Screening of 71 P. multocida proteins for protective efficacy in a fowl cholera infection model and characterization of the protective antigen PlpE.
BACKGROUND
There is a strong need for a recombinant subunit vaccine against fowl cholera. We used a reverse vaccinology approach to identify putative secreted or cell surface associated P. multocida proteins that may represent potential vaccine candidate antigens.


RESULTS
A high-throughput cloning and expression protocol was used to express and purify 71 recombinant proteins for vaccine trials. Of the 71 proteins tested, only one, PlpE in denatured insoluble form, protected chickens against fowl cholera challenge. PlpE also elicited comparable levels of protection in mice. PlpE was localized by immunofluorescence to the bacterial cell surface, consistent with its ability to elicit a protective immune response. To explore the role of PlpE during infection and immunity, a plpE mutant was generated. The plpE mutant strain retained full virulence for mice.


CONCLUSIONS
These studies show that PlpE is a surface exposed protein and was the only protein of 71 tested that was able to elicit a protective immune response. However, PlpE is not an essential virulence factor. This is the first report of a denatured recombinant protein stimulating protection against fowl cholera.
Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia. tamas.hatfaludi@monash.edu
Tamás
T
Hatfaludi
Keith
K
Al-Hasani
Lan
L
Gong
John D
JD
Boyce
Mark
M
Ford
Ian W
IW
Wilkie
Noelene
N
Quinsey
Michelle A
MA
Dunstone
David E
DE
Hoke
Ben
B
Adler
D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D001428:Bacterial Vaccines / Q000276:immunology*; D002645:Chickens / Q000276:immunology / Q000382:microbiology; D004195:Disease Models, Animal; D005260:Female; D015870:Gene Expression; D051379:Mice; D050505:Mutant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D010326:Pasteurella Infections / Q000517:prevention & control / Q000662:veterinary*; D016979:Pasteurella multocida / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D011201:Poultry Diseases / Q000517:prevention & control*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D014614:Vaccines, Synthetic / Q000276:immunology; D037521:Virulence Factors / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines; D050505:Mutant Proteins; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; D037521:Virulence Factors