Increased Immunogenicity of a DNA-Launched Venezuelan Equine Encephalitis Virus-Based Replicon DNA Vaccine

Ljungberg, Karl; Whitmore, Alan C.; Fluet, M.E.; Moran, Timothy P.; Shabman, Reed S.; Collier, Martha; Kraus, Annette; Thompson, Jeff. E.; Montefiori, David C.; Beard, Clayton W.; Johnston, Robert E.

doi:10.1128/jvi.01799-07

Cited by 48 publications

(51 citation statements)

References 55 publications

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“…Moreover, DREPs also possess intrinsic adjuvant properties, since the replicase and RNA intermediates stimulate the production of type 1 interferons (IFNs) and apoptosis (32)(33)(34). Promising results have been reported for DNA replicons generated from other alphaviruses, including Semliki Forest virus (35)(36)(37), Sindbis virus (38,39), and Venezuelan equine encephalitis virus (40), when they are used for priming immunizations prior to boosting with other vaccine modalities (36). The heterologous prime-boost approach takes advantage of the unique immune profiles induced by the different vaccine platforms.…”

Section: Hikungunya Virus (Chikv) Is An Alphavirus Of the Familymentioning

confidence: 79%

Prime-Boost Immunization Strategies against Chikungunya Virus

Holzmann

Lum

Kümmerer

et al. 2014

J Virol

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Chikungunya virus (CHIKV) is a reemerging mosquito-borne alphavirus that causes debilitating arthralgia in humans. Here we describe the development and testing of novel DNA replicon and protein CHIKV vaccine candidates and evaluate their abilities to induce antigen-specific immune responses against CHIKV. We also describe homologous and heterologous prime-boost immunization strategies using novel and previously developed CHIKV vaccine candidates. Immunogenicity and efficacy were studied in a mouse model of CHIKV infection and showed that the DNA replicon and protein antigen were potent vaccine candidates, particularly when used for priming and boosting, respectively. Several prime-boost immunization strategies eliciting unmatched humoral and cellular immune responses were identified. Further characterization by antibody epitope mapping revealed differences in the qualitative immune responses induced by the different vaccine candidates and immunization strategies. Most vaccine modalities resulted in complete protection against wild-type CHIKV infection; however, we did identify circumstances under which certain immunization regimens may lead to enhancement of inflammation upon challenge. These results should help guide the design of CHIKV vaccine studies and will form the basis for further preclinical and clinical evaluation of these vaccine candidates. IMPORTANCE As of today, there is no licensed vaccine to prevent CHIKV infection. In considering potential new vaccine candidates, a vaccinethat could raise long-term protective immunity after a single immunization would be preferable. While humoral immunity seems to be central for protection against CHIKV infection, we do not yet fully understand the correlates of protection. Therefore, in the absence of a functional vaccine, there is a need to evaluate a number of different candidates, assessing their merits when they are used either in a single immunization or in a homologous or heterologous prime-boost modality. Here we show that while single immunization with various vaccine candidates results in potent responses, combined approaches significantly enhance responses, suggesting that such approaches need to be considered in the further development of an efficacious CHIKV vaccine.

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Section: Hikungunya Virus (Chikv) Is An Alphavirus Of the Familymentioning

confidence: 79%

Prime-Boost Immunization Strategies against Chikungunya Virus

Holzmann

Lum

Kümmerer

et al. 2014

J Virol

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“…PRR signaling leads to production of large amounts of type I interferons (IFNs) (17) and apoptosis (4, 11) and promotes antigen-specific adaptive immune responses (21, 31). In mice, DREP has been shown to be more potent than conventional plasmid DNA vaccines in inducing antigen-specific CD8 ϩ T cell and antibody responses (5,16,27,33). To further increase immunogenicity, nonreplicating vaccines such as plasmid DNA are often combined into prime-boost regimens with other heterologous vectors delivering a common, pathogen-derived immunogen (26,34,36,42).…”

mentioning

confidence: 99%

“…We and others have previously constructed DNA replicon (DREP) vectors based on alphaviruses such as Semliki Forest virus (SFV) (5,33), Sindbis virus (10,16), and Venezuelan equine encephalitis virus (VEE) (27). Transfection with DREP results in production of an mRNA that is self-amplifying due to the presence of the genes encoding the alphavirus replicase.…”

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confidence: 99%

Superior Induction of T Cell Responses to Conserved HIV-1 Regions by Electroporated Alphavirus Replicon DNA Compared to That with Conventional Plasmid DNA Vaccine

Knudsen

Mbewe-Mvula

Rosario

et al. 2012

J Virol

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f Vaccination using "naked" DNA is a highly attractive strategy for induction of pathogen-specific immune responses; however, it has been only weakly immunogenic in humans. Previously, we constructed DNA-launched Semliki Forest virus replicons (DREP), which stimulate pattern recognition receptors and induce augmented immune responses. Also, in vivo electroporation was shown to enhance immune responses induced by conventional DNA vaccines. Here, we combine these two approaches and show that in vivo electroporation increases CD8 ؉ T cell responses induced by DREP and consequently decreases the DNA dose required to induce a response. The vaccines used in this study encode the multiclade HIV-1 T cell immunogen HIVconsv, which is currently being evaluated in clinical trials. Using intradermal delivery followed by electroporation, the DREP.HIVconsv DNA dose could be reduced to as low as 3.2 ng to elicit frequencies of HIV-1-specific CD8 ؉ T cells comparable to those induced by 1 g of a conventional pTH.HIVconsv DNA vaccine, representing a 625-fold molar reduction in dose. Responses induced by both DREP.HIVconsv and pTH.HIVconsv were further increased by heterologous vaccine boosts employing modified vaccinia virus Ankara MVA.HIVconsv and attenuated chimpanzee adenovirus ChAdV63.HIVconsv. Using the same HIVconsv vaccines, the mouse observations were supported by an at least 20-fold-lower dose of DNA vaccine in rhesus macaques. These data point toward a strategy for overcoming the low immunogenicity of DNA vaccines in humans and strongly support further development of the DREP vaccine platform for clinical evaluation. " N aked" DNA constitutes an attractive vaccine platform for delivery of pathogen-or cancer-derived immunogens. Three veterinary DNA vaccines have been licensed for use in dogs, salmon, and horses, demonstrating that DNA vaccines are capable of inducing protective immunity (8, 48). In humans, plasmid DNA vaccines have been shown to be safe and well tolerated in thousands of volunteers (14,41,48); however, their strong immunogenicity observed in smaller animals does not transfer to primates, including humans. Thus, the potency of DNA vaccines in humans must be significantly improved for the vaccines to become a practical and commercially attractive health care tool.The use of in vivo electroporation (EP) was shown to improve DNA transfection into cells at the site of injection and to promote local inflammation, thereby increasing the immunogenicity of DNA vaccines (7,18,37,39). Safety and tolerability of intramuscular (i.m.) and intradermal (i.d.) DNA EP were demonstrated in both preclinical and clinical settings (28,49,51). Although the i.m. delivery route has been more extensively studied, i.d. EP offers an attractive route of delivery due to the characteristics of the skin, with many resident antigen-presenting cells such as Langerhans and dermal dendritic cells. Intradermal EP is also considerably less painful, and any possible residual pain may be further controlled by topical anesthetics (38,48).The D...

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“…Recently, DNA-based replicon systems, in which transcription is controlled by a cytomegalovirus (CMV) promoter, have been developed from alphavirus, arterivirus, and flavivirus (4-7). The DNA-based replicons are more stable than RNA-based constructs and the replicons can be directly transfected (thus without in vitro transcription) (5,6). Reporter replicon systems have been used for the analysis of flavivirus replication mechanisms and for conducting high-throughput screening for antiviral compounds (8)(9)(10)(11)(12)(13)(14)(15).…”

mentioning

confidence: 99%

Development of a Novel Dengue-1 Virus Replicon System Expressing Secretory <i>Gaussia</i> luciferase for Analysis of Viral Replication and Discovery of Antiviral Drugs

et al. 2014

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SUMMARY: Replicon systems have been used for high-throughput screening of anti-dengue virus (anti-DENV) inhibitors and for understanding mechanisms of viral replication. In the present study, we constructed novel DENV-1 replicons encoding Gaussia luciferase that was secreted into the culture medium. Two types of constructs were generated: RNA-based and DNA-based. Each type was translated in an internal ribosome entry site (IRES)-dependent or IRES-independent manner. Among these constructs, the DNA-based replicon employing IRES-dependent translation (DGL2) produced the highest titer. Luciferase levels in the culture medium revealed that the DGL2 replicon was inhibited by ribavirin (a well-known DENV inhibitor) at levels similar to those measured for drug inhibition of multi-round DENV-1 infection. These results indicate that the DNA-based IRES-driven DENV-1 replicon may facilitate studies on viral replication and antiviral compound discovery.Dengue virus (four serotypes [DENV-1-4]), which belongs to the genus Flavivirus of the family Flaviviridae, is transmitted to humans by Aedes mosquitoes and is the etiologic agent of dengue fever and dengue hemorrhagic fever (1). DENV annually infects 50-100 million humans in tropical and sub-tropical regions, posing a considerable public health threat in over 100 countries (2). However, at present, no specific antiviral drug or licensed vaccine is available for DENV infection (3). Therefore, the development of effective prophylactic and therapeutic measures is urgently required. The virus is an enveloped RNA virus with a single-stranded positive-sense genome of approximately 11 kb. A single long open reading frame (ORF) encodes a polyprotein that is processed by cellular and viral proteases into 3 structural (C, prM, and E) and 7 non-structural (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) proteins. The structural proteins form the virus particle, whereas the NS proteins are involved in the replication of the viral genome.A subgenomic replicon is a self-replicating segment of the viral genome that lacks the genes encoding structural proteins. In general, a subgenomic replicon is established by transfection of in vitro transcribed RNA. Recently, DNA-based replicon systems, in which transcription is controlled by a cytomegalovirus (CMV) promoter, have been developed from alphavirus, arterivirus, and flavivirus (4-7). The DNA-based replicons are more stable than RNA-based constructs and the replicons can be directly transfected (thus without in vitro transcription) (5,6). Reporter replicon systems have been used for the analysis of flavivirus replication mechanisms and for conducting high-throughput screening for antiviral compounds (8-15). The incorporation of firefly and Renilla luciferase reporter genes into DENV replicon constructs has facilitated the study of this virus. Recently, genes encoding secretory luciferases have been used in studies on other viruses such as retrovirus, togavirus, herpesvirus, and flavivirus (16)(17)(18)(19).To generate a more useful reporter replic...

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Increased Immunogenicity of a DNA-Launched Venezuelan Equine Encephalitis Virus-Based Replicon DNA Vaccine

Cited by 48 publications

References 55 publications

Prime-Boost Immunization Strategies against Chikungunya Virus

Prime-Boost Immunization Strategies against Chikungunya Virus

Superior Induction of T Cell Responses to Conserved HIV-1 Regions by Electroporated Alphavirus Replicon DNA Compared to That with Conventional Plasmid DNA Vaccine

Development of a Novel Dengue-1 Virus Replicon System Expressing Secretory <i>Gaussia</i> luciferase for Analysis of Viral Replication and Discovery of Antiviral Drugs

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