Evaluation of the immunization of camels with Brucella abortus vaccine (RB51) in Egypt

Abstract

Background: Brucellosis is a highly contagious zoonotic disease caused by an intracellular facultative microorganism termed Brucella spp. Control of brucellosis depends on test and slaughter policy as well as vaccination programs. Aim: Estimation of the cell-mediated immunity (total leukocytic count (TLC), phagocytic activity, phagocytic index, Interleukin 6 (IL-6) and Tumor necrosis factor-alpha (TNF-α)) in camels after vaccination with RB51 using real-time PCR. Methods: A total of eight camels were grouped into 2 groups as follows: group (A): vaccinated with RB51 vaccine (1 dose / 2 ml S/C [3x1010 CFU]) and group (B): control group. Interleukin 6 (IL-6) and Tumor necrosis factor-alpha (TNF-α) were used for estimation of the cell-mediated immunity using real-time PCR on serum samples that were collected at 0, 7, 14, 21, 28, and 60 days after vaccination from each group. Also, total leukocytic count, phagocytic activity, and phagocytic index were evaluated on heparinized blood samples at 0 and 60 days post-vaccination. Results: RB51 vaccine provides a protective immune response which progressively increases from the first week to 60 days after vaccination. Moreover, the levels of TNF-α and IL-6 differed between camels in the vaccinated group. Conclusion: Vaccination of camels with RB51 vaccine (with dose 3x1010 CFU) could induce good protective immune responses and this immunological response will be a good indication for a safe field vaccine that can be used for the control of camel brucellosis.