Recombinant transferrin binding protein A (rTbpA) fragments of Pasteurella multocida serogroup B:2 provide variable protection following homologous challenge in mouse model

•Production of recombinant TbpA fragments of Pasteurella multocida serogroup B:2.•Mice immunization resulted in a significant rise in serum total IgG and subtypes (IgG1 and IgG2a) antibodies titers.•Challenge studies with homologous strain resulted in varied protection up to 50%.•Full length TbpA provides protection, whereas no protection with N-plug domain protein.

Transferrin binding protein A (TbpA), an iron acquisition surface protein that also acts as virulence factor, is widely distributed among strains of Pasteurella multocida. In the present study, a total of seven clones of TbpA fragments (39D to F777; 39D to Q697; 188V to F777; 188V to Q697; 39D to P377; 188V to P377 and 39D to F187) belonging to P. multocida B:2 were constructed, over-expressed and purified as recombinant fusion proteins from Escherichia coli using affinity chromatography. Immunization of mice with rTbpA fragments resulted in a significant (p < 0.05) rise in antigen specific serum total IgG and subtypes (IgG1 and IgG2a) tires. All immunized mice challenged with 8 LD50 of P. multocida B:2 resulted in a variable protective efficacy up to 50%. The study indicated the potential possibilities to incorporate full length TbpA in subunit vaccine formulation composed of synergistic subunit antigens against haemorrhagic septicaemia (HS) in cattle and buffalo.