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Publications (6)24.41 Total impact

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    ABSTRACT: The Balb/c mice were infected with Coxiella burnetii and samples of blood and major organs from the infected mice were collected on days 1 to 14 after infection. The DNAs extracted from the samples were detected by a developed real-time quantitative PCR specific for C. burnetii and high loads of C. burnetii were found in spleens, livers, and lungs, particularly in spleens. The Balb/c mice were immunized with whole cell antigen (WCA) of C. burnetii and coxiella loads in spleens of mice were assessed by the real-time quantitative PCR on day 7 after challenge with C. burnetii. The analysis suggested that phase I whole cells were excellent immunogen that elicited complete protection against coxiella infection by two-booster but not one-booster immunization. The results suggest that the combination of Balb/c model and the real-time quantitative PCR assay is a reliable and sensitive way to evaluate the efficiency of vaccines against Q fever.
    Annals of the New York Academy of Sciences 01/2006; 1063:171-5. · 4.38 Impact Factor
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    ABSTRACT: The gene fragments encoding outer membrane protein 1 (P1) and heat-shock protein B (HspB) amplified from genomic DNA of Coxiella burnetii Xinqiao by PCR were inserted into prokaryotic expression vector pQE30 to construct recombinant expression plasmids pQE30/p1 and pQE30/hspB, respectively. The p1 fragment from pQE30/p1 was ligated with hspB of pQE30/hspB to construct pQE30/p1-hspB. Recombinant proteins, P1, HspB, and P1-HspB, were expressed in Escherichia coli cells transformed with pQE30/p1, pQE30/hspB, and pQE30/p1-hspB, respectively. The purified recombinant proteins and whole-cell antigen (WCA) of C. burnetii were used to immunize BALB/c mice. The antibody detection, T-cell proliferation assay, and cytokine detection demonstrated that the animals immunized with P1-HspB or WCA exhibited stronger humoral and cellular immune responses compared with animals immunized with P1 or HspB individually. Seven days after challenge of 10-fold 50% infection dose of C. burnetii, mice were euthanized and their spleens were collected. The splenic weights of mice immunized with P1-HspB or WCA were significantly lighter than that of mice immunized with P1 or HspB. By real-time PCR assay, the coxiella loads of spleens of mice immunized with P1-HspB or WCA were also significantly lower than that of mice immunized with P1 or HspB. The data from this study indicate that fusion antigen P1-HspB is a good immunogen for eliciting immunoresponses against C. burnetii, and it may be a more suitable candidate for preparing subunit vaccine against Q fever.
    Annals of the New York Academy of Sciences 01/2006; 1063:130-42. · 4.38 Impact Factor
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    ABSTRACT: A truncated gene ompA was amplified from Rickettsia heilongjiangensis isolated in China and a 56-kDa truncated OmpA protein was expressed in E. coli cells transformed with the ompA-recombined expression plasmid. High levels of serum antibodies to R. heilongjiangensis and proliferation of the splenic cells were found in mice immunized with the truncated OmpA. After challenge with R. heilongjiangensis or R. rickettsii, fever and pathological damages of the guinea pigs immunized with the truncated OmpA were significantly slighter as compared with those of nonimmunized guinea pigs. These results suggest that the truncated OmpA of R. heilongjiangii is immunogenic for effectively inducing humoral and cell-mediated immune responses against homologous and heterologous species in the spotted fever group.
    Annals of the New York Academy of Sciences 01/2006; 1063:261-5. · 4.38 Impact Factor
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    ABSTRACT: A partial gene sequence encoding the 56-kD scrub typhus antigen (Sta56) was amplified from genomic DNA of the Orientia tsutsugamushi Karp strain by a polymerase chain reaction (PCR). The PCR product was ligated with the 47-kD scrub typhus antigen (Sta47) gene in the pQE30/47 expression vector, and the resulting recombinant expression vector was designated pQE30/56-47. A fusion antigen (Sta56-47) was expressed in Escherichia coli cells transformed with pQE30/56-47 after induction with isopropyl-beta-d-thiogalactopyranoside. The Sta56-47 antigen was recognized by both Sta47 and Sta56 immune sera and by immune serum to Sta56-47 in an immunoblot assay. This antigen was purified and used to immunize BALB/c mice. The animals immunized with Sta56-47 exhibited profound humoral and cellular immune responses, as well as increased resistance to O. tsutsugamushi Karp compared with mice immunized with Sta56 or Sta47. These results strongly suggest that Sta56-47 contains antigenic epitopes of the Sta56 and Sta47 antigens of O. tsutsugamushi Karp, and is a more suitable candidate for replacing whole-cell antigen of O. tsutsugamushi Karp to induce protective immunity against scrub typhus.
    The American journal of tropical medicine and hygiene 05/2005; 72(4):458-64. · 2.53 Impact Factor
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    ABSTRACT: In this study, the fragment of 47 kDa gene (301 bp-1428 bp) was cloned into a prokaryotic expression vector pBV220 to construct a recombinant plasmid pBV-47. The E. coli cells were transformed with pBV-47 and the transformants were induced to express the recombinant protein at 42 degrees C. The expression product (40 kDa) was detected by SDS-PAGE analysis and the 40kDa protein was recognized by mouse polyclonal antibodies against O. tsutsugamushi Karp strain in western blot analysis. The entire 47 kDa protein gene was inserted into an eukaryotic expression vector pcDNA3.1(+) to construct a recombinant plasmid pcDNA3.1/47 and Balb/c mice were immunized with recombinant pcDNA3.1/47, control vector pcDNA3.1, PBS buffer, 40 kDa protein, and recombinant pcDNA3.1/47 plus 40 kDa protein (pcDNA3.1/47/40), respectively. The results showed that spleen cells from pcDNA3.1/47/40-immunized mice gave higher proliferation than other groups. A significant IgG rise was detected in mice immunized with 40 kDa protein, but it was less strong than that in mice immunized with pcDNA3.1/47/40. The results suggested that immunization with pcDNA3.1/47 and 40 kDa protein simultaneously could induce a strong immune response.
    Annals of the New York Academy of Sciences 07/2003; 990:527-34. · 4.38 Impact Factor
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    ABSTRACT: In this study, the fragment of 47 kDa gene (301 bp-1428 bp) was cloned into a prokaryotic expression vector pBV220 to construct a recombinant plasmid pBV-47. The E. coli cells were transformed with pBV-47 and the transformants were induced to express the recombinant protein at 42°C. The expression product (40 kDa) was detected by SDS-PAGE analysis and the 40kDa protein was recognized by mouse polyclonal antibodies against O. tsutsugamushi Karp strain in western blot analysis. The entire 47 kDa protein gene was inserted into an eukaryotic expression vector pcDNA3.1(+) to construct a recombinant plasmid pcDNA3.1/47 and Balb/c mice were immunized with recombinant pcDNA3.1/47, control vector pcDNA3.1, PBS buffer, 40 kDa protein, and recombinant pcDNA3.1/47 plus 40 kDa protein (pcDNA3.1/47/40), respectively. The results showed that spleen cells from pcDNA3.1/47/40-immunized mice gave higher proliferation than other groups. A significant IgG rise was detected in mice immunized with 40 kDa protein, but it was less strong than that in mice immunized with pcDNA3.1/47/40. The results suggested that immunization with pcDNA3.1/47 and 40 kDa protein simultaneously could induce a strong immune response.
    Annals of the New York Academy of Sciences 05/2003; 990(1):527 - 534. · 4.38 Impact Factor