[Frontiers in Bioscience 3, c27-33, May 1, 1998] |
LURIE’S TUBERCLE-COUNT METHOD TO TEST TB VACCINE EFFICACY IN RABBITS
Departments of Environmental Health Sciences, Molecular Microbiology and Immunology, and Epidemiology, School of Hygiene and Public Health; and the Department of Pathology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland 21205
Received 3/9/98 Accepted 3/14/98
9. SINGLE PRIMARY TB LESIONS
Early clinical tuberculosis is usually occurs as a single Xray-visible lesion, because a period of weeks or months usually elapses before the next inhaled bacillus could establish another lesion. A few weeks after the single primary lesion begins, the host’s immune forces have been enhanced so much that lesions created by additional inhaled bacilli are usually aborted at a microscopic stage, leaving the initial lesion as the only one visible in the lungs. Single primary lesions were also produced in rabbits (1,9,30) and guinea pigs (31) when these animals repeatedly inhaled an occasional virulent tubercle bacillus over periods of many weeks.
In humans, a single grossly visible primary pulmonary lesion often progresses. Therefore, the calculation of ratios, i.e., the number of inhaled bacilli required to produce such a single visible lesion, is a good quantitative measure of a vaccine’s ability to prevent clinical tuberculosis.