Recombinant GMA56 and ROP17 of Eimeria magna conferred protection against infection by homologous species

Abstract

One of the most common rabbits coccidia species, Eimeria magna is mainly parasitic in the ileal and jejunal epithelial cells. E. magna infection can affect the growth performance of rabbits or cause other secondary diseases. Traditional methods of anticoccidial treatment typically result in drug resistance and drug residue. Therefore, vaccination is a promising alternative. Gametocyte antigen 56 (GAM56) and rhoptry kinase family proteins (ROPs) are involved in oocyst wall formation and parasite invasion, respectively. A virulence factor, ROP17 contains a serine/threonine kinase catalytic domain. In this study, recombinant E. magna GAM56 (rEmGAM56) and ROP17 (rEmROP17) proteins were obtained from a prokaryotic expression system and their reactogenicity was investigated with immunoblotting. To assess the potential of rEmGAM56 and rEmROP17 as coccidiosis vaccines, New Zealand White rabbits were subcutaneously immunized with 100 μg rEmGAM56 (rGC group) or rEmROP17 (rRC group) twice at 2-week intervals followed by homologous oocyst challenge. The rabbit serum was collected weekly to detect the specific antibody levels. The cytokine levels of pre-challenge serum were measured by enzyme-linked immunosorbent assay and the rabbits were observed and recorded post-challenge for the onset of clinical symptoms. The weight gain, oocyst output, and feed conversion ratio were calculated at the end of the experiment. The results showed that both rEmGAM56 and rEmROP17 had good reactogenicity. The rEmGAM56- or rEmROP17-immunized rabbits had milder clinical symptoms and feed conversion ratios of 3.27:1 and 3.37:1, respectively. The rEmGAM56-immunized rabbits had 81.35% body weight gain and 63.85% oocyst output reduction; the rEmROP17-immunized rabbits had 79.03% body weight gain and 80.10% oocyst output reduction. The ACI of rGC and rRC groups were 162.35 and 171.03, respectively. The specific antibody levels increased rapidly after immunization. Significantly increased interleukin (IL)-2, interferon (IFN)-γ, and IL-17 levels were evident in the rGC and rRC groups (p < 0.05). The rEmGAM56 and rEmROP17 elicited humoral and cellular responses, which protected against E. magna infection in rabbits. Thus, rEmGAM56 and rEmROP17 are potential vaccine candidates against E. magna, and rEmROP17 performed better than rEmGAM56.

Assessment of the Immunoprotective Efficacy of Recombinant 14-3-3 Protein and Dense Granule Protein 10 (GRA10) as Candidate Antigens for Rabbit Vaccines against Eimeria intestinalis

“…The immunization of r with recombinant E. stiedae surface antigen rEs-SAG13 [27], apical membrane antige AMA1 [28], and immune-mapped protein rEs-IMP1 [28] resulted in 82.8%, 74.6% 80.0% oocyst reductions, respectively, and significantly higher relative body w growth rates compared to the control group, reaching 88.77%, 78.1%, and 94.4%, r tively. The recombinant E. magna surface antigens rEm-SAG10 and rEm-SAG11 [2 microneme proteins rEm-MIC2 and rEm-MIC3 [30], the gametophyte antigen rEm-G [31], and the rhoptry protein rEm-ROP17 [31] provided good immune protection af immunization of the rabbits. There was only one study of a recombinant subunit v against E. intestinalis, indicating that rEi-AMA1 and rEi-IMP1 provided moderate im protection in rabbits, with ACI values of 152.09 and 147.17, respectively [17].…”