Construction Of Recombinant Lactobacillus Plantarum Expressing ROP18 And SAG1 And Their Protective Efficacy Against Toxoplasma Gondii Infection

Toxoplasmosis is an important parasitic zoonosis caused by the protozoan Toxoplasma gondii, which is widespread in worldwide and infecting almost all warm-blooded animals and humans. Nearly one-third of the world population has been infected with this parasite, and cause serious health problem to humans and animals. Humans are infected by ingesting oocysts shed by cats or consuming undercooked meat with parasite tissue cysts. To date, toxoplasmosis continues to be a significant public health problem around the world, and no commercial vaccines are available. So a safe and effective vaccine is needed for the prevention and control of T. gondii infections in medical and veterinary situations. Mucosa tissues are particularly important for the protection of an organism from diseases which invade the body through the mucosal system.Lactobacillus strains have been used as hosts to express many bacterial and viral antigens and have been proven to elicit immune responses after being used for inoculation by oral administration.In the present study, we constructed the recombinant p SIP409-ROP18-Nc8 and p SIP409-SAG1-Nc8 based on Lactobacillus plantarum Nc8 expressing protein of the Toxoplasmosis for the first time. SDS-PAGE and Western Blot was used to detect the immunogenicity of the recombinant p SIP409-ROP18-Nc8 and p SIP409-SAG1-Nc8. These results indicated that orally administered p SIP409-ROP18-Nc8 and p SIP409-SAG1-Nc8 were able to elicit both Toxoplasmosis-specific systemic and mucosal antibody responses. Then SDS-PAGE and Western blot was used to detect the immunogenicity of the recombinant p SIP409-ROP18-Nc8 and p SIP409-SAG1-Nc8. But the result is not very significant.The mucosal immunity of mice was studied by measuring the anti-Toxoplasmosis Ig A and Ig G response in serum and measuring the anti-Toxoplasmosis s Ig A response in small intestine and lung. To investigate cellular immune responses after oral immunization with Lactobacillus strains incorporating the recombinant plasmid, the CD4+ T cells and CD8+ cells was detected by flow cytometry.These results indicated that p SIP409-ROP18-Nc8 and p SIP409-SAG1-Nc8 groups rose to a higher level than the control groups. But the result is not very significant.So more research is needed to prevent and control of T. gondii infections.This study was the first time to make the recombinant Lactobacillus plantarum expressing ROP18 and SAG1 immune mice by orally. The results indicated that the recombinant Lactobacillus plantarum expressing ROP18 and SAG1 can resist the infection of T.gondii, which laid the foundation for the future development of the live vector vaccines against Toxoplasma gondii.