Study of cellular immune responses to the Internalin B protein extracted from Listeria monocytogenes in Mice

Abstract

This study was carried out to investigate the immunological activity of internalin B (InLB) protein which extracted from the cell wall of Listeria monocytogenes. Immunological activity was determined in vitro by the phagocytic activity assay and in vivo by bacterial clearance test in ninety six male white Swiss BALB/C mice were divided into five equal groups, G1 intrapertonailly injected with 0.5ml of InLB 50µg/ml;G2 intrapertonailly injected with 0.5ml of InLB 50µg/ml and inoculated with 1.2×103CFU/ml of L. monocytogenes.; G3 intrapertonailly injected with 0.5ml of InLB 50µg/ml followed by L. monocytogenes 24 hours later; G4 intrapertonailly injected with1.2×103CFU/ml L. monocytogenes a positive control; G5 intrapertonailly injected with 0.5ml of PBS a negative control, The results of the in vitro study showed the InLB at 50µg/ml induce the phagocytic activity by increase the Nitric oxide (NO) production as compared with Phytohemagglutinin-p (PHA); the results of the in vivo study was carried for 2weeks; at 4,8and 12days bacterial clearance assay; tissue of the internal organs (liver) of the G3 showed decrease in number of the bacteria at 12days (6×10-2 CFU) as compared to G2 and G4 (2×10-3CFU and 1.8×10-4CFU) respectively.The result presented in this study contribute for the first time in Iraq; that internalin B given intrapertonailly injection in mice for 12 days improves the immune responses by decreasing the bacterial number in liver tissue.

Keywords

• Bacterial clearance
• Phagocytic activity
• Male mice