Efficacy of bacteriophage Lysed Pasteurella marker vaccine in laboratory animal models with a novel DIVA for haemorrhagic septicaemia

Development of ELISA-based diagnostic methods for the detection of haemorrhagic septicaemia in animals

Haemorrhagic septicaemia (HS) is an acute infection of cattle and buffaloes caused by the B:2 serotype of Pasteurella multocida. This disease is highly endemic in South Asia. In some peracute cases, there is 100% mortality in infected animals within a few hours of infection. Therefore, timely diagnosis of infection may contribute to its treatment and control to minimize economic losses. The current work reported the development of ELISA-based assays for the detection of anti-P. multocida antibodies and pathogen i.e. P. multocida. Owing to high immunogenicity, membrane proteins (MPs) extracted from local isolates of P. multocida serotype B:2 (PM1, PM2, and PM3) were employed as a potential diagnostic antigen for the development of indirect ELISA (i-ELISA) to detect HS antibodies in animals. MPs extracted from PM1, PM2 and PM3 isolates showed very low heterogeneity; hence MPs from the PM3 isolate were selected for the development of i-ELISA. The concentration of MPs (as coating antigen) of 3.13 μg/well and test sera dilution 1:100 was found to be optimal to perform i-ELISA. The developed method was validated through the detection of anti-P. multocida antibodies in sera of mice, immunized with MPs and formalin killed cells from the three local isolates (PM1, PM2 and PM3) of P. multocida. The significantly higher antibody titer in immunized mice was determined compared to unimmunized mice with the cut off value of 0.139. To detect P. multocida directly from the blood of infected animals, whole cell-based ELISA (cb-ELISA) assay was developed. A better detection signal was observed in the assay where bacterial cells were directly adsorbed on plate wells as compared to poly L-lysine (PLL) assisted attachment at a cell concentration of 10⁶ CFU and 10⁷ CFU respectively. The developed assays can be scaled up and potentially be used for the rapid detection of HS antibodies to gauge the immune status of the animal as well as vaccination efficacy and pathogen detection.

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

Animals provide food and other critical resources to most of the global population. As such, diseases of animals can cause dire consequences, especially disease with high rates of morbidity or mortality. Transboundary animal diseases (TADs) are highly contagious or transmissible, epidemic diseases, with the potential to spread rapidly across the globe and the potential to cause substantial socioeconomic and public health consequences. Transboundary animal diseases can threaten the global food supply, reduce the availability of non-food animal products, or cause the loss of human productivity or life. Further, TADs result in socioeconomic consequences from costs of control or preventative measures, and from trade restrictions. A greater understanding of the transmission, spread, and pathogenesis of these diseases is required. Further work is also needed to improve the efficacy and cost of both diagnostics and vaccines. This review aims to give a broad overview of 17 TADs, providing researchers and veterinarians with a current, succinct resource of salient details regarding these significant diseases. For each disease, we provide a synopsis of the disease and its status, species and geographic areas affected, a summary of in vitro or in vivo research models, and when available, information regarding prevention or treatment.

Isolation and genome analysis of a lytic Pasteurella multocida Bacteriophage PMP-GAD-IND

Currently used alum precipitated and oil adjuvant vaccines against HS caused by Pasteurella multocida B:2, have side effects and short-lived immunity, leading to regular catastrophic outbreaks in bovines in Asian subcontinent. The need for the development of an improved vaccine with longer immunity and the ability to differentiate between vaccinated and infected is essential. Pasteurella phage isolated in present study belongs to family Siphoviridae. PMP-GAD-IND phage exhibited lytic activity against vaccine strain (P52) as well as several field strains of P. multocida (B:2), and fowl cholera agent (P. multocida A:1).The phage has a double stranded DNA (dsDNA) with a genome of 46 335 bp. The complete genome sequence of the Pasteurella multocida phage has been deposited in Gen Bank with accession no: KY203335. PMP-GAD-IND being a lytic phage with broad activity range has a potential to be used in therapy against multidrug resistant P. multocida infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present work is a part of research for the development of an improved phage lysate marker vaccine and a companion DIVA assay against haemorhagic septicaemia. This study describes the isolation and genome analysis of PMP-GAD-IND a lytic Pasteurella multocida bacteriophage.