ORGINAL ARTICLES

Protective immunity induced by recombinant surface protein-1 and surface protein-4 against Toxoplasma gondii infection in mice

  • Kai LIANG ,
  • Yan-wen LI ,
  • Bei-bei WANG ,
  • Xiao-yin FU ,
  • Xiao-quan LIU ,
  • Shan-shan HE ,
  • Li-li TANG ,
  • Deng-yu LIU ,
  • Huan-huan SHI
Expand
  • Department of Parasitology, School of Preclinical Medicine, Guangxi Medical University, Nanning 530021, China

Received date: 2018-09-14

  Online published: 2019-05-13

Supported by

Supported by the Undergraduates Innovation and Entrepreneurship Training Program of Guangxi Medical University in 2015(No. 201510598041);and the Young and Middle?aged Teachers’Basic Ability Improvement Project of Guangxi in 2016(No. KY2016YB086)

Abstract

Objective To determine the protective immunity induced by the immunization of recombinant surface antigen-1 (rSAG1) and surface antigen-2 (rSAG2) against Toxoplasma gondii infection in mice and compare their potential as vaccine. Methods The DNAs coding for T. gondii SAG1 and SAG4 were amplified by PCR from T. gondii genomic DNA and cloned into expression plasmid pET-28a(+). The success of cloning was confirmed by DNA sequencing, The recombinant plasmid DNAs were transformed into E. coli BL21(DE3) for expression as recombinant proteins under isopropyl-β-D-thiogalactopyranoside(IPTG) induction. The induced bacteria were lysed and the expressed rSAG1 and rSAG4 were purified by Ni-NTA resin under denatured condition. The denatured recombinant proteins were refolded by dialysis method. The refolded recombinant proteins were formulated with Freund’s adjuvant and used to immunize mice (n = 25 for each group) for 3 times. PBS and PBS + adjuvant were used as controls. Sera were collected after each immunization and specific IgG in the sera were measured by ELISA. Each mouse was challenged with 3 000 T. gondii tachyzoite two weeks after the final immunization. The survival time of the infected mice was observed and the data was analyzed using SPSS 16.0. Results The DNAs coding for full length SAG1 (780 bp) and SAG4 (438 bp) were successfully amplified from T. gondii genomic DNA and then cloned into pET-28a(+) to generate recombinant pET-28a(+)-SAG1 and pET-28a(+)-SAG4. The correct sequence and reading frame were confirmed by DNA sequencing. After being transformed into E. coli BL21 (DE3), both rSAG1 and rSAG4 were expressed as inclusion bodies. After being denatured with urea, the rSAG1 and rSAG4 were purified and refolded as soluble proteins. All mice produced high level of specific IgG in sera after being immunized three times with each recombinant protein compared to pre-immunization sera (P < 0.05). The ELISA A450 value of rSAG1 group (1.821 ± 0.184) was significantly higher than rSAG4 group (0.695 ± 0.089) when sera were diluted at 1:400 (P < 0.05), but it is less than the combined group (rSAG1 + rSAG4) (1.955 ± 0.097) (P < 0.05). And the A450 value of 3 experimental groups was higher than PBS (0.019 ± 0.002) group and PBS + adjuvant group (0.020 ± 0.004). All control mice (without immunization) died 224 h after being infected with 3 000 T. gondii tachyzoite, however, the mice immunized with rSAG1, rSAG4 and rSAG1 + rSAG4 survived till 296 h, 288 h and 320 h, respectively, after being challenged with the same number of T. gondii tachyzoite, with significant difference compared to the control group (P < 0.05). The increased survival time in the rSAG1 + rSAG4 group was significantly longer than each individual antigen group (P < 0.05). Conclusion Mice immunized with rSAG1, rSAG4 and rSAG1 + rSAG4 produced significant protective immunity against T. gondii infection with prolonged survival time than group without immunization. The co-immunization with both rSAG1 and rSAG4 produced synergic protective immunity compared to the individual antigen.

Cite this article

Kai LIANG , Yan-wen LI , Bei-bei WANG , Xiao-yin FU , Xiao-quan LIU , Shan-shan HE , Li-li TANG , Deng-yu LIU , Huan-huan SHI . Protective immunity induced by recombinant surface protein-1 and surface protein-4 against Toxoplasma gondii infection in mice[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2019 , 37(2) : 155 -160 . DOI: 10.12140/j.issn.1000-7423.2019.02.007

References

[1] 全国人体重要寄生虫病现状调查办公室. 全国人体重要寄生虫病现状调查报告[J]. 中国寄生虫学与寄生虫病杂志, 2005, 23(增刊5): 332-340.
[2] Villena I, Ancelle T, Delmas C, et al. Congenital toxoplasmosis in France in 2007: first results from a national surveillance system[J]. Euro Surveill, 2010, 15(25): 19600.
[3] Moncada PA, Montoya JG.Toxoplasmosis in the fetus and newborn: an update on prevalence: diagnosis and treatment[J]. Expert Rev Anti infect Ther, 2012, 10(7): 815-828.
[4] 严晓岚, 闻礼永, 官亚宜, 等. 《弓形虫病的诊断》标准解读[J]. 中国寄生虫学与寄生虫病杂志, 2016, 34(4): 387-389.
[5] Liu Q, Wang Z, Huang S, et al. Diagnosis of toxoplasmosis and typing of Toxoplasma gondii[J]. Parasit Vectors, 2015, 8: 292.
[6] 蒋子阳, 董锴, 戴红, 等. 弓形虫疫苗研究进展[J]. 热带医学杂志, 2018, 18(2): 269-274.
[7] Di Cristina M, Del Porto P, Buffolano W, et al. The Toxoplasma gondii bradyzoite antigens BAG1 and MAG1 induce early humoral and cell-mediated immune responses upon human infection[J]. Microbes Infect, 2004, 6(2): 164-171.
[8] 郭凯, 陈兴智. 弓形虫主要抗原的研究进展[J]. 蚌埠医学院学报, 2012, 37(4): 486-490.
[9] 孙怡, 何深一, 丛华, 等. 弓形虫SAG1-SAG2复合DNA疫苗免疫小鼠诱导的免疫保护性[J]. 国际医学寄生虫病杂志, 2006, 33(1): 2-5.
[10] 王钊哲, 许瑞, 洪炀, 等. 刚地弓形虫表面抗原1、2 B细胞表位基因的融合表达和鉴定[J]. 中国寄生虫学与寄生虫病杂志, 2017, 35(6): 575-579.
[11] 张佃波, 周林涛, 王海防, 等. 刚地弓形虫ROP2-P30复合重组蛋白疫苗对BALB/c小鼠免疫保护性的研究[J]. 中国病原生物学杂志, 2008, 3(10): 763-767.
[12] Wang Y, Yin H.Research progress on surface antigen 1 (SAG1) of Toxoplasma gondii[J]. Parasit Vectors, 2014, 7: 180.
[13] 吴斌, 吕芳丽. CD8+T细胞免疫应答在刚地弓形虫感染免疫中的功能研究进展[J]. 中国寄生虫学与寄生虫病杂志, 2014, 32(2): 143-147.
[14] Zhou J, Wang L.SAG4 DNA and peptide vaccination provides partial protection against T. gondii infection in BALB/c mice[J]. Front Microbiol, 2017, 8: 1733.
[15] 杨雯, 田春林, 朱穗京, 等. 弓形虫表面抗原SAG1基因的克隆表达、纯化与鉴定[J]. 广西医科大学学报, 2010, 27(2): 205-208.
[16] 杨雯, 万孝玲, 田春林, 等. 弓形虫表面抗原SAG4基因的克隆、表达和鉴定[J]. 中国寄生虫学与寄生虫病杂志, 2009, 27(4): 340-343.
Outlines

/

〈 〉