The Regional Biocontainment Laboratory (RBL) at the University of Pittsburgh is a state-of-the-art ABSL-3 facility that supports research on highly pathogenic viruses and bacteria. Recent advances in radiologic imaging provide several noninvasive, in vivo imaging modalities that can be used to longitudinally monitor animals following experimental infection or vaccination. The University of Pittsburgh RBL provides digital radiography, bioluminescence imaging, and PET/CT. Operating these platforms in an ABSL-3 poses unique challenges. This review will discuss the development and refinement of these imaging platforms in high containment, emphasizing specific challenges and how they were overcome.
The only licensed vaccine (BCG) for tuberculosis (TB) has variable efficacy and does not protect against pulmonary TB. New vaccines are in development and in human clinical trials. However, vaccine trials are long and expensive without useful surrogate markers of protection. A problem thus emerges: what does a protective response to TB look like? This project’s goal is to identify markers of vaccine efficacy that can further be developed as new clinical endpoints. We posit that exploiting differences in vaccine outcome (protected vs. unprotected) will identify novel immunologic markers that correlate with outcome, and serial PET/CT will predict outcome early in infection. Vaccine-induced protection could work at any point in early infection: movement of bacilli from airway to parenchyma; formation of primary lesions; migration of bacteria to LN; and development of secondary lesions. In both our rhesus and cynomolgus macaque models of infection, prime-boost vaccination with BCG followed by viral-expressed or protein antigens protects against TB disease better than BCG alone or no vaccine. However, granuloma formation is not prevented and the vaccines do not reduce initial granuloma numbers. However, total PET signal, as a surrogate for inflammation and disease, in lungs of vaccinated animals is significantly lower at early time points. Future work will develop the predictive markers to elucidate early immune mechanisms that confer protection in the lungs.
Lung granulomas are the pathologic hallmark of Tuberculosis (TB). T cells are a major cellular component of tuberculosis lung granulomas and are known to play an important role in containment and progression of Mtb infection. We used cynomolgus macaques, a non-human primate model that recapitulates human TB, with clinically active disease and latent infection, to understand the functional characteristics and dynamics of T cells in individual granulomas and to correlate T cell cytokine response of granulomas to its bacterial burden and its systemic response. Our results suggest that each granuloma within an individual host is independent with respect to total cell numbers, proportion of T cells, pattern of cytokine response, and bacterial burden. The spectrum of these components overlaps greatly amongst various clinical status of these animals, indicating that a diversity of granulomas exist in individual hosts. Multi-parametric flow cytometry analysis of functional T cells in granulomas suggests that on average only ~6% of T cells respond to Mtb antigens with production of Th1/Th17 or IL-10 cytokines. An inverse correlation was observed between bacterial burden and Th1/Th17 response in individual granulomas. The systemic responses do not accurately reflect responses in granulomas, and suggests that, especially in active TB, the blood is a negative reflection of granuloma responses. Overall, these data provide insight into the local and systemic responses in tuberculosis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.