Protective Cellular Immunity Research Articles

Unrelated respiratory infections compromise established cellular immunity by promoting apoptosis of pre-existing lung-resident memory CD8 T cells

Abstract Lung-resident memory T cells (lung TRM) are critical for protective heterosubtypic immunity against influenza viruses. However, the efficacy of cellular immunity against respiratory pathogens such as influenza wanes over time due to the gradual loss of flu-specific lung TRM. One possible mechanism for this decline is frequent exposure to environmental and biological insults resulting in localized inflammation that promotes the death of established lung TRM. We investigated whether unrelated infections could exacerbate the loss of pre-existing, flu-specific lung TRM and reduce the efficacy of cellular immunity to subsequent influenza challenge. Infection of influenza-immune mice with Sendai virus, an unrelated murine parainfluenza virus, resulted in significantly higher viral titers and greater morbidity following influenza challenge compared to PBS-treated controls. This loss of protective cellular immunity corresponded to a significant decrease in the number of pre-existing flu-specific lung CD8 TRM compared to PBS controls due to increased apoptosis. This loss of pre-existing lung TRM following Sendai infection was not due to competition for limited resources or tissue niches between flu- and Sendai-specific lung TRM. Sendai infection had no impact on the number of systemic flu-specific memory CD8 T cells in the spleen. The loss of lung TRM required a respiratory infection, as LCMV infection and intranasal delivery of TLR agonists did not significantly reduce the number of pre-existing flu-specific lung CD8 TRM. Together, these data suggest that tissue damage induced by unrelated respiratory infections can promote the loss of pre-existing lung TRM and compromise cellular immunity against respiratory pathogens.

Chemokine Receptor 7 Is Essential for Coxiella burnetii Whole-Cell Vaccine-Induced Cellular Immunity but Dispensable for Vaccine-Mediated Protective Immunity.

Protective immunity against Coxiella burnetii infection is conferred by vaccination with virulent (PI-WCV), but not avirulent (PII-WCV) whole-cell inactivated bacterium. The only well-characterized antigenic difference between virulent and avirulent C. burnetii is they have smooth and rough lipopolysaccharide (LPS), respectively. Mice were vaccinated with PI-WCV and PII-WCV. Humoral and cellular responses were evaluated using protein chip microarrays and ELISpots, respectively. Dendritic cell (DC) maturation after stimulation with PI-WVC and PII-WVC was evaluated using flow cytometry. Vaccine-challenge studies were performed to validate the importance of the receptor CCR7. Other than specific antibody response to PI-LPS, similar antibody profiles were observed but IgG titers were significantly higher after vaccination with PI-WCV. Furthermore, higher frequency of antigen-specific CD4+ T cells was detected in mice immunized with PI-WCV. PI-WCV-stimulated DCs displayed significantly higher levels of CCR7 and migratory ability to secondary lymphoid organs. Challenge-protection studies in wild-type and CCR7-deficient mice confirmed that CCR7 is critical for PI-WCV-induced cellular immunity. PI-WVC stimulates protective immunity to C. burnetii in mice through stimulation of migratory behavior in DCs for protective cellular immunity. Additionally, the humoral immune response to LPS is an important component of protective immunity.

Antigens reversibly conjugated to a polymeric glyco-adjuvant induce protective humoral and cellular immunity.

Fully effective vaccines for complex infections must elicit a diverse repertoire of antibodies (humoral immunity) and CD8+ T-cell responses (cellular immunity). Here, we present a synthetic glyco-adjuvant named p(Man-TLR7), which, when conjugated to antigens, elicits robust humoral and cellular immunity. p(Man-TLR7) is a random copolymer composed of monomers that either target dendritic cells (DCs) via mannose-binding receptors or activate DCs via Toll-like receptor 7 (TLR7). Protein antigens are conjugated to p(Man-TLR7) via a self-immolative linkage that releases chemically unmodified antigen after endocytosis, thus amplifying antigen presentation to T cells. Studies with ovalbumin (OVA)-p(Man-TLR7) conjugates demonstrate that OVA-p(Man-TLR7) generates greater humoral and cellular immunity than OVA conjugated to polymers lacking either mannose targeting or TLR7 ligand. We show significant enhancement of Plasmodium falciparum-derived circumsporozoite protein (CSP)-specific T-cell responses, expansion in the breadth of the αCSP IgG response and increased inhibition of sporozoite invasion into hepatocytes with CSP-p(Man-TLR7) when compared with CSP formulated with MPLA/QS-21-loaded liposomes-the adjuvant used in the most clinically advanced malaria vaccine. We conclude that our antigen-p(Man-TLR7) platform offers a strategy to enhance the immunogenicity of protein subunit vaccines.

The Combined Use of Melatonin and an Indoleamine 2,3-Dioxygenase-1 Inhibitor Enhances Vaccine-Induced Protective Cellular Immunity to HPV16-Associated Tumors.

Immunotherapy has become an important ally in the fight against distinct types of cancer. However, the metabolic plasticity of the tumor environment frequently influences the efficacy of therapeutic procedures, including those based on immunological tools. In this scenario, immunometabolic adjuvants arise as an alternative toward the development of more efficient cancer therapies. Here we demonstrated that the combination of melatonin, a neuroimmunomodulator molecule, and an indoleamine 2,3-dioxygenase (IDO) inhibitor (1-methyl-DL-tryptophan, DL-1MT) improves the efficacy of an immunotherapy (gDE7) targeting human papillomavirus (HPV)-associated tumors. Melatonin or IDO inhibitors (D-1MT and DL-1MT) directly reduced proliferation, migration, adhesion and viability of a tumor cell line (TC-1), capable to express the HPV-16 E6 and E7 oncoproteins, but could not confer in vivo antitumor protection effects. Nonetheless, combination of gDE7 with melatonin or D-1MT or DL-1MT enhanced the antitumor protective immunity of gDE7-based vaccine in mice. Notably, expression of IDO1 in stromal cells and/or immune cells, but not in tumor cells, inhibited the antitumor effects of the gDE7, as demonstrated in IDO1-deficient mice. Finally, co-administration of gDE7, melatonin and DL-1MT further improved the protective antitumor effects and the numbers of circulating E7-specific CD8+ T cells in mice previously transplanted with TC-1 cells. The unprecedented combination of melatonin and IDO inhibitors, as immunometabolic adjuvants, thus, represents a new and promising alternative for improving the efficacy of immunotherapeutic treatments of HPV-associated tumors.

Induction of influenza-specific local CD8 T-cells in the respiratory tract after aerosol delivery of vaccine antigen or virus in the Babraham inbred pig.

There is increasing evidence that induction of local immune responses is a key component of effective vaccines. For respiratory pathogens, for example tuberculosis and influenza, aerosol delivery is being actively explored as a method to administer vaccine antigens. Current animal models used to study respiratory pathogens suffer from anatomical disparity with humans. The pig is a natural and important host of influenza viruses and is physiologically more comparable to humans than other animal models in terms of size, respiratory tract biology and volume. It may also be an important vector in the birds to human infection cycle. A major drawback of the current pig model is the inability to analyze antigen-specific CD8+ T-cell responses, which are critical to respiratory immunity. Here we address this knowledge gap using an established in-bred pig model with a high degree of genetic identity between individuals, including the MHC (Swine Leukocyte Antigen (SLA)) locus. We developed a toolset that included long-term in vitro pig T-cell culture and cloning and identification of novel immunodominant influenza-derived T-cell epitopes. We also generated structures of the two SLA class I molecules found in these animals presenting the immunodominant epitopes. These structures allowed definition of the primary anchor points for epitopes in the SLA binding groove and established SLA binding motifs that were used to successfully predict other influenza-derived peptide sequences capable of stimulating T-cells. Peptide-SLA tetramers were constructed and used to track influenza-specific T-cells ex vivo in blood, the lungs and draining lymph nodes. Aerosol immunization with attenuated single cycle influenza viruses (S-FLU) induced large numbers of CD8+ T-cells specific for conserved NP peptides in the respiratory tract. Collectively, these data substantially increase the utility of pigs as an effective model for studying protective local cellular immunity against respiratory pathogens.

Cellular stress mediated by the local microenvironment regulates the homeostatic loss of tissue-resident memory CD8 T cells in different compartments of the lung

Abstract Lung-resident memory T cells (lung TRM) are important for protective heterosubtypic immunity against influenza viruses; however, the efficacy of this cellular immunity wanes over time. To better understand the mechanisms leading to the decline of protective cellular immunity, we investigated the long-term maintenance of airway and parenchyma lung TRM. In contrast to circulating flu-specific memory T cells and TRM in other tissues, lung TRM numbers in the airways and parenchyma steadily decline for several months following influenza infection. All flu-specific lung TRM decline at similar rates regardless of expression of the tissue residency markers CD69 and CD103. Parabiosis experiments demonstrate that established lung TRM in the airways or parenchyma do not freely interchange with circulating memory T cells. Thus the gradual loss of these cells is likely due to increased cell death in the tissue. In support of this, airway and parenchyma lung TRM show increased apoptosis compared to systemic flu-specific memory T cells during homeostasis. To identify epigenetic and transcriptional programs specific to lung TRM, we performed parallel RNA-seq and ATAC-seq on flu-specific memory CD8 T cells from the airways, lung parenchyma, and spleen. We found that lung TRM populations have increased expression of genes associated with cellular stress, and airway TRM in particular have a signature associated with amino acid starvation and ER stress. Finally, intratracheal transfer experiments determined that the airway environment was sufficient to program the lung TRM transcriptional signature. Together, these data show that the decline of lung TRM is a direct result of cellular stresses driven by the lung microenvironment.

Імуногістохімічна характеристика субпопуляцій лімфоцитів селезінки голубів та курей

<p>The article is devoted to the study of immunohistochemical features of the spleen of birds based on the detection and morphometric calculation of clusters of the T- and B-lymphocytes. For the research, the selection of the spleen is performed at the stage of morphofunctional maturity in clinically healthy sexually mature birds of both sexes in the ratio 1: 1: blue pigeons (age 10-14 months), chickens of domestic breeds of Poltava clay (age 19-20 weeks). The slices of material are fixed in 10-12% chilled solution of neutral formalin, embedded in paraffin. Histological sections made on a microtome MS-2 and have a thickness not exceeding 5 micrometres. The mouse monoclonal antibodies of the Danish firm DAKO are used to detect and study subpopulations of lymphocytes. Morphometric studies are performed under light microscopy (Microscope Biolam-Lomo and Micros MC-50). The microphotography of histological preparations was carried out with CAM V 200 video camera. It is mounted on a microscope Micros MC-50. Subpopulations of lymphocytes CD4 +, CD8 +, СD19 +, СD20 + were detected in the red and white pulp of the spleen of pigeons and chickens, they are situated singly and diffusely, more often formed chains or aggregations. The CD4 + cells in pigeons and chickens are dominated in lymphoid sheaths near the vessels, amounted the 56.63 ± 4.03 pieces per conditional unit of area and 85.71 ± 6.09 pieces per conditional unit of area respectively. The populations of CD8 + cells are also predominated in lymphoid sheaths near the vessels, but their number was smaller than the CD4+ population by 1.81 times in chickens and by 2.36 times in pigeons. In the red pulp, CD4 + cells are occupied 7.67% of the total population of the splenic cells in chickens and 5.99% in pigeons. The CD8 + cell in the red pulp are less concentrated: 2,8% and 4,45% respectively. The index of immunoregulation of the spleen of chickens was 1.85, and the pigeons – 2.0. B-lymphocytes (cluster CD19 +, CD20 +) are concentrated in the B-dependent zone of the spleen – the lymphoid nodules. Most of the CD20 + cells are in lymphoid nodules of chickens (77.27%), in pigeons this indicator is 61.66%. Cells of CD19 + in lymphoid nodes are occupied approximately the same relative square of pigeons and chickens from their total amount in the pulp – 74.14% and 76.60%. The total number of T-lymphocytes (the population of CD4 +, CD8 +) are prevailed almost by two times in chickens, B-lymphocytes (populations CD19 +, CD20 +) in pigeons – by 1,6 times. In the spleen of pigeons and chickens are developed both humoral and cellular immune protection.</p>

Protective cellular immunity generated by cross-presenting recombinant overlapping peptide proteins.

Priming of naive CD8+ and CD4+ T cells by dendritic cells (DCs) requires effective antigen presentation on both MHC class I and II molecules. We have developed a novel technology to use recombinant overlapping peptides (ROP) that stimulate both CD8+ and CD4+ T cell immune responses. The single chain protein of a ROP is made up of overlapping peptides linked by the target sequence (LRMK) for cathepsin S, a protease found in the endosomes of DCs. We designed synthetic genes encoding ROPs derived from ovalbumin (OVA), tuberculosis protein (CFP10-ESAT6), human papilloma virus (HPV) protein (E7) and survivin, a protein commonly over-expressed in tumour cells. An epitope from ROP-OVA was cross-presented and detected by a CD8+ T cell receptor-like antibody (TCR like Ab). Human DCs pulsed with ROP-survivin activated CD8+ T cells. CD4-low PBMCs from HIV and TB co-infected patients recognized ROP-CFP10-ESAT6 compared to a soluble form of the antigen. Immunization of mice with ROP-survivin or ROP-HPV-E7 generated specific cellular immune responses and protected mice from inoculation with melanoma B16 cells expressing survivin or HPV-E7 proteins. Together these data provide evidence to support ROP as a central component of a new platform for therapeutic vaccines and diagnostics.

Vaccination of adult patients receiving hematopoietic stem cell transplantation: Perspective of Costa Rica

In this article the present recommendations for immunization of adult patients who received hematopoietic stem cell transplantation -a common procedure in therapy of many types of hematological diseases and serious inborn defects of the immune system- are reviewed and discussed. Patients that undergo this kind of transplantation procedure exhibit, compared to the general population, an elevated susceptibility of immune-preventable infections, due to loss of the humoral and cellular protective immunity. A revaccination strategy for transplanted patients can result in a significant diminution of morbidity and mortality related to the treatment of these diseases. Few data are published about the duration and magnitude of the vaccination response in this specific population of patients. Moreover, deviation from international guidelines recommendations for post-transplant immune prophylaxis can be observed frequently, partly as a result of the absence of specific vaccines in some countries. Multiple factors as intensity of the pharmacologic immune suppression, myeloablative regimen, administration of monoclonal and polyclonal antibodies, duration of the post-transplant period or the presence of graft-versus-host disease (GVHD), can influence the immune response and establish special considerations for certain biological agents, as observed in case of living attenuated virus composed vaccines. This conditions are responsible for the fact that an optimal time point for vaccination of transplanted patients remains not clearly defined. More specific studies about the underlying immunological mechanisms during immunocompromised periods are necessary to understand better the immunogenicity and security of existing vaccines. The development of innovative vaccines as well can induce certain advances in the post-transplant therapy.

Saponin-based adjuvants induce cross-presentation in dendritic cells by intracellular lipid body formation.

Saponin-based adjuvants (SBAs) are being used in animal and human (cancer) vaccines, as they induce protective cellular immunity. Their adjuvant potency is a factor of inflammasome activation and enhanced antigen cross-presentation by dendritic cells (DCs), but how antigen cross-presentation is induced is not clear. Here we show that SBAs uniquely induce intracellular lipid bodies (LBs) in the CD11b+ DC subset in vitro and in vivo. Using genetic and pharmacological interference in models for vaccination and in situ tumour ablation, we demonstrate that LB induction is causally related to the saponin-dependent increase in cross-presentation and T-cell activation. These findings link adjuvant activity to LB formation, aid the application of SBAs as a cancer vaccine component, and will stimulate development of new adjuvants enhancing T-cell-mediated immunity.

Vaccination to Prevent Cancer.

Vaccines stimulate the immune system, mimicking infectious attacks and thereby promoting the development of protective antibodies and/or cellular immunity so that the body is immune to infection when live native infections attack. Some of these infections are associated with cancer-causing changes in the body; thus some vaccines may help prevent cancer.

Immunity Elicited by an Experimental Vaccine Based on Recombinant Flagellin-Porcine Circovirus Type 2 Cap Fusion Protein in Piglets.

In a recent study, we reported that a recombinant protein from fusion expression of flagellin to porcine circovirus type 2 (PCV2) Cap induced robust humoral and cell-mediated immunity that afforded full protection for PCV2 infection using BALB/c mice. Here, we further evaluated the immunogenicity and protection of the recombinant protein using specific pathogen free (SPF) pigs. Twenty-five 3-week-old piglets without passively acquired immunity were divided into 5 groups. All piglets except negative controls were challenged with a virulent PCV2 at 21 days after booster vaccination and necropsied at 21 days post-challenge. Vaccination of piglets with the recombinant protein without adjuvant induced strong humoral and cellular immune responses as observed by high levels of PCV2-specific IgG antibodies and neutralizing antibodies, as well as frequencies of PCV2-specific IFN-γ-secreting cells that conferred good protection against PCV2 challenge, with significant reduced PCV2 viremia, mild lesions, low PCV2 antigen-positive cells, as well as improved body weight gain, comparable to piglets vaccinated with a commercial PCV2 subunit vaccine. These results further demonstrated that the recombinant flagellin-Cap fusion protein is capable of inducing solid protective humoral and cellular immunity when administered to pigs, thereby becoming an effective PCV2 vaccine candidate for control of PCV2 infection.

Leishmaniasis and IFN-γ dependent chemokines.

Leishmaniasis is a disease caused by Leishmania and spread by the bite of certain types of sandflies. Leishmaniasis affects as many as 12 million people worldwide, with 2 million new cases each year. Leishmania infection, and Leishmaniasis, following occupational exposure has been also reported. Three forms of Leishmaniasis are known: a- Cutaneous Leishmaniasis (CL); b-Mucocutaneous Leishmaniasis; c- Visceral Leishmaniasis (VL). The visceral form of Leishmaniasis has an estimated incidence of 500,000 new cases. Cytokines and chemokines primarily orchestrate leukocyte recruitment to the areas of leishmania infection, and they are critical mediators of immune and inflammatory responses, in particular of the induction of Interferon (IFN)-γ and IFN-γ dependent chemokines. Skin biopsies from patients with CL showed higher expression of interferon-γ-induced protein (IP)-10, in recent lesions than in late lesions. Following L. braziliensis infection, enhanced expression of IP-10 and its receptor, chemokine C-X-C receptor (CXCR) 3, was predominantly detected in CD14(+) monocyte; this may contribute to disease severity by increasing cellular recruitment. It has been shown that IP-10 renders protection against VL, and it is associated with a strong host-protective T helper cell (Th)1 immune response. High clinical scores were positively correlated with IP-10 expression. Furthermore IP-10 is critical for rendering a protective cellular immunity during soluble leishmanial antigen (SLA) pulsed-CpG-ODN stimulated dendritic cells (SLA-CpG-DCs) vaccination that confers protection against L. donovani infection. Further studies are needed to evaluate IP-10 in Leishmaniosis, and to evaluate it as a potential therapeutic target.

Using MHC Molecules to Define a Chlamydia T Cell Vaccine.

Vaccines based on humoral immunity alone are unlikely to protect against infections caused by intracellular pathogens and today's most pressing infectious diseases of public health importance are caused by intracellular infections that include tuberculosis, malaria, HIV/AIDS, and others such as Chlamydia trachomatis. For these infections, vaccines that induce cellular immune responses are essential. Major impediments in developing such vaccines include difficulty in identifying relevant T cell antigens and delivering them in ways that elicit protective cellular immunity. Genomics and proteomics now provide tools to allow unbiased empirical identification of candidate T cell antigens. This approach represents an advance on bioinformatic searches for candidate T cell antigens. This chapter discusses an immunoproteomic approach we have used to identify Chlamydia T cell antigens. We further discuss how these T cell antigens can be developed into a human vaccine.

ID: 8: Innate immune defense against influenza virus infection

The mucosal surfaces represent major sites of entry for numerous infectious agents. Consequently, the vast mucosal surfaces are intricately lined with cells and lymphoid organs specialized in providing protective antibody and cellular immunity. Our laboratory’s goal is to understand how immunity is initiated and maintained at the mucosal surfaces that serve as natural portals of entry for pathogens of significant health concerns in the world. In this study, we focused on understanding how viruses are recognized by the innate immune system and how that information is used to generate protective immunity. The myxovirus resistance protein 1 (Mx1) is a dynamin-like GTPase that blocks primary transcription of influenza presumably by binding to viral nucleoproteins. Many inbred laboratory mouse strains have mutations in the Mx1 gene including the C57BL/6 mice. By using mice that have intact Mx1, we demonstrate the critical role of innate sensors in viral control. Further, we reveal a lethal consequence of triggering caspase-1 activation in the absence of innate resistance. Therefore, our results demonstrate that caspase-1 in the absence of antiviral resistance can trigger lethal disease and such conditions may underlie vulnerability to IAV disease in humans.

Antigen expression determines adenoviral vaccine potency independent of IFN and STING signaling.

Recombinant adenoviral vectors (rAds) are lead vaccine candidates for protection against a variety of pathogens, including Ebola, HIV, tuberculosis, and malaria, due to their ability to potently induce T cell immunity in humans. However, the ability to induce protective cellular immunity varies among rAds. Here, we assessed the mechanisms that control the potency of CD8 T cell responses in murine models following vaccination with human-, chimpanzee-, and simian-derived rAds encoding SIV-Gag antigen (Ag). After rAd vaccination, we quantified Ag expression and performed expression profiling of innate immune response genes in the draining lymph node. Human-derived rAd5 and chimpanzee-derived chAd3 were the most potent rAds and induced high and persistent Ag expression with low innate gene activation, while less potent rAds induced less Ag expression and robustly induced innate immunity genes that were primarily associated with IFN signaling. Abrogation of type I IFN or stimulator of IFN genes (STING) signaling increased Ag expression and accelerated CD8 T cell response kinetics but did not alter memory responses or protection. These findings reveal that the magnitude of rAd-induced memory CD8 T cell immune responses correlates with Ag expression but is independent of IFN and STING and provide criteria for optimizing protective CD8 T cell immunity with rAd vaccines.

Mechanistic insight into the TH1-biased immune response to recombinant subunit vaccines delivered by probiotic bacteria-derived outer membrane vesicles.

Recombinant subunit vaccine engineering increasingly focuses on the development of more effective delivery platforms. However, current recombinant vaccines fail to sufficiently stimulate protective adaptive immunity against a wide range of pathogens while remaining a cost effective solution to global health challenges. Taking an unorthodox approach to this fundamental immunological challenge, we isolated the TLR-targeting capability of the probiotic E. coli Nissle 1917 bacteria (EcN) by engineering bionanoparticlate antigen carriers derived from EcN outer membrane vesicles (OMVs). Exogenous model antigens expressed by these modified bacteria as protein fusions with the bacterial enterotoxin ClyA resulted in their display on the surface of the carrier OMVs. Vaccination with the engineered EcN OMVs in a BALB/c mouse model, and subsequent mechanism of action analysis, established the EcN OMV’s ability to induce self-adjuvanted robust and protective humoral and TH1-biased cellular immunity to model antigens. This finding appears to be strain-dependent, as OMV antigen carriers similarly engineered from a standard K12 E. coli strain derivative failed to generate a comparably robust antigen-specific TH1 bias. The results demonstrate that unlike traditional subunit vaccines, these biomolecularly engineered “pathogen-like particles” derived from traditionally overlooked, naturally potent immunomodulators have the potential to effectively couple recombinant antigens with meaningful immunity in a broadly applicable fashion.

Priming of CD8(+) T Cell Responses to Liver Stage Malaria Parasite Antigens.

While the role of malaria parasite-specific memory CD8+ T cells in the control of exo-erythrocytic stages of malaria infection is well documented and generally accepted, a debate is still ongoing regarding both the identity of the anatomic site where the activation of naive pathogen-specific T cells is taking place and contribution of different antigen-presenting cells (APCs) into this process. Whereas some studies infer a role of professional APCs present in the lymph nodes draining the site of parasite injection by the mosquito, others argue in favor of the liver as a primary organ and hepatocytes as stimulators of naïve parasite-specific T cell responses. This review aims to critically analyze the current knowledge and outline new lines of research necessary to understand the induction of protective cellular immunity against the malaria parasite.

A single intramuscular vaccination of mice with the HSV-1 VC2 virus with mutations in the glycoprotein K and the membrane protein UL20 confers full protection against lethal intravaginal challenge with virulent HSV-1 and HSV-2 strains.

Herpes Simplex Virus type-1 (HSV-1) and type-2 (HSV-2) establish life-long infections and cause significant orofacial and genital infections in humans. HSV-1 is the leading cause of infectious blindness in the western world. Currently, there are no available vaccines to protect against herpes simplex infections. Recently, we showed that a single intramuscular immunization with an HSV-1(F) mutant virus lacking expression of the viral glycoprotein K (gK), which prevents the virus from entering into distal axons of ganglionic neurons, conferred significant protection against either virulent HSV-1(McKrae) or HSV-2(G) intravaginal challenge in mice. Specifically, 90% of the mice were protected against HSV-1(McKrae) challenge, while 70% of the mice were protected against HSV-2(G) challenge. We constructed the recombinant virus VC2 that contains specific mutations in gK and the membrane protein UL20 preventing virus entry into axonal compartments of neurons, while allowing efficient replication in cell culture, unlike the gK-null virus, which has a major defect in virus replication and spread. Intramuscular injection of mice with 107 VC2 plaque forming units did not cause any significant clinical disease in mice. A single intramuscular immunization with the VC2 virus protected 100% of mice against lethal intravaginal challenge with either HSV-1(McKrae) or HSV-2(G) viruses. Importantly, vaccination with VC2 produced robust cross protective humoral and cellular immunity that fully protected vaccinated mice against lethal disease. Quantitative PCR did not detect any viral DNA in ganglionic tissues of vaccinated mice, while unvaccinated mice contained high levels of viral DNA. The VC2 virus may serve as an efficient vaccine against both HSV-1 and HSV-2 infections, as well as a safe vector for the production of vaccines against other viral and bacterial pathogens.

Polarized immune responses modulated by layered double hydroxides nanoparticle conjugated with CpG

Modulation of the immune response is an important step in the induction of protective humoral and cellular immunity against pathogens. In this study, we investigated the possibility of using a nanomaterial conjugated with the toll-like receptor (TLR) ligand CpG to modulate the immune response towards the preferred polarity. MgAl-layered double hydroxide (LDH) nanomaterial has a very similar chemical composition to Alum, an FDA approved adjuvant for human vaccination. We used a model antigen, ovalbumin (OVA) to demonstrate that MgAl-LDH had comparable adjuvant activity to Alum, but much weaker inflammation. Conjugation of TLR9 ligand CpG to LDH nanoparticles significantly enhanced the antibody response and promoted a switch from Th2 toward Th1 response, demonstrated by a change in the IgG2a:IgG1 ratio. Moreover, immunization of mice with CpG-OVA-conjugated LDH before challenge with OVA-expressing B16/F10 tumor cells retarded tumor growth. Together, these data indicate that LDH nanomaterial can be used as an immune adjuvant to promote Th1 or Th2 dominant immune responses suitable for vaccination purposes.