Photodynamic Therapy in Combination with the Hepatitis B Core Virus-like Particles (HBc VLPs) to Prime Anticancer Immunity for Colorectal Cancer Treatment.

Photodynamic therapy (PDT), which combines light and oxygen with a photosensitizer to induce reactive oxygen species (ROS)-mediated killing of primary tumor cells, benefits from non-invasive properties and its negligible toxicity to surrounding healthy tissues. In this study, we have shown that the second-generation photosensitizer FOSCAN can be internalized by tumor cells and effectively induce tumor cell death when exposed to laser irradiation in vitro. In addition, these dying tumor cells can be phagocytosed by dendritic cells and lead to their activation and maturation as assessed by in vitro co-culture models. While PDT induces immunogenic tumor cell apoptosis, its application for the treatment of tumors located in deep tissues and advanced malignancies has been limited. In this study, we demonstrate that hepatitis B core virus-like particles (HBc VLPs) can serve as a vaccine to enhance PDT-induced anti-cancer immunity by priming humoral immune responses and inducing CD8+ T cell responses. The combination of PDT and HBc VLPs increased the survival rate of MC-38 tumor-bearing mice to 55%, compared to 33% in PDT alone and no tumor-free mice in vaccine alone. Moreover, the combination effectively prevented tumor recurrence in vivo through enhanced immune memory T cells after therapy. Therefore, as both are clinically approved techniques, this combination provides a promising strategy for cancer therapy.

HeberNasvac, a Therapeutic Vaccine for Chronic Hepatitis B, Stimulates Local and Systemic Markers of Innate Immunity: Potential Use in SARS-CoV-2 Postexposure Prophylaxis.

INTRODUCTION: More than 180 million people have been infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and more than 4 million coronavirus disease-2019 (COVID-19) patients have died in 1.5 years of the pandemic. A novel therapeutic vaccine (NASVAC) has shown to be safe and to have immunomodulating and antiviral properties against chronic hepatitis B (CHB). MATERIALS AND METHODS: A phase I/II, open-label controlled and randomized clinical trial of NASVAC as a postexposure prophylaxis treatment was designed with the primary aim of assessing the local and systemic immunomodulatory effect of NASVAC in a cohort of suspected and SARS-CoV-2 risk-contact patients. A total of 46 patients, of both sexes, 60 years or older, presenting with symptoms of COVID-19 were enrolled in the study. Patients received NASVAC (100 µg per Ag per dose) via intranasal at days 1, 7, and 14 and sublingual, daily for 14 days. RESULTS AND DISCUSSION: The present study detected an increased expression of toll-like receptors (TLR)-related genes in nasopharyngeal tonsils, a relevant property considering these are surrogate markers of SARS protection in the mice model of lethal infection. The HLA-class II increased their expression in peripheral blood mononuclear cell's (PBMC's) monocytes and lymphocytes, which is an attractive property taking into account the functional impairment of innate immune cells from the periphery of COVID-19-infected subjects. NASVAC was safe and well tolerated by the patients with acute respiratory infections and evidenced a preliminary reduction in the number of days with symptoms that needs to be confirmed in larger studies. CONCLUSIONS: Our data justify the use of NASVAC as preemptive therapy or pre-/postexposure prophylaxis of SARS-CoV-2 and acute respiratory infections in general. The use of NASVAC or their active principles has potential as immunomodulatory prophylactic therapies in other antiviral settings like dengue as well as in malignancies like hepatocellular carcinoma where these markers have shown relation to disease progression. HOW TO CITE THIS ARTICLE: Fleites YA, Aguiar J, Cinza Z, et al. HeberNasvac, a Therapeutic Vaccine for Chronic Hepatitis B, Stimulates Local and Systemic Markers of Innate Immunity: Potential Use in SARS-CoV-2 Postexposure Prophylaxis. Euroasian J Hepato-Gastroenterol 2021;11(2):59-70.

Role of Pegylated Interferon in Patients with Chronic Liver Diseases in the Context of SARS-CoV-2 Infection.

The coronavirus 2019 (COVID-19) pandemic has resulted in 168 million cases and about 3.5 million deaths (as of May 26, 2021) during the last 18 months. These 18 months of the COVID-19 pandemic have been characterized by phases or waves of new cases, the emergence of new variants of the deadly virus, and several new complications. After providing emergency approval to several drugs and adherence to several public health measures with frequent full and partial lockdowns, the incidence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could not be contained till now on a global basis. Although prophylactic vaccines have inspired optimism, the scarcity of vaccines and several vaccine-related regulations indicate that the vaccine's benefit would not be reaching the people of developing countries anytime soon. In the course of our clinical practice, we used pegylated interferon (Peg-IFN) in 35 patients with chronic liver diseases (CLD), and we found that only two of them were infected with SARS-CoV-2 that was mild in nature. These two patients with CLD have a mild course of disease cured without any specific therapy. Patients with CLD are usually immune-compromised. However, three CLD patients remained free of SARS-CoV-2 although they had COVID-19 patients among their family members. Next, we accomplished two studies for assessing the immune-modulatory capacities of Peg-IFN, 1 and 12 injections following administration of Peg-IFN. The data revealed that peripheral blood mononuclear cells (PBMCs) of Peg-IFN-administered CLD patients produced significantly higher levels of some cytokines of innate immunity in comparison with the cytokines produced by PBMC of CLD patients before Peg-IFN intake. The pattern of cytokine responses and absence of infection of SARS-CoV-2 in 33 of 35 CLD patients represent some preliminary observations indicating a possible role of Peg-IFN in patients with CLD. The study may be extended to other chronic infections and cancers in which patients receive Peg-IFN. The role of Peg-IFN for pre- or postexposure prophylaxis in the acquisition of SARS-CoV-2 infection and influencing the natural course of COVID-19 remains to be clarified. HOW TO CITE THIS ARTICLE: Akbar SMF, Mahtab MA, Aguilar JC, et al. Role of Pegylated Interferon in Patients with Chronic Liver Diseases in the Context of SARS-CoV-2 Infection. Euroasian J Hepato-Gastroenterol 2021;11(1):27-31.

Effectiveness of Manual Toothbrushing Techniques on Plaque and Gingivitis: A Systematic Review.

PURPOSE: Currently, there is no consensus on recommendations for manual toothbrushing techniques between dentists, oral health therapists and dental companies. The aim of this systematic review is to identify and assess the quality of evidence of the effectiveness of manual toothbrushing techniques in the existing literature. METHODS: A broad search was conducted on the electronic databases Medline via Ovid, PubMed and EBSCO Dentistry & Oral Sciences. Included studies examined manual toothbrushing technique efficiency. Articles were assessed utilising the Cochrane Collaboration's tool for assessing risk of bias. Thirteen studies met the inclusion criteria and were included in this review. These included five randomised controlled trials (RCT), seven experimental non-randomised control studies and one in vitro study. RESULTS: Of the 3190 articles identified, 40 were relevant to manual toothbrushing and 13 were included in the final review. Studies indicating statistically significantly superior plaque removal for a given technique were Bass (one), modified Bass (one), Charter's (two), Fones (two), scrub (two), roll (one), modified Stillman (one), toothpick method (one). Four studies exhibited no statistically significant difference in effectiveness of plaque removal. Unfortunately, considerable variation was found between studies, making a definitive conclusion impossible in terms of an ideal manual toothbrushing technique that would promote plaque removal and reduce gingivitis. CONCLUSION: There is still insufficient evidence for suggesting that one toothbrushing method is more effective than another in plaque removal and reduction of gingivitis. Excessive variability in many aspects of the design and methodology of the selected studies hinder conclusions on an ideal manual toothbrushing technique. Experimental randomised controlled trials that follow the CONSORT guidelines are required to provide adequate-quality evidence and make any definitive conclusions on the relative effectiveness of manual toothbrushing techniques.

HBV genotypic variability in Cuba.

The genetic diversity of HBV in human population is often a reflection of its genetic admixture. The aim of this study was to explore the genotypic diversity of HBV in Cuba. The S genomic region of Cuban HBV isolates was sequenced and for selected isolates the complete genome or precore-core sequence was analyzed. The most frequent genotype was A (167/250, 67%), mainly A2 (149, 60%) but also A1 and one A4. A total of 77 isolates were classified as genotype D (31%), with co-circulation of several subgenotypes (56 D4, 2 D1, 5 D2, 7 D3/6 and 7 D7). Three isolates belonged to genotype E, two to H and one to B3. Complete genome sequence analysis of selected isolates confirmed the phylogenetic analysis performed with the S region. Mutations or polymorphisms in precore region were more common among genotype D compared to genotype A isolates. The HBV genotypic distribution in this Caribbean island correlates with the Y lineage genetic background of the population, where a European and African origin prevails. HBV genotypes E, B3 and H isolates might represent more recent introductions.

Enhanced immunogenicity and cross-reactivity of HIV-1 V3-peptide and multiple antigen peptides conjugated to distinct carrier proteins.

To be effective, vaccines against the highly variable HIV-1 must elicit antibodies to a huge number of clinical isolates. For this purpose, new strategies to overcome this variability are needed. We previously reported a useful immunogenic strategy which consists of conjugating multiple antigen peptides (MAPs) to HBsAg. This vaccine candidate reduces the dose of immunogen required and increases the cross-reactivity towards other HIV strains. In the present study, we have expanded on those results by working with other carrier proteins. Thus, JY1-peptide (V3 regions of gp120 of HIV-1, subtype D) and JY1-MAP8 were synthesized and coupled to several carrier proteins such as KLH, HBsAg and P64k (recombinant meningococcal protein). Mice were immunized with various conjugates and their antigenicity, immunogenicity, and the level of cross-reactivity to a panel of five heterologous V3 peptides were compared. Our results show that conjugate JY1-MAP8 were not only more immunogenic than conjugate, they were also more or equally as immunogenic as 4-fold more JY1-MAP8 alone. Furthermore, conjugates to HBsAg and KLH were more immunogenic than those to P64k. Moreover, conjugates to HBsAg, KLH and P64k showed enhanced cross-reactivity to heterologous V3 peptides compared to JY1-peptide and JY1-MAP8. The analysis showed that conjugate-based immunogens are more prompt to elicit immunogenicity and cross-reactivity. These results can find application in the development of HIV vaccine candidates.

Recombinant in vitro assembled hepatitis C virus core particles induce strong specific immunity enhanced by formulation with an oil-based adjuvant.

In the present work, immunogenicity of recombinant in vitro assembled hepatitis C virus core particles, HCcAg.120-VLPs, either alone or in combination with different adjuvants was evaluated in BALB/c mice. HCcAg.120-VLPs induced high titers of anti-HCcAg.120 antibodies and virus-specific cellular immune responses. Particularly, HCcAg.120-VLPs induced specific delayed type hypersensitivity, and generated a predominant T helper 1 cytokine pro file in immunized mice. In addition, HCcAg.120-VLPs prime splenocytes proliferate in vitro against different HCcAg.120-specific peptides, depending on either the immunization route or the adjuvant used. Remarkably, immunization with HCcAg.120-VLPs/Montanide ISA888 formulation resulted in a significant control of vaccinia virus titer in mice after challenge with a recombinant vaccinia virus expressing HCV core protein, vvCore. Animals immunized with this formulation had a marked increase in the number of IFN-gamma producing spleen cells, after stimulation with P815 cells infected with vvCore. These results suggest the use of recombinant HCV core particles as components of therapeutic or preventive vaccine candidates against HCV.

Recombinant in vitro assembled hepatitis C virus core particles induce strong specific immunity enhanced by formulation with an oil-based adjuvant

In the present work, immunogenicity of recombinant in vitro assembled hepatitis C virus core particles, HCcAg.120-VLPs, either alone or in combination with different adjuvants was evaluated in BALB/c mice. HCcAg.120-VLPs induced high titers of anti-HCcAg.120 antibodies and virus-specific cellular immune responses. Particularly, HCcAg.120-VLPs induced specific delayed type hypersensitivity, and generated a predominant T helper 1 cytokine pro file in immunized mice. In addition, HCcAg.120-VLPs prime splenocytes proliferate in vitro against different HCcAg.120-specific peptides, depending on either the immunization route or the adjuvant used. Remarkably, immunization with HCcAg.120-VLPs/Montanide ISA888 formulation resulted in a significant control of vaccinia virus titer in mice after challenge with a recombinant vaccinia virus expressing HCV core protein, vvCore. Animals immunized with this formulation had a marked increase in the number of IFN-γ producing spleen cells, after stimulation with P815 cells infected with vvCore. These results suggest the use of recombinant HCV core particles as components of therapeutic or preventive vaccine candidates against HCV.

Anti-HIV-1 and anti-HBV immune responses in mice after parenteral and nasal co-administration of a multiantigenic formulation.

The cell-mediated immune response to HIV-1 is an essential element of the mechanisms for viral replication control. Currently, most of the vaccine candidates in clinical trials were developed to stimulate HIV-1-specific CD8+ cytotoxic (CTL) and CD4+ T helper (Th) lymphocytes. We have been working on a novel approach to develop a vaccine formulation for HIV-1 using a recombinant multiepitopic protein (named CR3), which comprises CTL and Th epitope-rich regions of HIV-1 from several subtype B isolates, co-inoculated with the hepatitis B virus surface (HBsAg) and core (HBcAg) antigens of the hepatitis B virus (HBV) as adjuvant. According to our studies in mice, the nasal-subcutaneous co-administration of this multiantigenic formulation induces a strong Th1-biased specific response against CR3, CD8+ T cells in mice spleen and IFN-gamma-secreting cells in mesenteric lymph nodes. Cross-reactive p24-specific IFN-gamma-secreting cells in spleen were also detected. Moreover, Nef-specific antibodies were elicited in mice sera which might avoid the toxic effects of this antigen. However, a marginal anti-CR3 antibody response was elicited in vaginal mucosa. Additionally, we observed anti-HBsAg and anti-HBcAg cellular and humoral responses. In this regard, our multiantigenic formulation might provide immunity against HBV as an additional benefic considering the high HIV-1-HBV co-infection rate reported worldwide.

Coinoculation with hepatitis B surface and core antigen promotes a Th1 immune response to a multiepitopic protein of HIV-1.

It has been defined that strong and multispecific cellular immune responses correlate with a better prognosis during the course of chronic diseases. A cross-enhancing effect on the resulting immune response obtained by the coadministration of recombinant hepatitis B virus (HBV) surface and core Ag was recently observed. With the objective of studying the effect of such Ag on the immune response to coinoculated heterologous Ag and vice versa, several formulations containing the recombinant HBV Ag and a multiepitopic protein (CR3) composed by CTL and Th epitopes from HIV-1 were evaluated by s.c. and mucosal administration. Combinations of two and three Ag were evaluated for cellular and humoral immune responses. The results showed that the best Ag combination for nasal immunization was the mixture comprising the CR3 recombinant HIV protein and both HBV Ag. Similarly, it was also the best formulation for s.c. immunization in aluminium phosphate adjuvant. In conclusion, it is possible to induce a Th1 stimulation of the cellular immune response specific for a HIV-based recombinant protein by formulating this Ag with the recombinant HBV Ag.

Influence of aluminum-based adjuvant on the immune response to multiantigenic formulation.

Several adjuvants have been described and tested in humans. However, the aluminum-based adjuvants remain the most widely used component in vaccines today. Emerging data suggest that aluminum phosphate and aluminum hydroxide adjuvants do not promote a strong commitment to the helper T cell type 2 (Th2) pathway when they are coadministered with some Th1 adjuvants. In this regard, subtle differences between both aluminum-based adjuvants have been demonstrated. We have previously shown that subcutaneous immunization, in aluminum phosphate, of a mixture comprising the surface and core antigens of hepatitis B virus (HBV) and the multiepitopic protein CR3 of human immunodeficiency virus type 1 elicits a CR3-specific Th1 immune response. In these experiments, the antigens were adjuvated at the same time. As the final selection of the best adjuvant should be based on experimental evidence, we asked whether aluminum hydroxide allows a better Th1 immune deviation than aluminum phosphate. We also studied several ways to mix the antigens and the impact on CR3-specific interferon (IFN)-gamma secretion. Our findings indicate that aluminum hydroxide allows better Th1 immunodeviation than aluminum phosphate adjuvant for the mixture of HBV antigens and CR3. In addition, CR3-specific IFN-gamma secretion of the various formulations tested was the same irrespective of the order in which the antigens were combined.

A C-terminal truncated hepatitis C virus core protein variant assembles in vitro into virus-like particles in the absence of structured nucleic acids.

Little is known about the assembly pathway or structure of the hepatitis C virus (HCV). In this work a truncated HCcAg variant covering the first 120 aa (HCcAg.120) with a 32 aa N-terminal fusion peptide (6x Histag-Xpress epitope) was purified as a monomer under strong denaturing conditions. In addition, minor HCcAg.120 peaks exhibiting little different molecular mass by SDS-PAGE which possibly represents alternative forms harboring the N-termini of HCcAg.120 were detected. Analysis using gel filtration chromatography showed that HCcAg.120 assembled into high molecular weight structures in vitro in the absence of structured nucleic acids. The negative-stain electron microscopy analysis revealed that these structures correspond with spherical VLPs of uniform morphology and size distribution. The diameters of these particles ranged from 20 to 43nm with an average diameter of approximately 30 nm and were specifically immunolabelled with a mouse monoclonal antibody against the residues 5-35 of HCcAg. Results presented in this work showed that HCcAg.120 assembled in vitro into VLPs in the absence of structured nucleic acids with similar morphology and size distribution to those found in sera and hepatocytes from HCV-infected patients. Therefore, these VLPs would be important to elucidate the mechanisms behind the ability of HCcAg to assemble into a nucleocapsid structure.

Broader cross-reactivity after conjugation of V3 based multiple antigen peptides to HBsAg.

Vaccines against highly variable pathogens should elicite antibodies to a huge number of clinical isolates. For this purpose, new strategies to overcome the variability are needed. We have previously reported a useful method to conjugate multiple antigen peptides (MAPs) to carrier proteins. Also, we have suggested that these conjugates might enhance cross-reactivity in comparison to other synthetic structures. In this work, MAPs were synthesized and their respective conjugates to HBsAg were obtained. Two peptides from the V3 loop of HIV-1 were included in the MAPs as B cell epitopes because of their variability. Groups of mice were immunized and the immunogenicity and the level of cross-reaction to a panel of five heterologous V3 peptides were studied. Our results show that sera from mice immunized with MAPs coupled to HBsAg recognize a higher number of heterologous peptides (P < 0.05). This behavior was related neither to the immunogenicity nor the antigenicity of the synthetic structures. These results have important implications for the choice of better immunogens against variable epitopes.

Different immune response of mice immunized with conjugates containing multiple copies of either consensus or mixotope versions of the V3 loop peptide from human immunodeficiency virus type 1.

The critical role that antibody responses to the V3 loop epitope play in human immunodeficiency virus type 1 (HIV-1) neutralization has caused this peptide to be used in many HIV-1 vaccine candidates. To enhance cross-reactivity toward several V3 sequences, a database of 50 peptides of the V3 region from HIV-1 subtype A was used to design both a consensus peptide and a combinatorial peptide (mixotope) library representative of these sequences. The two immunogens (consensus and mixotope) were incorporated into multiple antigen peptide (MAP) constructions, conjugated to a recombinant surface antigen from hepatitis B virus (HbsAg) carrier protein, and inoculated to mice in combination with a C4 (CD4-binding) peptide MAP construction, also conjugated to HBsAg. The respective responses and cross-reactivity to several V3 loop sequences of both types of immunogens were compared. Mice inoculated with the V3 consensus-MAP-HBsAg + C4-MAP-HBsAg mixture elicited higher antibody responses than those given the V3 mixotope-MAP-HBsAg + C4-MAP-HBsAg mixture. In addition, pooled serum from the first group of immunogens analyzed at dilution 1:100 had higher cross-reactivity against V3 peptides on cellulose membranes than those from mice given the combinatorial immunogen. Fine epitope mapping of both consensus and C4 peptide by the spot synthesis technique showed that sera of the first group strongly recognized both sequences in their entirety, whereas mice immunized with the mixotope library recognized only the N-terminal region of V3. These results seem to suggest that the V3 consensus peptide is superior to the combinatorial strategy in inducing potent and cross-reactive responses to HIV.

A comparative study of different presentation strategies for an HIV peptide immunogen.

Different strategies have been used to increase the immunogenicity of an antigenic HIV peptide as a vaccine candidate. The selected B-cell epitope comprises 15 amino acids (317-331) of the V3 region of HIV-1, JY1 isolate (subtype D), in tandem with a T-helper epitope corresponding to the 830-844 region of tetanus toxoid. Several presentations, including oligomerization, multiple antigenic peptide dendrimers, and conjugation to dextran beads or to other macromolecular carriers, have been synthesized and evaluated. Murine sera from the different presentations of the V3 epitope have been compared with regard to antibody titers and cross-reactivity with heterologous HIV subtypes. The dendrimer version of the peptide conjugated to HBsAg protein was a better immunogen than the dendrimer alone and showed a higher immunogenicity than other multimeric presentations or than the peptide alone conjugated to dextran. The dendrimer version, either alone or conjugated to HBSAg, enhanced cross-reactivity toward heterologous V3 sequences relative to monomeric peptide. In addition, fine epitope mapping of the entire JY1 sequence by sera from the different immunization groups was performed by the spot synthesis technique. Results showed that the amino acids involved in molecular recognition were LXQXXY or LXQXLY, with particularly strong recognition of the C-terminal region LGQALY. However, cross-reactivity toward the heterologous sequences did not completely correlate with recognition of particular amino acids in the primary sequences. These results can find application in the development of HIV vaccine candidates.

Scanning electrochemical microscopy. 46. Shielding effects on reversible and quasireversible reactions.

An approximate theory for the feedback mode of the scanning electrochemical microscope (SECM) is developed to interpret the effects of substrate shielding on an ultramicroelectrode tip during a recording of iT versus d curves (approach curves) for reversible and quasireversible kinetics at a substrate surface. The resulting expressions for the tip current, iT, show a good fit to more accurate SECM simulations as well as to the experimental response of a reversible and quasireversible reaction. SECM shielding experiments thus give an interesting new insight into SECM approach curves over electrodes at different potentials, which suggest possible applications to measuring heterogeneous kinetics for fast reactions and diffusion coefficient determination.

HCV core protein modulates the immune response against the HBV surface antigen in mice.

Mucosal vaccination is currently arousing a great deal of interest, since mucosally induced immunity is able to protect not only against microorganisms using mucosa as a door of entry, but also against those parenterally transmitted. Hepatitis C virus (HCV) is considered a worldwide health problem and a current vaccine is not available. In the present work, immunogenicity of particulate HCcAg was evaluated, administered alone and also in formulations with the main protective antigen of HBV, the surface antigen (HBsAg), both by mucosal (i.n.) and parenteral (i.m) routes. HCcAg was able to induce strong immune responses after nasal as well as parenteral administration, developing a strong Th1-like antibody response in serum. Preliminary data also suggested the ability of HCcAg to efficiently enhance and modulate the host immune response against HBsAg. These results support the use of the particulate HCcAg in the rational design of candidates for HCV therapeutic or preventive vaccine strategies or inclusively in the development of future combined vaccines.