Preparation and immunogenicity of an inactivated hepatitis A vaccine

Protein Cages: From Fundamentals to Advanced Applications

Proteins that self-assemble into polyhedral shell-like structures are useful molecular containers both in nature and in the laboratory. Here we review efforts to repurpose diverse protein cages, including viral capsids, ferritins, bacterial microcompartments, and designed capsules, as vaccines, drug delivery vehicles, targeted imaging agents, nanoreactors, templates for controlled materials synthesis, building blocks for higher-order architectures, and more. A deep understanding of the principles underlying the construction, function, and evolution of natural systems has been key to tailoring selective cargo encapsulation and interactions with both biological systems and synthetic materials through protein engineering and directed evolution. The ability to adapt and design increasingly sophisticated capsid structures and functions stands to benefit the fields of catalysis, materials science, and medicine.

Production- and Purification-Relevant Properties of Human and Murine Cytomegalovirus

There is a large unmet need for a prophylactic vaccine against human cytomegalovirus (HCMV) to combat the ubiquitous infection that is ongoing with this pathogen. A vaccination against HCMV could protect immunocompromised patients and prevent birth defects caused by congenital HCMV infections. Moreover, cytomegalovirus (CMV) has a number of features that make it a very interesting vector platform for gene therapy. In both cases, preparation of a highly purified virus is a prerequisite for safe and effective application. Murine CMV (MCMV) is by far the most studied model for HCMV infections with regard to the principles that govern the immune surveillance of CMVs. Knowledge transfer from MCMV and mice to HCMV and humans could be facilitated by better understanding and characterization of the biological and biophysical properties of both viruses. We carried out a detailed investigation of HCMV and MCMV growth kinetics as well as stability under the influence of clarification and different storage conditions. Further, we investigated the possibilities to concentrate and purify both viruses by ultracentrifugation and ion-exchange chromatography. Defective enveloped particles were not separately analyzed; however, the behavior of exosomes was examined during all experiments. The effectiveness of procedures was monitored using CCID₅₀ assay, Nanoparticle tracking analysis, ELISA for host cell proteins, and quantitative PCR for host cell DNA. MCMV generally proved to be more robust in handling. Despite its greater sensitivity, HCMV was efficiently (100% recovery) purified and concentrated by anion-exchange chromatography using QA monolithic support. The majority of the host genomic DNA as well as most of the host cell proteins were removed by this procedure.

Experimental Infection of Mid-Gestation Pregnant Female and Intact Male Sheep with Zika Virus

Zika virus (ZIKV) is an arbovirus that causes birth defects, persistent male infection, and sexual transmission in humans. The purpose of this study was to continue the development of an ovine ZIKV infection model; thus, two experiments were undertaken. In the first experiment, we built on previous pregnant sheep experiments by developing a mid-gestation model of ZIKV infection. Four pregnant sheep were challenged with ZIKV at 57–64 days gestation; two animals served as controls. After 13–15 days (corresponding with 70–79 days of gestation), one control and two infected animals were euthanized; the remaining animals were euthanized at 20–22 days post-infection (corresponding with 77–86 days of gestation). In the second experiment, six sexually mature, intact, male sheep were challenged with ZIKV and two animals served as controls. Infected animals were serially euthanized on days 2–6 and day 9 post-infection with the goal of isolating ZIKV from the male reproductive tract. In the mid-gestation study, virus was detected in maternal placenta and spleen, and in fetal organs, including the brains, spleens/liver, and umbilicus of infected fetuses. Fetuses from infected animals had visibly misshapen heads and morphometrics revealed significantly smaller head sizes in infected fetuses when compared to controls. Placental pathology was evident in infected dams. In the male experiment, ZIKV was detected in the spleen, liver, testes/epididymides, and accessory sex glands of infected animals. Results from both experiments indicate that mid-gestation ewes can be infected with ZIKV with subsequent disruption of fetal development and that intact male sheep are susceptible to ZIKV infection and viral dissemination and replication occurs in highly vascular tissues (including those of the male reproductive tract).

Experimental Infection of Pregnant Female Sheep with Zika Virus During Early Gestation

Zika virus (ZIKV) is a vertically and sexually transmissible virus resulting in severe congenital malformation. The goal of this study was to develop an ovine model of ZIKV infection. Between 28–35 days gestation (DG), four pregnant animals were infected with two doses of 6 × 10⁶ PFU of ZIKV; four control animals received PBS. Animals were evaluated for 45 days (D) post-infection (PI) and necropsies were performed. Viral RNA was detected in infected ewe peripheral blood mononuclear cells (PBMC) during the first week PI; however, all fluids and tissues were negative upon culture. Anti-ZIKV IgM (1:400) and neutralizing antibodies were detected in all infected animals. Clinical disease, virus, or ZIKV antibodies were not detected in control ewes. After two weeks PI, fetal loss occurred in two infected animals, and at necropsy, three infected animals had placental petechiation and ecchymosis and one had hydramnion. Fetal morphometrics revealed smaller cranial circumference to crown-rump length ratios (p < 0.001) and relative brain weights (p = 0.038) in fetuses of infected animals compared with control fetuses. Immunophenotyping indicated an increase in B cells (p = 0.012) in infected sheep. Additionally, in vitro experiments using both adult and fetal cell lines demonstrated that ovine cells are highly permissive to ZIKV infection. In conclusion, ZIKV infection of pregnant sheep results in a change in fetal growth and gestational outcomes.

Comparison of β-Propiolactone and Formalin Inactivation on Antigenicity and Immune Response of West Nile Virus

West Nile Virus (WNV) is a pathogenic arbovirus that belongs to genus Flavivirus under family Flaviviridae. Till now there are no approved vaccines against WNV for human use. In this study, the effect of two alkylating agents, formaldehyde and β-PL, generally used for inactivated vaccine preparation, was assessed on the basis of antigenic and immunogenic potential of the inactivated WNV. Lineage 5 WNV isolates were inactivated by both formalin and β-PL treatments. Inactivation was confirmed by repeated passage in BHK-21 cell line and infant mice. Viruses inactivated by both the treatments showed higher antigenicity. Immune response in mice model showed serum anti-WNV antibody titre was moderately higher in formalin inactivated antigen compared to β-PL inactivated antigen. However, no significant differences were observed in neutralization antibody titre. In conclusion, we can state that both formaldehyde and β-PL inactivation processes were found to be equally efficient for inactivation of WNV. However, they need to be compared with other inactivating agents along with study on cell mediated immune response.

Hematopoietic cancer cell lines can support replication of Sabin poliovirus type 1

Viral vaccines can be produced in adherent or in suspension cells. The objective of this work was to screen human suspension cell lines for the capacity to support viral replication. As the first step, it was investigated whether poliovirus can replicate in such cell lines. Sabin poliovirus type 1 was serially passaged on five human cell lines, HL60, K562, KG1, THP-1, and U937. Sabin type 1 was capable of efficiently replicating in three cell lines (K562, KG1, and U937), yielding high viral titers after replication. Expression of CD155, the poliovirus receptor, did not explain susceptibility to replication, since all cell lines expressed CD155. Furthermore, we showed that passaged virus replicated more efficiently than parental virus in KG1 cells, yielding higher virus titers in the supernatant early after infection. Infection of cell lines at an MOI of 0.01 resulted in high viral titers in the supernatant at day 4. Infection of K562 with passaged Sabin type 1 in a bioreactor system yielded high viral titers in the supernatant. Altogether, these data suggest that K562, KG1, and U937 cell lines are useful for propagation of poliovirus.

Human diploid MRC-5 cells exhibit several critical properties of human umbilical cord-derived mesenchymal stem cells

MRC-5 is the most common human diploid cell line used in production of viral vaccines; mesenchymal stem cells (MSCs) is a type of adult multipotent stem cells. Both cell types share the same fibroblast-like morphology and maintain a normal diploid karyotype over long in vitro expansion. However, other than these similarities, very little is known about MRC-5 in terms of biological properties possessed by MSCs. In this study, we compared MRC-5 with human umbilical cord-derived MSCs (hUC-MSCs), which serves as a representative of human MSCs, in expression of cell surface markers, abilities to differentiate into multiple cell lineages, inhibition of lymphocyte proliferation and promotion of Regulatory T lymphocytes (Treg), and IDO1 expression in response to inflammatory cytokines, all of which are critical properties of MSCs. It was revealed that MRC-5 was almost identical to hUC-MSCs in expression of both positive and negative surface markers of MSCs. Similar to hUC-MSCs, MRC-5 was also able to differentiate into osteocytes and chondrocytes, effectively inhibit mitogen-activated lymphocyte proliferation and promote Tregs, and express IDO1 in response to inflammatory cytokines IFN-γ and TNF-α. In addition, both MRC-5 and hUC-MSCs were non-tumorigenic with an extremely low telomerase activity. Moreover, both cells demonstrated a similar sensitivity to infection by EV71 and rubella viruses, which served as model viruses, in a virus infectivity assay. Therefore, this study suggests that MRC-5 is very likely a previously undefined MSC cell line, thus suggesting the feasibility of developing MSCs of at least umbilical cord origin as new cell substrates to be used in production of viral vaccines.

Temperature and density dependent induction of a cytopathic effect following infection with non-cytopathic HAV strains

Hepatitis A virus infection and growth in cultured cells is protracted, cell-type restricted, and generally not accompanied by the appearance of a cytopathic effect, with the exception of some culture-adapted strains. We demonstrate that the non-cytopathic HAV strain HM175/clone 1 can be induced to exhibit a cytopathic phenotype in both persistently or acutely infected cells under co-dependent conditions of lower incubation temperature (<34°C) and reduced cell density in both monkey (FRhK-4) and human (A549) cells. This phenotype is not virus-strain restricted, as it was also observed in cells infected with HAV strains, HAS-15 and LSH/S. Cytopathic effect was accompanied by rRNA cleavage, indicating activation of the RNase L pathway, viral negative strand synthesis, caspase-3 activation, and apoptosis. The results indicate that a cytopathic phenotype may be present in some HAV strains that can be induced under appropriate conditions, suggesting the potential for development of a plaque assay for this virus.

Detection of infectious hepatitis A virus by integrated cell culture/strand-specific reverse transcriptase-polymerase chain reaction

AIMS

A novel integrated cell culture/strand-specific reverse transcriptase-polymerase chain reaction (RT-PCR) assay was established for detection of infectious hepatitis A virus (HAV).

METHODS AND RESULTS

The specificity of tagged RT-PCR was assessed using HAV genomic positive-strand RNA extracted from HAV virions as reference. Water samples artificially contaminated with infectious or formalin-inactivated HAV were subjected to integrated cell culture (ICC)/RT-PCR and ICC/strand-specific RT-PCR assays respectively. The tagged RT-PCR had high specificity for HAV negative-strand RNA. By demonstrating the formation of negative-strand RNA replicative intermediate, ICC/strand-specific RT-PCR can distinguish between infectious and non-infectious HAV. The described method detected infectious HAV at inoculation level of 10(0) TCID50 per flask within 4 days.

CONCLUSIONS

The ICC/strand-specific RT-PCR is a novel, rapid, sensitive and reliable method for detection of infectious HAV.

SIGNIFICANCE AND IMPACT OF THE STUDY

Coupled with a suitable virus concentration and purification system, ICC/strand-specific RT-PCR will provide a novel and rapid method for detection of infectious HAV in clinical, environmental and food samples. This assay may be used as an alternative method to test the effective inactivation of inactivated virus vaccines. It may also be adapted to assess the efficacy of disinfection of HAV and enteric viruses in foods and water.

Genetic stability of attenuated mengovirus vectors with duplicate primary cleavage sequences

Short poly(C)-tract Mengoviruses have proven vaccine efficacy in many species of animals. A novel vector for the delivery of foreign proteins was created by insertion of a second autoproteolytic primary cleavage cassette linked to a multiple cloning site (MCS) into an attenuated variant of Mengo. Nineteen cDNAs from foreign sequences that ranged from 39 to 1653 bases were cloned into the MCS. The viral reading frame was maintained and translation resulted in dual, autocatalytic excision of the foreign peptides without disruption of any Mengo proteins. All cDNAs except those with the largest insertions produced viable virus. Active proteins such as GFP, CAT, and SIV p27 were expressed within infected cells. Relative to parental Mengo, the growth kinetics and genetic stability of each vector was inversely proportional to the size of the inserted sequence. While segments up to 1000 bases could be carried, inserts greater than 500-600 bases were usually reduced in size during serial passage. The limit on carrying capacity was probably due to difficulties in virion assembly or particle stability. Yet for inserts less than 500-600 bases, the Mengo vectors provided an effective system for the delivery of foreign epitopes into cells and mice.

In vitro potency assay for hepatitis A vaccines: development of a unique economical test

Prior to the official release of each Hepatitis A vaccine lot to the market, a quality control performed by a National Control Authority requires an in vivo or an in vitro potency assay. At the beginning of our work, no standardised in vitro test common to all hepatitis A vaccines was available for both manufacturers and National Control Laboratories. In this study, a unique polyvalent enzyme-linked immunosorbent assay (ELISA) method was developed to appraise all commercially available HAV vaccines. After comparing a direct and an indirect sandwich method with commercial antibodies, the indirect assay was selected and an evaluation of sensitivity, linearity, accuracy and precision was performed before being applied to HAV antigen determination from four different manufacturers. The results are satisfactory and incline us to use routinely this method to release Hepatitis A vaccines.

Dose range evaluation of a new inactivated hepatitis A vaccine administered as a single dose followed by a booster

A total of 242 healthy adults were immunised with a first dose of an investigational inactivated hepatitis A vaccine. Three concentrations (3, 6 and 12 EU [ELISA units]) of the experimental vaccine were used and compared to a licensed reference vaccine. The aim was to determine the antigenic concentration of the study vaccine inducing the highest seroconversion rate and anti-Hepatitis A virus (HAV) antibody response at 2 weeks after the primary immunisation. A booster dose was given at month 6. At 15 days after the primary immunisation the seroconversion rates in subjects vaccinated with the 6 and 12 EU vaccines were 78 and 94%, respectively. At 30 and 180 days after the primary immunisation the percentages of seropositivity were 100% for both groups. The antibody response to the 12 EU study vaccine was similar to that to the reference vaccine. The percentages of seropositivity at 15 and 180 days after the primary immunisation were 94 vs 93%, and 100 vs 93% in the experimental and reference vaccine respectively. Thus, because it induces early and lasting seroconversion, the 12 EU study vaccine seems to be the most effective as a high potency HAV vaccine.

Hepatitis A vaccine administration: comparison between jet-injector and needle injection

INTRODUCTION

Type A hepatitis virus (HAV) is a serious health problem throughout the world and can be spread via fecal-oral contact. Both immune globulin and an HAV vaccine provide protection, but the vaccine gives complete protection. Efficacy of methods of vaccination in relation to the formation of anti-HAV antibodies is unclear; thus, this study seeks to determine if significant differences exist between the syringe as compared to the jet injection technique. The purpose of this study was to compare in a randomized trial Biojet jet-injection system to a needle-syringe method. To determine if a significant difference between these two methods in seroconversion rates or geometric mean titers of anti HAV antibody occurs at day 15, 30, and 210 days after vaccination.

METHOD

Anti-HAV IgG(-) adult hospital employees were randomized to receive 1440 EL.U of hepatitis a vaccine (HAVRIX(R)) in 2 doses by either needle or jet-injector (Biojector(R)) system at month 0 and 6. HAV seroconversion titer results were measured by the Boehringer-Mannheim method.

RESULTS/DISCUSSION

A higher proportion of persons who received HAV vaccine via the Biojector(R) seroconverted with anti-HAV level >/=20 mIU at day 15, 30, and month 7 when compared with a needle injection.Side-effect profiles reported by participants in both methods were below those identified in current published and insert information, but the Biojector(R) had greater local reactivity in all categories when compared to the needle method.

Inactivated hepatitis A vaccine: long-term antibody persistence

During the clinical development of safe, well tolerated and immunogenic vaccines against hepatitis A the persistence of protective antibodies was estimated, based on relatively short observation periods of 18 months to 3 years. We report here on longterm persistence of antibodies in volunteers who participated in one of the early clinical trials on inactivated hepatitis A candidate vaccines. In a randomized trial three groups of altogether 110 healthy adults, initially hepatitis A virus (HAV) seronegative persons were vaccinated with an inactivated hepatitis A vaccine according to the schedule 0-1-2-12 months. One group received 180 ELISA units, one group 360, and one 720 ELISA units per dose. Blood samples were taken prior to the first vaccination and at months 1, 2, 3, 4, 6, 12, 13, 18, 24, 36 and 84. The decrease of antibodies was characterized by two disappearance rates: a rapidly decreasing component and a slower decreasing one becoming predominant ca 12 months after booster vaccination. The disappearance of antibodies could be described by a two-component model which holds for t > or = 13 months. The estimated disappearance rates for the slow component (annual decrease) was found to be 11 and 13% for the 180 and 360 El. U groups, respectively (the 720 El. U group showed no decline, which was probably due to the small sample size). The estimated persistence of antibodies within protective range varied between 24 and 47 years depending on individual titres reached at month 13 and vaccination dose.

Does immunoglobulin interfere with the immunogenicity to Pasteur Mérieux inactivated hepatitis A vaccine?

BACKGROUND/AIMS

The aim of this study was to compare the immunogenicity of Pasteur Mérieux (P.M. s.v.) inactivated hepatitis A vaccine when given alone with its immunogenicity when given in combination with immunoglobulin.

METHODS

We enrolled 80 healthy volunteers who were seronegative for anti-HAV. Forty subjects (group A) were given two doses of vaccine at 0 and 6 months plus 4 ml of immunoglobulin given simultaneously with the first vaccine injection; and 40 subjects (group B) were given vaccine alone. The population characteristics (age, sex, height and weight) of the two groups were comparable.

RESULTS

Anti-HAV antibody was detectable at week 1 in 100% of group A and in 5.7% of group B, and in 100% of both groups at 4 and 8 weeks. Seroconversion rates (> or = 20 mIU/ml) were 97.4% in group A and 100% in group B at week 24 and were 100% in both groups 4 weeks after a booster injection at 6 months. The antibody response level was lower after concomitant administration of vaccine with immunoglobulin. The antibody geometric mean titer was higher at week 1 in subjects who had been given vaccine and immunoglobulin, but nearly 50% lower at week 4 and thereafter, indicating inhibition of the vaccine-induced immune response by immunoglobulin. At week 28, i.e. 4 weeks after the booster injection, geometric mean titers had increased about 13-15 times in both groups, reaching highly protective antibody levels (3351 mIU/ml in group A and 5843 mIU/ml in group B). No serious adverse effects were observed during the follow-up.

CONCLUSIONS

These data indicate that P.M. s.v. hepatitis A vaccine is highly immunogenic and safe, even when given simultaneously with immunoglobulin. Despite the interference of the immunoglobulin with the active immune response, individuals who were immunized passively plus actively also developed high titers of anti-HAV antibody. It is therefore reasonable to expect that this inhibition will not affect the overall protection conferred by the vaccine.

Hepatitis vaccines

The past two decades have seen a series of breakthroughs in the understanding, prevention, and treatment of viral hepatitis. Developed countries have an increasing number of adults who are susceptible to hepatitis A virus (HAV) infection. The licensing of an effective hepatitis A vaccine presents new opportunities for prevention in persons at risk for HAV infection. Hepatitis B virus infection is an important cause of chronic liver disease throughout the world. Although a hepatitis B vaccine has been available in the United States for 15 years, recommendations for its use have undergone changes. Report of the discovery of hepatitis C virus (HCV) in 1989 has led to marked decrease in the risk of transfusion-transmitted viral hepatitis. HCV infection, however, remains a common cause of chronic liver disease, and a hepatitis C vaccine is needed to prevent the consequences of the disease. Basic research into the hepatitis C viral genome has elucidated some of the obstacles in the way of hepatitis C vaccine development.

Good immunogenicity of GBM strain inactivated hepatitis A vaccine in healthy male adults

A formalin-inactivated aluminium hydroxide adsorbed hepatitis A vaccine was evaluated in a dose-response study on 195 healthy male adults (age range: 18-31 years) in two French hospitals (Lyon, Rouen). Four doses (20, 40, 80, 160 RIA antigen units) were administered intramuscularly (i.m.) in two injections over a 6-month period. At the time of the first vaccine injection, 32 subjects (16.4%) were found positive (> 20 mIU ml-1) for HAV antibody (total Ig RIA HAVAB assay, Abbott Laboratories) and were excluded from the analysis of immunogenicity criteria. Fourteen days after the first vaccine injection, 78.1% (95% confidence interval (CI): 62-90) of seronegative subjects who received the 160 RIA antigen unit dose seroconverted with a geometric mean titre (GMT) of 43 mIU ml-1 (95% CI: 33-56). Seroconversion was 100% (95% CI: 91-100) at 1 month with a GMT of 95 mIU ml-1 (95% CI: 79-112). Statistical analysis revealed a significant dose-related effect (p < 0.0001) on GMT by multivariate regression analysis of the results after the first injection. Biological safety was evaluated and alanine aminotransferase and aspartate aminotransferase levels were similar prior to and 14 days after the first injection in the four groups. Reactions after injection were similar in the four dosage groups: 6.2% of subjects reported immediate reactions after first vaccination (feeling sick, spontaneous pain, headache), 8.9% reported local reactions at the site of injection (spontaneous pain, haematoma, local adenopathy) and 13.5% reported general reactions ('flu-like' syndrome, gastrointestinal tract disorders, fatigue, headache).(ABSTRACT TRUNCATED AT 250 WORDS)