Route and method of delivery of DNA vaccine influence immune responses in mice and non-human primates.

BACKGROUND: In spite of the large number of studies that have evaluated DNA-based immunization, few have directly compared the immune responses generated by different routes of immunization, particularly in non-human primates. Here we examine the ability of a hepatitis B surface antigen (HBsAg)-encoding plasmid to induce immune responses in mice and non-human primates (rhesus monkeys: Macaca mulatta) after delivery by a number of routes. MATERIALS AND METHODS: Eight different injected [intraperitoneal (IP), intradermal (ID), intravenous (IV), intramuscular (IM), intraperineal (IPER), subcutaneous (SC), sublingual (SL), vaginal wall (VW)] and six noninjected [intranasal inhalation (INH), intranasal instillation (INS), intrarectal (IR), intravaginal (IVAG), ocular (Oc), oral feeding (oral)] routes and the gene gun (GG) were used to deliver HBsAg-expressing plasmid DNA to BALB/c mice. Sera were assessed for HBsAg-specific antibodies (anti-HBs, IgG, IgG1, IgG2a) and cytotoxic T lymphocyte (CTL) activity measured. Three of the most commonly used routes (IM, ID, GG) were compared in rhesus monkeys, also using HBsAg-expressing vectors. Monkeys were immunized with short (0-, 4- and 8-week) or long (0-, 12- and 24-week) intervals between boosts, and in the case of GG, also with different doses, and their sera were assessed for anti-HBs. RESULTS: In one study, anti-HBs were detected in plasma of mice treated by five of eight of the injected and none of the six noninjected routes. The highest levels of anti-HBs were induced by IM and IV injections, although significant titers were also obtained with SL and ID. Each of these routes also induced CTL, as did IPER and VW and one noninjected route (INH) that failed to induce antibodies. In a second study, GG (1.6 microg) was compared to ID and IM (100 microg) delivery. Significant titers were obtained by all routes after only one boost, with the highest levels detected by IM. Delivery to the skin by GG induced exclusively IgG1 antibodies (Th2-like) at 4 weeks and only very low IgG2a levels at later times; ID-immunized mice had predominantly IgG1 at 4 weeks and this changed to mixed IgG1/IgG2a over time. Responses with IM injection (in the leg or tongue) were predominantly IgG2a (Th1-like) at all times. IV injection gave mixed IgG1/IgG2a responses. In monkeys, in the first experiment, 1 mg DNA IM or ID at 0, 4, and 8 weeks gave equivalent anti-HB titers and 0.4 microg at the same times by GG induced lower titers. In the second experiment, 1 mg DNA IM or ID, or 3.2 microg by GG, at 0, 12, and 24 weeks, gave anti-HB values in the hierarchy of GG > IM > ID. Furthermore, high titers were retained after a single immunization in mice but fell off over time in the monkeys, even after boost. CONCLUSIONS: Route of administration of plasmid DNA vaccines influences the strength and nature of immune responses in mice and non-human primates. However, the results in mice were not always predictive of those in monkeys and this is likely true for humans as well. Optimal dose and immunization schedule will most likely vary between species. It is not clear whether results in non-human primates will be predictive of results in humans, thus additional studies are required. http://link.springer-ny.com/link/service/journals/00020/bibs /5n5p287. html     

A combination of intradermal jet-injection and electroporation overcomes in vivo dose restriction of DNA vaccines

ABSTRACT: BACKGROUND: The use of optimized delivery devices has been shown to enhance the potency of DNA vaccines. However, further optimization of DNA vaccine delivery is needed for this vaccine modality to ultimately be efficacious in humans. METHODS: Herein we evaluated antigen expression and immunogenicity after intradermal delivery of different doses of DNA vaccines by needle or by the Biojector jet-injection device, with or without the addition of electroporation (EP). RESULTS: Neither needle injection augmented by EP nor Biojector alone could induce higher magnitudes of immune responses after immunizations with a high dose of a DNA vaccine as compared to immunizations with a considerably lower dose. Biojector delivery followed by EP, however, overcame this observed dose restriction and induced significantly higher cellular and humoral immune responses after immunization with a high dose of DNA. Furthermore, a close correlation between in vivo antigen expression and cell-mediated immune responses was observed. CONCLUSIONS: These results show that two optimized DNA vaccine delivery devices can act together to overcome dose restrictions of plasmid DNA vaccines.     

重组质粒与重组蛋白共免疫诱导HBsAg特异性T细胞免疫抑制

摘要：【目的】为了探索治疗急性乙型肝炎和爆发性乙型肝的新策略,本研究将HBV DNA疫苗和相应抗原的蛋白质分子联合免疫小鼠,旨在探讨联合免疫对小鼠抗原特异性T细胞增殖反应的影响。【方法】我们将HBV DNA疫苗（pcDS2）和相应抗原蛋白质分子(HBsAg)联合免疫BALB/c小鼠;分别在第0、2和4周进行免疫,在第6周用ELISA方法检测抗-HBs IgG效价,MTT和流式细胞仪检测T细胞增殖反应,及流式细胞仪检测细胞因子表达水平。【结果】pcDS2和HBsAg联合免疫组小鼠的抗-HBs水平显著提高;免疫小鼠的T细胞体外经HBsAg刺激后, 联合免疫组刺激指数(SI)明显降低;经流式细胞仪检测进一步证实联合免疫组T细胞增殖反应被显著抑制;联合免疫组T细胞表达IL-10和Foxp3水平显著升高。【结论】pcDS2和HBsAg联合免疫能诱导产生特异性体液免疫应答,但不能诱导产生抗原特异性T细胞增殖反应;T细胞增殖反应被显著抑制可能与T细胞表达IL-10和Foxp3上调有关;本研究为急性乙型肝炎和爆发性乙型肝炎治疗及HBV疫苗的研究奠定了基础。     

Novel protein and poxvirus-based vaccine combinations for simultaneous induction of humoral and cell-mediated immunity

The presence of both cell-mediated and humoral immunity is important in protection from and clearance of a number of infectious pathogens. We describe novel vaccine regimens using combinations of plasmid DNA, poxvirus and protein to induce strong Ag-specific T cell and Ab responses simultaneously in a murine model. Intramuscular (i.m.) immunization with plasmid DNA encoding the middle Ag of hepatitis B (DNA) concurrently with a commercial hepatitis B virus (HBV) vaccine (Engerix-B) followed by boosting immunizations with both modified vaccinia virus Ankara (MVA) encoding the middle Ag of HBV and Engerix-B induced high levels of CD4(+) and CD8(+) T cells and high titer Ab responses to hepatitis B surface Ag (HbsAg). Substitution of Engerix-B with adjuvant-free rHBsAg induced similar T cell responses and greatly enhanced Ab levels. Repeated immunizations with recombinant or nonrecombinant MVA mixed with Ag induced higher titers of Abs compared with immunization with either Ag or Engerix-B further demonstrating this novel adjuvant effect of MVA. The poxviruses NYVAC, fowlpox (FP9) and ALVAC, and to a lesser extent, adenovirus, also displayed similar adjuvant properties when used in combination with rHBsAg. The use of poxviruses as an adjuvant for protein to concurrently induce Ag-specific T cells and Abs could be applied to the development of vaccines for many diseases, including HIV and malaria, where both cell mediated and humoral immunity may be important for protection.     

乙型肝炎病毒全S基因疫苗诱导小鼠的特异性免疫应答

乙型肝炎病毒 (ＨＢＶ)感染是我国常见病及多发病。ＨＢＶ难以清除的原因之一就是机体的免疫功能障碍。目前虽然基因重组ＨＢＶ表面抗原 (ＨＢｓＡｇ)疫苗预防ＨＢＶ感染取得了较好的效果 ,但基因重组ＨＢｓＡｇ疫苗主要能诱导特异性体液免疫 ,不能刺激机体的细胞免疫应答。近年来发现基因疫苗可诱导机体产生细胞及体液免疫反应 ,特别是诱导细胞免疫反应的能力优于蛋白、多肽类疫苗 ,更适应于慢性病毒感染的预防与治疗[1,2 ] 。为了探讨应用ＨＢＶ基因疫苗预防ＨＢＶ感染的可能性 ,本文构建了ＨＢＶ全Ｓ基因和ＨＢｓＡｇ基因疫苗 ,观察和比…     

Cationic Lipid-Formulated DNA Vaccine against Hepatitis B Virus: Immunogenicity of MIDGE-Th1 Vectors Encoding Small and Large Surface Antigen in Comparison to a Licensed Protein Vaccine

Currently marketed vaccines against hepatitis B virus (HBV) based on the small (S) hepatitis B surface antigen (HBsAg) fail to induce a protective immune response in about 10% of vaccinees. DNA vaccination and the inclusion of PreS1 and PreS2 domains of HBsAg have been reported to represent feasible strategies to improve the efficacy of HBV vaccines. Here, we evaluated the immunogenicity of SAINT-18-formulated MIDGE-Th1 vectors encoding the S or the large (L) protein of HBsAg in mice and pigs. In both animal models, vectors encoding the secretion-competent S protein induced stronger humoral responses than vectors encoding the L protein, which was shown to be retained mainly intracellularly despite the presence of a heterologous secretion signal. In pigs, SAINT-18-formulated MIDGE-Th1 vectors encoding the S protein elicited an immune response of the same magnitude as the licensed protein vaccine Engerix-B, with S protein-specific antibody levels significantly higher than those considered protective in humans, and lasting for at least six months after the third immunization. Thus, our results provide not only the proof of concept for the SAINT-18-formulated MIDGE-Th1 vector approach but also confirm that with a cationic-lipid formulation, a DNA vaccine at a relatively low dose can elicit an immune response similar to a human dose of an aluminum hydroxide-adjuvanted protein vaccine in large animals.     

Live attenuated recombinant vaccine protects nonhuman primates against Ebola and Marburg viruses

Vaccines and therapies are urgently needed to address public health needs stemming from emerging pathogens and biological threat agents such as the filoviruses Ebola virus (EBOV) and Marburg virus (MARV). Here, we developed replication-competent vaccines against EBOV and MARV based on attenuated recombinant vesicular stomatitis virus vectors expressing either the EBOV glycoprotein or MARV glycoprotein. A single intramuscular injection of the EBOV or MARV vaccine elicited completely protective immune responses in nonhuman primates against lethal EBOV or MARV challenges. Notably, vaccine vector shedding was not detectable in the monkeys and none of the animals developed fever or other symptoms of illness associated with vaccination. The EBOV vaccine induced humoral and apparent cellular immune responses in all vaccinated monkeys, whereas the MARV vaccine induced a stronger humoral than cellular immune response. No evidence of EBOV or MARV replication was detected in any of the protected animals after challenge. Our data suggest that these vaccine candidates are safe and highly efficacious in a relevant animal model.     

免疫共刺激分子OX40L对乙型肝炎核酸疫苗的免疫佐剂作用

[目的]为了进一步增强HBV DNA疫苗的免疫反应,本研究将共刺激分子OX40L 作为HBV DNA疫苗的分子佐剂免疫小鼠,旨在探讨共刺激分子OX40L对HBV DNA疫苗诱导体液和细胞免疫应答的影响.[方法]我们将HBV DNA疫苗(pcDS2)单独或联合共刺激分子质粒pOX40L免疫C57BL/6小鼠;分别在第0,2,4周进行免疫,在第6周检测抗-HBs IgG、IgG1和IgG2a,T淋巴细胞增殖指数,细胞因子表达水平和体内细胞毒性T淋巴细胞杀伤作用(CTL)等免疫学指标.[结果]pceDS2联合pOX40L免疫组小鼠的抗-HBs水平显著提高,抗-HBs IgG亚类以IgG2a占优;免疫小鼠的T淋巴细胞体外经乙型肝炎表面抗原(HBsAg)刺激后,联合免疫组刺激指数(SI)明显高于pcDS2组;联合免疫组CD4 + T淋巴细胞的IL-4和IFN-γ表达水平及CD8 + T淋巴细胞的IFN-γ表达水平显著升高;DNA疫苗免疫的各组小鼠,HBsAg特异性体内CTL高于对照组,其中联合免疫组小鼠的体内CTL杀伤作用最强.[结论]共刺激分子OX40L不仅能增强HBV DNA疫苗诱导特异性体液免疫应答,还能增强特异性细胞免疫反应,尤其增强体内CTL的杀伤活性,为HBV DNA疫苗的研究奠定了基础.     

Immunomodulation activity of new vaccines for pertussis prophylaxis--acellular pertussis vaccine and adsorbed DPT vaccine with acellular component

The immunomodulating activity of acellular pertussis vaccine (APV) and adsorbed DPT vaccine with acellular pertussis component (DPTA vaccine) was studied. The study revealed that only large doses of APV, 10 immunizing doses (ID), suppressed humoral and cell-mediated response to sheep red blood cells (SRBC). 1 ID produced no influence on the formation of antibody producing cells, but increased the development of delayed hypersensitivity (DH) to SRBC. The modulation of cell-mediated immune response, induced by APV, returned to normal after the injection of purified staphylococcal toxoid, used as immunomodulator, in doses of 0.15 BU per mouse and 1.5 BU per mouse. DPTA vaccine containing 1 ID, as well as 10 ID, produced no immunomodulating effect. This was established by the evaluation of humoral response to SRBC in CBA mice and the study of the formation of DH to SRBC in BALB/c mice. As indicated by the total of the presented data, the inclusion of APV into DPTA vaccine enhanced the immunological safety of its pertussis component.     

Vaxfectin Adjuvant Improves Antibody Responses of Juvenile Rhesus Macaques to a DNA Vaccine Encoding the Measles Virus Hemagglutinin and Fusion Proteins

DNA vaccines formulated with the cationic lipid-based adjuvant Vaxfectin induce protective immunity in macaques after intradermal (i.d.) or intramuscular (i.m.) delivery of 0.5 to 1 mg of codon-optimized DNA encoding the hemagglutinin (H) and fusion (F) proteins of measles virus (MeV). To characterize the effect of Vaxfectin at lower doses of H+F DNA, rhesus macaques were vaccinated twice with 20 μg of DNA plus Vaxfectin i.d., 100 μg of DNA plus Vaxfectin i.d., 100 μg of DNA plus Vaxfectin i.m. or 100 μg of DNA plus phosphate-buffered saline (PBS) i.m. using a needleless Biojector device. The levels of neutralizing (P = 0.036) and binding (P = 0.0001) antibodies were higher after 20 or 100 μg of DNA plus Vaxfectin than after 100 μg of DNA plus PBS. Gamma interferon (IFN-γ)-producing T cells were induced more rapidly than antibody, but were not improved with Vaxfectin. At 18 months after vaccination, monkeys were challenged with wild-type MeV. None developed rash or viremia, but all showed evidence of infection. Antibody levels increased, and IFN-γ- and interleukin-17-producing T cells, including cells specific for the nucleoprotein absent from the vaccine, were induced. At 3 months after challenge, MeV RNA was detected in the leukocytes of two monkeys. The levels of antibody peaked 2 to 4 weeks after challenge and then declined in vaccinated animals reflecting low numbers of bone marrow-resident plasma cells. Therefore, Vaxfectin was dose sparing and substantially improved the antibody response to the H+F DNA vaccine. This immune response led to protection from disease (rash/viremia) but not from infection. Antibody responses after challenge were more transient in vaccinated animals than in an unvaccinated animal.     

Priming of immune responses to hepatitis B surface antigen in young mice immunized in the presence of maternally derived antibodies

Early vaccination is necessary to protect infants from various infectious diseases. However, this is often unsuccessful largely due to the immaturity of the neonatal immune system. Furthermore, maternally derived antibodies can interfere with active immunization. We have previously shown in young mice that immune responses against several different antigens can be improved by the addition of oligodeoxynucleotides containing immunostimulatory CpG motifs (CpG ODN). In this study we have evaluated immunization of newborn (1-7-day-old) BALB/c mice against hepatitis B surface antigen (HBsAg), with alum and/or CpG ODN, in the presence of high levels of maternal antibody against HBsAg (anti-HBs). Seroconversion rates and anti-HBs titers were compared to those induced by a HBsAg-expressing plasmid, since other studies had suggested DNA vaccines to be superior to protein vaccines in young mice with maternal antibody. HBsAg/alum/CpG ODN was superior to DNA vaccine in inducing HBsAg-specific CTL responses in young mice in the presence of maternally transferred anti-HBs antibodies. However, B cell responses to both HBsAg/alum/CpG ODN and DNA vaccines remained weak in the presence of maternally transferred anti-HBs antibodies.     

Removing N-terminal sequences in pre-s1 domain enhanced antibody and B-cell responses by an HBV large surface antigen DNA vaccine

Although the use of recombinant hepatitis B virus surface (HBsAg) protein vaccine has successfully reduced global hepatitis B infection, there are still a number of vaccine recipients who do not develop detectable antibody responses. Various novel vaccination approaches, including DNA vaccines, have been used to further improve the coverage of vaccine protection. Our previous studies demonstrated that HBsAg-based DNA vaccines could induce both humoral and CMI responses in experimental animal models. However, one form of the the HBsAg antigen, the large S antigen (HBs-L), expressed by DNA vaccine, was not sufficiently immunogenic in eliciting antibody responses. In the current study, we produced a modified large S antigen DNA vaccine, HBs-L(T), which has a truncated N-terminal sequence in the pre-S1 region. Compared to the original HBs-L DNA vaccine, the HBs-L(T) DNA vaccine improved secretion in cultured mammalian cells and generated significantly enhanced HBsAg-specific antibody and B cell responses. Furthermore, this improved HBsL DNA vaccine, along with other HBsAg-expressing DNA vaccines, was able to maintain predominantly Th1 type antibody responses while recombinant HBsAg protein vaccines produced in either yeast or CHO cells elicited mostly Th2 type antibody responses. Our data indicate that HBsAg DNA vaccines with improved immunogenicity offer a useful alternative choice to recombinant protein-based HBV vaccines, particularly for therapeutic purposes against chronic hepatitis infection where immune tolerance led to poor antibody responses to S antigens.     

Plasmodium vivax thrombospondin related adhesion protein: immunogenicity and protective efficacy in rodents and Aotus monkeys

The thrombospondin related adhesion protein (TRAP) is a malaria pre-erythrocytic antigen currently pursued as malaria vaccine candidate to Plasmodium falciparum. In this study, a long synthetic peptide (LSP) representing a P. vivax TRAP fragment involved in hepatocyte invasion was formulated in both Freund and Montanide ISA 720 adjutants and administered by IM and subcutaneous routes to BALB/c mice and Aotus monkeys. We measured specific humoral immune responses in both animal species and performed a sporozoite challenge in Aotus monkeys to assess the protective efficacy of the vaccine. After immunization both mice and Aotus seroconverted as shown by ELISA, and the specific anti-peptide antibodies cross reacted with the parasite in IFAT assays. Only two out of six immunized animals became infected after P. vivax sporozoite challenge as compared with four out of six animals from the control group. These results suggest that this TRAP fragment has protective potential against P. vivax malaria and deserves further studies as vaccine candidate.     

Homologous Boosting with Adenoviral Serotype 5 HIV Vaccine (rAd5) Vector Can Boost Antibody Responses despite Preexisting Vector-Specific Immunity in a Randomized Phase I Clinical Trial

Background

Needle-free delivery improves the immunogenicity of DNA vaccines but is also associated with more local reactogenicity. Here we report the first comparison of Biojector and needle administration of a candidate rAd5 HIV vaccine.

Methods

Thirty-one adults, 18–55 years, 20 naive and 11 prior rAd5 vaccine recipients were randomized to receive single rAd5 vaccine via needle or Biojector IM injection at 10¹⁰ PU in a Phase I open label clinical trial. Solicited reactogenicity was collected for 5 days; clinical safety and immunogenicity follow-up was continued for 24 weeks.

Results

Overall, injections by either method were well tolerated. There were no serious adverse events. Frequency of any local reactogenicity was 16/16 (100%) for Biojector compared to 11/15 (73%) for needle injections. There was no difference in HIV Env-specific antibody response between Biojector and needle delivery. Env-specific antibody responses were more than 10-fold higher in subjects receiving a booster dose of rAd5 vaccine than after a single dose delivered by either method regardless of interval between prime and boost.

Conclusions

Biojector delivery did not improve antibody responses to the rAd5 vaccine compared to needle administration. Homologous boosting with rAd5 gene-based vectors can boost insert-specific antibody responses despite pre-existing vector-specific immunity.

Trial Registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00709605","term_id":"NCT00709605"}}NCT00709605 {"type":"clinical-trial","attrs":{"text":"NCT00709605","term_id":"NCT00709605"}}NCT00709605     

Immunogenicity of hepatitis B surface antigen derived from the baculovirus expression vector system: a mouse potency study

A standard mouse potency test was performed to evaluate the immunogenicity of recombinant hepatitis B surface antigen (HBsAg) produced in the baculovirus/insect cell expression system. Groups of NIH Swiss mice were immunized with serial four-fold amounts of either baculovirus-derived HBsAg adsorbed to aluminum sulfate or a commercially available yeast-derived recombinant HBsAg vaccine preparation. Results from these experiments showed that the effective dose of baculovirus- and yeast-derived HBsAg vaccine preparations necessary to seroconvert 50% of the animals were similar. The duration of the antibody response to HBsAg was studied in mice immunized with the highest doses of the two recombinant vaccine preparations 3 and 6 months after injection. No decrease in the anti-HBs response was observed 6 months after injection. No decrease in the anti-HBs response was observed 6 months after immunization with either of the two vaccine preparations. These results indicate that the baculovirus-derived recombinant HBsAg could serve as an alternative vaccine candidate for hepatitis B virus.     

热休克蛋白HSP70和gp96增强乙肝DNA疫苗的细胞和体液免疫应答

旨在以乙肝病毒 (HBV) 的主要结构蛋白-表面蛋白 (HBsAg) 和核心蛋白 (HBcAg) 作为抗原设计DNA疫苗,研究热休克蛋白HSP70和gp96作为新型免疫佐剂增强疫苗的细胞免疫和体液免疫水平。利用酶联免疫斑点实验、流式细胞内因子染色、3H-TdR实验、酶联免疫吸附实验技术分析,结果显示HSP70和gp96可使疫苗的细胞免疫水平提高1~6倍,提高体液免疫水平20％~60％。研究结果为设计以HSP70和gp96作为免疫佐剂的新型乙肝治疗性疫苗提供了依据。     

Adaptation of a strain of Plasmodium vivax from India to New World monkeys, chimpanzees, and anopheline mosquitoes.

A strain of Plasmodium vivax from India was adapted to develop in splenectomized Saimiri boliviensis, Aotus lemurinus griseimembra, A vociferans, A. nancymai, A. azarae boliviensis, hybrid Aotus monkeys, and splenectomized chimpanzees. Infections were induced via the inoculation of sporozoites dissected from the salivary glands of Anopheles stephensi and An. dirus mosquitoes to 12 Aotus and 8 Saimiri monkeys; transmission via the bites of infected An. stephensi was made to 1 Aotus monkey and 1 chimpanzee. The intravenous passage of infected erythrocytes was made to 9 Aotus monkeys and 4 chimpanzees. Gametocytes in 13 Aotus monkeys and 4 chimpanzees were infectious to mosquitoes. Infection rates were markedly higher in mosquitoes fed on chimpanzees. PCR studies on 10 monkeys injected with sporozoites revealed the presence of parasites before their detection by microscopic examination. The India VII strain of P. vivax develops in Aotus and Saimiri monkeys and chimpanzees following the injection of parasitized erythrocytes, or sporozoites, or both. The transmission rate via sporozoites to New World monkeys of approximately 50% may be too low for the testing of sporozoite vaccines or drugs directed against the exoerythrocytic stages. However, the strain is highly infectious to commonly available laboratory-maintained anopheline mosquitoes. Mosquito infection is especially high when feedings are made with gametocytes from splenectomized chimpanzees.     

Seropositivity for hepatitis B virus, vaccination coverage, and vaccine response in dentists from Campo Grande, Mato Grosso do Sul, Brazil

This study investigated the seropositivity for hepatitis B virus (HBV), the vaccination index, and the vaccine response index in dentists from Campo Grande, MS. Blood samples from 474 dentists (63.7% women and 36.3% men), with a mean age of 38.5 +/- 10.5 years were analyzed by enzyme-linked immunosorbent assay to detect the serological markers: HBsAg, anti-HBs, and anti-HBc. The HBsAg positive samples were tested for anti-HBc IgM, HBeAg, and anti-HBe. A total of 51 (10.8%) dentists showed seropositivity for HBV. Three (0.6%) were HBsAg/anti-HBc/anti-HBe positive, 43 (9.1%) were anti-HBc/anti-HBs positive, and 5 (1.1%) had only anti-HBc. Viral DNA was detected by polymerase chain reaction in 9 (17.6%) out of 51 HBV seropositive samples. A vaccination index of 96.6% (458/474) was observed, although 73.1% (335/458)completed the three-dose schedule. Excluding 46 HBV seropositive individuals from 458 that reported vaccination, 412 were analyzed for vaccine response index. It was observed that 74.5% (307/412) were anti-HBs positive; this percentage increased to 79.1% when three doses were administered. The results showed a high vaccination index and a good rate of vaccine response; however, the failure in completing the three-dose schedule and the occurrence of HBV infection reinforce the need for more effective prevention strategies.     

The importance of adjuvant formulation in the development of a tuberculosis vaccine

An effective protein-based vaccine for tuberculosis will require a safe and effective adjuvant. There are few adjuvants in approved human vaccines, including alum and the oil-in-water-based emulsions MF59 (Novartis Vaccines and Diagnostics), AS03 and AS04 (GlaxoSmithKline Biologics), AF03 (Sanofi), and liposomes (Crucell). When used with pure, defined proteins, both alum and emulsion adjuvants are effective at inducing primarily humoral responses. One of the newest adjuvants in approved products is AS04, which combines monophosphoryl lipid A, a TLR-4 agonist, with alum. In this study, we compared two adjuvants: a stable oil-in-water emulsion (SE) and a stable oil-in-water emulsion incorporating glucopyranosyl lipid adjuvant, a synthetic TLR-4 agonist (GLA-SE), each together with a recombinant protein, ID93. Both the emulsion SE and GLA-SE adjuvants induce potent cellular responses in combination with ID93 in mice. ID93/SE induced Th2-biased immune responses, whereas ID93/GLA-SE induced multifunctional CD4(+) Th1 cell responses (IFN-γ, TNF-α, and IL-2). The ID93/GLA-SE vaccine candidate induced significant protection in mice and guinea pigs, whereas no protection was observed with ID93/SE, as assessed by reductions in bacterial burden, survival, and pathology. These results highlight the importance of properly formulating subunit vaccines with effective adjuvants for use against tuberculosis.     

Electroporation enhances immunogenicity of a DNA vaccine expressing woodchuck hepatitis virus surface antigen in woodchucks

The development of therapeutic vaccines for chronic hepatitis B virus (HBV) infection has been hampered by host immune tolerance and the generally low magnitude and inconsistent immune responses to conventional vaccines and proposed new delivery methods. Electroporation (EP) for plasmid DNA (pDNA) vaccine delivery has demonstrated the enhanced immunogenicity of HBV antigens in various animal models. In the present study, the efficiency of the EP-based delivery of pDNA expressing various reporter genes first was evaluated in normal woodchucks, and then the immunogenicity of an analog woodchuck hepatitis virus (WHV) surface antigen (WHsAg) pDNA vaccine was studied in this model. The expression of reporter genes was greatly increased when the cellular uptake of pDNA was facilitated by EP. The EP of WHsAg-pDNA resulted in enhanced, dose-dependent antibody and T-cell responses to WHsAg compared to those of the conventional hypodermic needle injection of WHsAg-pDNA. Although subunit WHsAg protein vaccine elicited higher antibody titers than the DNA vaccine delivered with EP, T-cell response rates were comparable. However, in WHsAg-stimulated mononuclear cell cultures, the mRNA expression of CD4 and CD8 leukocyte surface markers and Th1 cytokines was more frequent and was skewed following DNA vaccination compared to that of protein immunization. Thus, the EP-based vaccination of normal woodchucks with pDNA-WHsAg induced a skew in the Th1/Th2 balance toward Th1 immune responses, which may be considered more appropriate for approaches involving therapeutic vaccines to treat chronic HBV infection.