Specific antibody immune response against the parasitic portion of a glutathione-S-transferase fusion protein

Differential humoral and cellular immunity induced by vaccination using plasmid DNA and protein recombinant expressing the NS3 protein of dengue virus type 3

Background

The dengue non-structural 3 (NS3) is a multifunctional protein, containing a serine-protease domain, located at the N-terminal portion, and helicase, NTPase and RTPase domains present in the C-terminal region. This protein is considered the main target for CD4+ and CD8+ T cell responses during dengue infection, which may be involved in protection. However, few studies have been undertaken evaluating the use of this protein as a protective antigen against dengue, as well as other flavivirus. In the present work we evaluated the potential of the NS3 (protease domain) as a protective antigen by comparing the administration of a recombinant protein versus a DNA vaccine in the mouse model.

Results

BALB/c mice were immunized with the recombinant protein NS3-DEN3 via intraperitoneal and with plasmid pcDNA3/NS3-DEN3 intramuscularly and the immune response was evaluated. The activity of T lymphocytes was analyzed by the MTT assay, and cells of mice immunized with the recombinant protein showed no activity when stimulated with the homologous protein. However, cells from mice immunized with DNA, responded to stimulation with the recombinant protein. When the expression (RT-PCR) and cytokine production (ELISA) was evaluated in the splenocytes, different behavior depending on the type of immunization was observed, splenocytes of mice immunized with the recombinant protein expressed cytokines such as IL-4, IL-10 and produced high concentrations of IL-1, IL-6 and TNFα. Splenocytes from mice immunized with DNA expressed IL-2 and IFNγ and did not produce IL-6. In addition, immunization with the recombinant protein induced the production of antibodies that are detected up to a dilution 1:3200 by ELISA and Western blot assays, however, the serum of mice immunized with DNA presented no detectable antibody titers.

Conclusion

The results obtained in this study show that administration of pcDNA3/NS3-DEN3 induces a favorable response in the activation of T lymphocytes with low production of specific antibodies against NS3-DEN3.

A novel adjuvant-free H fusion system for the production of recombinant immunogens in Escherichia coli: Its application to a 12 kDa antigen from Cryptosporidium parvum

The production of recombinant antigens in Escherichia coli and specific polyclonal antibodies for diagnosis and therapy is still a challenge for world-wide researchers. Several different strategies have been explored to improve both antigen and antibody production, all of them depending on a successful expression and immunogenicity of the antigen. Gene fusion technology attempted to address these challenges: fusion partners have been applied to optimize recombinant antigen production in E. coli, and to increase protein immunogenicity. Taking a 12-kDa surface adhesion antigen from Cryptosporidium parvum (CP12) by example, the novel H fusion partner was presented in this work as an attractive option for the development of recombinant immunogens and its adjuvant-free immunization. The H tag (of only 1 kDa) efficiently triggered a CP12-specific immune response, and it also improved the immunization procedure without requiring co-administration of adjuvants. Moreover, polyclonal antibodies raised against the HCP12 fusion antigen detected native antigen structures displayed on the surface of C. parvum oocysts. The H tag proved to be an advanced strategy and promising technology for the diagnosis and therapy of C. parvum infections in animals and humans, allowing a rapid and simple recombinant production of the CP12 antigen.

Expression, purification, and evaluation of diagnostic potential and immunogenicity of a recombinant NS3 protein from all serotypes of dengue virus

Dengue is one of the major public health concerns in the world. Since all the four serotypes are actively circulating in Mexico, there is a need to develop an efficient diagnosis system to improve case management of the patients. There exist few studies evaluating the use of the NS3 protein as a protective antigen against dengue virus (DENV). In this paper we show the expression of a recombinant NS3 protein from all serotypes of dengue virus (GST-DVNS3-1-4) and report a reliable "in-house detection system" for the diagnosis of dengue infection which was field-tested in a small village (Tezonapa) in the state of Veracruz, Mexico. The fusion proteins were immunogenic, inducing antibodies to be able to recognize to antigens up to a 1 : 3200 dilution. The purified proteins were used to develop an in-house detection system (ELISA) and were further tested with a panel of 239 serum samples. The in-house results were in excellent agreement with the commercial kits with κ = 0.934 ± 0.064 (95%  CI = 0.808-1.061), and κ = 0.872 ± 0.048 (95%  CI = 0.779-0.965) for IgM and IgG, respectively. The agreement between the NS1 antigen detection versus the rNS3 ELISA, κ = 0.837 ± 0.066 (95%  CI = 0.708-0.966), was very good. Thus, these results demonstrate that recombinant NS3 proteins have potential in early diagnosis of dengue infections.

Subcellular distribution of theEntamoeba histolytica140 kDa FN-binding molecule during host-parasite interaction

Entamoeba histolyticatrophozoites recovered from the host-parasite interface during abscess development obtain different stimuli compared with long-term cultured cells. In order to have a better understanding about the mechanisms in which the 140 kDa fibronectin (FN)-binding molecule (EhFNR) is involved during the invasive process, we decided to compare the regulation process of this molecule among long-term cultured trophozoites, FN-stimulated trophozoites, and trophozoites recently recovered from a liver abscess. A cDNA clone (5A) containing a fragment of theEhFNR that shows identity to the C-terminal region of the intermediate galactose lectin subunit Igl, was selected with a mAb (3C10). Identity ofEhFNR with Igl was confirmed by immunoprecipitation with 3C10 and EH3015 (against the Gal/GalNAc intermediate subunit) mAbs. The 3C10 mAb was used as a tool to explore the modulation of the amoebic receptor (EhFNR). Our results showed specific regulation of theEhFNR in FN-interacted amoebas, as well as in trophozoites recovered at different stages of abscess development. This regulation involved mobilization of the receptor molecule from internal vesicles to the plasma membrane. Therefore, we suggest that in the host-parasite interface, theEhFNR (Igl) plays an important role in the adhesion process during abscess development.