A new tool for tuberculosis vaccine screening: Ex vivo Mycobacterial Growth Inhibition Assay indicates BCG-mediated protection in a murine model of tuberculosis

BMC Infectious Diseases

Research Article

David A. Hokey¹  Michael Brennan¹  Barry Walker¹  Sheldon Morris²  Angelo Izzo³  Andrea Zelmer⁴  Timon Damelang⁴  Helen Fletcher⁴  Sally Sharpe⁵  Ann Williams⁵  Rachel Tanner⁶  Elena Stylianou⁶  Helen McShane⁶  Ilaria Pepponi⁷ 

[1] Aeras, Rockville, MD, USA;Center for Biologics Evaluation and Research, Silver Spring, MD, USA;Colorado State University, Fort Collins, CO, USA;London School of Hygiene and Tropical Medicine, London, UK;Public Health England, Porton Down, UK;The Jenner Institute, Oxford University, Oxford, UK;The Jenner Institute, Oxford University, Oxford, UK;Animal and Plant Health Agency, Weybridge, UK;Translational Research Unit, National Institute for Infectious Diseasess “Lazzaro Spallanzani”, Rome, Italy;

关键词: Mycobacteria;    Tuberculosis;    Vaccines;    Growth inhibition assay;   

DOI  :  10.1186/s12879-016-1751-4

 received in 2016-03-08, accepted in 2016-08-03,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundIn the absence of a validated animal model and/or an immune correlate which predict vaccine-mediated protection, large-scale clinical trials are currently the only option to prove efficacy of new tuberculosis candidate vaccines. Tools to facilitate testing of new tuberculosis (TB) vaccines are therefore urgently needed.MethodsWe present here an optimized ex vivo mycobacterial growth inhibition assay (MGIA) using a murine Mycobacterium tuberculosis infection model. This assay assesses the combined ability of host immune cells to inhibit mycobacterial growth in response to vaccination. C57BL/6 mice were immunized with Bacillus Calmette-Guérin (BCG) and growth inhibition of mycobacteria by splenocytes was assessed. Mice were also challenged with Mycobacterium tuberculosis Erdman, and bacterial burden was assessed in lungs and spleen.ResultsUsing the growth inhibition assay, we find a reduction in BCG CFU of 0.3–0.8 log10 after co-culture with murine splenocytes from BCG vaccinated versus naïve C57BL/6 mice. BCG vaccination in our hands led to a reduction in bacterial burden after challenge with Mycobacterium tuberculosis of approx. 0.7 log10 CFU in lung and approx. 1 log10 CFU in spleen. This effect was also seen when using Mycobacterium smegmatis as the target of growth inhibition. An increase in mycobacterial numbers was found when splenocytes from interferon gamma-deficient mice were used, compared to wild type controls, indicating that immune mechanisms may also be investigated using this assay.ConclusionsWe believe that the ex vivo mycobacterial growth inhibition assay could be a useful tool to help assess vaccine efficacy in future, alongside other established methods. It could also be a valuable tool for determination of underlying immune mechanisms.

【 授权许可】

CC BY   
© The Author(s). 2016