Construction and immunogencity of a DeltaapxIC/DeltaapxIIC double mutant of Actinobacillus pleuropneumoniae serovar 1.
The apxIC and apxIIC genes of the Actinobacillus pleuropneumoniae serovar 1 strain SLW01, encoding the ApxI- and ApxII-activating proteins, respectively, were deleted successively by a method involving sucrose counterselection. The resulting strain, SLW03, contained no foreign DNA and could secrete unactivated ApxIA and ApxIIA RTX toxins with complete antigenicity. Strain SLW03 was attenuated at least 1000-fold in Balb/C mice and caused no adverse effects in pigs at doses of up to 1 x 10(9) CFU mL(-1). SLW03 was able to induce a significant immune response and provide complete protection from clinical signs upon homologous (serovar 1) and heterologous (serovar 9) challenge of A. pleuropneumoniae. Pigs vaccinated via the intranasal (i.n.) route had significantly higher serum titers and fewer pulmonary lesions than pigs vaccinated via the intramuscular route postchallenge. These results suggest that the mutant strain SLW03 could be used as a candidate live vaccine that can induce reliable cross-serovar protection following i.n. immunization.
Lin
Liwen
L
Division of Animal Infectious Disease in the State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, PR China.
Bei
Weicheng
W
Sha
Yonggang
Y
Liu
Jinlin
J
Guo
Yi
Y
Liu
Weihong
W
Tu
Shuxin
S
He
Qigai
Q
Chen
Huanchun
H
D000189:Actinobacillus Infections / Q000517:prevention & control; D016977:Actinobacillus pleuropneumoniae / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D001428:Bacterial Vaccines / Q000382:microbiology*; D051379:Mice; D009154:Mutation; D013552:Swine / Q000276:immunology / Q000382:microbiology; D014613:Vaccines, Attenuated; D014774:Virulence
D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated