Owing to its critical functions in worm physiology, glyceraldehyde-3-phosphate dehydrogenase in Haemonchus contortus (HcGAPDH) is potential candidates for vaccine to control haemonchosis. In this study, DNA vaccine expressing HcGAPDH antigen was tested for protection against experimental H. contortus infections in goats. Fifteen goats (9-10 months of age) were allocated into three trial groups. Group 1 was vaccinated with HcGAPDH DNA vaccine twice on days 0 and 14, and then challenged with 5000 infective H. contortus L3 (third stage larvae) on days 28. Group 2 was an unvaccinated positive control group challenged with H. contortus L3 on days 28. Group 3 was an unvaccinated negative control group that was not challenged with L3. By the method of RT-PCR and Western-blot, transcription and expression of HcGAPDH DNA vaccine were identified at local injection sites post immunizations, respectively. After immunization with the DNA vaccine, significantly high levels of serum IgG, serum IgA, mucosal IgA, CD4(+) T lymphocytes and B lymphocytes were generated. Also, increased numbers of blood eosinophils and decreased haemoglobin level after challenge were observed in the vaccinated group. Meanwhile, cumulative mean faecal worm egg counts and worm burdens in vaccinated group were reduced by 34.9% and 37.73%, respectively. In brief, recombinant HcGAPDH DNA vaccine induced partial immune response against H. contortus infection in goats.
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