Biomedical subjects

Liangmei He

Publications and source records attributed to Liangmei He.

At least 19 recordsLinked to original sources

PubMed2006

A DNA vaccine encoding a single-chain trimer of HLA-A2 linked to human mesothelin peptide generates anti-tumor effects against human mesothelin-expressing tumors.

Mesothelin is highly expressed in a majority of ovarian cancer cells and is expressed at low levels in normal cells. Therefore, mesothelin represents a potential target antigen for ovarian cancer vaccine development. DNA vaccines employing single-chain trimers (SCT) have been shown to bypass antigen processing and presentation and result in significant enhancement of DNA vaccine potency. In the current study, we created a DNA vaccine employing an SCT targeting human mesothelin and characterized the ensuing antigen-specific CD8+ T cell-mediated immune responses and anti-tumor effects against human mesothelin-expressing tumors in HLA-A2 transgenic mice. Our results showed that vaccination with DNA employing an SCT of HLA-A2 linked to human mesothelin epitope aa540-549 (pcDNA3-Hmeso540-beta2m-A2) generated strong human mesothelin peptide (aa540-549)-specific CD8+ T cell immune responses in HLA-A2 transgenic mice. Vaccination with pcDNA3-Hmeso540-beta2m-A2 prevented the growth of HLA-A2 positive human mesothelin-expressing tumor cell lines in HLA-A2 transgenic mice in contrast to vaccination with DNA encoding SCT linked to OVA CTL epitope. Thus, the employment of SCT of HLA-A2 linked to the human mesothelin epitope aa540-549 represents a potential opportunity for the clinical translation of DNA vaccines against human mesothelin-expressing tumors, particularly ovarian cancer cells.

Animals↗

PubMed2006

A DNA vaccine encoding a codon-optimized human papillomavirus type 16 E6 gene enhances CTL response and anti-tumor activity.

The HPV oncoproteins E6 and E7 are consistently expressed in HPV-associated cancer cells and are responsible for their malignant transformation. Therefore, HPV E6 and E7 are ideal target antigens for developing vaccines and immunotherapeutic strategies against HPV-associated neoplasms. Recently, it has been demonstrated that codon optimization of the HPV-16 E7 gene resulted in highly efficient translation of E7 and increased the immunogenicity of E7-specific DNA vaccines. Since vaccines targeting E6 also represent an important strategy for controlling HPV-associated lesions, we developed a codon-optimized HPV-16 E6 DNA vaccine (pNGVL4a-E6/opt) and characterized the E6-specific CD8+ T cell immune responses as well as the protective and therapeutic anti-tumor effects in vaccinated C57BL/6 mice. Our data indicated that transfection of human embryonic kidney cells (293 cells) with pNGVL4a-E6/opt resulted in highly efficient translation of E6. In addition, vaccination with pNGVL4a-E6/opt significantly enhanced E6-specific CD8+ T cell immune responses in C57BL/6 mice. Mice vaccinated with pNGVL4a-E6/opt are able to generate potent protective and therapeutic antitumor effects against challenge with E6-expressing tumor cell line, TC-1. Thus, DNA vaccines encoding a codon-optimized HPV-16 E6 may be a promising strategy for improving the potency of prophylactic and therapeutic HPV vaccines with potential clinical implications.

Analysis of Variance↗

PubMed2005

Characterization of HPV-16 E6 DNA vaccines employing intracellular targeting and intercellular spreading strategies.

Human papillomavirus (HPV) E6 and E7 are consistently expressed and are responsible for the malignant transformation of HPV-associated lesions. Thus, E6 and E7 represent ideal targets for therapeutic HPV vaccine development. We have previously used the gene gun approach to test several intracellular targeting and intercellular spreading strategies targeting HPV-16 E7. These strategies include the use of the sorting signal of lysosome-associated membrane protein (LAMP-1), Mycobacterium tuberculosis heat shock protein 70 (HSP70), calreticulin (CRT) and herpes simplex virus type 1 (HSV-1) VP22 proteins. All of these strategies have been shown to be capable of enhancing E7-DNA vaccine potency. In the current study, we have characterized DNA vaccines employing these intracellular targeting or intercellular spreading strategies targeting HPV-16 E6 for their ability to generate E6-specific CD8+ T cell immune responses and antitumor effects against an E6-expressing tumor cell line, TC-1, in C57BL/6 mice. We found that all the intracellular targeting strategies (CRT, LAMP-1, HSP70) as well as the intercellular spreading strategy (VP22) were able to enhance E6 DNA vaccine potency, although the orientation of HSP70 linked to E6 antigen in the E6 DNA vaccine appears to be important for the HSP70 strategy to work. The enhanced E6-specific CD8+ T cell immune response in vaccinated mice also translated into potent antitumor effects against TC-1 tumor cells. Our data indicate that all of the intracellular targeting and intercellular spreading strategies that have been shown to enhance E7 DNA vaccine potency were also able to enhance E6 DNA vaccine potency.

Animals↗

PubMed2005

Modification of professional antigen-presenting cells with small interfering RNA in vivo to enhance cancer vaccine potency.

RNA interference using small interfering RNA (siRNA) is an effective means of silencing gene expression in cells. Intradermal administration of nucleic acids via gene gun represents an efficient method for delivering nucleic acids to professional antigen-presenting cells in vivo. In this study, we show that the coadministration of DNA vaccines encoding human papillomavirus type 16 E7 with siRNA targeting key proapoptotic proteins Bak and Bax prolongs the lives of antigen-expressing dendritic cells in the draining lymph nodes, enhances antigen-specific CD8(+) T-cell responses, and elicits potent antitumor effects against an E7-expressing tumor model in vaccinated mice. Our data indicate that intradermal administration of siRNA to manipulate gene expression represents a plausible strategy for modification of the properties of professional antigen-presenting cells in vivo to enhance cancer vaccine potency.

Animals↗

PubMed2005

DNA vaccines employing intracellular targeting strategies and a strategy to prolong dendritic cell life generate a higher number of CD8+ memory T cells and better long-term antitumor effects compared with a DNA prime-vaccinia boost regimen.

We have previously shown that intradermal coadministration of DNA encoding Bcl-x(L), an antiapoptotic protein, with DNA encoding E7 antigen linked to the sorting signal of the lysosome-associated membrane protein type 1 (Sig/E7/LAMP-1) prolongs dendritic cell life and enhances antigen presentation through the MHC class I and II pathways. In the current study, we compared this approach with a conventional DNA prime-vaccinia boost protocol on the basis of their ability to generate antigen-specific CD8(+) memory T cells and longterm antitumor effects against an E7-expressing tumor. Mice primed and boosted with Sig/E7/LAMP-1 DNA mixed with Bcl-x(L) DNA generated significantly higher numbers of E7-specific CD8(+) memory T cells and a better long-term protective antitumor effect compared with mice primed with Sig/E7/LAMP-1 DNA and boosted with Sig/E7/LAMP-1 vaccinia (Vac-Sig/E7/LAMP-1). Furthermore, coadministration of Sig/E7 /LAMP-1 DNA mixed with Bcl-x(L) DNA also generated higher avidity E7-specific CD8(+) T cells than did vaccination with Sig/E7/LAMP-1 DNA followed by a Vac-Sig/E7/LAMP-1 booster. Our results indicate that coadministration of a DNA vaccine employing intracellular targeting strategies and a DNA encoding antiapoptotic proteins may potentially generate a higher number of memory CD8(+) T cells and better long-term protective antitumor effects compared with the conventional DNA prime-vaccinia boost regimen.

Animals↗

PubMed2005

Vaccination with dendritic cells transfected with BAK and BAX siRNA enhances antigen-specific immune responses by prolonging dendritic cell life.

Dendritic cell-based vaccines have become an important approach for the treatment of malignancies. Numerous techniques have recently been designed to optimize dendritic cell activation, tumor antigen delivery to dendritic cells, and induction of tumor-specific immune responses in vivo. Dendritic cells (DCs), however, have a limited life span because they are subject to apoptotic cell death mediated by T cells, hindering their long-term ability to prime antigen-specific T cells. Small interfering RNA targeting Bak and Bax antiapoptotic proteins can be used to allow transfected DCs to resist killing by T cells in vivo. In this study, we show that human papillomavirus E7-loaded dendritic cells transfected with BAK/BAX siRNA downregulate Bak and Bax protein expression and become resistant to killing by T cells, leading to enhanced E7-specific CD8+ T cell activation and antitumor effects in vivo. More importantly, we found that vaccination with E7-loaded DCs transfected with BAK/BAX siRNA was capable of generating a strong therapeutic effect in vaccinated mice, compared with DCs transfected with control siRNA. Our data indicate that transfection of dendritic cells with BAK/BAX siRNA represents a plausible strategy for enhancing dendritic cell-based vaccine potency.

Animals↗

PubMed2004

Enhancement of vaccinia vaccine potency by linkage of tumor antigen gene to gene encoding calreticulin.

Vaccinia vaccines have become important vectors for antigen-specific immunotherapy. Calreticulin has been shown to enhance MHC class I presentation of linked peptide/protein and may be useful for antigen-specific cancer treatment. An innovative vaccine administering antigen linked to calreticulin via a vaccinia vector may generate a potent antigen-specific antitumor response. We tested the efficacy of linking calreticulin (CRT) to model antigen human papilloma virus type 16 (HPV-16) E7 in the context of a vaccinia vaccine (Vac-CRT/E7). Intraperitoneal vaccination of C57BL/6 mice with Vac-CRT/E7 led to a dramatic increase in E7-specific IFN-gamma-secreting CD8+ T cells and a potent antitumor effect against E7-expressing tumors compared to immunization with Vac-E7 or Vac-CRT. When compared to other chimeric vaccinia vaccines employing various intracellular targeting strategies previously developed in our lab, Vac-CRT/E7 elicited the highest number of E7-specific CD8+ T cells. Thus, vaccination with vaccinia expressing CRT linked to a tumor antigen may represent an advantageous strategy for cancer immunotherapy.

Adenoviridae↗

PubMed2004

Enhancement of DNA vaccine potency by coadministration of a tumor antigen gene and DNA encoding serine protease inhibitor-6.

Serine protease inhibitor 6 (SPI-6), also called Serpinb9, inhibits granzyme B and thus may provide a method for delaying apoptotic cell death in dendritic cells. We have previously enhanced DNA vaccine potency by targeting antigen to MHC antigen presentation pathways, using proteins such as Mycobacterium tuberculosis heat shock protein 70, calreticulin, domain II of Pseudomonas aeruginosa exotoxin A, or the sorting signal of the lysosome-associated membrane protein type 1. In this study, we explored intradermal coadministration of DNA encoding SPI-6 with DNA constructs encoding human papillomavirus type 16 E7 linked to these intracellular targeting molecules for its ability to generate E7-specific CD8+ T-cell immune responses and E7-specific antitumor effects. This combination of strategies resulted in significantly increased E7-specific CD8+ T-cell and CD4+ Th1-cell responses, enhanced tumor treatment ability, and stronger tumor protection when compared with vaccination without SPI-6. Among these targeting strategies tested, mice vaccinated with Sig/E7/lysosome-associated membrane protein type 1 mixed with SPI-6 showed the greatest fold increase in E7-specific CD8+ T cells ( approximately 5-fold). Vaccination with a nonfunctional mutant of SPI-6 did not result in immune enhancement, indicating that enhancement was dependent on the antiapoptotic function of SPI-6. Our results suggest that DNA vaccines combining strategies that enhance MHC class I and II antigen processing with SPI-6 have potential clinical implications for control of viral infection and neoplasia.

Animals↗

PubMed2004

Naked RNA vaccine controls tumors with down-regulated MHC class I expression through NK cells and perforin-dependent pathways.

One of the major issues facing cancer immunotherapy is that many human cancers down-regulate expression of MHC class I molecules. The understanding of the mechanisms of antitumor effects against tumors with down-regulated MHC class I will facilitate rational design of vaccines and immunotherapeutic strategies to control such tumors. A naked Sindbis RNA replicon vector (SINrep5) encoding the herpes simplex virus type 1 protein VP22 linked to E7 (SINrep5-VP22/E7) generated significant antitumor effects against TC-1 and TC-1 P3(A15), tumors with down-regulated MHC class I expression. Naked SINrep5 RNA without the insert or an E7 vaccine also produced antitumor effects against TC-1 P3(A15) but not TC-1. Mice vaccinated with any of these naked RNA vaccines generated higher percentages of NK cells. In vivo Ab depletion experiments revealed that NK cells were important for the antitumor effects of naked RNA vaccines against TC-1 P3(A15) and that the antitumor effects were perforin-dependent. Poly I:C also increased the percentage of NK cells and generated antitumor effects against the tumors with down-regulated MHC class I. Thus, the SINrep5-VP22/E7 naked RNA vaccine controls MHC class I-positive and MHC class I-down-regulated tumor cells via different mechanisms, and NK cells play an important role in the antitumor effects generated by naked RNA replicon vaccines.

Adoptive Transfer↗

PubMed2004

Vaccination with a DNA vaccine encoding herpes simplex virus type 1 VP22 linked to antigen generates long-term antigen-specific CD8-positive memory T cells and protective immunity.

Intradermal vaccination with DNA encoding herpes simplex virus type 1 (HSV-1) VP22 linked to antigen leads to spread of antigen within the epithelium and results in enhanced antigen-specific CD8+ T cell immune responses in vaccinated mice. In this study, we characterized the number of antigen-expressing dendritic cells (DCs) in the draining lymph nodes of vaccinated mice and determined whether the linkage of VP22 to antigen would influence the ability of antigen-expressing DCs to activate antigen-specific CD8+ T cells in vivo. Vaccination with DNA encoding HSV-1 VP22 linked to human papillomavirus type 16 E7 antigen generated more antigen-expressing DCs in the draining lymph nodes of vaccinated mice than E7 alone. In addition, the linkage of VP22 to E7 improved the MHC class I presentation of E7 in transfected DCs and led to enhanced activation of E7-specific CD8+ T cells. We also observed that vaccination with DNA encoding VP22 linked to E7 generated more E7-specific CD8+ memory T cells, and enhanced long-term protective antitumor immunity against an E7-expressing tumor in vaccinated mice compared with vaccination with DNA encoding E7 alone. Thus, administration of DNA encoding VP22 linked to antigen represents a plausible approach for the development of protective DNA vaccines.

Animals↗

PubMed2004

Development of a DNA vaccine targeting human papillomavirus type 16 oncoprotein E6.

Human papillomavirus (HPV), particularly type 16 (HPV-16), is present in more than 99% of cervical cancers. The HPV oncoproteins E6 and E7 are constantly expressed and therefore represent ideal targets for HPV vaccine development. We previously developed DNA vaccines encoding calreticulin (CRT) linked to HPV-16 E7 and generated potent E7-specific CD8(+) T-cell immune responses and antitumor effects against an E7-expressing tumor. Since vaccines targeting E6 also represent an important strategy for controlling HPV-associated lesions, we developed a DNA vaccine encoding CRT linked to E6 (CRT/E6). Our results indicated that the CRT/E6 DNA vaccine, but not a wild-type E6 DNA vaccine, generated significant E6-specific CD8(+) T-cell immune responses in vaccinated mice. Mapping of the immunodominant epitope of E6 revealed that an E6 peptide comprising amino acids (aa) 48 to 57 (E6 aa48-57), presented by H-2K(b), is the optimal peptide and that the region of E6 comprising aa 50 to 57 represents the minimal core sequence required for activating E6-specific CD8(+) T lymphocytes. We also demonstrated that E6 aa48-57 contains cytotoxic T-lymphocyte epitopes naturally presented by E6-expressing TC-1 cells. Vaccination with a CRT/E6 but not a CRT/mtE6 (lacking aa 50 to 57 of E6) DNA vaccine could protect vaccinated mice from challenge with E6-expressing TC-1 tumors. Thus, our data indicate that E6 aa48-57 contains the immunodominant epitope and that a CRT/E6 DNA vaccine may be useful for control of HPV infection and HPV-associated lesions.

Amino Acid Sequence↗

PubMed2004

Generation and characterization of DNA vaccines targeting the nucleocapsid protein of severe acute respiratory syndrome coronavirus.

Severe acute respiratory syndrome (SARS) is a serious threat to public health and the economy on a global scale. The SARS coronavirus (SARS-CoV) has been identified as the etiological agent for SARS. Thus, vaccination against SARS-CoV may represent an effective approach to controlling SARS. DNA vaccines are an attractive approach for SARS vaccine development, as they offer many advantages over conventional vaccines, including stability, simplicity, and safety. Our investigators have previously shown that DNA vaccination with antigen linked to calreticulin (CRT) dramatically enhances major histocompatibility complex class I presentation of linked antigen to CD8(+) T cells. In this study, we have employed this CRT-based enhancement strategy to create effective DNA vaccines using SARS-CoV nucleocapsid (N) protein as a target antigen. Vaccination with naked CRT/N DNA generated the most potent N-specific humoral and T-cell-mediated immune responses in vaccinated C57BL/6 mice among all of the DNA constructs tested. Furthermore, mice vaccinated with CRT/N DNA were capable of significantly reducing the titer of challenging vaccinia virus expressing the N protein of the SARS virus. These results show that a DNA vaccine encoding CRT linked to a SARS-CoV antigen is capable of generating strong N-specific humoral and cellular immunity and may potentially be useful for control of infection with SARS-CoV.

Amino Acid Sequence↗

PubMed2003

Enhancing DNA vaccine potency by combining a strategy to prolong dendritic cell life with intracellular targeting strategies.

We have recently shown that intradermal coadministration of DNA encoding Ag with DNA encoding inhibitors of apoptosis, including Bcl-x(L), prolongs dendritic cell (DC) life and thereby enhances the potency of DNA vaccines in vivo. We have also demonstrated that DNA vaccines targeting Ag to subcellular compartments, using proteins such as Mycobacterium tuberculosis heat shock protein 70, calreticulin, or the sorting signal of the lysosome-associated membrane protein type 1 (LAMP-1), enhanced DNA vaccine potency. In this study, we reasoned that the combination of a strategy to prolong DC life with intracellular targeting strategies might produce a more effective DNA vaccine against human papillomavirus E7. We showed that coadministration of DNA encoding Bcl-x(L) with DNA encoding E7/heat shock protein 70, calreticulin/E7, or Sig/E7/LAMP-1 resulted in further enhancement of the E7-specific CD8(+) T cell response for all three constructs. Of these strategies, mice vaccinated with Sig/E7/LAMP-1 DNA mixed with Bcl-x(L) DNA showed the greatest increase in E7-specific CD8(+) T cells ( approximately 13-fold increase). This combination of strategies resulted in increased CD8(+) T cell functional avidity, an increased E7-specific CD4(+) Th1 cell response, enhanced tumor treatment ability, and stronger long-term tumor protection when compared with mice vaccinated without Bcl-x(L) DNA. Therefore, DNA vaccines that combine strategies to enhance intracellular Ag processing and prolong DC life have potential clinical implications for control of viral infection and neoplasia.

Adjuvants, Immunologic↗

PubMed2003

Comparison of the CD8+ T cell responses and antitumor effects generated by DNA vaccine administered through gene gun, biojector, and syringe.

DNA vaccines have emerged as an attractive approach for antigen-specific cancer immunotherapy. We have previously linked Mycobacterium tuberculosis heat shock protein 70 (HSP70) to human papillomavirus type 16 (HPV-16) E7 in the context of a DNA vaccine. Vaccination with DNA encoding E7/HSP70 has generated a dramatic increase of E7-specific CD8+ T cell precursors and a strong antitumor effect against E7-expressing tumor (TC-1) in vaccinated mice. The success of our strategy has led to two phases I/II clinical trial proposals in patients with HPV-16 associated high-grade squamous intraepithelial lesion (HSIL) of the cervix and in patients with advanced HPV-associated head and neck squamous cell carcinoma (HNSCC). To translate our HPV DNA vaccines into the clinical domain, the efficacy of pNGVL4a-Sig/E7(detox)/HSP70 DNA vaccine and of various routes of administrations were assessed in mice. Our results indicated that pNGVL4a-Sig/E7(detox)/HSP70 DNA vaccine administered via gene gun generated the highest number of E7-specific CD8+ T cells. In addition, DNA vaccination via gene gun required the least dose to generate similar or slightly better antitumor effects compared to needle intramuscular (i.m.) and biojector administrations. Thus, our data suggest that DNA vaccination via gene gun represents the most potent regimen for DNA administration.

Animals↗

PubMed2003

Enhancing major histocompatibility complex class I antigen presentation by targeting antigen to centrosomes.

Several strategies that increase proteasomal degradation of antigen have been shown to improve MHC class I presentation of antigen. Because recent studies have demonstrated that the centrosome is a subcellular compartment rich in proteasomes, we hypothesized that targeting a tumor antigen to centrosomal compartments would enhance both the MHC class I presentation of antigen and the vaccine potency. We, therefore, created a chimera of gamma-tubulin, an established centrosomal marker, with a model tumor antigen, human papillomavirus type 16 (HPV-16) E7, in a DNA vaccine. The linkage of gamma-tubulin to E7-targeted antigen to centrosomal compartments, resulted in enhanced MHC class I presentation of E7, and led to a marked increase in the number of E7-specific CD8(+) T-cell precursors as well as a potent CD4-independent antitumor effect against an E7-expressing tumor cell line, TC-1. In addition, vaccination with gamma-tubulin/E7 DNA in transporter associated with antigen presentation (TAP)-1-knockout mice revealed that the enhancement of E7-specific CD8(+) T-cell immune responses is TAP-1-dependent. Our data suggest that the centrosome may be an important locus for MHC class I antigen processing and that targeting antigen to the centrosome can improve DNA vaccine potency.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2003

Boosting with recombinant vaccinia increases HPV-16 E7-Specific T cell precursor frequencies and antitumor effects of HPV-16 E7-expressing Sindbis virus replicon particles.

Immunotherapy using the heterologous prime-boost regimen has emerged as an attractive approach for generating antigen-specific T-cell-mediated immune responses against tumors and infectious diseases. We have previously linked the Mycobacterium tuberculosis heat-shock protein 70 (HSP70) to the HPV-16 E7 antigen creating a chimera, E7/HSP70. We found that nucleic acid vaccines encoding E7/HSP70 can generate strong antitumor immunity. Recently, replication-defective Sindbis virus replicon particle vaccines have been considered as an important vector system for vaccine development. In this study, we assessed whether the combination of E7/HSP70 Sindbis virus replicon particles (SINrep5-E7/HSP70) and E7/HSP70 vaccinia (Vac-E7/HSP70) can further enhance E7-specific immune responses using sequential vaccination. We found that priming with SINrep5-E7/HSP70 and boosting with Vac-E7/HSP70 generated the highest number of E7-specific CD8(+) T cells and best antitumor effect compared to other combinations. Moreover, our data showed that at the dosage and route of immunization used in this study, mice treated with the Sindbis virus replicon particle prime-vaccinia boost regimen generated stronger antitumor responses compared to mice treated with the DNA prime-vaccinia boost vaccine regimen. Our results encourage the use of the Sindbis virus replicon particle prime-vaccinia boost regimen in future clinical trials.

Animals↗

PubMed2003

Enhancing DNA vaccine potency by coadministration of DNA encoding antiapoptotic proteins.

Intradermal vaccination by gene gun efficiently delivers DNA vaccines into DCs of the skin, resulting in the activation and priming of antigen-specific T cells in vivo. DCs, however, have a limited life span, hindering their long-term ability to prime antigen-specific T cells. We reason that a strategy that prolongs the survival of DNA-transduced DCs will enhance priming of antigen-specific T cells and DNA vaccine potency. Here we show that codelivery of DNA encoding inhibitors of apoptosis (BCL-xL, BCL-2, XIAP, dominant negative caspase-9, or dominant negative caspase-8) with DNA encoding model antigens prolongs the survival of transduced DCs. More importantly, vaccinated mice exhibited significant enhancement in antigen-specific CD8+ T cell immune responses, resulting in a potent antitumor effect against antigen-expressing tumors. Among these antiapoptotic factors, BCL-xL demonstrated the greatest enhancement in antigen-specific immune responses and antitumor effects. Thus, coadministration of DNA vaccines with DNA encoding antiapoptotic proteins represents an innovative approach to enhance DNA vaccine potency.

Animals↗

PubMed2002

Cancer immunotherapy using Sindbis virus replicon particles encoding a VP22-antigen fusion.

Alphavirus vectors have emerged as a strategy for the development of cancer vaccines and gene therapy applications. The availability of a new packaging cell line (PCL), which is capable of generating alphavirus replicon particles without contamination from replication-competent virus, has advanced the field of vaccine development. This replication-defective vaccine vector has potential advantages over naked nucleic acid vaccines, such as increased efficiency of gene delivery and large-scale production. We have developed a new strategy to enhance nucleic acid vaccine potency by linking VP22, a herpes simplex virus type 1 (HSV-1) tegument protein, to a model antigen. This strategy facilitated the spread of linked E7 antigen to neighboring cells. In this study, we created a recombinant Sindbis virus (SIN)-based replicon particle encoding VP22 linked to a model tumor antigen, human papillomavirus type 16 (HPV-16) E7, using a stable SIN PCL. The linkage of VP22 to E7 in these SIN replicon particles resulted in a significant increase in the number of E7-specific CD8(+) T cell precursors and a strong antitumor effect against E7-expressing tumors in vaccinated C57BL/6 mice relative to wild-type E7 SIN replicon particles. Furthermore, a head-to-head comparison of VP22-E7-containing naked DNA, naked RNA replicons, or RNA replicon particle vaccines indicated that SINrep5-VP22/E7 replicon particles generated the most potent therapeutic antitumor effect. Our results indicated that the VP22 strategy used in the context of SIN replicon particles may facilitate the generation of a highly effective vaccine for widespread immunization.

Animals↗