In-vitro phagocytosis and intracellular killing of Pasteurella multocida B:2 by phagocytic cells of buffaloes

Abstract

Pasteurella multocida B:2 is a Gram-negative organism causing haemorrhagic septicaemia (HS) in buffaloes. It causes severe pulmonary infection, leading to infiltration of numerous macrophages and neutrophils. Despite the inflammatory response, buffaloes succumb to HS. This study aims to evaluate the in-vitro efficacy of macrophages and neutrophils of buffalo following exposure to P. multocida B:2. In-vitro infections were done using 10 ⁷ cfu/ml of P. multocida B:2 for Group 1, Escherichia coli for Group 2 and Mannhaemia haemolytica A:2 for Group 3 cells. The inoculated cell cultures were harvested at 0, 30, 60 and 120 min postexposure and the phagocytic, killing and cell death rates were determined. Both phagocytosis and killing rates of all bacteria increased over time. Phagocytosis involved between 71% and 73% neutrophils and between 60% and 64% macrophages at 120 min. Killing rate of all bacteria involved between 76% and 79% for neutrophils and between 70% and 74% for macrophages at 120 min. Death rate of neutrophils ranged between 67% in Group 3, and 88% in Group 1 at 120 min, significantly (p < 0.05) higher than Group 3 but insignificant (p > 0.05) than Group 2. Similar pattern was observed for death rate of macrophages. The phagocytosis and killing rates of P. multocida B:2 were similar to other bacterial species used in this study but more neutrophils and macrophages were dead following infection by P. multocida B:2 than M. haemolytica A:2.

Ultrastructural changes in endothelial cells of buffaloes following in-vitro exposure to Pasteurella multocida B:2

“…Moreover, recent in-vitro study revealed that P. multocida B:2 has high ability to cause death of phagocytic cells, particularly in the neutrophil and macrophage following infection with P. multocida B:2. This might be attributed by the release of large amount of LPS endotoxin upon intracellular lysis of P. multocida B:2 [20]. Crucially, during acute phase of infection, LPS-induced immune cell death could also results in collateral tissue damage, aggravating sepsis-like response [18,21].…”

“…Wild-type P. multocida B:2 isolated from an outbreak of HS was used in this study. It was prepared to achieve an infective dose of 1.0 × 10 7 cfu/ml of live P. multocida B:2 as previously described [20]. Briefly, it was cultured onto blood agar and incubated at 37°C for 24 h. Four colonies from this blood agar were transferred into a brain-heart infusion broth and incubated at 37°C for 18 h with shaking at 150 rpm for.…”

“…5), as previously described [26] with slight modification. Trypan blue exclusion test [20] was applied to determine the cells' viability using a standard haemocytometer (Hausser Scientific, USA).…”

Transboundary Animal Diseases, an Overview of 17 Diseases with Potential for Global Spread and Serious Consequences

“…Mathematical models to evaluate outbreak data and potential intervention strategies have been described [347]. In vitro assays have been performed using macrophages and aortic endothelial cells [348][349][350][351]. Mouse models can play an important role in investigation of pathogenesis and vaccine development [317,[351][352][353][354][355][356][357][358][359][360][361][362][363].…”

“…Mouse models can play an important role in investigation of pathogenesis and vaccine development [317,[351][352][353][354][355][356][357][358][359][360][361][362][363]. Rats with or without immunosuppression have also been used to explore pathogenesis and novel vaccines [349][350][351][364][365][366]. Rabbits are occasionally used for vaccine evaluation and, along with mice, were recently used to evaluate a novel phage lysate marker vaccine along with a DIVA ELISA [358].…”