Prevention and control of chicken coccidiosis construction of recombinant Lactococcus lactis expressing chicken IL-4 and IL-2 fusion protein and its immune synergistic effect on chicken coccidia live vaccine

Intestinal mucosa injury and loss of weight gain are unavoidable while using live vaccine strain to prevent chicken coccidiosis. In this study, recom-binant Lactococcus lactis NZ3900/pNZ8149-IL-4-IL-2, expressing the fusion protein of chicken IL-4 and IL-2, was constructed using food-grade NICE expression sys-tem, trying to develop a possible oral immune adjuvant to enhance the immune effect of the live vaccine against chicken coccidiosis and minimize its adverse effects. Chickens were given different doses of recombinant L. lactis together with the live vaccine, then experimently attacked with coccidia virulent strains. Results showed that weight gains of co-immunization groups, given both 1 x 109 or 1 x 1010 CFU recombinant L. lactis and the live vaccine, were significantly higher than the vaccine-only group (P < 0.05), while intestinal lesion scores ofduodenum, jejunum, and cecum were significantly lower than the vaccine-only group (P < 0.05), so was the oocyst shedding. The anticoccidial indexes (ACI) of the coimmunized groups given 1 x 109 and 1 x 1010 CFU recombinant L. lactis were 187.85 and 193.33, respectively, higher than 174.61 of the vaccine-only group. In addition, chickens in co-immunization groups gained more body weight than the vaccine-only group before being challenged with the virulent strains (P < 0.05). All the results indicated that the constructed recombinant L. lactis NZ3900/ pNZ8149-IL-4-IL-2 exhibited an immune synergistic function to coccidiosis live vaccine, and could alleviate its adverse effect affecting weight gain. The application of the recombinant L. lactis showed the potency to lift the anticoccidial efficiency of the live vaccine from a medium level to a high level.

Automated summary

In this study, a recombinant Lactococcus lactis expressing fusion protein of chicken IL-4 and IL-2 was constructed to enhance the immune effect of chicken coccidiosis vaccine and reduce its adverse effects. The co-immunization with the recombinant L. lactis resulted in significantly higher weight gains and lower intestinal lesion scores compared to the vaccine-only group.