Construction and immune effect of Haemophilus parasuis DNA vaccine encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in mice

► A novel DNA vaccine encoding GAPDH (pCgap) was constructed. ► A significant antibody response against GAPDH was generated and antibodies to the pCgap DNA vaccine were bactericidal. ► The DNA vaccine induced both Th1 and Th2 immune responses, but the IgG1 response was greater than the IgG2a response. ► The DNA vaccine pCgap provided protective efficacy against the H. parasuis challenge.