Protectivity conferred by immunization with intranasal recombinant outer membrane protein H from Pasteurella multocida serovar A:1 in chickens

Abstract

Recombinant outer membrane protein H (rOmpH) is a potential fowl cholera vaccine candidate. The present study was aimed at developing rOmpH formulations for intranasal administration. The rOmpH was purified and formulated with either Escherichia coli enterotoxin B (LTB) or CpG oligodeoxynucleotides (ODN) as an adjuvant. Antibody responses in chickens intranasally immunized with rOmpH in combination with 2 different adjuvants were significantly increased (P<0.05) post immunization. Chicken survival rates showed that rOmpH formulated with ODN and LTB elicited 90% and 70% protection, respectively. Our findings indicated that rOmpH formulated with ODN elicited protection better than that formulated with LTB. Therefore, the vaccines formulations in the present study can be considered new intranasal vaccine formulations for fowl cholera in chickens.

Fig. 1.

Immunoblotting of the rOmpH used in this study. The samples were run on a 12.5% SDS-polyacrylamide gel (a) and transferred to a nitrocellulose membrane. Immunoblotting of the rOmpH was done by probing with chicken sera against the rOmpH (b) or the anti-HisG-HRP antibody (c). Lane M, protein ladder; lane 1, cell lysates of the E. coli host (prior to purification); and lane 2, rOmpH fraction purified from the electroelutor. The numbers on the left indicate the positions of the molecular mass standards (in kilodaltons).

Fig. 2.

The antibody responses in the sera of chickens immunized with vaccines. (1) rOmpH + ODN via intranasal route, (2) rOmpH + LTB via intranasal route, (3) rOmpH + Freund’s incomplete adjuvant via intramuscular route, (4) DLD bacterin vaccine via intramuscular route, (5) ODN via intranasal route, (6) LTB via intranasal route and (7) rOmpH without adjuvant via intranasal route. The data were calculated as described in the test kit’s manual and presented as the log mean end-point titers, and the bars indicate the standard error of the means.

Fig. 3.

The antibody responses in the tracheal larvage of chickens immunized with vaccines. (1) rOmpH + ODN via intranasal route, (2) rOmpH + LTB via intranasal route, (3) rOmpH + Freund’s incomplete adjuvant via intramuscular route, (4) DLD bacterin vaccine via intramuscular route, (5) ODN via intranasal route, (6) LTB via intranasal route and (7) rOmpH without adjuvant via intranasal route. The data were calculated as described in the test kit’s manual and presented as the log mean end-point titers, and the bars indicate the standard error of the means.