BRUSSELS—Looking to improve the screening of vaccine candidates for slow-growing microbes, researchers at the WIV-Pasteur Institute Brussels and the University of Nebraska-Lincoln recently developed a luminescence-based assay that monitors bacterial viability directly, both in vitro and from mouse tissue samples. They described their work in Infection and Immunity.
Screening for Mycobacterium avian subsp. paratuberculosis, the microbial agent that causes paratuberculosis, generally requires a lengthy culturing process that can take six to eight weeks. To accelerate this process, the scientists engineered two strains of the bacterium to express luciferase, a luminescent enzyme. Using a simple luminometer, the researchers could easily monitor and quantify the bacteria, both in culture and from homogenized tissues of infected mice.
The scientists then tested the assay with live and attenuated tuberculosis vaccines. They could identify infection via the luminescence assay than through in vitro culturing techniques and the assay provided a more sensitive indication of vaccine efficacy. Thus, the researchers suggest the modified bacteria "may be a valuable tool for the rapid, simple and cheap in vivo screening of vaccine candidates."
