Evaluation Of Protective Effects Of Graded Doses Of Lipopolysaccharide Extracted From Pasteurella multocida Type B:2 Against Hemorrhagic Septicemia In Mice

Haemorrhagic septicaemia (HS) is one of the most leading cause of death in buffalos and cattle in Malaysia. Lipopolysaccharide (LPS) is one of the major immunogen of P. multocida serotype B:2. This study was designed to evaluate the protective effect of LPS derived from P. multocida B: 2 against haemorrhagic septicaemia in mice. Twenty five mice were divided into five groups consisting of five animals in each group. The control group was inoculated orally with 0.2 mL of phosphate buffer saline (PBS) pH 6.8, whereas groups 1, 2, 3 and 4 were orally inoculated with 0.2 mL LPS extracted from 103, 105, 107 and 109 colony forming units (CFU) of Pasteurella multocida serotypes B: 2, respectively. The experimental animals were observed for clinical signs for seventeen days. All the groups were further challenged with 0.2 mL of 107 wild type Pasteurella multocida B: 2 17 days post LPS inoculation. The groups were observed for clinical signs for seven days post challenge and surviving mice were euthanized and their organs harvested for histopathological examination and bacterial isolation and identification. The results of clinical observation showed 60% of the mice from all group had diarrhoea, 38.5% had severe ocular discharge and all mice had laboured breathing. Mild to moderate histopathological lesions were observed in the heart, lungs, liver, spleen, kidney, small intestine, large intestine and stomach of all groups. The study showed that oral inoculation of LPS extracted from P. multocida, both in low and high concentrations failed to give protection against P. multocida infection in mice.