CPG 7909 adjuvant improves hepatitis B virus vaccine seroprotection in antiretroviral-treated HIV-infected adults

Identification of novel T-cell epitopes on monkeypox virus and development of multi-epitopes vaccine using immunoinformatics approaches

Monkeypox virus (MPV) is closely related to the smallpox virus, and previous data from Africa suggest that the smallpox vaccine (VARV) is at least 85% effective in preventing MPV. No multi-epitope vaccine has yet been developed to prevent MPV infection. In this work, we used in silico structural biology and advanced immunoinformatic strategies to design a multi-epitope subunit vaccine against MPV infection. The designed vaccine sequence is adjuvanted with CpG-ODN and includes HTL/CTL epitopes for similar proteins between vaccinia virus (VACV) that induced T-cell production in vaccinated volunteers and the first draft sequence of the MPV genome associated with the suspected outbreak in several countries, May 2022. In addition, the specific binding of the modified vaccine and the immune Toll-like receptor 9 (TLR9) was estimated by molecular interaction studies. Strong interaction in the binding groove as well as good docking scores confirmed the stringency of the modified vaccine. The stability of the interaction was confirmed by a classical molecular dynamics simulation and normal mode analysis. Then, the immune simulation also indicated the ability of this vaccine to induce an effective immune response against MPV. Codon optimization and in silico cloning of the vaccine into the pET-28a (+) vector also showed its expression potential in the E. coli K12 system. The promising data obtained from the various in silico studies indicate that this vaccine is effective against MPV. However, additional in vitro and in vivo studies are still needed to confirm its efficacy.Communicated by Ramaswamy H. Sarma.

Immunological and Clinical Responses to Vaccinations among Adults Living with HIV

People living with human immunodeficiency virus (HIV) are at higher risk of morbidity and mortality due to vaccine-preventable diseases. At the same time, they are less likely to respond to vaccinations, and might have a higher rate of vaccine adverse event and faster waning of protective effect. International and national guidelines emphasize the importance of vaccinating people living with HIV against respiratory system disease pathogens including seasonal influenza, Streptococcus pneumoniae, and COVID-19, as well as against sexually transmitted infections, i.e., Hepatitis A and B (HAV, HBV) and human papillomavirus (HPV). This narrative review aims to provide a comprehensive examination of the current knowledge regarding the immune and clinical responses elicited by vaccinations in the older adult population living with HIV.

Revolutionizing medicine with toll-like receptors: A path to strengthening cellular immunity

Toll-like receptors play a vital role in cell-mediated immunity, which is crucial for the immune system's defense against pathogens and maintenance of homeostasis. The interaction between toll-like-receptor response and cell-mediated immunity is complex and essential for effectively eliminating pathogens and maintaining immune surveillance. In addition to pathogen recognition, toll-like receptors serve as adjuvants in vaccines, as molecular sensors, and recognize specific patterns associated with pathogens and danger signals. Incorporating toll-like receptor ligands into vaccines can enhance the immune response to antigens, making them potent adjuvants. Furthermore, they bridge the innate and adaptive immune systems and improve antigen-presenting cells' capacity to process and present antigens to T cells. The intricate signaling pathways and cross-talk between toll-like-receptor and T cell receptor (TCR) signaling emphasize their pivotal role in orchestrating effective immune responses against pathogens, thus facilitating the development of innovative vaccine strategies. This article provides an overview of the current understanding of toll-like receptor response and explores their potential clinical applications. By unraveling the complex mechanisms of toll-like-receptor signaling, we can gain novel insights into immune responses and potentially develop innovative therapeutic approaches. Ongoing investigations into the toll-like-receptor response hold promise in the future in enhancing our ability to combat infections, design effective vaccines, and improve clinical outcomes.

Adjuvant physiochemistry and advanced nanotechnology for vaccine development

Vaccines comprising innovative adjuvants are rapidly reaching advanced translational stages, such as the authorized nanotechnology adjuvants in mRNA vaccines against COVID-19 worldwide, offering new strategies to effectively combat diseases threatening human health. Adjuvants are vital ingredients in vaccines, which can augment the degree, extensiveness, and longevity of antigen specific immune response. The advances in the modulation of physicochemical properties of nanoplatforms elevate the capability of adjuvants in initiating the innate immune system and adaptive immunity, offering immense potential for developing vaccines against hard-to-target infectious diseases and cancer. In this review, we provide an essential introduction of the basic principles of prophylactic and therapeutic vaccination, key roles of adjuvants in augmenting and shaping immunity to achieve desired outcomes and effectiveness, and the physiochemical properties and action mechanisms of clinically approved adjuvants for humans. We particularly focus on the preclinical and clinical progress of highly immunogenic emerging nanotechnology adjuvants formulated in vaccines for cancer treatment or infectious disease prevention. We deliberate on how the immune system can sense and respond to the physicochemical cues (e.g., chirality, deformability, solubility, topology, and chemical structures) of nanotechnology adjuvants incorporated in the vaccines. Finally, we propose possible strategies to accelerate the clinical implementation of nanotechnology adjuvanted vaccines, such as in-depth elucidation of nano-immuno interactions, antigen identification and optimization by the deployment of high-dimensional multiomics analysis approaches, encouraging close collaborations among scientists from different scientific disciplines and aggressive exploration of novel nanotechnologies.

Vaccine adjuvants: mechanisms and platforms

Adjuvants are indispensable components of vaccines. Despite being widely used in vaccines, their action mechanisms are not yet clear. With a greater understanding of the mechanisms by which the innate immune response controls the antigen-specific response, the adjuvants' action mechanisms are beginning to be elucidated. Adjuvants can be categorized as immunostimulants and delivery systems. Immunostimulants are danger signal molecules that lead to the maturation and activation of antigen-presenting cells (APCs) by targeting Toll-like receptors (TLRs) and other pattern recognition receptors (PRRs) to promote the production of antigen signals and co-stimulatory signals, which in turn enhance the adaptive immune responses. On the other hand, delivery systems are carrier materials that facilitate antigen presentation by prolonging the bioavailability of the loaded antigens, as well as targeting antigens to lymph nodes or APCs. The adjuvants' action mechanisms are systematically summarized at the beginning of this review. This is followed by an introduction of the mechanisms, properties, and progress of classical vaccine adjuvants. Furthermore, since some of the adjuvants under investigation exhibit greater immune activation potency than classical adjuvants, which could compensate for the deficiencies of classical adjuvants, a summary of the adjuvant platforms under investigation is subsequently presented. Notably, we highlight the different action mechanisms and immunological properties of these adjuvant platforms, which will provide a wide range of options for the rational design of different vaccines. On this basis, this review points out the development prospects of vaccine adjuvants and the problems that should be paid attention to in the future.

Reduced protective efficacy of hepatitis B vaccine among fully vaccinated children in Ethiopia

BACKGROUND

Hepatitis B vaccination is recommended for all children at birth within 24 hours or during childhood.

OBJECTIVE

This study was aimed to evaluate protective efficacy of hepatitis B vaccine and estimate the sero-prevalence of hepatitis B virus infection among vaccinated children.

MATERIALS AND METHODS

A community-based cross-sectional study was conducted from March, 2021 to October, 2021 in Debre Markos town. A simple random sampling technique was used to select 165 fully vaccinated children aged 5-12 years old. A serum sample was used to determine hepatitis B surface antigen (HBsAg), anti-hepatitis B core antibody (anti-HBc), anti-hepatitis B surface antibody titer (anti-HBs) using ELISA.

RESULTS

The seroprevalence of HBsAg and anti-HBc anti-body was found to be 4.2% and 4.8% respectively. Of 165 fully vaccinated children, 129 (78.2%) had anti-HBs titer ≥ 10 mIU/ml. Among 129 sero-protected children, 76 (58.9%) were hypo-responders whereas the rest 53 (41.1%) were good responders. Those children within the age group of 5-7 years were 2.9 times (AOR: 2.873, 95% CI: 1.156, 7.141) (P<0.023) more likely to respond to HBV vaccine. Multivariate logistic regression revealed that children who were born from HBV positive mothers (AOR 3.917, 95% CI: 1.456, 5.365, P<0.027) and those who had history of injectable medications (AOR 9.232, 95% CI: 1.503, 11.697, P<0.016) were more likely to be HBsAg positive. Children who had history of hospital admission (AOR 6.973, 95% CI: 1.495, 8.530, P<0.013) were more likely to be anti-HBcAb positive.

CONCLUSIONS

There was an intermediate prevalence of childhood HBV infection despite being vaccinated suggesting low protective efficacy of hepatitis B vaccine in the study area.

Enhancement of Immune Response of Bioconjugate Nanovaccine by Loading of CpG through Click Chemistry

CpG is a widely used adjuvant that enhances the cellular immune response by entering antigen-presenting cells and binding with receptors. The traditional physical mixing of the antigen and CpG adjuvant results in a low adjuvant utilization rate. Considering the efficient delivery capacity of nanovaccines, we developed an attractive strategy to covalently load CpG onto the nanovaccine, which realized the co-delivery of both CpG and the antigen. Briefly, the azide-modified CpG was conjugated to a bioconjugate nanovaccine (NP-OPS) against Shigella flexneri through a simple two-step reaction. After characterization of the novel vaccine (NP-OPS-CpG), a series of in vitro and in vivo experiments were performed, including in vivo imaging, lymph node sectioning, and dendritic cell stimulation, and the results showed that more CpG reached the lymph nodes after covalent coupling. Subsequent flow cytometry analysis of lymph nodes from immunized mice showed that the cellular immune response was greatly promoted by the nanovaccine coupled with CpG. Moreover, by analyzing the antibody subtypes of immunized mice, NP-OPS-CpG was found to further promote a Th1-biased immune response. Thus, we developed an attractive method to load CpG on a nanovaccine that is simple, convenient, and is especially suitable for immune enhancement of vaccines against intracellular bacteria.

Immune Response to Hepatitis B Virus Vaccine Among People Living With HIV: A Meta-Analysis

Background

There is conflicting evidence about whether a double dose of the hepatitis B virus (HBV) vaccine induces better immunity than the standard-dose vaccine for people living with HIV (PLWH). This study provides a meta-analysis that summarizes the efficacy of HBV vaccine regimens among HIV-infected patients, clarifying the role of particular factors such as dose and frequency of vaccination in vaccine responsiveness and highlighting the need for evidence-based practice to assess HBV vaccination among PLWH.

Methods

Randomized clinical trials (RCTs) and prospective studies reporting vaccination response rates among PLWH were found through a search of PubMed, Cochrane, and the Web of Science. The key outcome was vaccine response. A random-effects model was used to estimate the pooled response rate. Subgroup analysis was conducted to evaluate key factors and explore sources of heterogeneity. Possible biases were assessed using quality and publication bias assessment.

Results

Eligible studies included controlled trials that examined the effects of 17 interventional studies with 1,821 participants. Among PLWH who received the HBV vaccine, the pooled response rate of HBV vaccination was 71.5% (95% CI 64.0%-77.9%, p < 0.001). Compared with the standard dose (65.5%, 95% CI 53.1%-76.1%), the double dose (75.2%, 95% CI 66.2%-82.5%) was associated with a better response rate [Q(1) = 19.617, p < 0.001]. When stratified by schedule, the four-dose schedule (89.7%, 95% CI 83.1%-93.9%) had a higher response rate than the three-dose schedule (63.3%, 95% CI 56.6%-69.4%) and the difference was significant [Q(1) = 88.305, p < 0.001]. PLWH with higher CD4⁺ T-cell counts (>500 cells/mm³) at the time of vaccination had better response rates [Q(1) = 88.305, p < 0.001].

Conclusions

In this meta-analysis, the double dose of the HBV vaccine and multiple injections were associated with better immune responses than the standard HBV vaccine regimen in PLWH. Higher seroconversion rates were observed in PLWH with high CD4⁺ T-cell levels, indicating that individuals infected with HIV should receive the HBV vaccine as soon as possible after diagnosis.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/.

Exploration of Pattern Recognition Receptor Agonists as Candidate Adjuvants

Adjuvants are used to maximize the potency of vaccines by enhancing immune reactions. Components of adjuvants include pathogen-associated molecular patterns (PAMPs) and damage-associate molecular patterns (DAMPs) that are agonists for innate immune receptors. Innate immune responses are usually activated when pathogen recognition receptors (PRRs) recognize PAMPs derived from invading pathogens or DAMPs released by host cells upon tissue damage. Activation of innate immunity by PRR agonists in adjuvants activates acquired immune responses, which is crucial to enhance immune reactions against the targeted pathogen. For example, agonists for Toll-like receptors have yielded promising results as adjuvants, which target PRR as adjuvant candidates. However, a comprehensive understanding of the type of immunological reaction against agonists for PRRs is essential to ensure the safety and reliability of vaccine adjuvants. This review provides an overview of the current progress in development of PRR agonists as vaccine adjuvants, the molecular mechanisms that underlie activation of immune responses, and the enhancement of vaccine efficacy by these potential adjuvant candidates.

Evaluation of the AV7909 Anthrax Vaccine Toxicity in Sprague Dawley Rats Following Three Intramuscular Administrations

AV7909 is a next-generation anthrax vaccine under development for post-exposure prophylaxis following suspected or confirmed Bacillus anthracis exposure, when administered in conjunction with the recommended antibacterial regimen. AV7909 consists of the FDA-approved BioThrax® vaccine (anthrax vaccine adsorbed) and an immunostimulatory Toll-like receptor 9 agonist oligodeoxynucleotide adjuvant, CPG 7909. The purpose of this study was to evaluate the potential systemic and local toxicity of AV7909 when administered via repeat intramuscular injection to the right thigh muscle (biceps femoris) to male and female Sprague Dawley rats. The vaccine was administered on Days 1, 15, and 29 and the animals were assessed for treatment-related effects followed by a 2-week recovery period to evaluate the persistence or reversibility of any toxic effects. The AV7909 vaccine produced no apparent systemic toxicity based on evaluation of clinical observations, body weights, body temperature, clinical pathology, and anatomic pathology. Necrosis and inflammation were observed at the injection sites as well as in regional lymph nodes and adjacent tissues and were consistent with immune stimulation. Antibodies against B. anthracis protective antigen (PA) were detected in rats treated with the AV7909 vaccine, confirming relevance of this animal model for the assessment of systemic toxicity of AV7909. In contrast, sera of rats that received saline or soluble CPG 7909 alone were negative for anti-PA antibodies. Overall, 3 intramuscular immunizations of Sprague Dawley rats with AV7909 were well tolerated, did not induce mortality or any systemic adverse effects, and did not result in any delayed toxicity.

CpG Oligonucleotides as Vaccine Adjuvants

CpG Oligonucleotides (ODN) are immunomodulatory synthetic oligonucleotides specifically designed to stimulate Toll-like receptor 9. TLR9 is expressed on human plasmacytoid dendritic cells and B cells and triggers an innate immune response characterized by the production of Th1 and pro-inflammatory cytokines. This chapter reviews recent progress in understanding the mechanism of action of CpG ODN and provides an overview of human clinical trial results using CpG ODN to improve vaccines for the prevention/treatment of cancer, allergy, and infectious disease.

TLR Agonists as Vaccine Adjuvants Targeting Cancer and Infectious Diseases

Modern vaccines have largely shifted from using whole, killed or attenuated pathogens to being based on subunit components. Since this diminishes immunogenicity, vaccine adjuvants that enhance the immune response to purified antigens are critically needed. Further advantages of adjuvants include dose sparing, increased vaccine efficacy in immunocompromised individuals and the potential to protect against highly variable pathogens by broadening the immune response. Due to their ability to link the innate with the adaptive immune response, Toll-like receptor (TLR) agonists are highly promising as adjuvants in vaccines against life-threatening and complex diseases such as cancer, AIDS and malaria. TLRs are transmembrane receptors, which are predominantly expressed by innate immune cells. They can be classified into cell surface (TLR1, TLR2, TLR4, TLR5, TLR6) and intracellular TLRs (TLR3, TLR7, TLR8, TLR9), expressed on endosomal membranes. Besides a transmembrane domain, each TLR possesses a leucine-rich repeat (LRR) segment that mediates PAMP/DAMP recognition and a TIR domain that delivers the downstream signal transduction and initiates an inflammatory response. Thus, TLRs are excellent targets for adjuvants to provide a "danger" signal to induce an effective immune response that leads to long-lasting protection. The present review will elaborate on applications of TLR ligands as vaccine adjuvants and immunotherapeutic agents, with a focus on clinically relevant adjuvants.

Inflammasome-Mediated Immunogenicity of Clinical and Experimental Vaccine Adjuvants

In modern vaccines, adjuvants can be sophisticated immunological tools to promote robust and long-lasting protection against prevalent diseases. However, there is an urgent need to improve immunogenicity of vaccines in order to protect mankind from life-threatening diseases such as AIDS, malaria or, most recently, COVID-19. Therefore, it is important to understand the cellular and molecular mechanisms of action of vaccine adjuvants, which generally trigger the innate immune system to enhance signal transition to adaptive immunity, resulting in pathogen-specific protection. Thus, improved understanding of vaccine adjuvant mechanisms may aid in the design of “intelligent” vaccines to provide robust protection from pathogens. Various commonly used clinical adjuvants, such as aluminium salts, saponins or emulsions, have been identified as activators of inflammasomes - multiprotein signalling platforms that drive activation of inflammatory caspases, resulting in secretion of pro-inflammatory cytokines of the IL-1 family. Importantly, these cytokines affect the cellular and humoral arms of adaptive immunity, which indicates that inflammasomes represent a valuable target of vaccine adjuvants. In this review, we highlight the impact of different inflammasomes on vaccine adjuvant-induced immune responses regarding their mechanisms and immunogenicity. In this context, we focus on clinically relevant adjuvants that have been shown to activate the NLRP3 inflammasome and also present various experimental adjuvants that activate the NLRP3-, NLRC4-, AIM2-, pyrin-, or non-canonical inflammasomes and could have the potential to improve future vaccines. Together, we provide a comprehensive overview on vaccine adjuvants that are known, or suggested, to promote immunogenicity through inflammasome-mediated signalling.

Hepatitis B Vaccination and Waning Hepatitis B Immunity in Persons Living with HIV

PURPOSE OF REVIEW

Persons with HIV are at a higher risk for acquiring HBV (hepatitis B virus) than the general population due to shared modes of transmission and are significantly more likely to develop and die from sequelae of chronic HBV infection. Early vaccination is key to achieving HBV protective immunity, but response rates are still much lower than in the general population, ranging from 35 to 70%. Individuals with HIV also experience more rapidly waning immunity than those without HIV. Strategies to augment initial response and improve long-term immunity in individuals with HIV include alterations in dose, frequency, and the use of immune adjuvants.

RECENT FINDINGS

Recent studies have focused on the use of different vaccine formulations, the use of vaccine adjuvants, increased number and strength of vaccine dosages, increased dose frequency, alternative routes of administration, dual vaccinations, and the use of booster vaccines. Although no consensus has been reached on the use of certain vaccination regimens, three and four double-dose vaccine schedules via the intramuscular route have demonstrated higher initial response rates. Early vaccination when CD4 cell counts are greater than 350/mm³ with low viral loads has been shown to improve initial response, along with completion of immunization series. Adjuvants such as TLR4 and TLR9 agonists appear to improve response to HBV vaccination, but further research is needed in individuals with HIV. Persons with HIV have significant lower initial and long-term seroresponse rates after HBV vaccination than immunocompetent individuals. Recent and ongoing studies continue to evaluate multiple strategies to improve these rates within a uniquely susceptible population.

Repeat-Dose Toxicity Study of a Lyophilized Recombinant Protective Antigen-Based Anthrax Vaccine Adjuvanted With CpG 7909

A recombinant protective antigen (rPA) anthrax vaccine candidate (rPA7909) was developed as a next-generation vaccine indicated for postexposure prophylaxis of disease resulting from suspected or confirmed Bacillus anthracis exposure. The lyophilized form of rPA7909-vaccinated candidate contains 75 µg purified rPA, 750 µg aluminum (as Alhydrogel adjuvant), and 250 µg of an immunostimulatory Toll-like receptor 9 agonist oligodeoxynucleotide CpG 7909 in a 0.5 mL phosphate-buffered suspension. General toxicity and local reactogenicity were evaluated in Sprague Dawley rats vaccinated with the full human dose of rPA7909 by intramuscular injection. Animals were immunized on study days 1, 15, and 29. Control groups were administered diluent only or adjuvant control (excipients, CpG 7909, and Alhydrogel adjuvant in diluent) intramuscularly at the same dose volume and according to the same schedule used for rPA7909. Toxicity was assessed based on the results of clinical observations, physical examinations, body weights, injection site reactogenicity, ophthalmology, clinical pathology (hematology, coagulation, and serum chemistry), organ weights, and macroscopic and microscopic pathology evaluation. The immune response to rPA7909 vaccination was confirmed by measuring serum anti-PA immunoglobulin G levels. The rPA7909 vaccine produced no apparent systemic toxicity and only transient reactogenicity at the injection site. The injection site reaction from animals receiving the adjuvant control was very similar to those receiving rPA7909 with respect to the inflammation. The inflammatory response observed in the injection site and the draining lymph nodes was consistent with expected immune stimulation. The overall results indicated a favorable safety profile for rPA7909.

Use of Anthrax Vaccine in the United States: Recommendations of the Advisory Committee on Immunization Practices, 2019

This report updates the 2009 recommendations from the CDC Advisory Committee on Immunization Practices (ACIP) regarding use of anthrax vaccine in the United States (Wright JG, Quinn CP, Shadomy S, Messonnier N. Use of anthrax vaccine in the United States: recommendations of the Advisory Committee on Immunization Practices [ACIP)], 2009. MMWR Recomm Rep 2010;59[No. RR-6]). The report 1) summarizes data on estimated efficacy in humans using a correlates of protection model and safety data published since the last ACIP review, 2) provides updated guidance for use of anthrax vaccine adsorbed (AVA) for preexposure prophylaxis (PrEP) and in conjunction with antimicrobials for postexposure prophylaxis (PEP), 3) provides updated guidance regarding PrEP vaccination of emergency and other responders, 4) summarizes the available data on an investigational anthrax vaccine (AV7909), and 5) discusses the use of anthrax antitoxins for PEP.

Changes from previous guidance in this report include the following: 1) a booster dose of AVA for PrEP can be given every 3 years instead of annually to persons not at high risk for exposure to Bacillus anthracis who have previously received the initial AVA 3-dose priming and 2-dose booster series and want to maintain protection; 2) during a large-scale emergency response, AVA for PEP can be administered using an intramuscular route if the subcutaneous route of administration poses significant materiel, personnel, or clinical challenges that might delay or preclude vaccination; 3) recommendations on dose-sparing AVA PEP regimens if the anthrax vaccine supply is insufficient to vaccinate all potentially exposed persons; and 4) clarification on the duration of antimicrobial therapy when used in conjunction with vaccine for PEP.

These updated recommendations can be used by health care providers and guide emergency preparedness officials and planners who are developing plans to provide anthrax vaccine, including preparations for a wide-area aerosol release of B. anthracis spores. The recommendations also provide guidance on dose-sparing options, if needed, to extend the supply of vaccine to increase the number of persons receiving PEP in a mass casualty event.

Toward a Functional Cure for Hepatitis B: The Rationale and Challenges for Therapeutic Targeting of the B Cell Immune Response

The central role of the cellular immune response in the control and clearance of the hepatitis B virus (HBV) infection has been well-established. The contribution of humoral immunity, including B cell and antibody responses against HBV, has been investigated for a long time but has attracted increasing attention again in recent years. The anti-HBs antibody was first recognized as a marker of protective immunity after the acute resolution of the HBV infection (or vaccination) and is now defined as a biomarker for the functional cure of chronic hepatitis B (CHB). In this way, therapies targeting HBV-specific B cells and the induction of an anti-HBs antibody response are essential elements of a rational strategy to terminate chronic HBV infection. However, a high load of HBsAg in the blood, which has been proposed to induce antigen-specific immune tolerance, represents a major obstacle to curing CHB. Long-term antiviral treatment by nucleoside analogs, by targeting viral translation by siRNA, by inhibiting HBsAg release via nucleic acid polymers, or by neutralizing HBsAg via specific antibodies could potentially reduce the HBsAg load in CHB patients. A combined strategy including a reduction of the HBsAg load via the above treatments and the therapeutic targeting of B cells by vaccination may induce the appearance of anti-HBs antibodies and lead to a functional cure of CHB.

A Global View to HBV Chronic Infection: Evolving Strategies for Diagnosis, Treatment and Prevention in Immunocompetent Individuals

Hepatitis B Virus (HBV) is a significant public health challenge. Around 250 million people live with chronic HBV infection. With a global approach to this issue, we focus on new perspective in diagnosis, management and prevention of HBV chronic infection. Precise diagnosis of HBV status is crucial to guide patient management. Although available drugs reduce the risk of liver disease progression, they are not able to definitely eradicate HBV, and new therapeutic options are urgently needed. Thus, prevention of HBV infection is still the most effective strategy to achieve the control of the disease. Key aspects of prevention programs include surveillance of viral hepatitis, screening programs and immunization strategies. In spite of the high success rate of licensed HBV vaccines, a need for improved vaccine persists, especially in order to provide coverage of current non-responders.

Travel vaccination recommendations and infection risk in HIV-positive travellers

BACKGROUND

With the advent of highly active antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) it has become possible for people with HIV to travel to destinations that may place them at risk of a number of infectious diseases. Prevention of infections by vaccination is therefore of paramount importance for these travellers. However, vaccine responsiveness in HIV-positive individuals is not infrequently reduced compared to HIV-negative individuals. An understanding of the expected immune responses to vaccines in HIV-positive travellers is therefore important in planning the best approach to a pretravel consultation.

METHODS

A PubMed search was performed on HIV or acquired immune deficiency syndrome together with a search for specific vaccines. Review of the literature was performed to develop recommendations on vaccinations for HIV-positive travellers to high-risk destinations.

RESULTS

The immune responses to several vaccines are reduced in HIV-positive people. In the case of vaccines for hepatitis A, hepatitis B, influenza, pneumococcus, meningococcus and yellow fever there is a good body of data in the literature showing reduced immune responsiveness and also to help guide appropriate vaccination strategies. For other vaccines like Japanese encephalitis, rabies, typhoid fever, polio and cholera the data are not as robust; however, it is still possible to gain some understanding of the reduced responses seen with these vaccines.

CONCLUSION

This review provides a summary of the immunological responses to commonly used vaccines for the HIV-positive travellers. This information will help guide travel medicine practitioners in making decisions about vaccination and boosting of travellers with HIV.

CpG enhances the immunogenicity of heterologous DNA-prime/protein-boost vaccination with the heavy chain myosin of Brugia malayi in BALB/c mice

The recombinant heavy chain myosin of Brugia malayi (Bm-Myo) has earlier been reported as a potent vaccine candidate in our lab. Subsequently, we further enhanced its efficacy employing heterologous DNA prime/protein boost (Myo-pcD+Bm-Myo) immunization approach that produced superior immune-protection than protein or DNA vaccination. In the present study, we evaluated the efficacy of heterologous prime boost vaccination in combination with CpG, synthetic oligodeoxynucleotides (ODN) adjuvant in BALB/c mice. The results showed that CpG/Myo-pcD+Bm-Myo conferred 84.5 ± 0.62% protection against B. malayi infective larval challenge which was considerably higher than Myo-pcD+Bm-Myo (75.6 ± 1.10%) following immunization. Although, both the formulations of immunization elicited robust production of specific IgG antibody and their isotypes (IgG1, IgG2a, IgG2b, and IgG3); however, CpG/Myo-pcD+Bm-Myo predominantly enhanced the level of IgG2a suggesting Th1 biased immune response in presence of CpG. Furthermore, spleen isolated from mice that immunized with CpG/Myo-pcD+Bm-Myo had greater accumulation of CD4+, CD8+, and CD19+ B cells and there was an augmented expression of co-stimulatory molecules CD40, CD86 on host dendritic cells (DCs). In contrast to Myo-pcD+Bm-Myo group, the splenocytes of CpG/Myo-pcD+Bm-Myo immunized mice developed comparatively higher pro-inflammatory cytokines IL-2 and IFN-γ leaving anti-inflammatory cytokine levels unchanged. Moreover, CpG formulation also upregulated the RNA expression of IL-12 and TNF-α in spleenocytes. The current findings suggest that the use of CpG would be more advantageous as an adjuvant predominantly in DNA/protein prime boost vaccine against Bm-Myo and presumably also for filarial infection.

Vaccine adjuvants: Understanding the structure and mechanism of adjuvanticity

In conjugate, inactivated, recombinant, and toxoid vaccines, adjuvants are extensively and essentially used for enhanced and long-lasting protective immune responses. Depending on the type of diseases and immune responses required, adjuvants with different design strategies are developed. With aluminum salt-based adjuvants as the most used ones in commercial vaccines, other limited adjuvants, e.g., AS01, AS03, AS04, CpG ODN, and MF59, are used in FDA-approved vaccines for human use. In this paper, we review the uses of different adjuvants in vaccines including the ones used in FDA-approved vaccines and vaccines under clinical investigations. We discuss how adjuvants with different formulations could affect the magnitude and quality of adaptive immune response for optimized protection against specific pathogens. We emphasize the molecular mechanisms of various adjuvants, with the aim to establish structure-activity relationships (SARs) for designing more effective and safer adjuvants for both preventative and therapeutic vaccines.

Vaccination in the Adult Patient Infected with HIV: A Review of Vaccine Efficacy and Immunogenicity

Patients infected with HIV remain at increased risk of mortality and morbidity from diseases that are preventable with vaccines partly due to the persisting immunopathology that results in impaired responses to vaccination despite virologic suppression. Because data on clinical effectiveness in patients who are immunocompromised remain limited, undervaccination of individuals with HIV poses a major concern. Multiple societies have published recommendations on vaccination in individuals infected with HIV. Many of these recommendations are based on extrapolation of data from clinical trials that usually exclude patients with HIV, although there is a growing body of data from patients infected with HIV as well. In this review, we describe the available literature on vaccine response in the adult patient with HIV as measured by immunogenicity or vaccine efficacy.

Rapid Acquisition of Cytomegalovirus-Specific T Cells with a Differentiated Phenotype, in Nonviremic Hematopoietic Stem Transplant Recipients Vaccinated with CMVPepVax

Early cytomegalovirus (CMV) reactivation remains a significant cause of morbidity and mortality in allogeneic hematopoietic cell transplant (HCT) recipients. CMVPepVax is an investigational peptide vaccine designed to control CMV infection in HCT recipients seropositive for CMV by stimulating the expansion of T cell subsets that target the CMV tegument protein pp65. In a randomized Phase Ib pilot trial (ClinicalTrials.gov NCT01588015), two injections of CMVPepVax (at days 28 and 56 post-HCT) demonstrated safety, immunogenicity, increased relapse-free survival, and reduced CMV reactivation and use of antivirals. In the present study, we assessed the phenotypes and time courses of the pp65-specific CD8 T cell subsets that expanded in response to CMVPepVax vaccination. The functionality and antiviral role of CMV-specific T cells have been linked to immune reconstitution profiles characterized predominantly by differentiated effector memory T (TEM) subsets that have lost membrane expression of the costimulatory molecule CD28 and often reexpress the RA isoform of CD45 (TEMRA). Major histocompatibility complex class I pp65_495-503 multimers, as well as CD28 and CD45 memory markers, were used to detect immune reconstitution in blood specimens from HCT recipients enrolled in the Phase Ib clinical trial. Specimens from the 10 (out of 18) vaccinated patients who had adequate (≥.2%) multimer binding to allow for memory analysis showed highly differentiated TEM and TEMRA phenotypes for pp65_495-503-specific CD8 T cells during the first 100days post-transplantation. In particular, by day 70, during the period of highest risk for CMV reactivation, combined TEM and TEMRA phenotypes constituted a median of 90% of pp65_495-503-specific CD8 T cells in these vaccinated patients. CMV viremia was not detectable in the patients who received CMVPepVax, although their pp65_495-503-specific CD8 T cell profiles were strikingly similar to those observed in viremic patients who did not receive the vaccine. Collectively, our findings indicate that in the absence of clinically relevant viremia, CMVPepVax reconstituted significant levels of differentiated pp65_495-503-specific CD8 TEMs early post-HCT. Our data indicate that the rapid reconstitution of CMV-specific T cells with marked levels of effector phenotypes may have been key to the favorable outcomes of the CMVPepVax clinical trial.

Interaction between Hepatitis B Virus and Toll-Like Receptors: Current Status and Potential Therapeutic Use for Chronic Hepatitis B

Immune defense against infection with the hepatitis B virus (HBV) is complex and involves both host innate and adaptive immune systems. It is well accepted that the development of sufficient HBV-specific T cell and B cell responses are required for controlling an HBV infection. However, the contribution of innate immunity to removing HBV has been explored in recent years. Toll-like receptors (TLRs) are recognized as the first line of antiviral immunity because they initiate intracellular signaling pathways to induce antiviral mediators such as interferons (IFNs) and other cytokines. Recent studies show that the activation of TLR-mediated signaling pathways results in a suppression of HBV replication in vitro and in vivo. However, HBV has also evolved strategies to counter TLR responses including the suppression of TLR expression and the blockage of downstream signaling pathways. Antiviral treatment in chronic HBV-infected patients leads to an upregulation of TLR expression and the restoration of its innate antiviral functions. Thus, TLR activation may serve as an additional immunotherapeutic option for treating chronic HBV infection in combination with antiviral treatment.

An Overview of Novel Adjuvants Designed for Improving Vaccine Efficacy

Adjuvants incorporated in prophylactic and/or therapeutic vaccine formulations impact vaccine efficacy by enhancing, modulating, and/or prolonging the immune response. In addition, they reduce antigen concentration and the number of immunizations required for protective efficacy, therefore contributing to making vaccines more cost effective. Our better understanding of the molecular mechanisms of immune recognition and protection has led research efforts to develop new adjuvants that are currently at various stages of development or clinical evaluation. In this review, we focus mainly on several of these promising adjuvants, and summarize recent work conducted in various laboratories to develop novel lipid-containing adjuvants.

Hepatitis B virus vaccination in HIV-infected people: A review

HBV immunization is highly recommended in people infected with HIV. However, the classical schedule used in the general population has been shown to be insufficient in people living with HIV. This review summarizes the main studies dealing with HBV vaccination in people living with HIV, depending on their baseline status (in particular, never vaccinated, already vaccinated, or with an isolated anti-HBc serological profile). It shows that reinforced 40µg intramuscular HBV vaccination schedules are now frequently recommended, either initially in people never vaccinated, or in the lack of an anamnestic response in other situations. Adjuvants cannot be currently recommended. Anti-HBs titers have to be checked 1 to 2 months following the last vaccine dose, and annually thereafter a booster is necessary if antiHBs titers decrease below 10 mIU/mL. In patients with a CD4 cell count <200/µL, guidelines recommend starting the vaccination regimen as soon as possible after HAART has been started.

CpG oligodeoxynucleotides augment antitumor efficacy of folate receptor α based DNA vaccine

Folate receptor α (FRα) is overexpressed in a variety of solid tumors and has become an attractive target antigen for immunotherapy purposes. A DNA vaccine was generated by ligation of FRα cDNA into the eukaryotic vector pcDNA3.1. Expression of FRα was confirmed in transiently transfected B16 cells. B16 cell lines that stably express FRα were set up by G418 selection. A total of 100 µg purified plasmid DNA alone or in combination with CpG oligodeoxynucleotides (CpG ODN) was injected intramuscularly in C57BL/6 mice four times at one week intervals. ELISA analysis confirmed that high titers of antibodies against FRα existed in the sera of the experimental animals. Specific cytotoxic T lymphocyte activity against FRα-expressing B16 cells was found and FRα specific lymphocyte proliferation was detected. Coinjection of CpG ODN increased both humoral and cellular immune responses. In the protective model, in which C57BL/6 mice were immunized with the FRα DNA vaccine four weeks before tumor cell inoculation, the growth of tumor was significantly inhibited, and the presence of CpG ODN further increased the inhibitory effect. FRα DNA vaccine alone did not show a significant inhibitory effect in the therapeutic model, in which the DNA vaccine was immediately injected after tumor inoculation. However, FRα DNA vaccine plus CpG ODN showed a significant inhibitory effect in tumor growth. Survival curves for both animal experiments confirmed that mice immunized with pcDNA3.1/FRα plus CpG ODN had a significantly prolonged survival period than that of the pcDNA3.1 control group, the CpG ODN group or the pcDNA3.1/FRα group. The above showed that human FRα based DNA vaccination with CpG ODN as an adjuvant was effective in growth inhibition of a FRα expressing tumor in mice and deserves further evaluation as a possible immunotherapy.

Targeting of C-type lectin-like receptor 2 or P2Y12 for the prevention of platelet activation by immunotherapeutic CpG oligodeoxynucleotides

Essentials CpG oligodeoxynucleotide (ODN) immuotherapeutics cause undesired platelet activating effects. It is crucial to understand the mechanisms of these effects to identify protective strategies. CpG ODN-induced platelet activation depends on C-type lectin-like receptor 2 (CLEC-2) and P2Y12. Targeting CLEC-2 or P2Y12 fully prevents CpG ODN-induced platelet activation and thrombosis.

SUMMARY

Background Synthetic phosphorothioate-modified CpG oligodeoxynucleotides (ODNs) show potent immunostimulatory properties that are widely exploited in clinical trials of anticancer treatment. Unexpectedly, a recent study indicated that CpG ODNs activate human platelets via the immunoreceptor tyrosine-based activation motif (ITAM)-coupled receptor glycoprotein VI. Objective To further analyze the mechanisms of CpG ODN-induced platelet activation and identify potential inhibitory strategies. Methods In vitro analyses were performed on human and mouse platelets, and on cell lines expressing platelet ITAM receptors. CpG ODN platelet-activating effects were evaluated in a mouse model of thrombosis. Results We demonstrated platelet uptake of CpG ODNs, resulting in platelet activation and aggregation. C-type lectin-like receptor 2 (CLEC-2) expressed in DT40 cells bound CpG ODNs. CpG ODN uptake did not occur in CLEC-2-deficient mouse platelets. Inhibition of human CLEC-2 with a blocking antibody inhibited CpG ODN-induced platelet aggregation. CpG ODNs caused CLEC-2 dimerization, and provoked its internalization. They induced dense granule release before the onset of aggregation. Accordingly, pretreating platelets with apyrase, or inhibiting P2Y12 with cangrelor or clopidogrel, prevented CpG ODN platelet-activating effect. In vivo, intravenously injected CpG ODN interacted with platelets adhered to mouse injured endothelium, and promoted thrombus growth, which was inhibited by CLEC-2 deficiency or by clopidogrel. Conclusions CLEC-2 and P2Y12 are required for CpG ODN-induced platelet activation and thrombosis, and might be targeted to prevent adverse events in patients at risk.

Serological response to trivalent inactivated influenza vaccine in HIV-infected adults in Singapore

A cohort of 81 HIV-infected participants received seasonal trivalent inactivated influenza vaccine (TIV) and their humoral responses were monitored using hemagglutination inhibition (HAI) assay and enzyme-linked immunosorbent assay (ELISA). Three weeks after the vaccination, the percentage of the cohort that had an HAI titer of >1:40 was 35% (for H1N1), 43% (for H3N2) and 19% (for influenza B). An increase in HAI titer can be achieved by an increase in magnitude of the antibody responses, which can be measured by an increase in ELISA titer; as well as a quality improvement of the antibody responses through increased avidity to the virus. For some individuals, an increase in avidity alone is sufficient to reach the sero-protective titer. Notably, a number of volunteers showed an increase in ELISA titer without a rise in HAI titer. A total of 24 participants (30%) did not show any significant increase in both HAI and ELISA tests after vaccination. Apart from a lower peripheral CD4⁺ T cell count, the non responders' peripheral blood mononuclear cells (PBMC) also had a higher IL-10 mRNA expression after TIV vaccination ex vivo. Cytokine profiling demonstrated that, apart from a weaker MCP-1 expression in the non-responder group, PBMC from both groups responded comparably to lipopolysaccharide (LPS) stimulation in vitro. Since only 3 participants developed sero-protective titers against all 3 subtypes after vaccination, our study highlights a need to enhance the immunogenicity of the subunit vaccine for this population, potentially through harnessing the innate immunity with an external adjuvant.

The TLR-specific adjuvants R-848 and CpG-B endorse the immunological reaction of neonatal antigen-presenting cells

BACKGROUND

Preterm neonates display an impaired vaccine response. Neonatal antigen-presenting cells (APCs) are less effective to induce an adaptive immune response and to promote the development of immunological memory. Efficient adjuvantal toll-like receptor (TLR)-triggering may overcome the neonatal immunological impairment. Accordingly, the aim of this study was to investigate the immunostimulatory action of R-848 and CpG-B on neonatal APCs.

METHODS

Surface marker and cytokine secretion of APCs were evaluated after incubation of cord blood and peripheral blood mononuclear cells with the indicated adjuvants and were analyzed using flow cytometry.

RESULTS

TLR-specific stimulation resulted in a significant induction of costimulatory molecules on neonatal APCs. Stimulation with R-848 resulted in significant higher secretion of TNFα, IL-6, IL-10, IL-12/IL-23p40, IL-12p70, and IFN-γ. Interestingly, CpG-B resulted in significant higher secretion of TNFα and IL-6.

CONCLUSION

In summary, the incubation of TLR-agonists induced activation and maturation of neonatal APCs. These data show that modern TLR-specific adjuvants achieve a direct effect and potent upregulation of activation and maturation markers and cytokines in preterm neonates. We thus conclude that agents triggering TLRs might possibly overcome neonatal lack of vaccine responses.

Immunogenicity of a peptide-based anti-IgE conjugate vaccine in non-human primates

The anti-human immunoglobulin E (IgE) monoclonal antibody, omalizumab (Xolair®, Genentech, South San Fransisco, CA), is effective in the treatment of poorly controlled moderate to severe allergic asthma and chronic idiopathic urticaria. It acts by specifically binding to the constant domain (Cϵ3) of free human IgE in the blood and interstitial fluid. Although efficacious, use of omalizumab is limited due to restrictions on patient weight and pre-existing IgE levels, and frequent dosing (q2-4 weeks). A vaccine inducing anti-IgE antibodies has the potential for similar clinical benefits with less frequent dosing and relatively lower cost of goods. We developed a vaccine containing two IgE peptide-conjugates targeting the Cϵ3 domain of human IgE. As part of preclinical evaluation of the vaccine to optimize formulation and dose prior to initiating clinical studies, we evaluated the vaccine in non-human primates, and demonstrate the induction of anti-peptide antibodies that can bind to conformationally intact human IgE and are capable, at least in some animals, of substantial lowering circulating IgE levels.

Factors Affecting the Development of an Antibody Response to Hepatitis B Immunization in Children With Intestinal Failure: Before and After Small Bowel Transplantation (With and Without Liver Graft)

BACKGROUND

Small bowel transplant with or without a liver graft (SBTx ± LTx) for children with intestinal failure involves checking their immunity to a range of microorganisms, including hepatitis B virus (HBV), at the time of assessment. HBV vaccination in the United Kingdom is recommended for transplant candidates. The aim of this audit was to find out how many SBTx ± LTx candidates received HBV vaccination before transplantation and how the timing of vaccination influenced the development of immunity.

MATERIALS AND METHODS

Retrospective review of case notes and hospital microbiology database formed the basis of the study. Vaccination history and serology were available in 56 of 87 subjects who had SBTx ± LTx.

RESULTS

All patients were seronegative for HBV when assessed for transplant. HBV vaccination was started before transplant in 25 children and after transplant in 31. Eight children died posttransplant before their immunity could be checked, but of the 48 survivors, 20 children developed immunity, of whom 13 (65%) received at least 1 vaccination before SBTx ± LTx ( P = .008). Lack of response to HBV vaccine was significantly associated with isolated bowel transplantation and intensification of immune suppression. Of 11 children, 5 lost hepatitis B surface antibody (HbsAb), and 28 never made HBsAb, despite repeated vaccinations.

CONCLUSION

Our study clearly shows that HBV vaccine before transplant is more effective. In line with renal failure patients, we suggest that children with chronic intestinal failure receive HBV vaccine when clinically stable, before referral for transplant. Higher-dose vaccines, accelerated schedules, and more frequent booster vaccinations are also strategies that may improve HBsAb levels after transplant.

Hepatitis B vaccination uptake and correlates of serologic response among HIV-infected and uninfected men who have sex with men (MSM) in Bangkok, Thailand

BACKGROUND

Vaccination against hepatitis B virus (HBV) is recommended for all HBV-susceptible men who have sex with men (MSM). There is limited information on correlates of immunity to HBV vaccination in this group. We present serologic response rates to hepatitis B vaccine and identify factors associated with impaired response among HIV-uninfected and HIV-infected Thai MSM.

METHODOLOGY

HBV-susceptible volunteers were offered hepatitis B vaccination at months zero, one, and six. We measured baseline (pre-vaccination) total serum IgG and IgG subclasses (all participants), baseline CD4 count, and plasma HIV-1 viral load (PVL) (HIV+ participants). HBV serologies were retested at 12 months. Serologic responses were compared between all groups in men receiving three vaccine doses.

RESULTS

511/651 HIV-negative and 64/84 HIV-positive participants completed the three-dose series. Response rates in HIV-uninfected and -infected participants were 90.1% vs. 50.0% (p<0.0001). Median pre-vaccination IgG was higher among non-responders than responders overall (1238.9.0 vs. 1057.0mg/dL, p=0.003) and among HIV-infected participants (1534.0 vs. 1244.5mg/dL, p=0.005), but not significantly among HIV-uninfected participants (1105.5 vs. 1054.3mg/dL, p=0.96). Pre-vaccination IgG1 and IgG3 levels were higher among HIV-positive than HIV-negative participants (median 866.0 vs. 520.3, and 105.8 vs. 83.1mg/dL, respectively, p<0.0001). Among HIV-infected participants, median CD4 count in non-responders was 378 cells/μL vs. 431 cells/μL in responders (p=0.20). Median PVL in non-responders was 64,800 copies/mL vs. 15500 copies/mL in responders (p=0.04). Participants with pre-vaccination plasma IgG >1550 mg/dL and PVL >10,000 copies/mL were almost always non-responsive (p<0.01).

CONCLUSIONS

HIV infection was associated with poor vaccine responses. High plasma viral load, elevated pre-vaccination total serum IgG and elevated pre-vaccination IgG1 are associated with poorer response to vaccination among HIV-infected MSM. In this group, the combination of high PVL and pre-vaccination total IgG is highly predictive of vaccine failure.

The generation of CD8+ T-cell population specific for vaccinia virus epitope involved in the antiviral protection against ectromelia virus challenge

Eradication of smallpox has led to cessation of vaccination programs. This has rendered the human population increasingly susceptible not only to variola virus infection but also to infections with other representatives of Poxviridae family that cause zoonotic variola-like diseases. Thus, new approaches for designing improved vaccine against smallpox are required. Discovering that orthopoxviruses, e.g. variola virus, vaccinia virus, ectromelia virus, share common immunodominant antigen, may result in the development of such a vaccine. In our study, the generation of antigen-specific CD8(+) T cells in mice during the acute and memory phase of the immune response was induced using the vaccinia virus immunodominant TSYKFESV epitope and CpG oligodeoxynucleotides as adjuvants. The role of the generated TSYKFESV-specific CD8(+) T cells was evaluated in mice during ectromelia virus infection using systemic and mucosal model. Moreover, the involvement of dendritic cells subsets in the adaptive immune response stimulation was assessed. Our results indicate that the TSYKFESV epitope/TLR9 agonist approach, delivered systemically or mucosally, generated strong CD8(+) T-cell response when measured 10 days after immunization. Furthermore, the TSYKFESV-specific cell population remained functionally active 2 months post-immunization, and gave cross-protection in virally challenged mice, even though the numbers of detectable antigen-specific T cells decreased.

Organosilane and Polyethylene Glycol Functionalized Magnetic Mesoporous Silica Nanoparticles as Carriers for CpG Immunotherapy In Vitro and In Vivo

Cytosine-guanine (CpG) containing oligodeoxynucleotides (ODN) have significant clinical potential as immunotherapeutics. However, limitations exist due to their transient biological stability in vivo, lack of specificity for target cells, and poor cellular uptake. To address these issues, we prepared amine magnetic mesoporous silica nanoparticles (M-MSN-A) then further modified with polyethylene glycol (PEG) for use as CpG delivery vectors. The PEG modified M-MSN-A (M-MSN-P) had notable CpG ODN loading capacity, negligible cytotoxicity, and were easily internalized into cells where they released the loaded CpG into the cytoplasm. As a result, such complexes were effective in activating macrophages and inhibiting tumor cells when combined with chemotherapeutics in vitro. Furthermore, these complexes had excellent immuno-stimulating activity in vivo, compared to the free CpG therapeutics. We report here a highly effective MSNs-based delivery system with great potential as a therapeutic CpG formulation in cancer immunotherapy.

Hepatitis B revaccination in HIV-infected vaccine non-responders: is double dosing always necessary?

Limited data exist on hepatitis B revaccination strategies for HIV-infected individuals who do not develop immunity after the first vaccination series. A retrospective cohort study was conducted to assess the immunogenicity of the second series of hepatitis B vaccine given in standard dosing (SD) and double dosing (DD) strategies among Thai HIV-infected adults during the period from January 2006 to December 2014. Of the 120 eligible patients, 68 (57%) were men, median age was 38 years old, 87 (73%) received SD and 33 (27%) received DD revaccination. The demographic and clinical characteristics of SD and DD groups were comparable. The overall vaccine response rate was significantly higher in DD group than SD group (97% vs. 70%; p = 0.001). Independent factors associated with no response to hepatitis B revaccination were receipt of SD vaccine (adjusted odds ratio [aOR] 16.04; p = 0.009), age ≥ 40 years (aOR 3.66; p = 0.009) and CD4 cell count at the time of revaccination less than 450 cells/µL (aOR 2.96; p = 0.04). These findings suggest that DD hepatitis B revaccination series should be given in HIV-infected patients who were at least 40 years old or had CD4 counts less than 450 cells/µL after no response to the first vaccination series.

Optically Triggered Immune Response through Photocaged Oligonucleotides

Bacterial and viral CpG oligonculeotides are unmethylated cytosine-phosphate-guanosine dinucleotide sequences and trigger an innate immune response through activation of the toll-like receptor 9 (TLR9). We have developed synthetic photocaged CpGs via site-specific incorporation of nitropiperonyloxymethyl (NPOM)-caged thymidine residues. These oligonucleotides enable the optical control of TLR9 function and thereby provide light-activation of an immune response. We provide a proof-of-concept model by applying a reporter assay in live cells and by quantification of endogenous production of interleukin 6.

In ovo delivery of CpG DNA reduces avian infectious laryngotracheitis virus induced mortality and morbidity

Endosomal toll-like receptor-21 and -9 sense CpG DNA activating production of pro-inflammatory mediators with antimicrobial effects. Here, we investigated the induction of antiviral response of in ovo delivered CpG DNA against infectious laryngotracheitis virus (ILTV) infection. We found that in ovo delivered CpG DNA significantly reduces ILTV infection pre-hatch correlating with the expression of IL-1β and increase of macrophages in lungs. As assessed in vitro, CpG DNA stimulated avian macrophages could be a potential source of IL-1β and other pro-inflammatory mediators. Since we also found that in ovo CpG DNA delivery maintains increased macrophages in the lungs post-hatch, we infected the chickens on the day of hatch with ILTV. We found that in ovo delivered CpG DNA significantly reduces mortality and morbidity resulting from ILTV infection encountered post-hatch. Thus, CpG DNA can be a candidate innate immune stimulant worthy of further investigation for the control of ILTV infection in chickens.

TLR7- and TLR9-responsive human B cells share phenotypic and genetic characteristics

B cells activated by nucleic acid-sensing TLR7 and TLR9 proliferate and secrete immune globulins. Memory B cells are presumably more responsive due to higher TLR expression levels, but selectivity and differential outcomes remain largely unknown. In this study, peripheral blood human B cells were stimulated by TLR7 or TLR9 ligands, with or without IFN-α, and compared with activators CD40L plus IL-21, to identify differentially responsive cell populations, defined phenotypically and by BCR characteristics. Whereas all activators induced differentiation and Ab secretion, TLR stimulation expanded IgM(+) memory and plasma cell lineage committed populations, and favored secretion of IgM, unlike CD40L/IL-21, which drove IgM and IgG more evenly. Patterns of proliferation similarly differed, with CD40L/IL-21 inducing proliferation of most memory and naive B cells, in contrast with TLRs that induced robust proliferation in a subset of these cells. On deep sequencing of the IgH locus, TLR-responsive B cells shared patterns of IgHV and IgHJ usage, clustering apart from CD40L/IL-21 and control conditions. TLR activators, but not CD40L/IL-21, similarly promoted increased sharing of CDR3 sequences. TLR-responsive B cells were characterized by more somatic hypermutation, shorter CDR3 segments, and less negative charges. TLR activation also induced long positively charged CDR3 segments, suggestive of autoreactive Abs. Testing this, we found culture supernatants from TLR-stimulated B cells to bind HEp-2 cells, whereas those from CD40L/IL-21-stimulated cells did not. Human B cells possess selective sensitivity to TLR stimulation, with distinctive phenotypic and genetic signatures.

In vitro immunomodulatory activity of interferon alpha on toll-like receptor 9 signaling pathway in chronic hepatitis B

Interferon alpha (IFN-α) is registered for chronic hepatitis B (CHB) treatment. However, the antiviral mechanism of IFN-α and the biological function of many IFN-α responsive genes have not been fully elucidated. We investigated to determine the regulative effect of IFN-α on toll-like receptor (TLR) 9 signaling in peripheral blood mononuclear cells (PBMCs) from CHB patients in vitro. We examined the changes of expression and function of TLR9 signaling pathway in the PBMCs with different treatment methods and investigated the synergism of IFN-α and TLR9 ligand on antiviral cytokine secretions in vitro. The data showed that, for the TLR9 signaling pathway, IFN-α not only augmented the expressions of TLR9 signal transduction molecules but also activated the TLR9 signal function. This study has clearly demonstrated that the TLR9 ligand could stimulate PBMCs that have been pretreated with IFN-α. Furthermore, the quantity of antiviral cytokines secreted by the pretreated PBMCs was greater than those without pretreatment. The interaction between IFN-α and TLR9 ligand appears to be synergistic. Data revealed IFN-α could influence TLR9 signaling transduction and synergistically improve the immune efficacy of TLR9 ligand against CHB. The present study suggests a potential novel mechanism for the antiviral activity against hepatitis B virus and a new individualized antiviral strategy.

Monocyte-derived dendritic cells identified as booster of T follicular helper cell differentiation

Adjuvants play an essential role in the induction of acquired immunity upon vaccination with protein antigen. In this issue of EMBO Molecular Medicine, a classical type of adjuvant made of DNA oligonucleotide containing CpG motifs, which has already been used in humans, is shown to boost humoral immunity primarily by acting on monocyte-derived dendritic cells. This study provides novel insight on the mode of action of adjuvant targeting Toll-like receptors.

Contribution of Toll-like receptors to the control of hepatitis B virus infection by initiating antiviral innate responses and promoting specific adaptive immune responses

It is well accepted that adaptive immunity plays a key role in the control of hepatitis B virus (HBV) infection. In contrast, the contribution of innate immunity has only received attention in recent years. Toll-like receptors (TLRs) sense pathogen-associated molecule patterns and activate antiviral mechanisms, including intracellular antiviral pathways and the production of antiviral effector interferons (IFNs) and pro-inflammatory cytokines. Experimental results from in vitro and in vivo models have demonstrated that TLRs mediate the activation of cellular signaling pathways and the production of antiviral cytokines, resulting in a suppression of HBV replication. However, HBV infection is associated with downregulation of TLR expression on host cells and blockade of the activation of downstream signaling pathways. In primary HBV infection, TLRs may slow down HBV infection, but contribute only indirectly to viral clearance. Importantly, TLRs may modulate HBV-specific T- and B-cell responses in vivo, which are essential for the termination of HBV infection. Thus, TLR agonists are promising candidates to act as immunomodulators for the treatment of chronic HBV infection. Antiviral treatment may recover TLR expression and function in chronic HBV infection and may increase the efficacy of therapeutic approaches based on TLR activation. A combined therapeutic strategy with antiviral treatment and TLR activation could facilitate the restoration of HBV-specific immune responses and thereby, achieve viral clearance in chronically infected HBV patients.

Hepatitis B vaccination for reducing morbidity and mortality in persons with HIV infection

BACKGROUND

Hepatitis B vaccine has been recommended for use in people living with HIV (PLHIV) mostly because of the similarities in routes of infection and their prevalence in the same geographic areas. PLHIV may not develop sero-protection after receiving standard hepatitis B vaccine due to their compromised immune status.

OBJECTIVES

To evaluate the efficacy of hepatitis B virus vaccine in PLHIV compared to placebo or no vaccine.

SEARCH METHODS

We searched 6 English language databases in July 2012, and updated the search in June 2013 and August 2014. We searched the grey literature, conference proceedings, specialised web sites, and contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials of hepatitis B vaccine compared to placebo or no vaccine, evaluating relevant outcomes of efficacy and safety.

DATA COLLECTION AND ANALYSIS

Two review authors independently sought and extracted data on study design, participants, hepatitis B infection, hepatitis B related morbidity and mortality, anti-HBs immunogenicity and adverse effects related to vaccines from published articles or through correspondence with authors. Data were analysed qualitatively.

MAIN RESULTS

One double-blind randomised controlled trial with 26 participants who were on antiretroviral therapy (ART), comparing hepatitis B vaccine to placebo conducted in Spain met our eligibility criteria and was included in this review. The study ran for three years and participants were followed up on a monthly basis. The study reported adequate humoral response to vaccine at 12 months and no local or systematic side effects in both intervention and control groups. This humoral response was lost when the participants stopped taking ART. The sample size of the study was small and the study was conducted in a high income setting unlike the areas of highest burden of hepatitis B and HIV co-infections.

AUTHORS' CONCLUSIONS

The evidence from this study is insufficient to support any recommendations regarding the use of hepatitis B vaccine in PLHIV. Neither does this evidence demonstrate that hepatitis B vaccine is unsafe in PLHIV. Further randomised controlled trials in high prevalence areas are required to generate evidence on the long term efficacy and safety of hepatitis B vaccine in PLHIV with and without ART. Different regimens and routes of administration should also be explored.

Hepatitis B vaccine responsiveness and clinical outcomes in HIV controllers

Background

Hepatitis B virus (HBV) vaccine responsiveness is associated with reduced risk of AIDS or death in HIV-infected individuals. Although HIV controllers (HIC) typically have favorable immunologic and clinical characteristics compared to non-controllers, vaccine responsiveness has not been studied.

Methods and Findings

In the U.S. Military HIV Natural History Study, HBV vaccine response was defined as antibody to hepatitis B surface antigen (anti-HBs) ≥10 IU/L after last vaccination. For determination of vaccine responsiveness, HIC (n = 44) and treatment-naïve non-controllers (n = 476) were not on highly active antiretroviral therapy (HAART) when vaccinated while treated non-controllers (n = 284) received all HBV vaccine doses during viral load (VL)-suppressive HAART. Progression to AIDS or death was also compared for all HIC (n = 143) and non-controllers (n = 1566) with documented anti-HBs regardless of the timing of HBV vaccination. Positive vaccine responses were more common in HIC (65.9%) compared to HAART-naïve non-controllers (36.6%; P<0.001), but similar to non-controllers on HAART (59.9%; P = 0.549). Factors associated with vaccine response for HIC compared to HAART-naïve non-controllers include HIC status (OR 2.65, 95% CI 1.23–5.89; P = 0.014), CD4 count at last vaccination (OR 1.28, 1.15–1.45 for every 100 cells/uL; P<0.001), and number of vaccine doses administered (OR 0.56, 0.35–0.88; P = 0.011). When HIC were compared to non-controllers on HAART, only CD4 count at last vaccination was significant (OR 1.23, 1.1–1.38 for every 100 cells/uL; P<0.001). The rate of AIDS or death per 100 person/years for HIC compared to non-controllers was 0.14 (95% CI 0–0.76) versus 0.98 (95% CI 0.74–1.28) for vaccine responders and 0 (95% CI 0–2.22) versus 4.11 (95% CI 3.38–4.96) for non-responders, respectively.

Conclusions

HIC have improved HBV vaccine responsiveness compared to treatment-naïve non-controllers, but similar to those on VL-suppressive HAART. Progression to AIDS or death can be predicted by HBV vaccine responder status for non-controllers, however these events are rarely observed in HIC.

Clinical evaluation of CpG oligonucleotides as adjuvants for vaccines targeting infectious diseases and cancer

Synthetic oligonucleotides (ODN) that express unmethylated "CpG motifs" trigger cells that express Toll-like receptor 9. In humans this includes plasmacytoid dendritic cells and B cells. CpG ODN induce an innate immune response characterized by the production of Th1 and pro-inflammatory cytokines. Their utility as vaccine adjuvants was evaluated in a number of clinical trials. Results indicate that CpG ODN improve antigen presentation and the generation of vaccine-specific cellular and humoral responses. This work provides an up-to-date overview of the utility of CpG ODN as adjuvants for vaccines targeting infectious agents and cancer.

A monoclonal antibody against the human SUMO-1 protein obtained by immunization with recombinant protein and CpG-DNA-liposome complex

Post-translational modification regulated by conjugation of a small ubiquitin-like modifier (SUMO) is involved in various cellular processes. In this study, we expressed and purified recombinant human SUMO-1 (hSUMO-1). BALB/c mice were immunized with a complex of hSUMO-1 protein and Lipoplex(O) to produce hSUMO-1-specific antibodies. Using conventional hybridoma technology, we obtained four hybridoma clones derived from the mouse with the highest antibody titer against hSUMO-1. Based on Western blot analysis, our hSUMO-1 monoclonal antibody specifically recognizes hSUMO-1, but not other SUMO proteins. These results support that the anti-hSUMO-1 monoclonal antibody produced with the aid of Lipoplex(O) adjuvant is specific and that Lipoplex(O) is useful for development of monoclonal antibodies against recombinant protein. In addition, we analyzed human tissues to examine the distribution of hSUMO-1. Higher expression of hSUMO-1 was detected in normal adrenal gland, esophagus, pancreas, liver, stomach, kidney, and uterus than in corresponding cancer tissues, suggesting a tumor suppressive function of hSUMO-1.

Incorporation of CpG into a liposomal vaccine formulation increases the maturation of antigen-loaded dendritic cells and monocytes to improve local and systemic immunity

Liposomal vaccine formulations incorporating stimulants that target innate immune receptors have been shown to significantly increase vaccine immunity. Following vaccination, innate cell populations respond to immune stimuli, phagocytose and process Ag, and migrate from the injection site, via the afferent lymphatic vessels, into the local lymph node. In this study, the signals received in the periphery promote and sculpt the adaptive immune response. Effector lymphocytes then leave the lymph node via the efferent lymphatic vessel to perform their systemic function. We have directly cannulated the ovine lymphatic vessels to detail the in vivo innate and adaptive immune responses occurring in the local draining lymphatic network following vaccination with a liposome-based delivery system incorporating CpG. We show that CpG induces the rapid recruitment of neutrophils, enhances dendritic cell-associated Ag transport, and influences the maturation of innate cells entering the afferent lymph. This translated into an extended period of lymph node shutdown, the induction of IFN-γ-positive T cells, and enhanced production of Ag-specific Abs. Taken together, the results of this study quantify the real-time in vivo kinetics of the immune response in a large animal model after vaccination of a dose comparable to that administered to humans. This study details enhancement of numerous immune mechanisms that provide an explanation for the immunogenic function of CpG when employed as an adjuvant within vaccines.

Safety of Toll-like receptor 9 agonists: a systematic review and meta-analysis

CONTEXT

The promising efficacy of Toll-like receptor 9 (TLR9) agonists for use against pathogenic infections, allergies, malignant neoplasms and autoimmunity have been demonstrated well in clinical studies, but the safety of TLR9 agonists is controversial.

OBJECTIVE

In light of the safety concerns, we conducted a systematic review and meta-analysis of clinical studies of TLR9 agonists.

METHODS

A systematic literature search was conducted. We selected studies in which the subjects were treated with a TLR9 agonist and in which the safety of the TLR9 agonist was monitored. We extracted data on adverse events (AEs) when available. A meta-analysis was performed to determine the commonest and clinical significant AEs observed in the controlled studies.

RESULTS

Nine single-arm studies and 12 controlled studies met our selection criteria. Subjects treated with TLR9 agonists were at a higher risk of anemia (risk ratio [RR] 1.04, 95% confidence interval [CI]: 1.02-1.06), neutropenia (RR 1.16, 95% CI: 1.11-1.21), leukopenia (RR 1.16, 95% CI: 1.11-1.22), lymphopenia (RR 1.17, 95% CI: 1.10-1.25), thrombocytopenia (RR 1.20, 95% CI: 1.14-1.27), flu-like symptoms (RR 10.59, 95% CI: 3.66-30.66), diarrhea (RR 1.40, 95% CI: 1.18-1.67) and headache (RR 1.61, 95% CI: 1.26-2.06). Injection-site reactions, such as erythema, pain, pruritus and swelling, were mild to moderate. TLR9 agonist therapies have not been associated with clinically significant autoimmune diseases, and few deaths potentially attributable to TLR9 agonists have been reported.

CONCLUSION

The toxicity of TLR9 agonists is generally acceptable, except when the agonist is combined with immunosuppressive agents in patients with advanced non-small-cell lung cancer.