Adenovirus based HPV L2 vaccine induces broad cross-reactive humoral immune responses

Oncogenic high-risk human papillomavirus (HPV) infections cause a substantial number of genital and non-genital cancers worldwide. Approximately 70% of all cervical cancers are caused by the high-risk HPV16 and 18 types. The remaining 30% can be attributed to twelve other high-risk HPV-types. Highly efficacious 2-valent, 4-valent and 9-valent L1 protein based prophylactic HPV vaccines are available however with limited cross-protection. To further increase the coverage, development of a multivalent cross-protective HPV vaccine is currently focused on the conserved N-terminus of HPV’s L2 protein. We have developed a vaccine candidate based on the rare human adenovirus type 35 (HAdV35) vector that displays a concatemer of L2 protein epitopes from four different HPV-types via protein IX (pIX). A mix of two heterologous HAdV35 pIX-L2 display vectors present highly conserved linear epitopes of nine HPV-types. Each HAdV35 pIX-L2 display vector exhibits a good manufacturability profile. HAdV35 pIX-L2 display vaccine vectors were immunogenic and induced neutralizing antibodies against HPV-types included in the vaccine and cross-neutralizing antibodies against distant a HPV-type not included in the vaccine in mice. The HAdV35 pIX-L2 display vectors offer an opportunity for a multivalent HAdV-based prophylactic HPV vaccine.     

Development of a novel ZIKV vaccine comprised of immunodominant CD4+ and CD8+ T cell epitopes identified through comprehensive epitope mapping in Zika virus infected mice

Zika virus (ZIKV) caused over two million human infections in more than 80 countries around 2015–2016. Current vaccines under development are mostly focused on inducing antibodies that despite capable of inhibiting the virus, may have the potential to trigger antibody dependent enhancement (ADE). T cell vaccines that do not induce antibodies targeting viral surface will unlikely cause ADE, but be capable of potentiating the effectiveness of an antibody-inducing vaccine. To develop such a protective T cell vaccine, we first examined the repertoire of antigen-specific T cells in immunocompetent mice that have been transiently infected by ZIKV. Through epitope mapping using 427 overlapping peptides spanning the entire length of ZIKV polyprotein, we discovered 27 immunodominant epitopes scattered throughout the virus on C, E, NS1-NS5 proteins. Among them, 8 were confirmed as CD4+ T cell epitopes, and 16 as CD8+ T cell epitopes, while 3 for both T cell subsets. From these 27 newly identified epitopes, the top 10 epitopes were selected to formulate three T cell vaccines comprised of either CD4+ T cell epitopes, or CD8+ T cell epitopes, or a mixture of both. Immunization with these T cell epitopes induced T cell-mediated cytotoxicity and cytokine production, and conferred varying degrees of protection against ZIKV challenge. Moreover, these new T cell vaccines also improved the protective efficacy of a neutralizing antibody-inducing recombinant E80 protein vaccine. Together, our results provided additional evidence in support of the protective role of ZIKV-specific CD4+ and CD8+ T cells, and laid foundation for future development of T cell vaccines for ZIKV.     

Overlapping CD8 + and CD4 + T-cell epitopes identification for the progression of epitope-based peptide vaccine from nucleocapsid and glycoprotein of emerging Rift Valley fever virus using immunoinformatics approach

Rift Valley fever virus (RVFV) is an emergent arthropod-borne zoonotic infectious viral pathogen which causes fatal diseases in the humans and ruminants. Currently, no effective and licensed vaccine is available for the prevention of RVFV infection in endemic as well as in non-endemic regions. So, an immunoinformatics-driven genome-wide screening approach was performed for the identification of overlapping CD8 + and CD4 + T-cell epitopes and also linear B-cell epitopes from the conserved sequences of the nucleocapsid (N) and glycoprotein (G) of RVFV. We identified overlapping 99.39% conserved 1 CD8 + T-cell epitope (MMHPSFAGM) from N protein and 100% conserved 7 epitopes (AVFALAPVV, LAVFALAPV, FALAPVVFA, VFALAPVVF, IAMTVLPAL, FFDWFSGLM, and FLLIYLGRT) from G protein and also identified IL-4 and IFN-γ induced (99.39% conserved) 1 N protein CD4 + T-cell epitope (HMMHPSFAGMVDPSL) and 100% conserved 5 G protein CD4 + T-cell epitopes (LPALAVFALAPVVFA, PALAVFALAPVVFAE, GIAMTVLPALAVFAL, GSWNFFDWFSGLMSW, and FFLLIYLGRTGLSKM). The overlapping CD8 + and CD4 + T-cell epitopes were bound with most conserved HLA-C*12:03 and HLA-DRB1*01:01, respectively with the high binding affinity (kcal/mol). The combined population coverage analysis revealed that the allele frequencies of these epitopes are high in endemic and non-endemic regions. Besides, we found 100% conserved and non-allergenic 2 decamer B-cell epitopes, GVCEVGVQAL and RVFNCIDWVH of G protein had the sequence similarity with the nonamer CD8 + T-cell epitopes, VCEVGVQAL and RVFNCIDWV, respectively. Consequently, these epitopes may be used for the development of epitope-based peptide vaccine against emerging RVFV. However, in vivo and in vitro experiments are required for their efficient use as a vaccine.     

A promiscuous T cell epitope-based HIV vaccine providing redundant population coverage of the HLA class II elicits broad,polyfunctional T cell responses in nonhuman primates

Over the last few decades, several emerging or reemerging viral diseases with no readily available vaccines have ravaged the world. A platform to fastly generate vaccines inducing potent and durable neutralizing antibody and T cell responses is sorely needed. Bioinformatically identified epitope-based vaccines can focus on immunodominant T cell epitopes and induce more potent immune responses than a whole antigen vaccine and may be deployed more rapidly and less costly than whole-gene vaccines. Increasing evidence has shown the importance of the CD4+ T cell response in protection against HIV and other viral infections. The previously described DNA vaccine HIVBr18 encodes 18 conserved, promiscuous epitopes binding to multiple HLA-DR-binding HIV epitopes amply recognized by HIV-1-infected patients. HIVBr18 elicited broad, polyfunctional, and durable CD4⁺ and CD8+ T cell responses in BALB/c and mice transgenic to HLA class II alleles, showing cross-species promiscuity. To fully delineate the promiscuity of the HLA class II vaccine epitopes, we assessed their binding to 34 human class II (HLA-DR, DQ, and -DP) molecules, and immunized nonhuman primates. Results ascertained redundant 100% coverage of the human population for multiple peptides. We then immunized Rhesus macaques with HIVBr18 under in vivo electroporation. The immunization induced strong, predominantly polyfunctional CD4+ T cell responses in all animals to 13 out of the 18 epitopes; T cells from each animal recognized 7–11 epitopes. Our results provide a preliminary proof of concept that immunization with a vaccine encoding epitopes with high and redundant coverage of the human population can elicit potent T cell responses to multiple epitopes, across species and MHC barriers. This approach may facilitate the rapid deployment of immunogens eliciting cellular immunity against emerging infectious diseases, such as COVID-19.     

Human papillomavirus and HPV vaccines: a review

Cervical cancer, the most common cancer affecting women in developing countries, is caused by persistent infection with "high-risk" genotypes of human papillomaviruses (HPV). The most common oncogenic HPV genotypes are 16 and 18, causing approximately 70% of all cervical cancers. Types 6 and 11 do not contribute to the incidence of high-grade dysplasias (precancerous lesions) or cervical cancer, but do cause laryngeal papillomas and most genital warts. HPV is highly transmissible, with peak incidence soon after the onset of sexual activity. A quadrivalent (types 6, 11, 16 and 18) HPV vaccine has recently been licensed in several countries following the determination that it has an acceptable benefit/risk profile. In large phase III trials, the vaccine prevented 100% of moderate and severe precancerous cervical lesions associated with types 16 or 18 among women with no previous infection with these types. A bivalent (types 16 and 18) vaccine has also undergone extensive evaluation and been licensed in at least one country. Both vaccines are prepared from non-infectious, DNA-free virus-like particles produced by recombinant technology and combined with an adjuvant. With three doses administered, they induce high levels of serum antibodies in virtually all vaccinated individuals. In women who have no evidence of past or current infection with the HPV genotypes in the vaccine, both vaccines show > 90% protection against persistent HPV infection for up to 5 years after vaccination, which is the longest reported follow-up so far. Vaccinating at an age before females are exposed to HPV would have the greatest impact. Since HPV vaccines do not eliminate the risk of cervical cancer, cervical screening will still be required to minimize cancer incidence. Tiered pricing for HPV vaccines, innovative financing mechanisms and multidisciplinary partnerships will be essential in order for the vaccines to reach populations in greatest need.     

Immunization with a consensus epitope from human papillomavirus L2 induces antibodies that are broadly neutralizing

Vaccines targeting conserved epitopes in the HPV minor capsid protein, L2, can elicit antibodies that can protect against a broad spectrum of HPV types that are associated with cervical cancer and other HPV malignancies. Thus, L2 vaccines have been explored as alternatives to the current HPV vaccines, which are largely type-specific. In this study we assessed the immunogenicity of peptides spanning the N-terminal domain of L2 linked to the surface of a highly immunogenic bacteriophage virus-like particle (VLP) platform. Although all of the HPV16 L2 peptide-displaying VLPs elicited high-titer anti-peptide antibody responses, only a subset of the immunogens elicited antibody responses that were strongly protective from HPV16 pseudovirus (PsV) infection in a mouse genital challenge model. One of these peptides, mapping to HPV16 L2 amino acids 65–85, strongly neutralized HPV16 PsV but showed little ability to cross-neutralize other high-risk HPV types. In an attempt to broaden the protection generated through vaccination with this peptide, we immunized mice with VLPs displaying a peptide that represented a consensus sequence from high-risk and other HPV types. Vaccinated mice produced antibodies with broad, high-titer neutralizing activity against all of the HPV types that we tested. Therefore, immunization with virus-like particles displaying a consensus HPV sequence is an effective method to broaden neutralizing antibody responses against a type-specific epitope.     

人乳头瘤病毒治疗性活载体疫苗的研究进展

高危型人乳头瘤病毒(HPV)-16和HPV-18在宫颈癌的致病过程中起着重要作用.近年来,HPV预防性疫苗已成功上市,但其费用较高,且不能治疗已感染的患者及相关的损伤.多种靶向E6/E7抗原的HPV治疗性疫苗已进入临床前模型和临床试验,包括活载体疫苗,多肽、蛋白疫苗,核酸疫苗及细胞疫苗.此文就HPV治疗性活载体疫苗进行...     

A novel, broad spectrum therapeutic HPV vaccine targeting the E7 proteins of HPV16, 18, 31, 45 and 52 that elicits potent E7-specific CD8T cell immunity and regression of large, established, E7-expressing TC-1 tumors

Persistent infection by high risk genotypes of human papillomavirus (HPV) is the cause of cervical cancer, which remains one of the most common cancers among women worldwide. In addition, there is a growing appreciation that high risk HPVs are associated with a number of other cancers including anogenital cancers as well as a subset of head and neck cancers. Recently, prophylactic HPV vaccines targeting the two most prevalent high risk HPVs (HPV16 and HPV18) have been deployed in large-scale vaccination campaigns. However, the extent to which these prophylactic vaccines confer protection against other high risk HPV genotypes is largely unknown and prophylactic vaccines have been shown to be ineffective against pre-existing infection. Thus there continues to be an urgent need for effective therapeutic vaccines against HPV. The E7 protein of HPV16 has been widely studied as a target for therapeutic vaccines in HPV-associated cancer settings because HPV16 is the most prevalent of the high risk HPV genotypes. However, HPV16 accounts for only about 50% of cervical cancers and there are at least 15 other high risk HPVs that are known to be oncogenic. We have developed a novel, broad-spectrum, therapeutic vaccine (Pentarix) directed at the E7 proteins from five of the most prevalent high-risk genotypes of HPV worldwide (HPV16, 18, 31, 45 and 52) that together account for more than 80% of all HPV-associated cancers. Pentarix is a recombinant protein-based vaccine that elicits strong, multi-genotype specific CD8 T cell immunity when administered to mice in combination with adjuvants comprised of agonists of the TLR3 or TLR9 family of innate immune receptors. Furthermore, large, established E7-expressing TC-1 tumors undergo rapid and complete regression after therapeutic vaccination of mice with Pentarix. Together, these data suggest that Pentarix may be of clinical value for patients with E7-positive, HPV-associated precancerous lesions or malignant disease.     

Vaccination against human papillomavirus for the prevention of cervical cancer

Persistent infections with high-risk Human papillomavirus (HPV) can lead to cervical cancer. This fact could imply that vaccination against HPV could prevent this disease. Such vaccines could be aimed at the prevention of HPV infections or the treatment of infections, cervical intraepithelial neoplasia (CIN) and cervical cancer. There are two prophylactic candidate vaccines against the high risk HPV types 16 and 18, which appear to be safe and effective in preventing incidental and persistent HPV infections. Phase III studies should reveal whether these vaccines will also have long-term effects by preventing the development of CIN and eventually cervical cancer. The introduction of such an HPV vaccine in the Netherlands, its cost-effectiveness and introduction into the existing national vaccination programmes needs to be studied. The vaccination of girls before they become sexually active seems to be the most effective approach, although older women can also profit from prophylactic vaccination. The current community-based screening, possibly complemented by an HPV test, needs to be continued to identify and treat presently HPV-infected women. In a population with an existing community-based screening program for cervical cancer, a vaccine preventing persisting infection with high-risk HPV will further reduce the incidence of HPV-related cervical cancer.     

Branched and linear lipopeptide vaccines have different effects on primary CD4+ and CD8+ T-cell activation but induce similar tumor-protective memory CD8+ T-cell responses

We compared murine T-cell responses to synthetic lipopeptide vaccines in which the TLR2 ligand Pam(2)Cys was attached to co-linear CD4+ and CD8+ T-cell epitopes of ovalbumin (OVA) in a linear or branched configuration. Mice received OVA-specific transgenic CD8+ and CD4+ T-cells followed by one injection of vaccine. Although the branched lipopeptide was more potent in activating OVA-specific CD4+ and CD8+ T-cells in the primary response, both vaccines induced cytolytic T lymphocytes (CTL) that expressed perforin, granzyme A-C, and IFN-gamma mRNAs and conferred long-term protection of most mice against challenge with OVA-expressing tumor cells. OVA epitope display was reduced in tumors that developed in some mice, suggesting CD8+ T-cell dependent selection.     

Population-Level Effects of Human Papillomavirus Vaccination Programs on Infections with Nonvaccine Genotypes

We analyzed human papillomavirus (HPV) prevalences during prevaccination and postvaccination periods to consider possible changes in nonvaccine HPV genotypes after introduction of vaccines that confer protection against 2 high-risk types, HPV16 and HPV18. Our meta-analysis included 9 studies with data for 13,886 girls and women ≤19 years of age and 23,340 women 20–24 years of age. We found evidence of cross-protection for HPV31 among the younger age group after vaccine introduction but little evidence for reductions of HPV33 and HPV45. For the group this same age group, we also found slight increases in 2 nonvaccine high-risk HPV types (HPV39 and HPV52) and in 2 possible high-risk types (HPV53 and HPV73). However, results between age groups and vaccines used were inconsistent, and the increases had possible alternative explanations; consequently, these data provided no clear evidence for type replacement. Continued monitoring of these HPV genotypes is important.     

Immunogenicity of next-generation HPV vaccines in non-human primates: Measles-vectored HPV vaccine versus Pichia pastoris recombinant protein vaccine

Human papillomavirus (HPV) infection is the most common sexually transmitted disease worldwide. HPVs are oncogenic small double-stranded DNA viruses that are the primary causal agent of cervical cancer and other types of cancers, including in the anus, oropharynx, vagina, vulva, and penis. Prophylactic vaccination against HPV is an attractive strategy for preventing cervical cancer and some other types of cancers. However, there are few safe and effective vaccines against HPV infections. Current first-generation commercial HPV vaccines are expensive to produce and deliver.The goal of this study was to develop an alternate potent HPV recombinant L1-based vaccines by producing HPV virus-like particles into a vaccine that is currently used worldwide. Live attenuated measles virus (MV) vaccines have a well-established safety and efficacy record, and recombinant MV (rMV) produced by reverse genetics may be useful for generating candidate HPV vaccines to meet the needs of the developing world.We studied in non-human primate rMV-vectored HPV vaccine in parallel with a classical alum adjuvant recombinant HPV16L1 and 18L1 protein vaccine produced in Pichia pastoris. A combined prime-boost approach using both vaccines was evaluated, as well as immune interference due to pre-existing immunity against the MV.The humoral immune response induced by the MV, Pichia-expressed vaccine, and their combination as priming and boosting approaches was found to elicit HPV16L1 and 18L1 specific total IgG and neutralizing antibody titres. Pre-existing antibodies against measles did not prevent the immune response against HPV16L1 and 18L1.     

Highly conserved influenza T cell epitopes induce broadly protective immunity

Influenza world-wide causes significant morbidity and mortality annually, and more severe pandemics when novel strains evolve to which humans are immunologically naïve. Because of the high viral mutation rate, new vaccines must be generated based on the prevalence of circulating strains every year. New approaches to induce more broadly protective immunity are urgently needed. Previous research has demonstrated that influenza-specific T cells can provide broadly heterotypic protective immunity in both mice and humans, supporting the rationale for developing a T cell-targeted universal influenza vaccine. We used state-of-the art immunoinformatic tools to identify putative pan-HLA-DR and HLA-A2 supertype-restricted T cell epitopes highly conserved among > 50 widely diverse influenza A strains (representing hemagglutinin types 1, 2, 3, 5, 7 and 9). We found influenza peptides that are highly conserved across influenza subtypes that were also predicted to be class I epitopes restricted by HLA-A2. These peptides were found to be immunoreactive in HLA-A2 positive but not HLA-A2 negative individuals. Class II-restricted T cell epitopes that were highly conserved across influenza subtypes were identified. Human CD4⁺ T cells were reactive with these conserved CD4 epitopes, and epitope expanded T cells were responsive to both H1N1 and H3N2 viruses. Dendritic cell vaccines pulsed with conserved epitopes and DNA vaccines encoding these epitopes were developed and tested in HLA transgenic mice. These vaccines were highly immunogenic, and more importantly, vaccine-induced immunity was protective against both H1N1 and H3N2 influenza challenges. These results demonstrate proof-of-principle that conserved T cell epitopes expressed by widely diverse influenza strains can induce broadly protective, heterotypic influenza immunity, providing strong support for further development of universally relevant multi-epitope T cell-targeting influenza vaccines.     

DNA vaccines encoding altered peptide ligands for SSX2 enhance epitope-specific CD8+ T-cell immune responses

Plasmid DNA serves as a simple and easily modifiable form of antigen delivery for vaccines. The USDA approval of DNA vaccines for several non-human diseases underscores the potential of this type of antigen delivery method as a cost-effective approach for the treatment or prevention of human diseases, including cancer. However, while DNA vaccines have demonstrated safety and immunological effect in early phase clinical trials, they have not consistently elicited robust anti-tumor responses. Hence many recent efforts have sought to increase the immunological efficacy of DNA vaccines, and we have specifically evaluated several target antigens encoded by DNA vaccine as treatments for human prostate cancer. In particular, we have focused on SSX2 as one potential target antigen, given its frequent expression in metastatic prostate cancer. We have previously identified two peptides, p41-49 and p103-111, as HLA-A2-restricted SSX2-specific epitopes. In the present study we sought to determine whether the efficacy of a DNA vaccine could be enhanced by an altered peptide ligand (APL) strategy wherein modifications were made to anchor residues of these epitopes to enhance or ablate their binding to HLA-A2. A DNA vaccine encoding APL modified to increase epitope binding elicited robust peptide-specific CD8+ T cells producing Th1 cytokines specific for each epitope. Ablation of one epitope in a DNA vaccine did not enhance immune responses to the other epitope. These results demonstrate that APL encoded by a DNA vaccine can be used to elicit increased numbers of antigen-specific T cells specific for multiple epitopes simultaneously, and suggest this could be a general approach to improve the immunogenicity of DNA vaccines encoding tumor antigens.     

Prophylactic HPV vaccines: reducing the burden of HPV-related diseases

HPV-associated diseases, such as cervical and other anogenital cancers, cervical and anal intraepithelial neoplasia, genital warts, and recurrent respiratory papillomatosis confer considerable morbidity and mortality, and are significant health care concerns. Successful vaccination strategies that protect against HPV infection are expected to substantially reduce HPV-related disease burden. Prophylactic HPV vaccines in late stages of clinical testing are composed of HPV L1 capsid protein that self-assemble into virus-like particles (VLPs) when expressed in recombinant systems. Proof-of-principle trials have suggested that intramuscular injections of VLPs results in strong adaptive immune responses, both B- and T-cell mediated, that are capable of neutralizing subsequent natural infections. Furthermore, phase 2 trials of a bivalent vaccine designed to protect against high-risk HPV types 16 and 18 and a quadrivalent vaccine designed to protect against HPV 16 and 18, and low-risk, genital wart-causing HPV 6 and 11 have demonstrated that VLP vaccines reduce the incidence of HPV-associated disease in vaccinated individuals. To derive the greatest public health benefit, HPV vaccines offering protection from cervical cancer and genital warts will, ideally, be administered prior to the initiation of sexual activity; therefore, educational initiatives will be essential to communicate the risks and adverse consequences of HPV infection and to foster widespread vaccine acceptance.     

An improved rearranged Human Papillomavirus Type 16 E7 DNA vaccine candidate (HPV-16 E7SH) induces an E7 wildtype-specific T cell response

A new and very promising approach in vaccine development is the application of naked DNA. In comparison to conventional vaccines it offers several advantages, especially if there is a need for the development of low cost vaccines. Infection with high-risk human papillomaviruses (hr-HPVs) is the major risk factor for the development of cervical cancer (cc), the third most common cancer in women worldwide. The HPV E7 oncogene is constitutively expressed in HPV-infected cells and represents an excellent target for immune therapy of HPV-related disease. Therefore, we chose the HPV-16 E7 as model antigen in the development of a therapeutic DNA vaccine candidate. For safety reasons the use of a transforming gene like the HPV-16 E7 for DNA vaccination is not feasible in humans. In consequence we have generated an artificial ("shuffled") HPV-16 E7-gene (HPV-16 E7SH), containing all putative cytotoxic T-lymphocyte (CTLs) epitopes and exhibiting high safety features. Here, we show the induction of a strong E7-wildtype (E7WT) directed cellular and humoral immune response including tumor protection and regression after in vivo immunization in the murine system. Moreover, the vaccine candidate demonstrated immunogenicity in humans, demonstrated by priming of antigen-specific T cells in vitro. Importantly, the artificial HPV-gene has completely lost its transforming properties as measured in soft agar transformation assays. These results may be of importance for the development of vaccines based on oncogenes or oncoproteins.     

Toward cervical cancer prevention: strategies employed in the development of HPV vaccines

An HPV persistent infection is doubtless the main factor involved in cervical cancer development. It is clear that the majority of HPV infections are self-limited and not all high-risk HPV infections are destined to progress to a higher grade lesion. Due to viral mechanisms that evade the immune system, in some cases the immune response against HPV is not as effective, allowing the establishment of persistent infections. The promise of a vaccine that can avoid HPV infections and therefore decrease cervical cancer incidence, has been motive of great interest and enthusiasm on the search of different strategies for obtaining an effective vaccine. At present, several prophylactic vaccines have been developed based in virus like particles (VLPs) produced with L1 viral proteins. Results of these vaccines applied to women between 16 and 23 years old show high tolerability and immunogenicity with higher antibody titers than those seen in an HPV natural infection. Even these vaccines can not wholly prevent infections caused by HPV types included in the vaccine design; its efficacy has been demonstrated for their ability to eliminate HPV persistent infections and to prevent the development of cervical intraepithelial neoplasia. These vaccines are currently in phase III of clinical trials, whose results will determine its impact in the general population. Therapeutic vaccines are focused in the elimination of established cervical lesions; nevertheless their efficacy has not been proved for clinical use.     

Vaccination for 2009 pandemic H1N1 influenza A did not induce conserved epitope-specific memory CD8 T cell responses in HIV+ northern Thai children

The influenza virus causes severe illness in susceptible populations, including children and people living with human immunodeficiency virus (HIV). Here, we investigated cell-mediated immune responses (CMI) against influenza CD8 T cell conserved epitopes in HIV-infected (HIV+) northern Thai children following the 2009 pandemic H1N1 influenza A vaccination. Sixty HIV+ children were vaccinated with two doses of the 2009 pandemic influenza vaccine and their CD8 T cell responses were assessed. We found no significant differences in the increase of cytokines-producing and CD107a-expressing CD8+ T cells or CD8+ memory T cells in response to pooled conserved epitopes stimulation in vitro between children with different serologic responses to the vaccine at all time points of the study. Our results suggest that the 2009 pandemic H1N1 vaccine did not induce the conserved epitope-specific immune responses in HIV+ children. Vaccine design and vaccination strategy against influenza in these populations warrant further studies.     

Trivalent Human Papillomavirus (HPV) VLP vaccine covering HPV type 58 can elicit high level of humoral immunity but also induce immune interference among component types

Both Human Papillomavirus (HPV) type 16/18 bivalent vaccine and type 16/18/6/11 quadrivalent vaccine have been proved to be safe and effective, and licensed for public use. However, these two vaccines do not quite match the distribution of HPV types in China, Southeast Asia and Latin America, where HPV 58 is highly prevalent. Here we produced three types of virus-like particles (VLPs) in baculovirus expression system, formulated a trivalent vaccine containing HPV 16, 18, and 58 L1 VLPs and examined its in vitro neutralizing titers. This vaccine could induce high level and long-term humoral immunity against the component types. But immune interference was observed when comparing type specific neutralizing antibody levels induced by trivalent vaccine to those by corresponding monovalent vaccines. This kind of interference would become more obvious when formulating more types of VLPs into multivalent vaccines, but could be greatly overcome by decreasing the antigen dosage and adding a proper adjuvant.     

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.