Vaccination of cattle with Mycobacterium bovis culture filtrate proteins and interleukin-2 for protection against bovine tuberculosis

In this study vaccines prepared from culture filtrate proteins (CFP) of Myc obacterium bovis and interleukin-2 (IL-2) were tested in cattle for their c apacity to stimulate immune responses and to protect against an intratrache al challenge with virulent M. bovis. Nine groups of cattle were vaccinated with combinations of different doses of CFP and bovine IL-2 mixed with a mo nophosphoryl lipid A (MPL) adjuvant. An additional group was vaccinated wit h M, bovis BCG, Immune responses in CFP-IL-2-vaccinated animals differed fr om those seen in BCG-vaccinated animals by inducing high antigen-specific a ntibody responses and low levels of gamma interferon and IL-2 released from purified protein derivative-stimulated whole-blood cultures. In a concurre nt experiment, additional animals were added to the high-dose CFP-IL-2, MPL control, and BCG groups and these expanded groups of animals were challeng ed intratracheally with virulent M, bovis. Although the lung lesion scores were significantly lower for both the CFP-IL-2-and BCG-vaccinated groups co mpared to the MPL control group, the overall level of protection was greate st for the BCG-vaccinated animals, There were more animals with extrathorac ic spread of disease in the CFP-IL-2 group than in the other groups. While vaccination of cattle with M. bovis CFP gave an encouraging reduction in tu berculous lesions and did not induce a delayed-type hypersensitivity respon se to PPD, future CFP vaccines must prevent any extrathoracic spread of dis ease.