Partial oxidation of alkanes by dioxiranes formed in situ at low temperature.

Partial oxidation catalysts capable of efficiently operating at low temperatures may limit the over-oxidation of alkane substrates and thereby improve selectivity. This work focuses on examining alkane oxidation using completely metal-free organocatalysts, dioxiranes. The dioxiranes employed here are synthesized by oxidation of a ketone using a terminal oxidant, such as hydrogen peroxide. Our work generates the dioxirane in situ, so that the process can be catalytic with respect to the ketone. To date, we have demonstrated selective partial oxidation of adamantane using ketone catalysts resulting in yields upwards of 60% towards 1-adamantanol with greater than 99% selectivity. Furthermore, we have demonstrated that changing the electrophilic character of the ketone R groups to contain more electron-donating ligands facilitates the dioxirane ring formation and improves overall oxidation yields. Isotopic labelling studies using H218O2 show the preferential incorporation of an 18O label into the parent ketone, providing evidence for a dioxirane intermediate formed in situ The isotopic labelling studies, along with solvent effect studies, suggest the formation of peracetic acid as a reactive intermediate.This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

Asymmetric recognition of the HIV-1 trimer by broadly neutralizing antibody PG9.

PG9 is the founder member of an expanding family of glycan-dependent human antibodies that preferentially bind the HIV (HIV-1) envelope (Env) glycoprotein (gp) trimer and broadly neutralize the virus. Here, we show that a soluble SOSIP.664 gp140 trimer constructed from the Clade A BG505 sequence binds PG9 with high affinity (∼11 nM), enabling structural and biophysical characterizations of the PG9:Env trimer complex. The BG505 SOSIP.664 gp140 trimer is remarkably stable as assessed by electron microscopy (EM) and differential scanning calorimetry. EM, small angle X-ray scattering, size exclusion chromatography with inline multiangle light scattering and isothermal titration calorimetry all indicate that only a single PG9 fragment antigen-binding (Fab) binds to the Env trimer. An ∼18 ŠEM reconstruction demonstrates that PG9 recognizes the trimer asymmetrically at its apex via contact with two of the three gp120 protomers, possibly contributing to its reported preference for a quaternary epitope. Molecular modeling and isothermal titration calorimetry binding experiments with an engineered PG9 mutant suggest that, in addition to the N156 and N160 glycan interactions observed in crystal structures of PG9 with a scaffolded V1/V2 domain, PG9 makes secondary interactions with an N160 glycan from an adjacent gp120 protomer in the antibody-trimer complex. Together, these structural and biophysical findings should facilitate the design of HIV-1 immunogens that possess all elements of the quaternary PG9 epitope required to induce broadly neutralizing antibodies against this region.

Identification of an HIV-1 clade A envelope that exhibits broad antigenicity and neutralization sensitivity and elicits antibodies targeting three distinct epitopes.

Broadly neutralizing antibodies (bNAbs) PG9 and PG16 were isolated from an International AIDS Vaccine Initiative (IAVI) Protocol G subject infected with human immunodeficiency virus type 1 (HIV-1) clade A. Both antibodies are highly potent and neutralize greater than 70% of viruses tested. We sought to begin immunogen design based on viral sequences from this patient; however, pseudoviruses prepared with 19 envelope sequences from this subject were resistant to neutralization by PG9 and PG16. Therefore, we used a bioinformatics approach to identify closely related viruses that were potentially sensitive to PG9 and PG16. A most-recent common ancestor (MRCA) sequence for the viral envelope (Env) was determined and aligned with 99 subtype A gp160 sequences from the Los Alamos HIV database. Virus BG505.W6M.ENV.C2 (BG505) was found to have the highest degree of homology (73%) to the MRCA sequence. Pseudoviruses prepared with this Env were sensitive to neutralization with a broad panel of bNAbs, including PG9 and PG16. When expressed by 293T cells as soluble gp120, the BG505 monomer bound well to both PG9 and PG16. We further showed that a point mutation (L111A) enabled more efficient production of a stable gp120 monomer that preserves the major neutralization epitopes. Finally, we showed that an adjuvanted formulation of this gp120 protein elicited neutralizing antibodies in rabbits (following a gp120 DNA vaccine prime) and that the antisera competed with bNAbs from 3 classes of nonoverlapping epitopes. Thus, the BG505 Env protein warrants further investigation as an HIV vaccine candidate, as a stand-alone protein, or as a component of a vaccine vector.

Varicella zoster virus-specific immune responses to a herpes zoster vaccine in elderly recipients with major depression and the impact of antidepressant medications.

BACKGROUND: The Depression Substudy of the Shingles Prevention Study (SPS) was designed to evaluate the association between major depression and immune responses to a high-titer live attenuated varicella zoster virus (VZV) vaccine (zoster vaccine), which boosts cell-mediated immunity (CMI) to VZV and decreases the incidence and severity of herpes zoster (HZ). The Depression Substudy was a 2-year longitudinal cohort study in 92 community-dwelling adults≥60 years of age who were enrolled in the SPS, a large, double-blind, placebo-controlled Veterans Affairs Cooperative zoster vaccine efficacy study. METHODS: Forty subjects with major depressive disorder, stratified by use of antidepressant medications, and 52 age- and sex-matched controls with no history of depression or other mental illness had their VZV-CMI measured prior to vaccination with zoster vaccine or placebo and at 6 weeks, 1 year, and 2 years postvaccination. RESULTS: Depressed subjects who were not treated with antidepressant medications had lower levels of VZV-CMI following administration of zoster vaccine than nondepressed controls or depressed subjects receiving antidepressants even when antidepressant medications failed to alter depressive symptom severity (P<.005). Similar results were obtained taking into account the time-varying status of depression and use of antidepressant medications, as well as changes in depressive symptoms, during the postvaccination period. CONCLUSIONS: Depressed patients have diminished VZV-CMI responses to zoster vaccine, and treatment with antidepressant medication is associated with normalization of these responses. Because higher levels of VZV-CMI correlate with lower risk and severity of HZ, untreated depression may increase the risk and severity of HZ and reduce the efficacy of zoster vaccine.

Small molecule mimetics of an HIV-1 gp41 fusion intermediate as vaccine leads.

We describe here a novel platform technology for the discovery of small molecule mimetics of conformational epitopes on protein antigens. As a model system, we selected mimetics of a conserved hydrophobic pocket within the N-heptad repeat region of the HIV-1 envelope protein, gp41. The human monoclonal antibody, D5, binds to this target and exhibits broadly neutralizing activity against HIV-1. We exploited the antigen-binding property of D5 to select complementary small molecules using a high throughput screen of a diverse chemical collection. The resulting small molecule leads were rendered immunogenic by linking them to a carrier protein and were shown to elicit N-heptad repeat-binding antibodies in a fraction of immunized mice. Plasma from HIV-1-infected subjects shown previously to contain broadly neutralizing antibodies was found to contain antibodies capable of binding to haptens represented in the benzylpiperidine leads identified as a result of the high throughput screen, further validating these molecules as vaccine leads. Our results suggest a new paradigm for vaccine discovery using a medicinal chemistry approach to identify lead molecules that, when optimized, could become vaccine candidates for infectious diseases that have been refractory to conventional vaccine development.

Major depressive disorder and immunity to varicella-zoster virus in the elderly.

Major depressive disorder has been associated with activation of inflammatory processes as well as with reductions in innate, adaptive and non-specific immune responses. The objective of this study was to evaluate the association between major depression and a disease-relevant immunologic response, namely varicella-zoster virus (VZV)-specific immunity, in elderly adults. A cross-sectional cohort study was conducted in 104 elderly community dwelling adults ≥ 60years of age who were enrolled in the depression substudy of the shingles prevention study, a double blind, placebo-controlled vaccine efficacy trial. Fifty-two subjects had a current major depressive disorder, and 52 age- and sex-matched controls had no history of depression or any mental illness. VZV-specific cell-mediated immunity (VZV-CMI) was measured by VZV responder cell frequency (VZV-RCF) and interferon-γ enzyme-linked immunospot (ELISPOT) assays, and antibody to VZV was measured by an enzyme-linked immunosorbent assay against affinity-purified VZV glycoproteins (gpELISA). VZV-CMI, measured by VZV-RCF, was significantly lower in the depressed group than in the controls (p<0.001), and VZV-RCF was inversely correlated with the severity of depressive symptoms in the depressed patients. In addition, an age-related reduction in VZV-RCF was observed in the depressed patients, but not in the controls. Furthermore, there was a trend for depressive symptom severity to be associated with lower ELISPOT counts. Finally, VZV-RCF was higher in depressed patients treated with antidepressant medications as compared to untreated depressed patients. Since lower levels of VZV-RCF appear to explain the increased risk and severity of herpes zoster observed in older adults, these findings suggest that, in addition to increasing age, depression may increase the risk and severity of herpes zoster.

Revaccination with a 23-valent pneumococcal polysaccharide vaccine induces elevated and persistent functional antibody responses in adults aged 65 > or = years.

BACKGROUND: Older adults are at high risk of developing invasive pneumococcal disease, but the optimal timing and number of vaccine doses needed to prevent disease among this group are unknown. We compared revaccination with 23-valent pneumococcal polysaccharide vaccine (PN23) with primary vaccination for eliciting initial and persistent functional antibody responses. METHODS: Subjects aged > or = 65 years were enrolled. Functional (opsonic) and total immunoglobulin (Ig) G antibody levels were measured following either PN23 primary vaccination (n = 60) or revaccination 3-5 years after receiving a first PN23 vaccination (n = 60). Antibody against vaccine serotypes 4, 14, and 23F was measured at prevaccination (day 0), 30 days after vaccination, and 5 years after vaccination. RESULTS: By day 30, both primary vaccination and revaccination induced significant increases in opsonic and IgG antibody levels. Day 30 levels following revaccination were slightly lower but not significantly different than those after primary vaccination. Year 5 levels were similar in both groups and remained significantly higher than prevaccination levels for primary vaccination subjects. There was good agreement between postvaccination opsonic and IgG antibody levels. CONCLUSIONS: Revaccination of older adults with PN23 was comparable to primary vaccination for inducing elevated and persistent functional and IgG antibody responses.

A novel automated method for enumeration of Chlamydia trachomatis inclusion forming units.

Chlamydia trachomatis is an obligate intracellular pathogen that primarily infects epithelial cells. Traditional methods for quantification of inclusion forming units (IFUs) rely upon infection of epithelial cell monolayers in vitro. Following incubation for approximately 2 days, inclusion bodies that result from infection of cells are detected by immunofluorescent staining with an antibody conjugated to a fluorescent dye. These inclusion bodies are then manually counted by microscopic examination of multiple, randomly selected fields of view. This requires substantial operator time and is subject to investigator bias. We have developed a novel method in which we utilize an automated microplate ImmunoSpot reader to count C. trachomatis IFUs. Following infection of epithelial cells in a 96-well plate and subsequent incubation, IFUs are fixed and detected with an anti-C. trachomatis LPS monoclonal antibody. Immobilized antibody is detected with a biotinylated secondary antibody and visualized enzymatically with streptavidin-alkaline phosphatase and the colorimetric substrate nitro-blue tetrazolium chloride/5-bromo-4-chloro-3-indolyl-phospate (NBT/BCIP). IFUs are then enumerated with the ImmunoSpot system. This method has been used to quantify IFUs from all cell lines traditionally used for chlamydial propagation, including L929, McCoy, HeLa and HaK cells. IFU numbers obtained are comparable to those determined by traditional microscopic counting. In addition, the method can be applied to rapid determination of serum-neutralizing titers for vaccine studies, and we have also applied this approach to quantify Chlamydia recovered from vaginal swabs collected from infected animals. This method provides for rapid enumeration of IFU counts while minimizing investigator bias and has potential applications for both research and diagnostic use.

Evaluation of cellular immune responses in subjects chronically infected with HIV type 1.

The importance of host cellular immune responses, particularly CD8(+) cytotoxic T-lymphocyte (CTL) responses, in control of human immunodeficiency virus type 1 (HIV-1) infection has been demonstrated in many clinical studies. These studies, along with vaccination challenge studies in rhesus macaques, indicate the importance of cellular immune responses against HIV-1. Toward this end, we evaluated anti-HIV-1 cellular immune responses in a cohort of 54 subjects who were chronically infected with HIV-1. By validation of IFN-gamma ELISpot assay, we established a dual cut-off criterion for scoring a positive response. The magnitude and frequency of cellular immune responses were measured against HIV-1 antigens (Gag, Pol, Nef, Rev, and Tat), using synthetic peptides as antigens in ELISpot assay. Here we showed that HIV-1 Gag, Pol, and Nef were frequent targets of T cell responses in these subjects, whereas Tat and Rev were less frequently recognized. We further evaluated the possible association between host cellular immune responses and corresponding plasma viral loads in this cohort. By performing ranking correlation analysis, we demonstrated a positive correlation between host viral loads and ELISpot responses of HIV Gag and Pol in untreated subjects. For the subjects under antiviral regimens, however, we did not find any significant association. Our findings suggest that the high levels of ELISpot responses in chronically infected subjects were reflective of their persistent viral infection.

High-throughput imaging of bacterial colonies grown on filter plates with application to serum bactericidal assays.

The ability to accurately enumerate viable bacteria has applications in antibiotic screening assays, toxicology testing, and serological assays for functional antibodies. An impediment to high-throughput bacterial assays is the requirement to grow bacteria as individual colonies on semisolid media containing agar. We have now developed a method for growth, staining, and counting of bacterial colonies in 96-well filter plates. A unique feature of the method is that colony size is inversely proportional to the number of colonies in each well, presumably due to nutrient depletion. As a result, as many as 300 colony-forming units (cfu) can be detected as discrete colonies within a single assay well. The resulting colonies can be counted automatically using an imaging system originally developed for ELISPOT assays. The method has been applied to the measurement of serum bactericidal activity (SBA) in human sera.

Pharmaceutical and immunological evaluation of a single-shot hepatitis B vaccine formulated with PLGA microspheres.

A single-shot Hepatitis B vaccine formulation using poly(d,l)-lactide-co-glycolide acid (PLGA) microspheres as a delivery system was examined using a variety of biophysical and biochemical techniques as well as immunological evaluation in C3H mice. PLGA microsphere encapsulation of the Hepatitis B surface antigen (HBsAg), a lipoprotein particle, resulted in good recoveries of protein mass, protein particle conformational integrity, and in vitro antigenicity. Some partial delipidation of the HBsAg, however, was observed. The loading and encapsulation efficiency of HBsAg into the PLGA microspheres were measured along with the morphology and size distribution of the vaccine-loaded PLGA microspheres. The in vitro release kinetics of HBsAg from the PLGA microspheres was evaluated and found to be affected by experimental conditions such as stirring rate. HBsAg showed enhanced storage stability at 37 degrees C in the slightly acidic pH range reported to be found inside PLGA microspheres; thus, the antigen is relatively stable under conditions of temperature and pH that may mimic in vivo conditions. The immunogenicity of the microsphere formulations of HBsAg was compared with conventional aluminum adjuvant formulated HBsAg vaccine in C3H mice. Comparisons were made between aluminum formulations (one and two injections), PLGA microsphere formulations (single injection), and a mixture of aluminum and PLGA microsphere formulations (single injection). The nine-month serum antibody titers indicate that a single injection of a mixture of aluminum and PLGA-formulated HBsAg results in equal or better immune responses than two injections of aluminum-formulated HBsAg vaccine. Based on these in vitro and in vivo studies, it is concluded that HBsAg can be successfully encapsulated and recovered from the PLGA microspheres and a mixture of aluminum-adjuvanted and PLGA-formulated HBsAg can auto-boost an immune response in manner comparable to multiple injections of an aluminum-formulated vaccine.

Identification of T-cell epitopes using ELISpot and peptide pool arrays.

Here we describe a method for T-cell epitope identification using a modified ELISpot assay that is both simple and efficient. By using a carefully constructed array of pools of overlapping peptides spanning the entire antigen sequence to stimulate T-cell responses, we are able to detect antigen-specific cytokine responses by both CD8+ and CD4+ T cells and identify the specific peptides to which the cells are responding. Additionally, by performing magnetic bead depletion of either CD8+ or CD4+ cells prior to the assay, we are able to determine the phenotype of the responding cells to each of the peptide epitopes identified. Use of this method will allow the identification of both CD4+ and CD8+ T-cell epitopes without the need for MHC allele-matched reagents and without the need for highly specialized instrumentation. By using an array of peptide pools, this method also dramatically reduces the number of immune cells required to test the entire antigen sequence, often a limiting factor in vaccine testing and other studies.

Rapid, quantitative mapping of anti-HIV type 1 envelope serum antibody specificities.

A new generation of extremely broad and potent neutralizing antibodies (bNAbs) has been isolated from HIV-infected subjects. This has refocused interest in the sites of vulnerability targeted by these bNAbs and in the potential for designing Envelope (Env) immunogens that display these sites. Standard methods for evaluating HIV-1 vaccine candidates do not enable epitope mapping on the HIV Env spike, the target for NAbs. To meet the need for rapid analysis of Ab specificity, we designed a multiplexed, quantitative mapping assay that can test for serum Ab competition for the binding of an HIV-1 Env gp120 to a panel of bNAbs directed to different sites of vulnerability on the Env that do not compete for one another in the assay. Using serum samples from rabbits immunized with various DNA prime/gp120 protein boost vaccines we were able to detect serum Ab competition for multiple classes of bNAbs in the postimmune samples that were significantly higher than background competition detected in samples obtained prior to vaccination. Importantly, application of this novel assay to our ongoing HIV-1 Env viral vector studies in mice has allowed us to distinguish qualitative differences in the Ab elicited by various regimens that ELISA cannot. Furthermore, pooled immunoglobulin from HIV-infected donors (HIVIg) competes for binding to the bNAb panel whereas a control pool from HIV-negative donors does not, highlighting the utility of this assay for human studies. This novel assay will add value in rational immunogen design and in the detailed, qualitative evaluation of binding and, potentially, neutralizing Abs elicited by natural infections and HIV-1 vaccine candidates.

Safety, tolerability, and immunogenicity after 1 and 2 doses of zoster vaccine in healthy adults ≥60 years of age.

BACKGROUND: Incidence and severity of herpes zoster (HZ) and postherpetic neuralgia increase with age, associated with age-related decrease in immunity to varicella-zoster virus (VZV). One dose of zoster vaccine (ZV) has demonstrated substantial protection against HZ; this study examined impact of a second dose of ZV. METHODS: Randomized, double-blind, multicenter study with 210 subjects ≥60 years old compared immunity and safety profiles after one and two doses of ZV, separated by 6 weeks, vs. placebo. Immunogenicity was evaluated using VZV interferon-gamma (IFN-γ) enzyme-linked immunospot (ELISPOT) assay and VZV glycoprotein enzyme-linked immunosorbent antibody (gpELISA) assay. Adverse experiences (AEs) were recorded on a standardized Vaccination Report Card. RESULTS: No serious vaccine-related AEs occurred. VZV IFN-γ ELISPOT geometric mean count (GMC) of spot-forming cells per 10(6) peripheral blood mononuclear cells increased in the ZV group from 16.9 prevaccination to 49.5 and 32.8 at 2 and 6 weeks postdose 1, respectively. Two weeks, 6 weeks and 6 months postdose 2, GMC was 44.3, 42.9, and 36.5, respectively. GMC in the placebo group did not change during the study. The peak ELISPOT response occurred ∼2 weeks after each ZV dose. The gpELISA geometric mean titers (GMTs) in the ZV group were higher than in the placebo group at 6 weeks after each dose. Correlation between the IFN-γ ELISPOT and gpELISA assays was poor. CONCLUSIONS: ZV was generally well-tolerated and immunogenic in adults ≥60 years old. A second dose of ZV was generally safe, but did not boost VZV-specific immunity beyond levels achieved postdose 1.

Optimization and validation of a multiplex, electrochemiluminescence-based detection assay for the quantitation of immunoglobulin G serotype-specific antipneumococcal antibodies in human serum.

Pneumovax 23 consists of a mixture of highly purified capsular polysaccharides (Ps) from 23 of the most prevalent serotypes of Streptococcus pneumoniae. Testing of vaccine immunogenicity has been historically performed on the enzyme-linked immunosorbent assay (ELISA) platform, validated to measure immunoglobulin G (IgG) antibodies to all 23 serotypes included in Pneumovax 23. In order to significantly improve the throughput of this form of testing, we have developed and validated a direct binding electrochemiluminescence (ECL)-based multiplex assay that can measure the antibody response in human serum to eight serotypes within a single microtiter well. The pneumococcal (Pn) ECL assay is based on the Meso Scale Discovery (MSD) technology which utilizes a Sulfo-Tag-labeled anti-human IgG antibody that emits light upon electrochemical stimulation. The Pn ECL assay exhibits a wide dynamic range and provides the ability to read concentrations down to the minimum reported concentration in the Merck ELISA (0.1 microg/ml). Cross-reactivity assessment using type-specific monoclonal antibodies showed no cross talk between antigen spots within a well. By use of the WHO Pn sample reference panel, the results obtained with the Pn ECL assay were compared to the results obtained with the international Pn ELISA. The results for the Pn ECL assay satisfied the WHO-recommended acceptance criterion for concordance for all seven serotypes with published Pn ELISA values, and the overall correlation (r value) across the seven serotypes was 0.994. The MSD methodology has great potential to be extremely useful for simultaneously quantitating IgG responses to several Pn serotypes while conserving serum volumes and laboratory testing time.

Varicella-zoster virus-specific immune responses to herpes zoster in elderly participants in a trial of a clinically effective zoster vaccine.

BACKGROUND: The objectives of this study were to evaluate the association between varicella-zoster virus (VZV)-specific humoral and cell-mediated immunity (CMI) to herpes zoster (HZ) and protection against HZ morbidity and to compare immune responses to HZ and zoster vaccine. METHODS: In 981 elderly persons who developed HZ during a zoster vaccine efficacy trial (321 vaccinees and 660 placebo recipients) and 1362 without HZ (682 vaccinees and 680 placebo recipients), CMI was measured by VZV responder cell frequency and interferon-gamma enzyme-linked immunospot, and antibodies were measured by VZV enzyme-linked immunosorbent assay against affinity-purified VZV glycoproteins (gpELISA). RESULTS: Robust VZV CMI at HZ onset correlated with reduced HZ morbidity, whereas VZV gpELISA titers did not. Three weeks after HZ onset, gpELISA titers were highest in those with more severe HZ and were slightly increased in placebo recipients (compared with zoster vaccine recipients) and in older individuals. VZV CMI responses to HZ were similar in zoster vaccine and placebo recipients and were not affected by demographic characteristics or antiviral therapy, except for responder cell frequency at HZ onset, which decreased with age. When responses to zoster vaccine and HZ could be compared, VZV CMI values were similar, but antibody titers were lower. CONCLUSIONS: Higher VZV CMI at HZ onset was associated with reduced HZ severity and less postherpetic neuralgia. Higher antibody titers were associated with increased HZ severity and occurrence of postherpetic neuralgia. HZ and zoster vaccine generated comparable VZV CMI.

Psychological effects of rapid weight loss and attitudes towards eating among professional jockeys.

We examined the psychological effects of rapid weight loss among a sample of 41 professional jockeys (mean age 30.9 years, s = 7.0). Participants completed the Brunel Mood Scale (BRUMS) and the Eating Attitudes Test-26 (EAT-26) to establish the relationships between rapid weight loss, mood, and attitudes towards eating. These instruments were administered on three occasions: at the jockeys' minimal weight (achieved through rapid weight loss), their optimal riding weight (when they were not excessively restricting their weight and felt healthy), and their relaxed weight (when there were no forthcoming light rides or no rides at all). It was hypothesized that when riding at minimal weight, jockeys would record a more negative mood profile compared with scores recorded at optimal or relaxed weights. The same trend was expected for eating attitudes. These hypotheses were supported as jockeys reported significantly more negative mood profiles and eating attitudes at minimal weight. The EAT-26 scores indicated the presence of disordered attitudes towards eating at this weight. These results suggest that jockeys' endeavours to reach the minimum weight limit stipulated by governing bodies are likely to jeopardize their psychological well-being. Dialogue surrounding the appropriateness of current weight regulations is therefore encouraged.

Establishing acceptance criteria for cell-mediated-immunity assays using frozen peripheral blood mononuclear cells stored under optimal and suboptimal conditions.

The enzyme-linked immunospot (ELISPOT) assay is a powerful tool for measuring antigen-specific cellular immune responses. The ability to use frozen peripheral blood mononuclear cells (PBMC) facilitates testing samples in multicenter clinical trials; however, unreliable ELISPOT responses may result if samples are not handled properly. Exposure of frozen PBMC to suboptimal storage temperature (-20 degrees C) or repeated cycling between more optimal storage temperatures (less than -130 degrees C and -70 degrees C) reduced the quality of frozen PBMC, as assessed by cell viability and functional ELISPOT response measures. Cell viability as assessed by trypan blue dye exclusion was reduced, and the percentage of apoptotic cells, as determined by the Guava Nexin assay, was significantly increased after these events. The functional gamma interferon ELISPOT responses to phytohemagglutinin (PHA) mitogen, a CD4 T-cell-specific antigen (varicella-zoster virus), and a CD8 T-cell-specific antigen (pool containing known cytomegalovirus, Epstein-Barr virus, and influenza virus peptides) were all significantly reduced after suboptimal storage events. However, for a given suboptimal storage event, the magnitude of the reduction varied between individuals and even among aliquots within an individual bleed, indicating the need for sample-specific acceptance criteria (AC). The percent viable or percent apoptotic cells after thaw, as well as the functional ELISPOT response to PHA, were all effective when applied with limits as AC for separating samples damaged during storage from valid control samples. Although all three AC measures could be effectively applied, the apoptosis AC limit applied was best for separating samples that could respond to antigenic stimulation from samples that could not effectively respond.

Effect of alternative aluminum adjuvants on the absorption and immunogenicity of HPV16 L1 VLPs in mice.

Aluminum adjuvants are commonly used in prophylactic vaccines to enhance antigen immunogenicity through induction of high-titer antibody responses. Three major forms of aluminum adjuvants with substantially different physical and chemical properties have been described: aluminum phosphate (AlPO(4)), aluminum hydroxide (AlOH) and amorphous aluminum hydroxyphosphate sulfate (AAHS). Here we describe the effect of these different aluminum adjuvants on the formulation and subsequent immunogenicity in mice of virus-like particles (VLPs) consisting of the L1 protein of Human Papillomavirus (HPV) Type 16. Electron microscopy demonstrated that the physical appearance of the phosphate-containing aluminum adjuvants was markedly different from that of aluminum hydroxide. All three aluminum adjuvants were found to display unique surface charge profiles over a range of pH, while AAHS demonstrated the greatest inherent capacity for adsorption of L1 VLPs. These differences were associated with differences in immunogenicity: anti-HPV L1 VLP responses from mice immunized with AAHS-formulated HPV16 vaccine were substantially greater than those produced by mice immunized with the same antigen formulated with aluminum hydroxide. In addition, HPV L1 VLPs formulated on AAHS also induced a substantial interferon-gamma secreting T cell response to L1 peptides indicating the potential for an enhanced memory response to this antigen. These results indicate that the chemical composition of aluminum adjuvants can have a profound influence on the magnitude and quality of the immune response to HPV VLP vaccines.

Safety, tolerability, and immunogenicity of a two-dose regimen of high-titer varicella vaccine in subjects > or =13 years of age.

A new manufacturing process, known as process upgrade varicella vaccine (PUVV) was developed for a refrigerated formulation of varicella vaccine and for an investigational zoster vaccine. Safety and tolerability of a two-dose regimen of high-titered (approximately 50,000 PFU) PUVV were compared to a lower-titer formulation (approximately 5400 PFU) of VARIVAX; in 1366 healthy subjects > or =13 years old. Only one vaccine-related clinical serious adverse experience (pruritus; no hospitalization) was reported, in the VARIVAX group. Injection-site adverse experiences following any dose were higher in the PUVV group, 70.0%, than in the VARIVAX group, 56.2%, but generally were mild. Immunogenicity were similar in both groups in seronegative subjects. PUVV was generally well tolerated, and elicited an immune response similar to that induced by the marketed formulation of VARIVAX.