Recombivax-HB: perspectives past, present and future

Virus-like Particles as Vaccines for Allergen-Specific Therapy: An Overview of Current Developments

Immune engineering and modulation are the basis of a novel but powerful tool to treat immune diseases using virus-like particles (VLPs). VLPs are formed by the viral capsid without genetic material making them non-infective. However, they offer a wide variety of possibilities as antigen-presenting platforms, resulting in high immunogenicity and high efficacy in immune modulation, with low allergenicity. Both animal and plant viruses are being studied for use in the treatment of food allergies. These formulations are combined with adjuvants, T-stimulatory epitopes, TLR ligands, and other immune modulators to modulate or enhance the immune response toward the presented allergen. Here, the authors present an overview of VLP production systems, their immune modulation capabilities, and the applicability of actual VLP-based formulations targeting allergic diseases.

Tailored Viral-like Particles as Drivers of Medical Breakthroughs

Despite the recognized potential of nanoparticles, only a few formulations have progressed to clinical trials, and an even smaller number have been approved by the regulatory authorities and marketed. Virus-like particles (VLPs) have emerged as promising alternatives to conventional nanoparticles due to their safety, biocompatibility, immunogenicity, structural stability, scalability, and versatility. Furthermore, VLPs can be surface-functionalized with small molecules to improve circulation half-life and target specificity. Through the functionalization and coating of VLPs, it is possible to optimize the response properties to a given stimulus, such as heat, pH, an alternating magnetic field, or even enzymes. Surface functionalization can also modulate other properties, such as biocompatibility, stability, and specificity, deeming VLPs as potential vaccine candidates or delivery systems. This review aims to address the different types of surface functionalization of VLPs, highlighting the more recent cutting-edge technologies that have been explored for the design of tailored VLPs, their importance, and their consequent applicability in the medical field.

Vaccines and Monoclonal Antibodies as Alternative Strategies to Antibiotics to Fight Antimicrobial Resistance

Antimicrobial resistance (AMR) is one of the most critical threats to global public health in the 21st century, causing a large number of deaths every year in both high-income and low- and middle-income countries. Vaccines and monoclonal antibodies can be exploited to prevent and treat diseases caused by AMR pathogens, thereby reducing antibiotic use and decreasing selective pressure that favors the emergence of resistant strains. Here, differences in the mechanism of action and resistance of vaccines and monoclonal antibodies compared to antibiotics are discussed. The state of the art for vaccine technologies and monoclonal antibodies are reviewed, with a particular focus on approaches validated in clinical studies. By underscoring the scope and limitations of the different emerging technologies, this review points out the complementary of vaccines and monoclonal antibodies in fighting AMR. Gaps in antigen discovery for some pathogens, as well as challenges associated with the clinical development of these therapies against AMR pathogens, are highlighted.

CHO cells for virus-like particle and subunit vaccine manufacturing

Chinese Hamster Ovary (CHO) cells, employed primarily for manufacturing monoclonal antibodies and other recombinant protein (r-protein) therapeutics, are emerging as a promising host for vaccine antigen production. This is exemplified by the recently approved CHO cell-derived subunit vaccines (SUV) against respiratory syncytial virus (RSV) and varicella-zoster virus (VZV), as well as the enveloped virus-like particle (eVLP) vaccine against hepatitis B virus (HBV). Here, we summarize the design, production, and immunogenicity features of these vaccine and review the most recent progress of other CHO-derived vaccines in pre-clinical and clinical development. We also discuss the challenges associated with vaccine production in CHO cells, with a focus on ensuring viral clearance for eVLP products.

Protein-based nano-vaccines against SARS-CoV-2: Current design strategies and advances of candidate vaccines

The outbreak of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has shaken the global health system. Various nanotechnology-based strategies for vaccine development have played pivotal roles in fighting against SARS-CoV-2. Among them, the safe and effective protein-based nanoparticle (NP) platforms display a highly repetitive array of foreign antigens on their surface, which is urgent for improving the immunogenicity of vaccines. These platforms greatly improved antigen uptake by antigen presenting cells (APCs), lymph node trafficking, and B cell activation, due to the optimal size, multivalence, and versatility of NPs. In this review, we summarize the advances of protein-based NP platforms, strategies of antigen attachment, and the current progress of clinical and preclinical trials in the development of SARS-CoV-2 vaccines based on protein-based NP platforms. Importantly, the lessons learnt and design approaches developed for these NP platforms against SARS-CoV-2 also provide insights into the development of protein-based NP strategies for preventing other epidemic diseases.

Glycoconjugate vaccines against antimicrobial resistant pathogens

INTRODUCTION

Antimicrobial resistance (AMR) is responsible for the death of millions worldwide and stands as a major threat to our healthcare systems, which are heavily reliant on antibiotics to fight bacterial infections. The development of vaccines against the main pathogens involved is urgently required as prevention remains essential against the rise of AMR.

AREAS COVERED

A systematic research review was conducted on MEDLINE database focusing on the six AMR pathogens defined as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli), which are considered critical or high priority pathogens by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). The analysis was intersecated with the terms carbohydrate, glycoconjugate, bioconjugate, glyconanoparticle, and multiple presenting antigen system vaccines.

EXPERT OPINION

Glycoconjugate vaccines have been successful in preventing meningitis and pneumoniae, and there are high expectations that they will play a key role in fighting AMR. We herein discuss the recent technological, preclinical, and clinical advances, as well as the challenges associated with the development of carbohydrate-based vaccines against leading AMR bacteria, with focus on the ESKAPE pathogens. The need of innovative clinical and regulatory approaches to tackle these targets is also highlighted.

Age-specific seroprotection after Hepatitis B virus vaccination among Korean American pediatric population in Queens, New York

Hepatitis B Virus (HBV) infection is a major health issue among Asian Americans. The prevalence of chronic Hepatitis B infection in New York City is estimated to be 2.7% compared with .3% in the overall United States. The efficacy and long-term immunity of HBV vaccination in the Korean American pediatric population in Queens, NY, are not well explored. This study aimed to 1) determine the age-specific prevalence of anti-HBs seropositivity in the Korean American pediatric population and 2) assess biologic/demographic factors influencing immunologic response to HBV vaccine. We performed a retrospective chart review of patients registered to a pediatric health clinic located in Queens, NY, from October 2014 to October 2020. Out of 604 medical records of patients aged ≤18 years who received a completed series of HBV vaccines during infancy, we analyzed 91 medical records where HBV serology test (HBsAg and anti-HBs) results were available. Three out of 91 subjects were born to HBsAg-positive mothers. Eight out of 91 subjects were born in South Korea. Overall, 54.9% of subjects were anti-HBs-seropositive. The seropositive rate in the 15 to 18-years-old-age group (14.3%) was significantly lower than that in other age groups: < 1 year (100%) (p = .015), 1–4 years (52.6%) (p = .033), 5–9 years (63.3%) (p = .0034), and 10–14 years (64%) (p = .0063). The mean duration since vaccination in seropositive subjects was 96.5 ± 53.9 months, and that in seronegative subjects was 121.7 ± 64.2 months (p < .047). Gender, BMI, and foreign birth were not significant risk factors affecting the nonseroprotective status. The role of routine screening of anti-HB titers and booster vaccination in this endemic community needs to be further explored.

Antibody response to an accelerated course of Hepatitis B vaccination

BACKGROUND

There are several courses with different dosing intervals for Hepatitis B vaccination. This independent study is looking at the antibody response after three doses of the accelerated course.

AIMS

The primary aim of the study was to examine data available at an Occupational Health Service for the antibody response to one or if nonresponsive, two accelerated Hepatitis B courses. A secondary aim is to determine if there is a difference in response for different sex and age groups.

METHODS

This is a retrospective anonymous and blinded study looking at the antibody response in 1032 healthcare personnel given the accelerated course of the Hepatitis B vaccine over a period of over 6 years. An anti-Hbs response 4 months after the start of the vaccination of >10 IU/ml was taken as indicative of a response.

RESULTS

After one course, 93% of the healthcare personnel developed antibody levels thought to confer immunity. After two courses, nearly 99% of the healthcare personnel had developed an adequate immune response. The response was better in females and <40 years old, a difference that was statistically significant for those aged <40.

CONCLUSIONS

The accelerated course confers high levels of immunity after 4 months and this supports the current practice of offering the accelerated dose to UK healthcare personnel who can be at immediate and higher risk of infection. Though some groups are less responsive, all groups mount a good response so all those at risk should be encouraged to have this vaccination.

6-Valent Virus-Like Particle-Based Vaccine Induced Potent and Sustained Immunity Against Noroviruses in Mice

Norovirus is a major cause of acute gastroenteritis worldwide, and no vaccine is currently available. The genetic and antigenic diversity of Norovirus presents challenges for providing broad immune protection, which calls for a multivalent vaccine application. In this study, we investigated the possibility of developing a virus-like particle (VLP)-based 6-valent Norovirus vaccine candidate (Hexa-VLPs) that covers GI.1, GII.2, GII.3, GII.4, GII.6, and GII.17 genotypes. Hexa-VLPs (30 µg) adjuvanted with 500 µg of aluminum hydroxide (alum) were selected as the optimal immunization dose after a dose-escalation study. Potent and long-lasting blockade antibody responses were induced by 2-or 3-shot Hexa-VLPs, especially for the emerging GII.P16-GII.2 and GII.17 (Kawasaki 2014) genotypes. Hexa-VLPs plus alum elicited Th1/Th2 mixed yet Th2-skewed immune responses, characterized by an IgG1-biased subclass profile and significant IL-4⁺ T-cell activation. Notably, simultaneous immunization with a mixture of six VLPs revealed no immunological interference among the component antigens. These results demonstrate that Hexa-VLPs are promising broad-spectrum vaccines to provide immunoprotection against major GI/GII epidemic strains in the future.

Humoral Response to Pfizer BNT162b2 Vaccine Booster in Maintenance Hemodialysis Patients

INTRODUCTION

Coronavirus disease is associated with increased morbidity and mortality in maintenance hemodialysis (MHD) patients. Recent breakthrough infection in vaccinated people has led some authorities to recommend a booster dose for patients fully vaccinated 5-8 months ago. We aimed to assess the humoral response of MHD patients following a booster dose with the BNT162b2 vaccine.

METHODS

The study included 102 MHD patients vaccinated with 2 doses of the BNT162b2 (Pfizer-BioNTech) vaccine. A third dose (booster) was recommended to all MHD patients in our center and was given to those who opted to receive it, resulting in a booster group and a control group that did not receive the booster. Previous exposure was excluded by testing for the presence of the anti-nucleocapsid antibody (SARS-CoV-2) or positive PCR. We assessed the humoral response before and after the booster dose.

RESULTS

Of 66 patients in the booster group, 65 patients (98.5%) developed a positive antibody response, from 472.7 ± 749.5 to 16,336.8 ± 15,397.3, as compared to a sustained decrease in the control group (695.7 ± 642.7 to 383.6 ± 298.6), p < 0.0001. No significant adverse effects were reported. Prior antibody titers were positively correlated to IgG levels following the booster dose. There was a significant association between malnutrition-inflammation markers and the humoral response.

CONCLUSIONS

Almost all MHD patients developed a substantial humoral response following the booster dose, which was significantly higher than levels reported for MHD patients following administration of 2 doses alone. Further studies and observations are needed to determine the exact timing and dosing schedule.

Comparative Immunogenicity of the Recombinant Receptor-Binding Domain of Protein S SARS-CoV-2 Obtained in Prokaryotic and Mammalian Expression Systems

The receptor-binding domain (RBD) of the protein S SARS-CoV-2 is considered to be one of the appealing targets for developing a vaccine against COVID-19. The choice of an expression system is essential when developing subunit vaccines, as it ensures the effective synthesis of the correctly folded target protein, and maintains its antigenic and immunogenic properties. Here, we describe the production of a recombinant RBD protein using prokaryotic (pRBD) and mammalian (mRBD) expression systems, and compare the immunogenicity of prokaryotic and mammalian-expressed RBD using a BALB/c mice model. An analysis of the sera from mice immunized with both variants of the protein revealed that the mRBD expressed in CHO cells provides a significantly stronger humoral immune response compared with the RBD expressed in E.coli cells. A specific antibody titer of sera from mice immunized with mRBD was ten-fold higher than the sera from the mice that received pRBD in ELISA, and about 100-fold higher in a neutralization test. The data obtained suggests that mRBD is capable of inducing neutralizing antibodies against SARS-CoV-2.

Advanced Nanomaterials for Preparedness Against (Re-)Emerging Viral Diseases

While the coronavirus disease (COVID-19) accounts for the current global pandemic, the emergence of other unknown pathogens, named "Disease X," remains a serious concern in the future. Emerging or re-emerging pathogens continue to pose significant challenges to global public health. In response, the scientific community has been urged to create advanced platform technologies to meet the ever-increasing needs presented by these devastating diseases with pandemic potential. This review aims to bring new insights to allow for the application of advanced nanomaterials in future diagnostics, vaccines, and antiviral therapies, thereby addressing the challenges associated with the current preparedness strategies in clinical settings against viruses. The application of nanomaterials has advanced medicine and provided cutting-edge solutions for unmet needs. Herein, an overview of the currently available nanotechnologies is presented, highlighting the significant features that enable them to control infectious diseases, and identifying the challenges that remain to be addressed for the commercial production of nano-based products is presented. Finally, to conclude, the development of a nanomaterial-based system using a "One Health" approach is suggested. This strategy would require a transdisciplinary collaboration and communication between all stakeholders throughout the entire process spanning across research and development, as well as the preclinical, clinical, and manufacturing phases.

Platforms for Production of Protein-Based Vaccines: From Classical to Next-Generation Strategies

To date, vaccination has become one of the most effective strategies to control and reduce infectious diseases, preventing millions of deaths worldwide. The earliest vaccines were developed as live-attenuated or inactivated pathogens, and, although they still represent the most extended human vaccine types, they also face some issues, such as the potential to revert to a pathogenic form of live-attenuated formulations or the weaker immune response associated with inactivated vaccines. Advances in genetic engineering have enabled improvements in vaccine design and strategies, such as recombinant subunit vaccines, have emerged, expanding the number of diseases that can be prevented. Moreover, antigen display systems such as VLPs or those designed by nanotechnology have improved the efficacy of subunit vaccines. Platforms for the production of recombinant vaccines have also evolved from the first hosts, Escherichia coli and Saccharomyces cerevisiae, to insect or mammalian cells. Traditional bacterial and yeast systems have been improved by engineering and new systems based on plants or insect larvae have emerged as alternative, low-cost platforms. Vaccine development is still time-consuming and costly, and alternative systems that can offer cost-effective and faster processes are demanding to address infectious diseases that still do not have a treatment and to face possible future pandemics.

Preclinical evaluation of recombinant HFMD vaccine based on enterovirus 71 (EV71) virus-like particles (VLP): Immunogenicity, efficacy and toxicology

Enterovirus 71 (EV71) is one of the major causative agents for hand, foot and mouth disease (HFMD) in children. Currently, three inactivated EV71 vaccines have been approved by Chinese government. We previously demonstrated that recombinant EV71 virus-like particles (VLP) produced in Pichia pastoris can be produced at a high yield with a simple manufacturing process, and the candidate vaccine elicited protective humoral immune responses in mice. In present study, the nonclinical immunogenicity, efficacy and toxicity of the EV71 vaccine was comprehensively evaluated in rodents and non-human primates. The immunogenicity assessment showed that EV71 VLPs vaccine elicited high and persistent neutralizing antibody responses, which could be comparable with a licensed inactivated vaccine in animals. The immune sera of vaccinated mice also exhibited cross-neutralization activities to the heterologous subtypes of EV71. Both passive and maternal antigen specific antibodies protected the neonatal mice against the lethal EV71 challenge. Furthermore, nonclinical safety assessment of EV71 VLP vaccine showed no signs of systemic toxicity in animals. Therefore, the excellent immunogenicity, efficacy and toxicology data supported further evaluation of the VLP-based EV71 vaccine in humans.

VLP-Based Vaccines as a Suitable Technology to Target Trypanosomatid Diseases

Research on vaccines against trypanosomatids, a family of protozoa that cause neglected tropical diseases, such as Chagas disease, leishmaniasis, and sleeping sickness, is a current need. Today, according to modern vaccinology, virus-like particle (VLP) technology is involved in many vaccines, including those undergoing studies related to COVID-19. The potential use of VLPs as vaccine adjuvants opens an opportunity for the use of protozoan antigens for the development of vaccines against diseases caused by Trypanosoma cruzi, Leishmania spp., and Trypanosoma brucei. In this context, it is important to consider the evasion mechanisms of these protozoa in the host and the antigens involved in the mechanisms of the parasite–host interaction. Thus, the immunostimulatory properties of VLPs can be part of an important strategy for the development and evaluation of new vaccines. This work aims to highlight the potential of VLPs as vaccine adjuvants for the development of immunity in complex diseases, specifically in the context of tropical diseases caused by trypanosomatids.

Long-term immune protection against HBV: associated factors and determinants

In Italy, vaccination against hepatitis B became compulsory for all the newborns and 12-years-old adolescents in 1991. The main purpose of this study was to evaluate the persistence of long-term protection against HBV in medical students of the University of L’Aquila and in postgraduates Medical Doctors (HCWs) working in San Salvatore Hospital. The second aim was to study the variables associated with a protective anti-HBs antibody level, such as age at vaccination, gender, time elapsed from the last dose of vaccination.

Three hundred and forty-two subjects were enrolled from January 2017 to January 2019 and a blood sample was collected to evaluate the levels of serum HBsAg, anti-HBs and anti-HBc. Statistical analysis calculated a multivariable logistic regression model to examine predictors of a protective anti-HBs titer. The larger part (239, 70%) of the students had an anti-HBs titer >10 mIU/mL, those were statistically significant older (26.7 vs 24.5 years, p < .001), vaccinated at age 12 years (83.5% vs 59.9% among vaccinate at infancy, p < .001) and more frequently attending postgraduate medical school (80.8% vs 57.5% among healthcare profession school, p < .001). The multivariable logistic regression model showed that HBV vaccination at age of 12 was significantly and independently associated with protective titers (OR = 10.27, p = .019).

The results agreed with literature on HBV vaccination, confirming the efficacy of vaccination after 20 years. In particular, our results suggest that adolescent administration is the main predictor of a protective title, regardless of gender, course and years since vaccinations.

Progress in the Production of Virus-Like Particles for Vaccination against Hepatitis E Virus

Hepatitis E virus (HEV), a pathogen that causes acute viral hepatitis, is a small icosahedral, quasi-enveloped, positive ssRNA virus. Its genome has three open reading frames (ORFs), with ORF1 and ORF3 encoding for nonstructural and regulatory proteins, respectively, while ORF2 is translated into the structural, capsid protein. ORF2 is most widely used for vaccine development in viral hepatitis. Hepatitis E virus-like particles (VLPs) are potential vaccine candidates against HEV infection. VLPs are composed of capsid subunits mimicking the natural configuration of the native virus but lack the genetic material needed for replication. As a result, VLPs are unable to replicate and cause disease, constituting safe vaccine platforms. Currently, the recombinant VLP-based vaccine Hecolin^® against HEV is only licensed in China. Herein, systematic information about the expression of various HEV ORF2 sequences and their ability to form VLPs in different systems is provided.

Towards the worldwide eradication of hepatitis B virus infection: A combination of prophylactic and therapeutic factors

Hepatitis B virus (HBV) is still a global health problem, mostly because of the intermediate/high rates of HBV chronic carriers living in most Asian, African and eastern European countries. The universal HBV vaccination of new-borns undertaken in most nations over the last 3 decades and effective HBV antiviral treatments (nucleos(t)ide analogue with high genetic barrier to viral resistance) introduced in the last decade have shown their beneficial effects in inducing a clear reduction of HBV endemicity in the countries where they have been extensively applied. Great hopes are now placed on new antiviral and immunotherapeutic drugs that are now at an advanced stage of study. It is in fact already conceivable that the synergistic use of new drugs targeting more than one HBV-lifecycle steps (covalent closed circular DNA destruction/silencing, HBV entry inhibitors, nucleocapsid assembly modulators targeting viral transcripts) and of some new immunotherapeutic agents might eliminate the intrahepatic covalent closed circular DNA and achieve the eradication of HBV infection. In spite of this, a strong effort should be given to extensive educational and screening programs for the at-risk population and to the implementation of HBV vaccination in developing countries.

Plant Viruses in Plant Molecular Pharming: Toward the Use of Enveloped Viruses

Plant molecular pharming has emerged as a reliable platform for recombinant protein expression providing a safe and low-cost alternative to bacterial and mammalian cells-based systems. Simultaneously, plant viruses have evolved from pathogens to molecular tools for recombinant protein expression, chimaeric viral vaccine production, and lately, as nanoagents for drug delivery. This review summarizes the genesis of viral vectors and agroinfection, the development of non-enveloped viruses for various biotechnological applications, and the on-going research on enveloped plant viruses.

From infancy and beyond… ensuring a lifetime of hepatitis B virus (HBV) vaccine-induced immunity

Despite the long-term efficacy and immune persistence observed following HBV vaccination of infants, the need for a booster dose following infant immunization continues to be deliberated. Evidence from HBV booster dose response studies and long-term immunization program reviews are the basis for the recommendation that a vaccine booster is not necessary. However, further studies continue to emerge and highlight the need for standardization among observational studies in order to appropriately compare outcomes. There is an assumption that neonatal and infant (within 12 months of age) vaccine immune responses are equivalent; however, evidence exists for distinct vaccine responses within the first year of life. HBV vaccine programs have evolved over time, particularly regarding the type and dosage of vaccine used. Several universal neonatal immunization programs initially incorporated a 2.5 μg dosage (Recombivax-HB, Merck). This dosage has been shown in multiple long-term studies and meta-analyses to be associated with a lower primary response, decreased antibody persistence over time, and a reduced booster response 10 to 20 years following immunization. Ongoing surveillance of this and other HBV neonatally-vaccinated populations, particularly in low endemic regions, is necessary to understand the impact on long-term protection in order to ensure lifelong protection against hepatitis B infection.

Response to hepatitis B vaccination in patients with liver cirrhosis

Hepatitis B vaccination is strongly recommended for all infants and children but also for adults who are at risk of HBV infection. Attempts to immunize patients with liver cirrhosis have been proven relatively ineffective, and several strategies have already been used to improve the immune response in this group. The primary aim of this review is to examine, discuss, and summarize the immunogenicity of hepatitis B vaccination in patients with liver cirrhosis. MEDLINE search identified 11 studies (n = 961). The dose of the vaccine and the schedule of the vaccination varied. The response rates to the HBV vaccination ranged from 16% to 87% among patients with cirrhosis regardless of the number and vaccine dose. In particular, patients who received the standard dose of vaccination achieved seroprotection rates ranged from 16% to 79% (mean response rate 38%) and those who received a double dose achieved relatively better seroprotection rates (range: 26%-87%; mean response rate 53%). The overall mean response rate to the HBV vaccination was 47%. In conclusion, cirrhotic patients achieve lower seroprotection rates after the completion of HBV vaccination series. Several strategies have tried to improve the immunogenicity; however, there is a great need for additional studies to further explore (1) the immune response in relation to poor vaccination responsiveness confounding factors, (2) novel strategies to improve immunogenicity, and (3) the immune mechanism underlying the differences in response rates to HBV vaccination.

Vaccination with a codon-optimized A27L-containing plasmid decreases virus replication and dissemination after vaccinia virus challenge

Smallpox is a disease caused by Variola virus (VARV). Although eradicated by WHO in 1980, the threat of using VARV on a bioterror attack has increased. The current smallpox vaccine ACAM2000, which consists of live vaccinia virus (VACV), causes complications in individuals with a compromised immune system or with previously reported skin diseases. Thus, a safer and efficacious vaccine needs to be developed. Previously, we reported that our virus-free DNA vaccine formulation, a pVAX1 plasmid encoding codon-optimized VACV A27L gene (pA27LOPT) with and without Imiquimod adjuvant, stimulates A27L-specific production of IFN-γ and increases humoral immunity 7days post-vaccination. Here, we investigated the immune response of our novel vaccine by measuring the frequency of splenocytes producing IFN-γ by ELISPOT, the TH1 and TH2 cytokine profiles, and humoral immune responses two weeks post-vaccination, when animals were challenged with VACV. In all assays, the A27-based DNA vaccine conferred protective immune responses. Specifically, two weeks after vaccination, mice were challenged intranasally with vaccinia virus, and viral titers in mouse lungs and ovaries were significantly lower in groups immunized with pA27LOPT and pA27LOPT+Imiquimod. These results demonstrate that our vaccine formulation decreases viral replication and dissemination in a virus-free DNA vaccine platform, and provides an alternative towards a safer an efficacious vaccine.

Persistence of immunity 18-19 years after vaccination against hepatitis B in 2 cohorts of vaccinees primed as infants or as adolescents in Italy

This study was aimed at assessing the anti-HBs persistence and immune memory 18-19 y after vaccination against hepatitis B in healthy individuals primed as infants or adolescents. We enrolled 405 teenagers (Group A) vaccinated as infants, and 409 young adults (Group B) vaccinated as adolescents. All vaccinees were tested for anti-HBs and anti-HBc antibodies; those found anti-HBc positive were further tested for HBsAg and HBV DNA. Eight individuals belonging to Group B were positive for anti-HBc alone, and were excluded from analysis. Individuals with anti-HBs concentration ≥ 10 mIU/ml were considered protected while those with anti-HBs concentration <10 mIU/ml were offered a booster dose and re-tested 2 weeks later. Overall, 67.9% individuals showed anti-HBs concentrations ≥ 10 mIU/ml (48.9% in Group A vs 87.0% in Group B, p < 0.001). The antibody geometric mean concentration (GMC) was higher in Group B than in Group A (102.5 mIU/ml vs 6.9 mIU/ml; p < 0.001). When boosted, 94.2% of vaccinees with anti-HBs <10 mIU/ml belonging to Group A and 94.7% to Group B showed an anamnestic response. Post-booster GMCs were similar in both groups (477.9 mIU/ml for Group A vs 710.0 mIU/ml for Group B, p = n.s.). Strong immunological memory persists for at least 18-19 y after immunization of infants or adolescents with a primary course of vaccination. Thus, booster doses are not needed at this time, but additional follow up is required to assess the long-life longevity of protection.

Escherichia coli-derived virus-like particles in vaccine development

Recombinant virus-like particle-based vaccines are composed of viral structural proteins and mimic authentic native viruses but are devoid of viral genetic materials. They are the active components in highly safe and effective vaccines for the prevention of infectious diseases. Several expression systems have been used for virus-like particle production, ranging from Escherichia coli to mammalian cell lines. The prokaryotic expression system, especially Escherichia coli, is the preferred expression host for producing vaccines for global use. Hecolin, the first licensed virus-like particle vaccine derived from Escherichia coli, has been demonstrated to possess good safety and high efficacy. In this review, we focus on Escherichia coli-derived virus-like particle based vaccines and vaccine candidates that are used for prevention (immunization against microbial pathogens) or disease treatment (directed against cancer or non-infectious diseases). The native-like spatial or higher-order structure is essential for the function of virus-like particles. Thus, the tool box for analyzing the key physicochemical, biochemical and functional attributes of purified virus-like particles will also be discussed. In summary, the Escherichia coli expression system has great potentials for producing a range of proteins with self-assembling properties to be used as vaccine antigens given the proper epitopes were preserved when compared to those in the native pathogens or disease-related target molecules.

Impact of universal infant hepatitis B vaccination in the US-affiliated Pacific Islands, 1985-2015

The US-affiliated Pacific Island countries (USAPI) is an endemic region for hepatitis B virus (HBV) infection. Universal infant hepatitis B vaccination was introduced in the USAPI in the mid-1980s to mitigate the HBV burden. We assessed the impact of universal infant vaccination on the HBV infection prevalence over time among children born in the 1980s, 1990s, and 2000s in the USAPI. Demographic and serologic data from serial sero-surveys conducted between 1985 and 2015 were obtained. Descriptive statistics and analysis of variance were performed. From data obtained from 4827 children (2-11years), HBV prevalence decreased markedly: 8.4% in the 1980s; 2.5% in the 1990s; and 0.2% in the 2000s (P<0.0001) as vaccination coverage increased: 76.4% in the 1980s; 87.3% in the 1990s; and 97.5% in the 2000s (P<0.0001). These findings underscore the protective effect of universal infant hepatitis B vaccination over time on the HBV burden in an HBV endemic region.

Long-term persistence in protection and response to a hepatitis B vaccine booster among adolescents immunized in infancy in the western region of China

OBJECTIVES

To evaluate the persistence of protection from hepatitis B (HB) vaccination among adolescents immunized with a primary series of HB vaccine as infants, and the immune response to booster doses.

METHODS

Healthy adolescents aged 15-17 y vaccinated with HB vaccine only at birth were enrolled. Baseline serum hepatitis B surface antigen (HBsAg), antibody against hepatitis B surface antigen (anti-HBs) and antibody against hepatitis B core antigen (anti-HBc) were detected by Enzyme-Linked Immunosorbent Assay (ELISA) and anti-HBs level was measured using Chemiluminescent Microparticle Immunoassay (CMIA). The rate of HBV infection was calculated. The seroprotection rate of anti-HBs (≥ 10 mIU/ml) and GMC level were used to evaluate the persistence of immunity from HB vaccination. Those with anti-HBs < 10 mIU/ml were immunized with booster doses of HB vaccine and the anamnestic response was assessed.

RESULTS

Of 180 adolescents who received a primary series of HB vaccinations as infants, 3 (1.7%) had HBV infection and 74 (41.1%) had anti-HBs ≥ 10 mIU/ml with a GMC of 145.11 mIU/ml. The remaining 103 (57.2%) with anti-HBs < 10 mIU/ml received a booster dose of 20 μg HB vaccine and achieved the seroprotection rate of 84% (84/100) and a GMC of 875.19 mIU/ml at one month post-booster. An additional dose of 60 μg HB vaccine was administered to the 16 adolescents with anti-HBs < 10 mIU/ml after the first booster. All of them obtained anti-HBs seroprotection with a GMC of 271.02 mIU/ml at 1.5 months after an additional dose.

CONCLUSIONS

Vaccine-induced immunity persisted for up to 15-17 y in 89.3% (158/177) of participants after a primary HB vaccination in infancy. Administering a booster dose of 20μg HB vaccine elicited an anamnestic immune responses in the majority of individuals with baseline anti-HBs <10 mIU/ml.

The combination of ISCOMATRIX adjuvant and TLR agonists induces regression of established solid tumors in vivo

The development of therapeutic vaccines for treatment of established cancer has proven challenging. Cancer vaccines not only need to induce a robust tumor Ag-specific immune response but also need to overcome the tolerogenic and immunosuppressive microenvironments that exist within many solid cancers. ISCOMATRIX adjuvant (ISCOMATRIX) is able to induce both tumor Ag-specific cellular and Ab responses to protect mice against tumor challenge, but this is insufficient to result in regression of established solid tumors. In the current study, we have used B16-OVA melanoma, Panc-OVA pancreatic, and TRAMP-C1 prostate cancer mouse tumor models to test therapeutic efficacy of ISCOMATRIX vaccines combined with other immune modulators. The coadministration of an ISCOMATRIX vaccine with the TLR3 agonist, polyinosinic-polycytidylic acid, and TLR9 agonist, CpG, reduced tumor growth in all tumor models and the presence of ISCOMATRIX in the formulation was critical for the therapeutic efficacy of the vaccine. This vaccine combination induced a robust and multifunctional CD8(+) T cell response. Therapeutic protection required IFN-γ and CD8(+) T cells, whereas NK and CD4(+) T cells were found to be redundant. ISCOMATRIX vaccines combined with TLR3 and TLR9 agonists represent a promising cancer immunotherapy strategy.

The hepatitis B vaccine protects re-exposed health care workers, but does not provide sterilizing immunity

BACKGROUND & AIMS

Infection with hepatitis B virus (HBV) can be prevented by vaccination with HB surface (HBs) antigen, which induces HBs-specific antibodies and T cells. However, the duration of vaccine-induced protective immunity is poorly defined for health care workers who were vaccinated as adults.

METHODS

We investigated the immune mechanisms (antibody and T-cell responses) of long-term protection by the HBV vaccine in 90 health care workers with or without occupational exposure to HBV, 10-28 years after vaccination.

RESULTS

Fifty-nine of 90 health care workers (65%) had levels of antibodies to HBs antigen above the cut-off (>12 mIU/mL) and 30 of 90 (33%) had HBs-specific T cells that produced interferon-gamma. Titers of antibodies to HBs antigen correlated with numbers of HBs-specific interferon-gamma-producing T cells, but not with time after vaccination. Although occupational exposure to HBV after vaccination did not induce antibodies to the HBV core protein (HBcore), the standard biomarker for HBV infection, CD4(+) and CD8(+) T cells against HBcore and polymerase antigens were detected. Similar numbers of HBcore- and polymerase-specific CD4(+) and CD8(+) T cells were detected in health care workers with occupational exposure to HBV and in patients who acquired immunity via HBV infection. Most of the HBcore- and polymerase-specific T cells were CD45RO(+)CCR7(-)CD127(-) effector memory cells in exposed health care workers and in patients with acquired immunity. In contrast, most of the vaccine-induced HBs-specific T cells were CD45RO(-)CCR7(-)CD127(-) terminally differentiated cells.

CONCLUSIONS

HBs antigen vaccine-induced immunity protects against future infection but does not provide sterilizing immunity, as evidenced by HBcore- and polymerase-specific CD8(+) T cells in vaccinated health care workers with occupational exposure to HBV. The presence of HBcore- and HBV polymerase-specific T-cell responses is a more sensitive indicator of HBV exposure than detection of HBcore-specific antibodies.

The potential of 1018 ISS adjuvant in hepatitis B vaccines: HEPLISAV™ review

Hepatitis B (HBV) virus infects the liver, and upon chronic infection, can cause liver cirrhosis and hepatocellular carcinoma. Despite universal vaccination programs against the virus, HBV still affects over 2 billion people worldwide, with over 240 million developing a chronic infection. While current alum-adjuvanted vaccines have shown efficacy in promoting seroprotection in healthy adults, 5-10% of immune-competent populations fail to achieve long-lasting seroprotection from these formulations. Furthermore, a large proportion of immunocompromised patients fail to achieve seroprotective antibody titers after receiving these vaccines. A novel vaccine candidate, HEPLISAV™, uses immunostimulatory sequences (ISS), in its formulation that helps induce a robust humoral and cell mediated immunity against HBV. In Phase III clinical trials, HEPLISAV™ has been shown to elicit seroprotective antibody titers with fewer immunizations. Similar safety profiles are demonstrated when compared with current HBV vaccines. For these reasons, HEPLISAV™ is an attractive vaccine to combat this global disease.

Inflammatory responses to hepatitis B virus vaccine in healthy term infants

Hepatitis B virus (HBV) infection continues to be a serious global health problem. During the course of HBV vaccination, we observed C-reactive protein (CRP) elevation in term infants without sepsis. Therefore, we prospectively studied interleukin-6 (IL-6) and CRP responses to HBV immunization. In 70 healthy term infants without signs and symptoms of sepsis and sepsis risk factors, IL-6, CRP, and white blood cell count levels were determined before and 24 h after immunization. Significant increases in CRP levels were seen 24 h after vaccination (p < 0.001). Although CRP levels of 22 infants at second evaluation were above the cutoff level for sepsis (4.82 mg/L), they had no clinical signs and symptoms of sepsis. After 48-72 h, CRP levels of these infants returned to normal levels with no blood culture positivity.

CONCLUSION

our study showed that HBV vaccine is responsible for CRP elevation in term infants after vaccination at birth. To the best of our knowledge, this is the first study evaluating CRP response to HBV vaccine at birth in term infants. We suggest that this response should be considered in differentiation of early neonatal sepsis to avoid unnecessary antibiotic use.

Response to hepatitis A and B vaccination in pediatric patients with celiac disease

OBJECTIVES

The aim of the study was to evaluate the response to hepatitis A and B vaccinations in pediatric patients with celiac disease (CD).

METHODS

Thirty patients with CD ages 1 to 15 years were compared with 50 healthy age-, sex-, and body mass index-matched controls. Screening for hepatitis A and B serology was carried out before vaccination. Susceptible cases received 20 μg of recombinant DNA vaccine for hepatitis B (0,1, and 6 months) and 720 milliELISA units of inactivated hepatitis A virus (HAV) vaccine (0 and 6 months). Postvaccination serologic evaluation was performed 1 month after the last dose of primary vaccination, 1 month after the booster dose, and once every year during follow-up.

RESULTS

Sixteen patients and 35 controls received hepatitis A vaccine; protective anti-HAV antibodies were developed in 12 (75%) of the patients and all of the controls (75% vs 100%, respectively; 95% confidence interval [CI] 0.47-0.92, P=0.007). Thirty patients and 50 controls received hepatitis B vaccine, and 70% of the patients vs 90% of the controls achieved seroprotection (anti-HBs titers ≥10 mIU/mL) 1 month after primary vaccination (95% CI 0.74-0.90, P=0.03). Four patients were unresponsive to both of the vaccines. The overall seroprotection rates were 96% in controls and 80% in patients after the whole hepatitis B vaccination series (95% CI 0.04-0.18, P=0.04). No significant reduction was observed in antibody response among patients and controls during follow-up period.

CONCLUSIONS

The rate of seroconversion to the hepatitis B virus- and HAV vaccine is lower in patients with CD than in healthy controls.

Plant-derived virus-like particles as vaccines

Virus-like particles (VLPs) are self-assembled structures derived from viral antigens that mimic the native architecture of viruses but lack the viral genome. VLPs have emerged as a premier vaccine platform due to their advantages in safety, immunogenicity, and manufacturing. The particulate nature and high-density presentation of viral structure proteins on their surface also render VLPs as attractive carriers for displaying foreign epitopes. Consequently, several VLP-based vaccines have been licensed for human use and achieved significant clinical and economical success. The major challenge, however, is to develop novel production platforms that can deliver VLP-based vaccines while significantly reducing production times and costs. Therefore, this review focuses on the essential role of plants as a novel, speedy and economical production platform for VLP-based vaccines. The advantages of plant expression systems are discussed in light of their distinctive posttranslational modifications, cost-effectiveness, production speed, and scalability. Recent achievements in the expression and assembly of VLPs and their chimeric derivatives in plant systems as well as their immunogenicity in animal models are presented. Results of human clinical trials demonstrating the safety and efficacy of plant-derived VLPs are also detailed. Moreover, the promising implications of the recent creation of "humanized" glycosylation plant lines as well as the very recent approval of the first plant-made biologics by the U. S. Food and Drug Administration (FDA) for plant production and commercialization of VLP-based vaccines are discussed. It is speculated that the combined potential of plant expression systems and VLP technology will lead to the emergence of successful vaccines and novel applications of VLPs in the near future.

Safety and immunogenicity of a recombinant hepatitis B vaccine manufactured by a modified process in healthy infants

A recent randomized, double-blind study carried out in healthy infants has demonstrated comparable safety and higher immunogenicity of modified process hepatitis B vaccine (mpHBV) - a novel hepatitis B vaccine with enhanced phosphate content in the aluminum adjuvant - compared with Recombivax HB™. Each infant was assigned to receive either 5 µg mpHBV vaccine, 10 µg mpHBV vaccine, 5 µg Recombivax HB vaccine or 10 µg Engerix-B vaccine at 2, 4 and 6 months of age. Findings of this study showed that 1 month after the third vaccine administration, both 5 µg mpHBV and Recombivax HB were able to induce adequate antibody seroprotection rates (SPRs; ≥10 mIU/ml), thus meeting the primary end point. Geometric mean titers (GMTs) were significantly higher among infants who were given either 5 or 10 µg of mpHBV formulations than among those who received Recombivax HB or Engerix-B. In addition, the 5 µg mpHBV over Recombivax HB GMT ratio indicates the noninferiority of the former vaccine compared with the latter. Finally the 10 µg mpHBV/5 µg mpHBV GMT ratio did not show superiority even though the difference was significant. These findings show that the enhanced content of the phosphate component contained in the mpHBV vaccine can potentiate the immune response to hepatitis B surface antigen by making it more available for uptake by dendritic cells. Additional studies are needed to establish whether this novel vaccine may be of benefit in improving immune responses in people who are less responsive to the currently licensed vaccines.

Viruses and Virus-Like Particles in Biotechnology

Although viruses are simple biological systems, they are capable of evolving highly efficient techniques for infecting cells, expressing their genomes, and generating new copies of themselves. It is possible to genetically manipulate most of the different classes of known viruses in order to produce recombinant viruses that express foreign proteins. Recombinant viruses have been used in gene therapy to deliver selected genes into higher organisms, in vaccinology and immunotherapy, and as important research tools to study the structure and function of these proteins.

Virus-like particles (VLPs) are multiprotein structures that mimic the organization and conformation of authentic native viruses but lack the viral genome. They have been applied not only as prophylactic and therapeutic vaccines but also as vehicles in drug and gene delivery and, more recently, as tools in nanobiotechnology.

In this article, basic and advanced features of viruses and VLPs are presented and their major applications are discussed. The different production platforms based on animal cell technology are explained, and their main challenges and future perspectives are explored. The implications of large-scale production of viruses and VLPs are discussed in the context of process control, monitorization, and optimization. The main upstream and downstream technical challenges are identified and discussed accordingly.

View and review on viral oncology research

To date, almost one and a half million cases of cancer are diagnosed every year in the US and nearly 560,000 Americans are expected to die of cancer in the current year, more than 1,500 people a day (data from the American Cancer Society at http://www.cancer.org/). According to the World Health Organization (WHO), roughly 20% of all cancers worldwide results from chronic infections; in particular, up to 15% of human cancers is characterized by a viral aetiology with higher incidence in Developing Countries. The link between viruses and cancer was one of the pivotal discoveries in cancer research during the past Century. Indeed, the infectious nature of specific tumors has important implications in terms of their prevention, diagnosis, and therapy. In the 21st Century, the research on viral oncology field continues to be vigorous, with new significant and original studies on viral oncogenesis and translational research from basic virology to treatment of cancer. This review will cover different viral oncology aspects, starting from the history of viral oncology and moving to the peculiar features of oncogenic RNA and DNA viruses, with a special focus on human pathogens.

Prevention of viral hepatitis (B and C) reassessed

As hepatitis B and C share modes of transmission, their combined occurrence is not uncommon, particularly in areas where both viruses are endemic and in individuals at high-risk of parenteral infection. Both viral hepatitis infections form an important global public health problem, responsible for over half a billion chronic infections worldwide. Their distinctive characteristics impact upon their epidemiology, transmission, and the success of the different prevention strategies. Since several decades a safe and effective vaccine has been available to prevent hepatitis B virus (HBV) infection. Universal vaccination is the cornerstone of global HBV control. Despite major success, vaccine uptake is hampered, and increasing efforts are required to eliminate acute and chronic hepatitis B. Unlike hepatitis C and HIV, HBV has not captured sufficient attention from policymakers, advocacy groups, or the general public: a major challenge for the future. Although progress has been made in the development of an hepatitis C vaccine, short-term successes are not expected. Even without a vaccine, successes can be reported in the field of hepatitis C due to e.g. implementation of universal precautionary measures in health-care settings, screening of blood and blood products, and identification and counselling of infected people. Despite important efforts, transmission in injecting drug users is increasing.

Vaccination against the Human Papillomavirus: the lessons we have not learned

Recent conversations regarding the vaccine against the Human Papillomavirus have focused on scientific concerns of effectiveness and scope of prevention as well as social, political and economic concerns including who should be eligible to receive the vaccine and why. However, discussions to date have not reflected on comparable historical perspectives including lessons learned in the development and marketing of the Hepatitis B vaccine. These two vaccines have remarkably similar public health implications in the prevention of specific cancers as well as generating alike social, political and financial concerns. The present paper examines these similarities with the intention of providing perspective on the current Human Papillomavirus vaccine debate and advocating for more expedient and expansive vaccine availability.

Benefits of early hepatitis B immunization programs for newborns and infants

Despite the availability of safe and effective hepatitis B virus (HBV) vaccines for >20 years, strategies targeting risk groups failed to sufficiently control hepatitis B disease at the population level; this is mainly because of difficulties in risk identification and in program implementation. Hence, the global burden of disease of HBV still is substantial. The World Health Organization recommends universal vaccination against hepatitis B to ultimately eliminate HBV; this recommendation had been progressively implemented to reach 168 countries with a universal program by the end of 2006. However, hepatitis B immunization is currently becoming endangered of losing its place on the agendas of governments, agencies, and international organizations, mainly because of the increasing success of these immunization programs and the interest in newer vaccine-preventable diseases and the related programs.This publication aims to show that vaccination programs targeting newborns and infants are preferable to achieve this goal. The benefits of universal HBV vaccination for newborns and infants are: higher impact on chronic carrier rate and transmission; established potential of high vaccine coverage in this age group; opportunities to combine HBV vaccination with existing universal vaccination programs for newborns and infants; and impact on perinatal transmission, if vaccination is started shortly after birth. Moreover, the safety, immunogenicity, and long-term efficacy of newborn and infant HBV vaccination have been proven extensively. In summary, newborn and infant HBV vaccination programs should be considered the preferred strategy, capable of providing important and sustained impact on global HBV incidence, even if they have a delayed impact on sexual transmission of HBV.

Hepatitis A/B vaccination of adults over 40 years old: Comparison of three vaccine regimens and effect of influencing factors

Challenged by contrasting data on low immune responses in the elderly with a combined hepatitis A/B vaccine, a randomised, controlled study was conducted to assess the immunogenicity of three hepatitis A and B vaccination regimens (group 1: combined hepatitis A/B vaccine Twinrix [GSK]; group 2: co-administered hepatitis A vaccine, Havrix [GSK]+hepatitis B vaccine Engerix -B [GSK], group 3: co-administered hepatitis A vaccine, Vaqta [Sanofi-Pasteur MSD]+hepatitis B vaccine HB VAX PRO [Sanofi-Pasteur MSD]) and the effect of influencing factors in subjects >40 years. On completion of the full vaccination course, anti-HBs seroprotection (SP) rates were 92, 80 and 71% in groups 1, 2 and 3, respectively; anti-HAV seropositivity (S+) rates were 97, 99 and 99%, respectively. In group 1, anti-HBs SP rate was non-inferior as well as superior and anti-HAV S+ rate was non-inferior to that in groups 2 and 3. Anti-HBs response was most significantly influenced by the vaccine regimen, followed by age, gender and BMI (stepwise multiple regression analysis). BMI had the most significant influence on HAV response followed by age, gender and vaccine regimen. In conclusion, Twinrix induced superior hepatitis B SP rates and similar hepatitis A S+ rates compared to concomitant administration of monovalent vaccines in subjects aged >40 years.