ELISPOT analysis of a new CTL based DNA vaccine for HIV-1 using GM-CSF in DNA prime/peptide boost strategy: GM-CSF induced long-lived memory responses

Ascorbic Acid and α-Tocopherol in the Inactivated SARS-CoV-2 Vaccine Formulation: Induction of the Th1 Pattern in Aged Mice

Aging is physiologically associated with a decline in the function of the immune system and subsequent susceptibility to infections. Interferon-gamma (IFN-γ), a key element in the activation of cellular immunity, plays an important role in defense against virus infections. Decreased levels of IFN-γ in the elderly may explain their increased risk for viral infectious diseases such as COVID-19. There is accumulating evidence that ascorbic acid (vitamin C [VitC]) and α-tocopherol together help improve the function of the immune system in the elderly, control infections, and decrease the treatment duration. A SARS-CoV-2 strain was isolated from a patient and then cultured in the Vero cell line. The isolated and propagated virus was then inactivated using formalin and purified by the column chromatography. The inactivated SARS-CoV-2 was formulated in the Alum adjuvant combined with VitC or α-tocopherol and/or both of them. The vaccines were injected twice to young and aged C57BL/6 mice. Two weeks later, IFN-γ, IL-4, and IL-2 cytokines were assessed using ELISA Kits. Specific IgG and IgG1/IgG2a were assessed by an in-house ELISA. In addition, the expression of PD1 and TERT genes in the spleen tissue of the mice was measured using real-time PCR. IL-4 and IFN-γ cytokines showed a significant increase in both aged and young mice compared with the Alum-based vaccine. In addition, our results exhibited a significant decrease and increase in specific total IgG and the IgG2a/IgG1 ratio, respectively. Furthermore, the vaccine formulated in α-tocopherol + VitC led to decreased PD1 and increased TERT gene expression levels. In conclusion, our results demonstrated that α-tocopherol + VitC formulated in the inactivated SARS-CoV-2 vaccine led to a shift toward Th1, which may be due to their effect on the physiology of cells, especially aged ones and changing their phenotype toward young cells.

Formulation of Recombinant H1N1 Hemagglutinin in MF59 and Alum Adjuvants: A Comparison of the Vaccines Potency and Efficacy in BALB/C Mice

In this study, we reported the expression and potency of the recombinant H1N1 hemagglutinin (HA) vaccine as our in-house vaccine in a BALB/c mouse model. Recombinant H1N1 HA was produced in SF9 cell line, purified and formulated in MF59 adjuvant. Experimental mice were injected on days 0 and 14 with MF59-formulated vaccine, alum-based vaccine, and phosphate-buffered saline (PBS). Interleukin (IL)-2, IL-4, and interferon (IFN)-γ were assessed with commercial enzyme-linked immunosorbent assay (ELISA). Antibody responses and cytotoxic T lymphocyte (CTL) activity were assessed by hemagglutination inhibition and granzyme B ELISA, respectively. Moreover, the mice were challenged to show the vaccine efficacy. A considerable rise in IFN-γ and IL-4, as well as IFN-γ/IL-4 ratio, was observed in comparison with the alum-based vaccine and PBS group. Furthermore, our candidate vaccine showed superiority in humoral immune responses and CTL activity versus the alum-based vaccine and PBS group. The challenge showed that the survival rate in the vaccinated groups revealed a significant increase as compared with that in the PBS group. In conclusion, our candidate vaccine showed a robust Th1 response and CTL activity the alum-based vaccine. Moreover, a significant humoral immune response and a higher survival rate were detected in our vaccine as compared with the alum-based vaccine. It seems that the superiority of the MF59-based vaccine is due to the type of vaccine formulation in the candidate vaccine.

Nanoadjuvants Produced by Advanced Nanochelating Technology in the Inactivated-Severe Acute Respiratory Syndrome Coronavirus-2 Vaccine Formulation: Preliminary Results on Cytokines and IgG Responses

Despite the great success of vaccines in various infectious diseases, most current vaccines are not effective enough, and on the contrary, clinically approved alum adjuvants cannot induce sufficient immune responses, including a potent cellular immune response to confer protection. In this study, we used Nanochelating Technology to develop novel nanoadjuvants to boost the potency of the alum-adjuvanted inactivated severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccine. BALB/c mice were immunized twice over 2 weeks with different doses of adjuvanted-vaccine formulations and immune responses were assessed. The analysis results of IFN-γ and IL-17 cytokines demonstrated the effectiveness of the nanoadjuvants produced by the Nanochelating Technology in shifting the alum-based vaccine toward a stronger Th1 pattern. In addition, these nanoadjuvants improved IL-2 cytokine response, which shows the efficacy of these novel formulations in inducing specific T lymphocyte proliferation. Using these nanoadjuvants increased IL-10 cytokine secretion that may be representative of a better immunoregulatory impact and may also potentially prevent immunopathology responses. Moreover, specific IgG titer analysis revealed the potency of these nanoadjuvants in improving humoral immune responses. The enzyme-linked immunosorbent assay of receptor-binding domain (RBD)-specific IgG response showed that the developed novel formulations induced strong IgG responses against this protein. This study shows that the nanostructures produced by the Advanced Nanochelating Technology have potent adjuvant effects on alum-based SARS-CoV-2 vaccines to not only compensate for alum weakness in inducing the cellular immune responses by smart regulation of the immune system but also significantly improve the humoral and cellular immune responses simultaneously.

Different Formulations of Inactivated SARS-CoV-2 Vaccine Candidates in Human Compatible Adjuvants: Potency Studies in Mice Showed Different Platforms of Immune Responses

Several inactivated SARS-CoV-2 vaccines have been approved for human use, but are not highly potent. In this study, different formulations of the inactivated SARS-CoV-2 virus were developed in Alum, Montanide 51VG, and Montanide ISA720VG adjuvants, followed by assessment of immune responses. The SARS-CoV-2 virus was inactivated with formalin and formulated in the adjuvants. BALB/c mice were immunized subcutaneously with 4 μg of vaccines on days 0 and 14; (IL-4) and (IFN-g), cytotoxic T lymphocyte (CTL) activity, and specific immunoglobulin G (IgG) titer and IgG1, IgG2a, and IgG2a/IgG1 ratio, and anti-receptor-binding domain (RBD) IgG response were assessed 2 weeks after the final immunization. Immunization with SARS-CoV-2-Montanide ISA51VG showed a significant increase in the IFN-γ cytokine versus SARS-CoV-2-Alum, SARS-CoV-2-Montanide ISA720VG, and control groups (p < 0.0033). Cytokine IL-4 response in SARS-CoV-2-Alum group showed a significant increase compared with SARS-CoV-2-Montanide ISA51VG, SARS-CoV-2-Montanide ISA720VG, and control groups (p < 0.0206). In addition, SARS-CoV-2-Montanide ISA51VG vaccine induced the highest IFN-γ/IL-4 cytokine ratio versus other groups (p < 0.0004). CTL activity in SARS-CoV-2-Montanide ISA51VG and SARS-CoV-2-Montanide ISA720VG groups showed a significant increase compared with SARS-CoV-2-Alum and control groups (p < 0.0075). Specific IgG titer in SARS-CoV-2-Montanide ISA51 VG and SARS-CoV-2-Montanide ISA720VG showed a significant increase compared with SARS-CoV-2-Alum and control groups (p < 0.0143). Results from specific IgG1and IgG2a in SARS-CoV-2-Alum, SARS-CoV-2-Montanide ISA51VG, and SARS-CoV-2-Montanide ISA720VG vaccine showed a significant increase compared with phosphate buffer saline (PBS) group (p < 0.0001), but SARS-CoV-2-Montanide ISA51VG and SARS-CoV-2-Montanide ISA 720VG groups showed the highest IgG2a/IgG1 ratio and a significant increase compared with SARS-CoV-2-Alum group (p < 0.0379). Moreover, inactivated SARS-CoV-2+Alum and SARS-CoV-2-Montanide ISA 720VG groups demonstrated a significant increase in anti-RBD IgG response versus the SARS-CoV-2-Montanide ISA51VG group. It seems that the type of vaccine formulation is a critical parameter, influencing the immunologic pattern and vaccine potency and human-compatible oil-based adjuvants were more potent than Alum adjuvant in the vaccine formulation.

Glucomannan as a Dietary Supplement for Treatment of Breast Cancer in a Mouse Model

Konjac glucomannan (KGM) is a water-soluble polysaccharide derived from the Amorphophallus’s tuber and, as herbal medicine has shown, can suppress tumor growth or improve health. However, there has been no investigation into the effects of KGM on breast tumor-bearing mice. Therefore, in two cohort experiments, we assessed the effect of glucomannan at daily doses of 2 and 4 mg for 28 days as a dietary supplement and also glucomannan in combination with tumor lysate vaccine as an adjuvant. Tumor volume was monitored twice weekly. In addition, TNF-α cytokines and granzyme B (Gr–B) release were measured with ELISA kits, and IL-2, IL-4, IL-17, and IFN-γ were used as an index for cytotoxic T lymphocyte activity. Moreover, TGF-β and Foxp3 gene expression were assessed in a real-time PCR test. The results show that glucomannan as a dietary supplement increased the IFN-γ cytokine and Th1 responses to suppress tumor growth. Glucomannan as a dietary supplement at the 4 mg dose increased the IL-4 cytokine response compared to control groups. In addition, cell lysate immunization with 2 or 4 mg of glucomannan suppressed tumor growth. As an adjuvant, glucomannan at both doses showed 41.53% and 52.10% tumor suppression compared with the PBS group. Furthermore, the administration of glucomannan as a dietary supplement or adjuvant reduced regulatory T cell response through decreasing TGF-β and Foxp3 gene expression in the tumor microenvironment. In conclusion, glucomannan as a dietary supplement or adjuvant enhanced the immune responses of tumor-bearing mice and decreased immune response suppression in the tumor milieu, making it a potentially excellent therapeutic agent for lowering breast tumor growth.

Adjuvant Effects of Pseudomonas aeruginosa Flagellin on the Immunological Patterns of the HIV-1 Vaccine Candidate: Vaccine Formulations Versus Different Routes of Immunization

New strategies to increase the immune response to HIV-1 vaccine using immunological adjuvants such as Toll-like receptor agonists are needed. In this study, HIV-1 p24-Nef and conjugated form of the vaccine candidate to type-A flagellin (FLA) were injected in the BALB/c mice in different routes. Two weeks after the last immunization, lymphocyte proliferation was measured by the BrdU method. The IL-4 and IFN-γ levels, as well as the total IgG antibody and its isotypes titer, were evaluated by the enzyme-linked immunosorbent assay method. The IFN-γ ELISPOT was also performed. Our data showed that the HIV-1 p24-Nef alone and conjugated to type-A flagellin (FLA) significantly increased lymphocyte proliferation responses as well as higher levels of cytokines and IFN-γ producing lymphocytes and the level of humoral immune responses compared with the control groups. The cell-mediated immune responses through the subcutaneous route and humoral immune responses through the intramuscular route were significantly higher in the conjugated form than in the mere vaccine candidate. In conclusion, when the FLA as an adjuvant is constructed in the HIV-1 vaccine candidate, it could effectively improve both humoral and cellular immune responses. Furthermore, modification in the vaccine formulation could change the optimal route of vaccine inoculation.

Formulation of HBsAg in Montanide ISA 51VG adjuvant: Immunogenicity study and monitoring long-lived humoral immune responses

Montanide ISA 51VG adjuvant has been approved for human clinical application and stimulates cellular and humoral immune responses. Here, HBsAg was formulated in Montanide ISA51VG adjuvant to compare its potency with the Fendrix and HBsAg-alum vaccines. In particular, the long-term humoral response was assessed up to 220 days after the final immunization. BALB/c mice were allocated into six groups. Treatment groups were injected with HBsAg-Montanide ISA51VG, the Fendrix and commercial HBsAg-alum, respectively. Montanide ISA51 VG, Alum and PBS injected mice were considered as control groups. Mice were immunized three times with 2-week intervals on days 0, 14 and 28 by subcutaneous injection. Lymphocyte proliferation was assessed with the BrdU method. IFN-γ, IL-2 and IL-4 cytokines, specific total IgG and IgG1/IgG2a isotypes were assessed using ELISA. The HBsAg-Montanide ISA51VG vaccine resulted in a significant increase in lymphocyte proliferation versus HBsAg-alum and higher IL-2 cytokine production versus the Fendrix. Comparable IL-4 and IFN-γ cytokines responses were observed for these vaccines. Following the first immunization, IgG increased more in HBs-Montanide 51VG group versus the HBs-alum group, while after the second and third shots comparable responses were observed in comparison to the HBs-alum group. Monitoring for 220 days after the final vaccination showed the superiority of HBsAg-Montanide ISA 51VG vaccine versus HBsAg-alum and even the Fendrix vaccine in the induction of long-term antibody responses. This study suggests that HBsAg-Montanide ISA51VG as a novel vaccine formulation can trigger both cellular and long-lasting humoral immune responses more efficiently than conventional HBsAg vaccines.

Formulation of a recombinant HIV-1 polytope candidate vaccine with naloxone/alum mixture: induction of multi-cytokine responses with a higher regulatory mechanism

The potency of a vaccine highly depends upon the nature of the adjuvant used. There are a variety of ineffective vaccines, such as HIV-1 vaccine candidates, that need to be optimized with new adjuvant formulations to improve vaccine potency and efficacy. Studies show the potency of naloxone (NLX)/alum mixture in the induction of Th1/Th2 response for vaccine. However, other immunologic patterns inducing by this adjuvant and its immunoregulatory effect is unclear. In this regard, the aim of the present study was to investigate the effect of the NLX/alum mixture, as an adjuvant, on cytokine networks and immunoregulatory activity for an HIV-1 polytope vaccine. BALB/c mice were divided into six groups (n = 6) and immunized subcutaneously with 10 μg of the vaccine formulated with NLX/alum, NLX, alum, and Freund's adjuvants. At the same time, the mice in the control groups received an equal volume of PBS or NLX. The lymphocyte proliferation assay was carried out using the BrdU method. ELISA was used to measure the levels of IFN-γ, IL-2, IL-4, IL-10, IL-12, and IL-17 cytokines, total IgG, as well as IgG1 and IgG2a subtypes in serum samples. Our findings showed that mice receiving the NLX/alum-adjuvanted vaccine exhibited increased antibody levels compared with other groups. In addition, there was a considerable difference in the levels of IgG1, IgG2a, IFN-γ, IL-2, IL-10, IL-12, and IL-17 in mice receiving the NLX/alum-adjuvanted vaccine as compared with other groups. The NLX/alum mixture, as an adjuvant, may have a positive effect on the induction of multi-cytokine responses, as well as the increased level of IL-10, showing its higher immunogenicity with a higher immunoregulatory mechanism.

Co-delivery of PSMA antigen epitope and mGM-CSF with a cholera toxin-like chimeric protein suppressed prostate tumor growth via activating dendritic cells and promoting CTL responses

Subunit vaccines derived from tumor antigens play a role in tumor therapy because of their unique advantages. However, because of the weak immunogenicity of peptides in subunit vaccines, it is difficult to trigger an effective cytotoxic T lymphocyte (CTL) response, which is critical for cancer therapy. A requirement for the activation of CTL cells by exogenous antigens is the stimulation of antigen presenting cells (APC) with the help of adjuvants and cross-presentation to T lymphocytes. Standard nonconjugated adjuvant-peptide mixtures do not ensure co-targeting of the antigen and the adjuvant to the same APC, which limits the effects of adjuvants. In this study, a fusion protein consisting of murine granulocyte-macrophage colony stimulating factor (mGM-CSF) fused with CTA2 (A2 subunit of cholera toxin) was generated and assembled with CTB-PSMA624-632 (prostate specific membrane antigen (PSMA) peptide 624-632 fused to CTB) to obtain a cholera toxin-like protein. The chimeric protein retained the biological activity of mGM-CSF and had stronger GM1 binding activity than (CTB-PSMA624-632)5. C57BL/6J mice immunized with the CT-like chimeric protein exhibited delayed tumor growth following challenge with human PSMA-EGFP-expressing RM-1 cells. Experiment results showed that the CT-like chimeric protein could induce the maturation of DC cells and improve CTL responses. Overall, these results indicate that the nasal administration of a CT-like chimeric protein vaccine results in the development of effective immunity against prostate tumor cells and might be useful for future clinical anti-tumoral applications.

Immune responses to HIV-1 polytope vaccine candidate formulated in aqueous and alcoholic extracts of Propolis: Comparable immune responses to Alum and Freund adjuvants

Today's, vaccination is the most cost-effective approaches for preventing infectious diseases. In this strategy, adjuvants play an important role. Propolis from honey bee can stimulate the immune system and several studies have shown the modulating effects of Propolis on the immune responses. Here, the adjuvant effects of aqueous and alcoholic extracts of Propolis were studied on the multi-epitope vaccines against HIV-1. A recombinant vaccine against HIV-1 was prepared and BALB/c mice were immunized. subcutaneously on day 0 with 100 μl of candidate vaccine (10 μg) formulated in an alcoholic extract of Propolis. The second group of mice was immunized with the vaccine (10 μg) formulated in aqueous extract of Propolis. Also, candidate vaccine was formulated in Freund's and Alum adjuvants in the third and fourth groups. Experimental mice were immunized three times with two week intervals under the same conditions and suitable control groups. After final injection, lymphocyte proliferation was measured by BrdU method, IL-4 and IFN-γ cytokines, specific total IgG antibodies, IgG1 and IgG2a isotypes were evaluated using ELISA. The results show that the aqueous and alcoholic extracts were able to enhance lymphocyte proliferation, IL-4 and IFN-γ cytokines and antibody responses with dominant IgG1 pattern and comparable to Freund's and Alum adjuvants. It seems that aqueous and alcoholic extracts of Propolis show adjuvant activity and may be useful for vaccine formulation.

Leishmaniasis in humans: drug or vaccine therapy?

Leishmania is an obligate intracellular pathogen that invades phagocytic host cells. Approximately 30 different species of Phlebotomine sand flies can transmit this parasite either anthroponotically or zoonotically through their bites. Leishmaniasis affects poor people living around the Mediterranean Basin, East Africa, the Americas, and Southeast Asia. Affected regions are often remote and unstable, with limited resources for treating this disease. Leishmaniasis has been reported as one of the most dangerous neglected tropical diseases, second only to malaria in parasitic causes of death. People can carry some species of Leishmania for long periods without becoming ill, and symptoms depend on the form of the disease. There are many drugs and candidate vaccines available to treat leishmaniasis. For instance, antiparasitic drugs, such as amphotericin B (AmBisome), are a treatment of choice for leishmaniasis depending on the type of the disease. Despite the availability of different treatment approaches to treat leishmaniasis, therapeutic tools are not adequate to eradicate this infection. In the meantime, drug therapy has been limited because of adverse side effects and unsuccessful vaccine preparation. However, it can immediately make infections inactive. According to other studies, vaccination cannot eradicate leishmaniasis. There is no perfect vaccine or suitable drug to eradicate leishmaniasis completely. So far, no vaccine or drug has been provided to induce long-term protection and ensure effective immunity against leishmaniasis. Therefore, it is necessary that intensive research should be performed in drug and vaccine fields to achieve certain results.

Granulocyte-macrophage colony-stimulating factor, a potent adjuvant for polarization to Th-17 pattern: an experience on HIV-1 vaccine model

Cytokines are mediators for polarization of immune response in vaccines. Studies show that co-immunization of DNA vaccines with granulocyte-macrophage colony-stimulating factor (GM-CSF) can increase immune responses. Here, experimental mice were immunized with HIV-1_{tat/pol/gag/env} DNA vaccine with GM-CSF and boosted with recombinant vaccine. Lymphocyte proliferation with Brdu and CTL activity, IL-4, IFN-γ, IL-17 cytokines, total antibody, and IgG1 and IgG2a isotypes were assessed with ELISA. Results show that GM-CSF as adjuvant in DNA immunization significantly increased lymphocyte proliferation and IFN-γ cytokines, but CTL response was tiny increased. Also GM-CSF as adjuvant decreased IL-4 cytokine vs mere vaccine group. IL-17 in the group that immunized with mixture of DNA vaccine/GM-CSF was significantly increased vs DNA vaccine group. Result of total antibody shows that GM-CSF increased antibody response in which both IgG1 and IgG2a increased. Overall, results confirmed the beneficial effect of GM-CSF as adjuvant to increase vaccine immunogenicity. The hallmark result of this study was to increase IL-17 cytokine with DNA vaccine/GM-CSF immunized group. This study for the first time provides the evidence of the potency of GM-CSF in the induction of IL-17 in response to a vaccine, which is important for control of infection such as HIV-1.

Co-utilization of a TLR5 agonist and nano-formulation of HIV-1 vaccine candidate leads to increased vaccine immunogenicity and decreased immunogenic dose: A preliminary study

Vaccines currently available for AIDS show poor efficiency, demonstrating the need for new strategies to increase their immunogenicity. In this study, the HIV-1P24-Nef peptide was used as a model vaccine, followed by utilization of a novel strategy to increase its immunogenicity. There is a growing interest in using TLR agonists for vaccine formulations. Such molecules bind to their receptors on immune cells, especially the cell surface of antigen presenting cells, thereby activating these cells and inflammatory responses. In the present study, FLiC (flagellin molecule sequence from Pseudomonas aeruginosa) was used as a TLR5 agonist. In addition, PLGA nanoparticles were used as a transmitter system to enhance vaccine efficiency and its effective transfer to immune systems. In light of this, the P24-Nef peptide was conjugated to FLiC through chemical reactions. The HIV-1P24-Nef/FLiC conjugate was constructed as a nano-vaccine using PLGA particles. Subsequently, mice were immunized intradermally three times with three-week intervals with HIV-p24-Nef/FLiC/PLGA, HIV-p24-Nef/PLGA, FLiC/PLGA, PLGA, and PBS in two doses (20 and 5μg). Three weeks after the last booster injection, cell proliferation was assessed using the Brdu/ELISA assay, and cytotoxicity was evaluated by CFSE and splenocyte cytokine secretion (IL-4 and IFN-γ); in addition, IgG1 and IgG2a antibody isotype titers were determined using a commercial ELISA kit. Our results showed that Co-utilization of TLR5 and nano-particles not only improves vaccine immunogenicity but also decreases the immunogenic dose of vaccine candidate required. We showed that the immune system was effectively stimulated via the nano-vaccination strategy using the TLR5 agonists. The effect of this strategy showed variations in different parameters of the immune system; in this regard, cellular immune responses had a higher stimulation level, compared with humoral immune responses.

Naloxone/alum mixture a potent adjuvant for HIV-1 vaccine: induction of cellular and poly-isotypic humoral immune responses

In the present study we used a fusion peptide from HIV-1 p24 and Nef as vaccine model and adjuvant activity of Naloxone/alum mixture was evaluated in a peptide vaccine model. HIV-1 p24-Nef fusion peptide was synthesized. Female BALB/c mice were divided into five groups. The first group immunized subcutaneously with the p24-Nef fusion peptide adjuvanted with Naloxone/alum mixture and boosted with same protocol. The second was immunized with fusion peptide adjuvanted in alum. The control groups were injected with NLX (Group 3), Alum (Group 4), or PBS (Groups 5) under the same conditions. To determine the type of induced immune response, sera and splenocytes were analyzed by commercial ELISA method for total IgG and isotypes and cytokine secretion (IL-4 & IFN-γ), respectively. We have also used the ELISPOT assay to monitor changes in the frequency of IFN-γ-producing T cells. The proliferation of T cells was assessed using Brdu method and T-cell cytotoxicity was assessed with CFSE method. Immunization of mice with HIV-1 p24-Nef fusion peptide formulated in Naloxone/alum mixture significantly increased lymphocyte proliferation and shifted cytokine responses toward Th1 profile compared to all other groups. Analysis of humoral immune responses revealed that administration of HIV-1 p24-Nef fusion peptide with Naloxone/alum mixture significantly increased specific IgG responses and also increased IgG1,IgG2a, IgG2b, IgG3, and IgM vs. alum-adjuvanted vaccine groups. Naloxone/alum mixture as an adjuvant could improve cellular and humoral immune response for HIV vaccine model and this adjuvant maybe useful for HIV vaccine model in human clinical trial.

Pseudomonas aeruginosa flagellin as an adjuvant: superiority of a conjugated form of flagellin versus a mixture with a human immunodeficiency virus type 1 vaccine candidate in the induction of immune responses

In the present study, the adjuvant activity of flagellin was compared, in the conjugated and mixed forms, against a peptide vaccine from human immunodeficiency virus type 1 (HIV-1) p24-Nef vaccine candidate. Mice were immunized with the HIV-1 p24-Nef peptide with flagellin in both conjugated and mixed forms. Lymphocyte proliferation, CTL activity, and IL-4 and IFN-γ cytokines were evaluated by bromodeoxyuridine, carboxyfluorescein succinimidyl ester and ELISA methods, respectively. At the same time, the frequency of IFN-γ-producing T-lymphocytes, as well as total and isotype-specific antibodies, were assessed by ELISPOT and indirect ELISA, respectively. Our experimental results showed that the immunized mice with the HIV-1 p24-Nef conjugated or mixed forms of flagellin led to increases in the proliferative responses and Th1 cytokine pattern. The conjugated form of vaccine led to increased CTL activity and a Th1 cytokine pattern of immune responses, as well as an IgM isotype of humoral responses in comparison with the mixed form. The flagellin-conjugated vaccine seems to be more potent in increasing vaccine immunogenicity.

Clustered epitopes within a new poly-epitopic HIV-1 DNA vaccine shows immunogenicity in BALB/c mice

Despite a huge number of studies towards vaccine development against human immunodeficiency virus-1, no effective vaccine has been approved yet. Thus, new vaccines should be provided with new formulations. Herein, a new DNA vaccine candidate encoding conserved and immunogenic epitopes from HIV-1 antigens of tat, pol, gag and env is designed and constructed. After bioinformatics analyses to find the best epitopes and their tandem, nucleotide sequence corresponding to the designed multiepitope was synthesized and cloned into pcDNA3.1+ vector. Expression of pcDNA3.1-tat/pol/gag/env plasmid was evaluated in HEK293T cells by RT-PCR and western-blotting. Seven groups of BALB/c mice were intramuscularly immunized three times either with 50, 100, 200 µg of plasmid in 2-week intervals or with similar doses of insert-free plasmid. Two weeks after the last injection, proliferation of T cells and secretion of IL4 and IFN-γ cytokines were evaluated using Brdu and ELISA methods, respectively. Results showed the proper expression of the plasmid in protein and mRNA levels. Moreover, the designed multiepitope plasmid was capable of induction of both proliferation responses as well as IFN-γ and IL-4 cytokine production in a considerable level compared to the control groups. Overall, our primary data warranted further detailed studies on the potency of this vaccine.

A peptide-based nanofibrous hydrogel as a promising DNA nanovector for optimizing the efficacy of HIV vaccine

This report shows that a nanovector composed of peptide-based nanofibrous hydrogel can condense DNA to result in strong immune responses against HIV. This nanovector can strongly activate both humoral and cellular immune responses to a balanced level rarely reported in previous studies, which is crucial for HIV prevention and therapy. In addition, this nanovector shows good biosafety in vitro and in vivo. Detailed characterizations show that the nanofibrous structure of the hydrogel is critical for the dramatically improved immune responses compared to existing materials. This peptide-based nanofibrous hydrogel shows great potential for efficacious HIV DNA vaccines and can be potentially used for delivering other vaccines and drugs.

Recombinant adenovirus expressing the haemagglutinin of Peste des petits ruminants virus (PPRV) protects goats against challenge with pathogenic virus; a DIVA vaccine for PPR

Peste des petits ruminants virus (PPRV) is a morbillivirus that can cause severe disease in sheep and goats, characterised by pyrexia, pneumo-enteritis, and gastritis. The socio-economic burden of the disease is increasing in underdeveloped countries, with poor livestock keepers being affected the most. Current vaccines consist of cell-culture attenuated strains of PPRV, which induce a similar antibody profile to that induced by natural infection. Generation of a vaccine that enables differentiation of infected from vaccinated animals (DIVA) would benefit PPR control and eradication programmes, particularly in the later stages of an eradication campaign and for countries where the disease is not endemic. In order to create a vaccine that would enable infected animals to be distinguished from vaccinated ones (DIVA vaccine), we have evaluated the immunogenicity of recombinant fowlpox (FP) and replication-defective recombinant human adenovirus 5 (Ad), expressing PPRV F and H proteins, in goats. The Ad constructs induced higher levels of virus-specific and neutralising antibodies, and primed greater numbers of CD8⁺ T cells than the FP-vectored vaccines. Importantly, a single dose of Ad-H, with or without the addition of Ad expressing ovine granulocyte macrophage colony-stimulating factor and/or ovine interleukin-2, not only induced strong antibody and cell-mediated immunity but also completely protected goats against challenge with virulent PPRV, 4 months after vaccination. Replication-defective Ad-H therefore offers the possibility of an effective DIVA vaccine.

Stimulation of IgY responses in gene gun immunized laying hens by combined administration of vector DNA coding for the target antigen Botulinum toxin A1 and for avian cytokine adjuvants

DNA immunization is a convenient and effective way of inducing a specific antibody response. In mammals, co-administration of vectors encoding immunostimulatory cytokines can enhance the humoral response resulting in elevated antibody titers. We therefore set out to investigate the effect using avian interleukin 1β (IL-1β) and avian interleukin 6 (IL-6) as genetic adjuvants when immunizing laying hens. A BoNT A1 holotoxoid DNA immunogen carrying two inactivating mutations was evaluated for its ability to induce a specific and sustained IgY antibody response. Both the holotoxoid and the cytokine sequences were codon-optimized. In vitro, the proteins were efficiently expressed in transfected HEK 293T cells and the cytokines were secreted into the culture supernatants. Whereas eggs from hens immunized via gene gun using a prime boost strategy showed no differences in their total IgY content, the specific αBoNT A1 response was slightly elevated up to 1.4× by the IL-1β adjuvant vector and increased by 3.8× by the IL-6 vector. Finally, although hens receiving the IL-1β adjuvant had laying capacities above the average, hens receiving the IL-6 adjuvant experienced laying problems.