Onderstepoort Journal of Veterinary Research
On-line version ISSN 2219-0635
Print version ISSN 0030-2465
LIU, Qiong et al. Construction and immunogenicity of a ΔapxIC/ompP2 mutant of Actinobacillus pleuropneumonias and Haemophilus parasuis. Onderstepoort j. vet. res. [online]. 2013, vol.80, n.1, pp.1-6. ISSN 2219-0635.
The apxIC genes of the Actinobacillus pleuropneumoniae serovar 5 (SC-1), encoding the ApxI-activating proteins, was deleted by a method involving sucrose counter-selection. In this study, a mutant strain of A. pleuropneumoniae (SC-1) was constructed and named AapxIC/ ompP2. The mutant strain contained foreign DNA in the deletion site of ompP2 gene of Haemophilus parasuis. It showed no haemolytic activity and lower virulence of cytotoxicity in mice compared with the parent strain, and its safety and immunogenicity were also evaluated in mice. The LD50 data shown that the mutant strain was attenuated 30-fold, compared with the parent strain (LD50 of the mutant strain and parent strain in mice were determined to be 1.0 x 107 CFU and 3.5 x 105 CFU respectively). The mutant strain that was attenuated could secrete inactivated ApxIA RTX toxins with complete antigenicity and could be used as a candidate live vaccine strain against infections of A. pleuropneumoniae and H. parasuis.