BACTEC MGIA can be used as a surrogate of protection in humans and preclinical animal models is now warranted.
authors.affiliation: The Jenner Institute, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford OX3 7DQ, UK. Leanne.marsay@ndm.ox.ac.uk
authors.forename: Leanne
authors.initials: L
authors.lastname: Marsay
authors.forename: Magali
authors.initials: M
authors.lastname: Matsumiya
authors.forename: Rachel
authors.initials: R
authors.lastname: Tanner
authors.forename: Hazel
authors.initials: H
authors.lastname: Poyntz
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Griffiths
authors.forename: Elena
authors.initials: E
authors.lastname: Stylianou
authors.forename: Philip D
authors.initials: PD
authors.lastname: Marsh
authors.forename: Ann
authors.initials: A
authors.lastname: Williams
authors.forename: Sally
authors.initials: S
authors.lastname: Sharpe
authors.forename: Helen
authors.initials: H
authors.lastname: Fletcher
authors.forename: Helen
authors.initials: H
authors.lastname: McShane
mesh_terms: D000818:Animals; D001500:BCG Vaccine / Q000276:immunology*; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D004195:Disease Models, Animal; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology; D018836:Inflammation Mediators / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009163:Mycobacterium bovis / Q000254:growth & development*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D013154:Spleen / Q000166:cytology / Q000378:metabolism / Q000382:microbiology*; D014376:Tuberculosis / Q000235:genetics / Q000276:immunology / Q000517:prevention & control*
chemical_list: D001500:BCG Vaccine; D016207:Cytokines; D018836:Inflammation Mediators
keywords: BCG; Gene expression; In-vitro assay; Tuberculosis; Vaccine