Liposomal gD ectodomain (gD1-306) vaccine protects against HSV2 genital or rectal infection of female and male mice

Generation of oligomers of subunit vaccine candidate glycoprotein D of Herpes Simplex Virus-2 expressed in fusion with IgM Fc domain(s) in Escherichia coli: A strategy to enhance the immunogenicity of the antigen

Glycoprotein D (gD) of Herpes Simplex Virus-2 is used as an antigen in various anti-herpes subunit vaccines owing to its involvement in binding the host cell receptors for host infectivity. However, most of these monomeric protein based candidates have shown low immunogenicity in animal models. To enhance the immunogenicity of gD, a fresh approach of fusing its ectodomain with the Fc domain(s) of IgM has been adopted to oligomerize the viral antigen and to exploite the immune-modulating potential of IgM Fc. Six vaccine constructs, generated by fusing three gD-ectodomain-length-variants with the Ig µ-chain domain 4 (µCH4) and µCH3-CH4 fragment, were cloned in Escherichia coli using pET28b( +) vector. The vaccine proteins were expressed in the form of inclusion bodies (IBs) and were in vitro refolded into protein oligomers of high stoichiometries of ~ 15–24, with 70–80% refolding yields. The conformations of gD and Fc components of the refolded oligomers were analyzed by ELISA and CD spectroscopy and were found to be native-like. The sizes and profiles of the size-distribution of oligomers were determined by dynamic light scattering (DLS). The candidate C2 (gD-μCH3-CH4), showing the most compact oligomer size and uniform distribution of its particles was chosen as the suitable candidate for mice immunization studies to assess the immunogenicity of the antigen gD. The C2 oligomer stimulated a strong anti-gD humoral response with an antibody titer of 102,400 and a strong, biased Th1 immune response in C57BL/6 mice, indicating its potential as a strong immunogen which may serve as an effective vaccine candidate.

B cells are the predominant mediators of early systemic viral dissemination during rectal LCMV infection

Determining the magnitude of local immune response during mucosal exposure to viral pathogens is critical to understanding the mechanism of viral pathogenesis. We previously showed that vaginal inoculation of lymphocytic choriomeningitis virus (LCMV) fails to induce a robust innate immune response in the lower female reproductive tract (FRT), allowing high titer viral replication and a delay in T-cell-mediated viral control. Despite this immunological delay, LCMV replication remained confined mainly to the FRT and the draining iliac lymph node. Here, we show that rectal infection with LCMV triggers type I/III interferon responses, followed by innate immune activation and lymphocyte recruitment to the colon. In contrast to vaginal exposure, innate immunity controls LCMV replication in the colon, but virus rapidly disseminates systemically. Virus-induced inflammation promotes the recruitment of LCMV target cells to the colon followed by splenic viral dissemination by infected B cells, and to a lesser extent by CD8 T cells. These findings demonstrate major immunological differences between vaginal and rectal exposure to the same viral pathogen, highlighting unique risks associated with each of these common routes of sexual viral transmission.

Efficient production of recombinant glycoprotein D of herpes simplex virus type 2 in Pichia pastoris and its protective efficacy against viral challenge in mice

Herpes simplex virus type 2 (HSV-2) infection is the leading cause of genital ulcer disease and a significant public health concern. However, there are no approved vaccines available to prevent HSV-2 infection. The glycoprotein D (gD) of HSV-2 is the most important candidate antigen for vaccine development. In this study, a truncated form of gD (codons 1-340, gD_1-340) was produced as a secretory protein in the methylotrophic yeast Pichia pastoris. The recombinant gD_1-340 with a His₆ tag was purified to homogeneity by one-step affinity chromatography. Mice immunized with the recombinant gD_1-340 developed high levels of antigen-specific antibody responses with HSV-2 neutralizing activity. Immunization with the recombinant gD_1-340 conferred significant protection against lethal HSV-2 infection in mice. Moreover, measurement of the secretion of gD_1-340-specific cytokines demonstrated that the recombinant gD_1-340 induced mixed Th1/Th2 cellular immune responses. These findings indicated that P. pastoris-derived gD_1-340 represents a promising HSV-2 vaccine candidate with strong immunogenicity and prophylactic efficacy.

Some new nano-sized Cr(III), Fe(II), Co(II), and Ni(II) complexes incorporating 2-((E)-(pyridine-2-ylimino)methyl)napthalen-1-ol ligand: Structural characterization, electrochemical, antioxidant, antimicrobial, antiviral assessment and DNA interaction

To estimate the biological preference of synthetic small drugs towards DNA target, new metal based chemotherapeutic agents of nano-sized Cr(III), Fe(II), Co(II) and Ni(II) Schiff base complexes having N,N,O donor system were synthesized and thoroughly characterized by physic-chemical techniques. The redox behavior of the Cr(III), Fe(II) and Co(II) complex was investigated by electrochemical method using cyclic voltammetry. IR results proven that the tridentate binding of Schiff base ligand with metal center during complexation reflects the proposed structure. Magnetic and spectroscopic data give support to octahedral geometry for Cr(III) and Fe(II) complexes and tetrahedral geometry for Ni(II) and Co(II) complexes. The activation thermodynamic parameters, such as, E(⁎), ΔH(⁎), ΔS(⁎) and ΔG(⁎) are calculated using Coats-Redfern method by analyzing the TGA data. The particle size of the investigated metal complexes was estimated by TEM. In addition to, the interaction of the nanosized complexes with CT-DNA was estimated by electronic absorption, viscosity and gel electrophoresis. These techniques revealed that the complexes could bind to CT-DNA through intercalation mode. Moreover, the in vitro cytotoxic and antiviral activities of the nanosized complexes were checked against Herpes Simplex virus and Tobacco Mosaic viruses. Moreover, investigation of antioxidant activities of the new nanosized compounds was done by ABTS assay. Among the compounds tested, Fe(II) complex showed the strongest potent radical scavenging activity with percent of 58.60%. Furthermore, the antimicrobial bustle of the prepared compounds was screened against different types of bacteria and fungi and the results show that all metal complexes have superior activity than its free ligand.

A Novel Prime and Boost Regimen of HIV Virus-Like Particles with TLR4 Adjuvant MPLA Induces Th1 Oriented Immune Responses against HIV

HIV virus-like particles (VLPs) present the HIV envelope protein in its native conformation, providing an ideal vaccine antigen. To enhance the immunogenicity of the VLP vaccine, we sought to improve upon two components; the route of administration and the additional adjuvant. Using HIV VLPs, we evaluated sub-cheek as a novel route of vaccine administration when combined with other conventional routes of immunization. Of five combinations of distinct prime and boost sequences, which included sub-cheek, intranasal, and intradermal routes of administration, intranasal prime and sub-cheek boost (IN+SC) resulted in the highest HIV-specific IgG titers among the groups tested. Using the IN+SC regimen we tested the adjuvant VesiVax Conjugatable Adjuvant Lipid Vesicles (CALV) + monophosphoryl lipid A (MPLA) at MPLA concentrations of 0, 7.5, 12.5, and 25 μg/dose in combination with our VLPs. Mice that received 12.5 or 25 μg/dose MPLA had the highest concentrations of Env-specific IgG2c (20.7 and 18.4 μg/ml respectively), which represents a Th1 type of immune response in C57BL/6 mice. This was in sharp contrast to mice which received 0 or 7.5 μg MPLA adjuvant (6.05 and 5.68 μg/ml of IgG2c respectively). In contrast to IgG2c, MPLA had minor effects on Env-specific IgG1; therefore, 12.5 and 25 μg/dose of MPLA induced the optimal IgG1/IgG2c ratio of 1.3. Additionally, the percentage of germinal center B cells increased significantly from 15.4% in the control group to 31.9% in the CALV + 25 μg MPLA group. These mice also had significantly more IL-2 and less IL-4 Env-specific CD8⁺ T cells than controls, correlating with an increased percentage of Env-specific central memory CD4⁺ and CD8⁺ T cells. Our study shows the strong potential of IN+SC as an efficacious route of administration and the effectiveness of VLPs combined with MPLA adjuvant to induce Env specific Th1-oriented HIV-specific immune responses.

HSV-2 vaccine: current status and insight into factors for developing an efficient vaccine

Herpes simplex virus type 2 (HSV-2), a globally sexually transmitted virus, and also one of the main causes of genital ulcer diseases, increases susceptibility to HIV-1. Effective vaccines to prevent HSV-2 infection are not yet available, but are currently being developed. To facilitate this process, the latest progress in development of these vaccines is reviewed in this paper. A summary of the most promising HSV-2 vaccines tested in animals in the last five years is presented, including the main factors, and new ideas for developing an effective vaccine from animal experiments and human clinical trials. Experimental results indicate that future HSV-2 vaccines may depend on a strategy that targets mucosal immunity. Furthermore, estradiol, which increases the effectiveness of vaccines, may be considered as an adjuvant. Therefore, this review is expected to provide possible strategies for development of future HSV-2 vaccines.

The immunologic basis for severe neonatal herpes disease and potential strategies for therapeutic intervention

Herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2) infect a large proportion of the world's population. Infection is life-long and can cause periodic mucocutaneous symptoms, but it only rarely causes life-threatening disease among immunocompetent children and adults. However, when HSV infection occurs during the neonatal period, viral replication is poorly controlled and a large proportion of infants die or develop disability even with optimal antiviral therapy. Increasingly, specific differences are being elucidated between the immune system of newborns and those of older children and adults, which predispose to severe infections and reflect the transition from fetal to postnatal life. Studies in healthy individuals of different ages, individuals with primary or acquired immunodeficiencies, and animal models have contributed to our understanding of the mechanisms that control HSV infection and how these may be impaired during the neonatal period. This paper outlines our current understanding of innate and adaptive immunity to HSV infection, immunologic differences in early infancy that may account for the manifestations of neonatal HSV infection, and the potential of interventions to augment neonatal immune protection against HSV disease.

Immune response to ORF5a protein immunization is not protective against porcine reproductive and respiratory syndrome virus infection

Porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped RNA virus responsible for PRRS in swine, a disease with globally significant animal welfare and economic concerns. There is no specific treatment and variably effective immune protection. Molecular mechanisms responsible for virulence, pathogenesis and protective immune response remain poorly understood. These factors limit progress toward development of effective measures for prevention and treatment of PRRS. A novel PRRSV ORF5a protein, encoded in an open reading frame (ORF) that overlaps the major envelope glycoprotein GP5 ORF, was recently identified. Because ORF5a is highly conserved in diverse PRRSV isolates, is a structural protein in the virion, and elicits a specific antibody response in infected pigs, we investigated its potential role in immune protection against PRRSV infection. Pigs immunized with ORF5a protein had robust serologic responses. However, the antibodies did not neutralize virus, and immunity did not protect against challenge infection. We conclude from these findings that the ORF5a antibody response is neither neutralizing nor protective.

Delayed but effective induction of mucosal memory immune responses against genital HSV-2 in the absence of secondary lymphoid organs

To examine whether local immunization in the absence of secondary lymphoid organs (SLOs) could establish effective antiviral memory responses in the female genital tract, we examined immunity in the vaginal tracts of LTα-/- mice, LTα-/- SPL (splenectomized), and control C57BL/6 (WT) mice. All three groups of mice were immunized intravaginally (IVAG) with attenuated thymidine kinase-negative (TK(-)) Herpes simplex virus type 2 (HSV-2) and challenged 4-6 weeks later with wild-type (WT) HSV-2. Both groups of LTα-/- mice exhibited delayed viral clearance and prolonged genital pathology after immunization. Following IVAG WT HSV-2 challenge, LTα-/- and LTα-/- SPL mice had significantly lower levels of HSV-2-specific IgG and IgA in the vaginal secretions. Although the frequency of B and T cells in the vaginal mucosa was comparable or higher in both groups of LTα-/- mice, lower frequency of HSV-2-specific interferon-γ (IFNγ)-producing CD3+ T cells was seen after immunization and after challenge, compared with WT group. Despite this, immunized mice in all three groups showed complete sterile protection against IVAG WT HSV-2 challenge. These results show that even in the absence of SLOs, IVAG immunization generates effector memory immune responses at genital mucosa that can provide antiviral protection against subsequent viral exposures. This will inform new strategies to design mucosal vaccines against sexually transmitted infections.

Enhancing nicotine vaccine immunogenicity with liposomes

A major liability of existing nicotine vaccine candidates is the wide variation in anti-nicotine immune responses among clinical trial participants. In order to address this liability, significant emphasis has been directed at evaluating adjuvants and delivery systems that confer more robust potentiation of the anti-nicotine immune response. Toward that end, we have initiated work that seeks to exploit the adjuvant effect of liposomes, with or without Toll-like receptor agonist(s). The results of the murine immunization study described herein support the hypothesis that a liposomal nicotine vaccine formulation may provide a means for addressing the immunogenicity challenge.

In vitro antiviral activity of dermaseptin S(4) and derivatives from amphibian skin against herpes simplex virus type 2

Herpes simplex virus (HSV) infections have become a public health problem worldwide. The emergence of acyclovir-resistant viral strains and the failure of vaccination to prevent herpetic infections have prompted the search for new antiviral drugs. Accordingly, the present study was undertaken to synthesize chemically and evaluate Dermaseptin S(4) (S(4)), an anti-microbial peptide derived from amphibian skin, and its derivatives in terms of anti-herpetic activity. The effects of biochemical modifications on their antimicrobial potential were also investigated. The peptides were incubated together with HSV-2 on target cells under various conditions, and the antiviral effects were examined via a cell metabolic labeling method. The findings revealed that DS(4) derivatives elicited concentration-dependent antiviral activity at micromole concentrations. The biochemical modifications of S(4) allowed for the reduction of peptide cytotoxicity without altering antiviral activity. Dermaseptins were added at different times during the viral cycle to investigate the mode of antiviral action. At the highest non-cytotoxic concentrations, most of the tested derivatives were noted to exhibit high antiviral activity particularly when pre-incubated with free herpes viruses prior to infection. Among these peptides, K(4)K(20)S(4) exhibited the highest antiviral activity against HSV-2 sensitive and resistant strains. Interestingly, the antiviral activity of K(4)K(20)S(4) was effective on both acyclovir-resistant and -sensitive viruses. The findings indicate that K(4)K(20)S(4) can be considered a promising candidate for future application as a therapeutic virucidal agent for the treatment of herpes viruses.

Herpes simplex virus-2 in the genital mucosa: insights into the mucosal host response and vaccine development

PURPOSE OF REVIEW

Herpes simplex virus (HSV)-2 is the predominant cause of genital herpes and has been implicated in HIV infection and transmission. Thus far, vaccines developed against HSV-2 have been clinically ineffective in preventing infection. This review aims to summarize the innate and adaptive immune responses against HSV-2 and examines the current status of vaccine development.

RECENT FINDINGS

Both innate and adaptive immune responses are essential for an effective primary immune response and the generation of immunity. The innate response involves Toll-like receptors, natural killer cells, plasmacytoid dendritic cells, and type I, II, and III interferons. The adaptive response requires a balance between CD4+ and CD8+ T-cells for optimal viral clearance. T-regulatory cells may be involved, although their exact function has yet to be determined. Current vaccine development involves the use of HSV-2 peptides or attenuated/replication-defective HSV-2 to generate adaptive anti-HSV-2 immune responses, however the generation of innate responses may also be an important consideration.

SUMMARY

Although vaccine development has primarily focused on the adaptive response, arguments for innate involvement are emerging. A greater understanding of the innate and adaptive processes underlying the response to HSV-2 infection will provide the foundation for the development of an effective vaccine.

Characterization of the murine Th2 response to immunization with liposomal M2e influenza vaccine

While the current influenza vaccine strategy is dependent on eliciting neutralizing antibodies to the hemagglutinin (H or HA) surface glycoprotein, antigenic drifts and occasional antigenic shifts necessitate constant surveillance and annual updates to the vaccine components. The ectodomain of the matrix 2 (M2e) channel protein has been proposed as a universal vaccine candidate, although it has not yet been shown to elicit neutralizing antibodies. Utilizing a liposome-based vaccine technology, an M2e vaccine (L-M2e-HD/MPL) was tested and shown to stimulate the production of anti-M2e antibodies which precipitated with whole virus and inhibited viral cell lysis by multiple type A strains of influenza virus using a novel in vitro assay. The anti-M2e antibodies also conferred complete protection following passive transfer from L-M2e-HD/MPL vaccinated mice to naïve mice challenged with H1N1 virus. Significantly higher levels of IL-4 compared to IFN-γ were secreted by the splenocytes of L-M2e-HD/MPL vaccinated mice incubated with M2e. In addition, depletion of CD4 cells or CD4 cells plus CD8 cells from L-M2e-HD/MPL vaccinated mice using monoclonal antibodies markedly decreased the level of protection of the vaccine when compared to just CD8 depletion of L-M2e-HD/MPL vaccinated mice. These results suggest that the protective immune response elicited by this vaccine is mediated primarily by a Th2 mechanism.