IngentaConnect Vaccination against Schistosoma japonicum Infection by DNA Vaccin...

Authors: DAI, Gan¹; WANG, Shiping; YU, Junlong¹; XU, Shaorui; PENG, Xianchu¹; HE, Zhuo¹; LIU, Xueqin¹; ZHOU, Songhua¹; LIU, Fen¹

Source: Acta Biochimica et Biophysica Sinica, Volume 39, Number 1, January 2007 , pp. 27-36(10)

Publisher: Blackwell Publishing

Abstract:

To observe the in vitro expression of DNA vaccine pcDNA3-Sj22.7 and its immunological effect in mice, the recombinant plasmid pcDNA3-Sj22.7 was used to transfect HeLa cells with liposome-mediated method and the expression of Sj22.7 mRNA and protein was examined using reverse transcription-polymerase chain reaction, sodium dodecylsulfate-polyacrylamide gel electrophoresis and Western blot. Then, the ability of pcDNA3-Sj22.7 to protect against Schistosoma japonicum challenge infections was analyzed according to worm reduction rate and egg reduction rate after vaccination of mice. The serum levels of specific IgG antibody and T lymphocyte proliferation response were also determined. After the challenge infection, Sj22.7-driven interferon (IFN)-γ and interleukin (IL)-4 was also quantified. Results showed that pcDNA3-Sj22.7 could express Sj22.7 mRNA and protein in vitro. Immunization resulted in a worm reduction rate of 29.70%, egg reduction rate of 47.25% (liver) and 51.73% (intestine), and egg reduction rate of 25.90% (eggs per female), suggesting induction of significant anti-fecundity in the pcDNA3-Sj22.7 group. Enzyme-linked immunosorbent assay and Western blot analysis indicated that immunized mice generated specific IgG against Sj22.7. T lymphocytes from mice immunized with pcDNA3-Sj22.7 showed a significant proliferation response to rSj22.7. The culture of spleen cells showed that secretion of IFN-γ increased but IL-4 decreased. The results indicate that DNA vaccination by pcDNA3-Sj22.7 is sufficient to elicit significant levels of protective immunity against S. japonicum infection. The DNA vaccine could induce significant cellular and humoral immune response, and display predominant T helper cell type 1 type immune responses, which contribute to the protective immunity against challenge infection in mice.

Edited by Changde LU

Keywords: Schistosoma japonicum; DNA vaccine; Sj22.7; gene expression; immune protection; immune response

Document Type: Research article

DOI: 10.1111/j.1745-7270.2007.00243.x

Affiliations: 1: Institute of Schistosomiasis Research, Xiangya School of Medicine, Central South University, Changsha 410078, China

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Vaccination against Schistosoma japonicum Infection by DNA Vaccine Encoding Sj22.7 Antigen