Clinico-pathology and hemato-biochemistry responses in buffaloes infected with Pasteurella multocida type B:2 immunogen outer membrane protein

•This study is a proof that oral vaccine against HS through feed could be developed in the near future for cattle and buffaloes.•The results obtained comparing buffaloes inoculated with outer membrane protein via different route of infections were documented for the first time.•Orally infected buffaloes were able to survive throughout the 21 days experiment with mild clinical responses, gross and histopathology lesions.

The aim of this study was to investigate the clinico-pathology and haemato-biochemistry alterations in buffaloes inoculated with Pasteurella multocida type B:2 immunogen outer membrane protein via subcutaneous and oral routes. Nine buffalo heifers were divided equally into 3 treatment groups. Group 1 was inoculated orally with 10 mL of phosphate buffer saline (PBS); Group 2 and 3 were inoculated with 10 mL of outer membrane protein broth subcutaneously and orally respectively. Group 2 buffaloes showed typical haemorrhagic septicaemia clinical signs and were only able to survive for 72 h of the experiment. However, Group 3 buffaloes were able to survive throughout the stipulated time of 21 days of experiment. There were significant differences (p < 0.05) in the rectal temperature between the experimental and control group. In the hematology and biochemistry findings, there were significant differences (p < 0.05) in packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin concentration, leukocytes, band neutrophils, segmented neutrophils, lymphocytes, eosinophils, basophils, gamma glutamyl transferase, total protein, and globulin between Group 2 and control group. In contrast, Group 3 and control group revealed significant differences (p < 0.05) in erythrocytes, haemoglobin, mean corpuscular haemoglobin concentration, segmented neutrophils, lymphocytes, monocytes, eosinophils, basophils, thrombocytes, gamma glutamyl transferase, total protein, globulin, and albumin:globulin ratio. In Group 2 buffaloes, there were gross lesions observed in the lung, trachea, heart, liver, spleen, kidney and submandibulae lymph nodes. In contrast, lesions were only observed in the lung, and liver of Group 3 buffaloes. There were significant differences (p < 0.05) in hemorrhage and congestion; necrosis and degeneration; and inflammatory cells infiltration between experimental groups and control group. However, there were no significant differences (p > 0.05) in edema between groups except for the lung. This study was a proof that oral route infection of Pasteurella multocida type B:2 immunogen outer membrane protein can be used to stimulate host cell.