Non-cytolytic antigen clearance in DNA-vaccinated mice with electroporation

Schools of Life Sciences and Technology, Shanghai Jiao Tong University, Shanghai 200240, China.
Acta Pharmacologica Sinica (Impact Factor: 2.91). 08/2007; 28(7):1024-30. DOI: 10.1111/j.1745-7254.2007.00591.x
Source: PubMed


To explore the potential of electroporation (EP)-mediated hepatitis B virus (HBV) DNA vaccination for the treatment of chronic HBV infection.
BALB/c mice were vaccinated with HBV DNA vaccine encoding for the HBV preS(2)-S antigen, combined with or without EP. HBV surface antigen expression plasmid was administered into mice liver via a hydrodynamic injection to mimic HBV infection. The clearance of antigen in the serum and liver was detected by ELISA assay and immunohistochemical staining. The histopathology of the liver tissues was examined by HE staining and serum alanine aminotransferase assay.
The immunogenicity of HBV DNA vaccine encoding for the HBV preS(2)- S antigen can be improved by EP-mediated vaccine delivery. The elicited immune responses can indeed reduce the expression of HBV surface antigen (HBsAg) in hepatocytes of the mouse model that was transfected to express HBsAg using the hydrodynamic injection method. The antigen clearance process did not cause significant toxicity to liver tissue, suggesting a non-cytolytic mechanism.
The EP-aided DNA vaccination may have potential in mediating viral clearance in chronic hepatitis B patients.

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    • "Mice used for studying the effects of preexisting HBcAg-specific immunity were injected intramuscularly in the tibialis anterior muscle with 100 µg of pVAX1-HBc or pVAX1 dissolved in 50 µl of PBS, thrice within a 2-week interval. Both injections were followed by in vivo electroporation to increase the expression levels of the injected plasmids [20], [21]. For the protein immunizations, mice were injected subcutaneously (s.c.) in the back with 2 µg of rHBsAg (GlaxoSmithKline Biologicals S.A.), thrice within a 2-week interval. "
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    ABSTRACT: Hepatitis B virus(HBV) infection remains a global problem, despite the effectiveness of the Hepatitis B vaccine in preventing infection. The resolution of Hepatitis B virus infection has been believed to be attributable to virus-specific immunity. In vivo direct evaluation of anti-HBV immunity in the liver is currently not possible. We have developed a new assay system that detects HBV clearance in the liver after the hydrodynamic transfer of a reporter gene and over-length, linear HBV DNA into hepatocytes, followed by bioluminescence imaging of the reporter gene (Fluc). We employed bioluminescence detection of luciferase expression in HBV-infected hepatocytes to measure the Hepatitis B core antigen (HBcAg)-specific immune responses directed against these infected hepatocytes. Only HBcAg-immunized, but not mock-treated, animals decreased the amounts of luciferase expression, HBsAg and viral DNA from the liver at day 28 after hydrodynamic infection with over-length HBV DNA, indicating that control of luciferase expression correlates with viral clearance from infected hepatocytes.
    Preview · Article · Apr 2013 · PLoS ONE
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    • "Electroporation (EP)-mediated delivery of DNA vaccines has been demonstrated to clearly outperform the standard needle injection (SI) of plasmid DNA (pDNA), via increasing cellular permeability, which results in high level protein expression and improved immunogenicity to DNA vaccines targeting different viruses in a number of animal models including large animal species and non human primates (Ahlen et al., 2007; Capone et al., 2006; Livingston et al., 2010; Luckay et al., 2007; Otten et al., 2004; Rosati et al., 2008; van Drunen Littel-van den Hurk et al., 2008, 2010). For HBV, it has been reported that EP-based delivery dramatically enhances humoral and cellular immune responses to DNA vaccines targeting HBV envelope and/or core antigens, in several animal species such as mice (Chen et al., 2011; Kim et al., 2008; Luxembourg et al., 2006, 2008b; Peng et al., 2007; Widera et al., 2000), rabbit (Luxembourg et al., 2006, 2008b), sheep (Babiuk et al., 2007), pigs (Babiuk et al., 2002, 2004), cattle (van Drunen Littel-van den Hurk et al., 2008), rhesus-macaques (Zhao et al., 2006) and recently in the woodchuck model (Liu et al., 2011). In these studies, cellular immune responses to HBV antigens Virology 425 (2012) 61–69 ⁎ Corresponding author at: UMR "
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    ABSTRACT: We explored in the duck hepatitis B virus (DHBV) model the impact of electroporation (EP)-mediated DNA vaccine delivery on the neutralizing humoral response to viral preS/S large envelope protein. EP enhanced the kinetics and magnitude of anti-preS response compared to the standard needle DNA injection (SI). Importantly, EP dramatically enhanced the neutralizing potency of the humoral response, since antibodies induced by low DNA dose (10 μg) were able to highly neutralize DHBV and to recognize ten antigenic regions, including four neutralization epitopes. Whereas, SI-induced antibodies by the same low DNA dose were not neutralizing and the epitope pattern was extremely narrow, since it was limited to only one epitope. Thus, EP-based delivery was able to improve the dose efficiency of DNA vaccine and to maintain a highly neutralizing, multi-specific B-cell response, suggesting that it may be an effective approach for chronic hepatitis B therapy at clinically feasible DNA dose.
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    ABSTRACT: There are many positive attributes to DNA vaccination that make it a conceptually desirable platform. In clinical studies, however, standard DNA injection alone generally induces low levels of transgene-specific immunity when compared to other vaccine approaches. In order to boost the immunogenicity of this platform, next-generation DNA vaccines require additional techniques such as the administration of electroporation. This new method involves the generation of a brief electric field in tissue around a local injection site that results in the transient poration, or permeabilization, of the cellular membranes. As a result, antigen-specific immune responses are greatly enhanced and are likely due to increased DNA uptake and antigen expression. Thus, electroporation-mediated DNA vaccination represents a promising new strategy for the elicitation of strong immune responses directed against the expressed antigen(s) and not the vector, and ongoing studies are currently underway to optimize the working parameters of this technique. Here, we review the uses of this technology in conjunction with vaccination and suggest future directions for its further exploration. KeywordsDNA vaccination-Electroporation-Electropermeabilization-Plasmid
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