Search

PedvaxHIB® is an effective pediatric vaccine for protecting infants from invasive gram-negative bacterium Haemophilus influenzae type b. It is a highly purified capsular polysaccharide, polyribosylribitol phosphate that is covalently linked to an outer membrane protein complex of Neisseria meningitidis. PRP is first derivatized with an organic linker, followed by the coupling of a butadiamine group, and then at the end terminal, a bromoacetyl group is attached for conjugation with thiolated OMPC. The stability of the bromide group in derivatized PRP is monitored by two different methods, capillary electrophoresis and NMR spectroscopy. The loss of the bromide group is detected by measuring the amount of free bromide ion liberated using capillary electrophoresis and by observing a change in amide proton peaks near the bromide group using NMR. The two methods give similar rate hydrolysis results, therefore both can be employed as quick stability tools for bromoacetylation PRP content during manufacturing.

The covalent attachment of a bacterial-derived capsular polysaccharide to protein is of critical importance in transforming the polysaccharide from an antigen with limited immunogenicity in infants and older adults to an antigen that can prevent potentially fatal disease. For a polysaccharide-protein conjugate vaccine (PCV) candidate to be successful, it must be sufficiently stable. Chemical breakage of carbohydrate bonds in the polysaccharide may result in the reduction of "conjugate dose" and could negatively impact immunogenicity and the ability of the vaccine to prime for memory responses. Therefore, development of analytical tools to monitor the integrity of a polysaccharide-protein conjugate (glycoconjugate) vaccine is of practical significance. In this work, reducing SDS-PAGE, Intrinsic Protein Fluorescence Spectroscopy (IPFS), Differential Scanning Fluorimetry (DSF) were evaluated methods to study the impact of time, temperature, and formulation composition on the stability of a glycoconjugate vaccine prepared by multisite coupling of polysaccharide to a carrier protein. In addition, an automated capillary Western system was also evaluated to study the impact of storage on glycoconjugate vaccine stability. Two streptococcus pneumoniae polysaccharide-protein conjugates (serotype 3 and serotype 19A) were chosen to examine their physicochemical stability when formulated as a single antigen vaccine. While all methods require only a small amount of test article and can test multiple samples per assay run, automated capillary Western has the additional advantage of being highly sensitive even at low concentrations in complex vaccine formulations that contain aluminum adjuvant and multiple antigens. Results suggest that automated capillary Western is stability-indicating and may be an effective analytical technology tool for the formulation development of a multivalent glycoconjugate vaccine.

CDTa, an actin ADP-ribosylation transferase, is a binary toxin produced by the bacterium Clostridium difficile which is commonly associated with the hypervirulent strain present in Clostridium difficile infections. The mutated form of CDTa, 4mCDTa, is one of the components in the tetravalent Clostridium difficile vaccine in which the residual toxicity of the ADP-ribosylation activity needs to be monitored for safety reasons. There are several ADP- ribosylation activity methods employing techniques such as ELISA, manual Western blot, or SDS PAGE, but all these methods are usually time consuming and labor intensive. Here we describe the development of new quantitative capillary based western for monitoring the presence of ADP-ribosylation activity in CDTa and 4mCDTa using novel, automated Simple Western™ technology. Furthermore, we have measured for the first time the enzyme's kinetic parameters, KM (NAD) and kcat for native CDTa using this new quantitative capillary western technology.

Both poly and mono ADP-ribosylation are common posttranslational protein modifications. For example, poly ADP-ribosylation is involved in DNA repair mechanisms through the poly (ADP-ribose) polymerase (PARP) family of enzymes. While mono ADP-ribosylation has been known to trigger cell death exhibited by many bacterial toxins. Because of the wide role of ADP-ribosylation, the detection and analysis are very important for further understanding of the PARP family of enzymes and the molecular mechanisms leading to cell toxicity in the presence of bacterial enzymes. Here, we describe a novel technique utilizing a CE-based Western technology to detect and analyze ADP-ribosylated proteins. The method is based on a nanovolume size separation that is automated, quantitative, offers great sensitivity, and is high-throughput for potential use in PARP drug screening inhibitor assays.

An international team that included 20 independent laboratories from biopharmaceutical companies, universities, analytical contract laboratories and national authorities in the United States, Europe and Asia was formed to evaluate the reproducibility of sample preparation and analysis of N-glycans using capillary electrophoresis of 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled glycans with laser induced fluorescence (CE-LIF) detection (16 sites) and ultra high-performance liquid chromatography (UHPLC, 12 sites; results to be reported in a subsequent publication). All participants used the same lot of chemicals, samples, reagents, and columns/capillaries to run their assays. Migration time, peak area and peak area percent values were determined for all peaks with >0.1% peak area. Our results demonstrated low variability and high reproducibility, both, within any given site as well across all sites, which indicates that a standard N-glycan analysis platform appropriate for general use (clone selection, process development, lot release, etc.) within the industry can be established.

Dengue is known to cause morbidity and mortality worldwide and currently there is neither available specific therapeutics to treat nor a vaccine to prevent this disease. Although efforts are being made, development of a vaccine against this disease remains challenging. Hawaii Biotech Inc developed a recombinant subunit envelope protein-based vaccine against all four serotypes produced in Drosophila S2 cells which were transferred over to Merck in 2010. Each subunit of the four dengue serotypes contains the N-terminal 80% of the amino acids comprising the envelope protein (DEN-80E). A Phase 1 study using only monovalent DEN1-80E was done by Hawaii Biotech Inc and most recently, a Phase 1 clinical trial of the tetravalent DEN-80E formulation (V180) was conducted. Here, we report the development of a dose assay for the tetravalent dengue vaccine-containing subunit protein of DEN1-80E, DEN2-80E, DEN3-80E, and DEN4-80E using various separation methods such as HPLC and CE. Based on the results of the comparison, the CZE separation was chosen as the most suitable method to perform the dose assay for the tetravalent dengue vaccine.

Simple Western is a new technology that allows for the separation, blotting, and detection of proteins similar to a traditional Western except in a capillary format. Traditionally, identity assays for biological products are performed using either an enzyme-linked immunosorbent assay (ELISA) or a manual dot blot Western. Both techniques are usually very tedious, labor-intensive, and complicated for multivalent vaccines, and they can be difficult to transfer to other laboratories. An advantage this capillary Western technique has over the traditional manual dot blot Western method is the speed and the automation of electrophoresis separation, blotting, and detection steps performed in 96 capillaries. This article describes details of the development of an automated identity assay for a 15-valent pneumococcal conjugate vaccine, PCV15-CRM197, using capillary Western technology.

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection, and developing a prophylactic vaccine is of high priority to public health. We recently reported a replication-defective human cytomegalovirus with restored pentameric complex glycoprotein H (gH)/gL/pUL128-131 for prevention of congenital HCMV infection. While the quantity of vaccine-induced antibody responses can be measured in a viral neutralization assay, assessing the quality of such responses, including the ability of vaccine-induced antibodies to cross-neutralize the field strains of HCMV, remains a challenge. In this study, with a panel of neutralizing antibodies from three healthy human donors with natural HCMV infection or a vaccinated animal, we mapped eight sites on the dominant virus-neutralizing antigen—the pentameric complex of glycoprotein H (gH), gL, and pUL128, pUL130, and pUL131. By evaluating the site-specific antibodies in vaccine immune sera, we demonstrated that vaccination elicited functional antiviral antibodies to multiple neutralizing sites in rhesus macaques, with quality attributes comparable to those of CMV hyperimmune globulin. Furthermore, these immune sera showed antiviral activities against a panel of genetically distinct HCMV clinical isolates. These results highlighted the importance of understanding the quality of vaccine-induced antibody responses, which includes not only the neutralizing potency in key cell types but also the ability to protect against the genetically diverse field strains. IMPORTANCE HCMV is the leading cause of congenital viral infection, and development of a preventive vaccine is a high public health priority. To understand the strain coverage of vaccine-induced immune responses in comparison with natural immunity, we used a panel of broadly neutralizing antibodies to identify the immunogenic sites of a dominant viral antigen—the pentameric complex. We further demonstrated that following vaccination of a replication-defective virus with the restored pentameric complex, rhesus macaques can develop broadly neutralizing antibodies targeting multiple immunogenic sites of the pentameric complex. Such analyses of site-specific antibody responses are imperative to our assessment of the quality of vaccine-induced immunity in clinical studies.

Capillary Electrophoresis (CE) is a versatile and indispensable analytical tool that can be applied to characterize proteins. In recent years, labor-intensive SDS-PAGE and IEF slab gels have been replaced with CE-SDS (CGE) and CE-IEF methods, respectively, in the biopharmaceutical industry. These two CE-based methods are now an industry standard and are an expectation of the regulatory agencies for biologics characterization. Another important and traditional slab gel technique is the western blot, which detects proteins using immuno-specific reagents after SDS-PAGE separation. This technique is widely used across industrial and academic laboratories, but it is very laborious, manual, time-consuming, and only semi-quantitative. Here, we describe the applications of a relatively new CE-based western blot technology which is automated, fast, and quantitative. We have used this technology for both charge- and size-based CE westerns to analyze biotherapeutic and vaccine products. The size-based capillary western can be used for fast antibody screening, clone selection, product titer, identity, and degradation while the charge-based capillary western can be used to study product charge heterogeneity. Examples using this technology for monoclonal antibody (mAb), Enbrel, CRM197, and Clostridium difficile (C. difficile) vaccine proteins are presented here to demonstrate the utility of the capillary western techniques. Details of sample preparation and experimental conditions for each capillary western mode are described in this chapter.

Capillary Electrophoresis (CE) is a versatile and indispensable analytical tool that can be applied to characterize proteins. In recent years, labor-intensive SDS-PAGE and IEF slab gels have been replaced with CE-SDS (CGE) and CE-IEF methods, respectively, in the biopharmaceutical industry. These two CE-based methods are now an industry standard and are an expectation of the regulatory agencies for biologics characterization. Another important and traditional slab gel technique is the western blot, which detects proteins using immuno-specific reagents after SDS-PAGE separation. This technique is widely used across industrial and academic laboratories, but it is very laborious, manual, time-consuming, and only semi-quantitative. Here, we describe the applications of a relatively new CE-based western blot technology which is automated, fast, and quantitative. We have used this technology for both charge- and size-based CE westerns to analyze biotherapeutic and vaccine products. The size-based capillary western can be used for fast antibody screening, clone selection, product titer, identity, and degradation while the charge-based capillary western can be used to study product charge heterogeneity. Examples using this technology for monoclonal antibody (mAb), Enbrel, CRM197, and Clostridium difficile (C. difficile) vaccine proteins are presented here to demonstrate the utility of the capillary western techniques. Details of sample preparation and experimental conditions for each capillary western mode are described in this chapter.

An in vitro relative potency (IVRP) assay has been developed as an alternative to the mouse potency assay used to release Merck's human papillomavirus (HPV) vaccine, Gardasil, for early phase clinical trials. The mouse potency assay is a classical, in vivo assay, which requires 4-6 weeks to complete and exhibits variability on the order of 40% relative standard deviation (RSD). The IVRP assay is a sandwich-type immunoassay that is used to measure relative antigenicity of the vaccine product. The IVRP assay can be completed in three days, has a variability of approximately 10% RSD and does not require the sacrifice of live animals. Because antigen detection is achieved using H16.V5, a neutralizing monoclonal antibody, which binds to a clinically-relevant epitope, the relative antigenicity measured by the IVRP assay is believed to be a good predictor of in vivo potency. In this study, the relationship between immunogenicity, as measured by the mouse potency assay and antigenicity as measured by the IVRP assay, is demonstrated. Freshly manufactured and aged samples produced using two different manufacturing processes were tested using both methods. The results demonstrate that there is an inverse correlation between the IVRP and mouse potency assays. Additionally, clinical results indicate IVRP is predictive of human immunogenicity. Thus, antigenicity, as defined by the H16.V5 epitope, can be used as a surrogate for immunogenicity and the IVRP assay is suitable for use as the sole potency test for Gardasil samples.

Capillary electrophoresis (CE) is a versatile analytical method used to characterize glycoproteins. We have used several modes of CE separation such as CE-SDS gel, imaged capillary isoelectric focusing (icIEF), and capillary zone electrophoresis (CZE) to study therapeutic glycoprotein products. CE-SDS gel is applied to characterize the glycan occupancy and number of glycosylation sites, and icIEF is used to study the charge heterogeneities due to sialic acids in glycoproteins. To further characterize the glycoprotein, removal of N-linked glycans is necessary and a CZE technique is employed to analyze each glycan moiety. Examples from a monoclonal antibody, erythropoietin, and granulocyte colony-stimulating factor are presented here to demonstrate the utility of these CE modes. The details of sample preparation and separation conditions for each CE mode are described in this chapter.

Many CE-based technologies such as imaged capillary IEF, CE-SDS, CZE, and MEKC are well established for analyzing proteins, viruses, or other biomolecules such as polysaccharides. For example, imaged capillary isoelectric focusing (charge-based protein separation) and CE-SDS (size-based protein separation) are standard replacement methods in biopharmaceutical industries for tedious and labor intensive IEF and SDS-PAGE methods, respectively. Another important analytical tool for protein characterization is a Western blot, where after size-based separation in SDS-PAGE the proteins are transferred to a membrane and blotted with specific monoclonal or polyclonal antibodies. Western blotting analysis is applied in many areas such as biomarker research, therapeutic target identification, and vaccine development. Currently, the procedure is very manual, laborious, and time consuming. Here, we evaluate a new technology called Simple Western™ (or Simon™) for performing automated Western analysis. This new technology is based on CE-SDS where the separated proteins are attached to the wall of capillary by a proprietary photo activated chemical crosslink. Subsequent blotting is done automatically by incubating and washing the capillary with primary and secondary antibodies conjugated with horseradish peroxidase and detected with chemiluminescence. Typically, Western blots are not quantitative, hence we also evaluated the quantitative aspect of this new technology. We demonstrate that Simon™ can quantitate specific components in one of our vaccine candidates and it provides good reproducibility and intermediate precision with CV

The thermostability of GARDASIL (Merck & Co., Inc, Whitehouse Station, NJ, USA), a developmental vaccine against human papillomavirus (HPV), was evaluated using an enzyme immunoassay, referred to as the in vitro relative potency (IVRP) assay and differential scanning calorimetry (DSC). Gardasil samples were stored at temperatures ranging from 4 to 42 degrees C and tested for IVRP at various time points. Extrapolation of the IVRP results indicates GARDASIL is extremely stable. The half-life of the vaccine is estimated to be 130 months or longer at temperatures up to 25 degrees C. At 37 degrees C, the half-life is predicted to be 18 months and at 42 degrees C, the half-life is predicted to be approximately three months. Differential scanning calorimetry (DSC) analysis was used to evaluate the process of protein denaturation during a rapid temperature increase (as opposed to long-term storage at a specific temperature). Differences were seen among the DSC profiles of the four HPV types tested. This indicates that small differences in the amino acid structure can have a significant effect on the intermolecular contacts that stabilize the L1 proteins and the VLP assembly. For the Gardasil samples evaluated here, DSC results demonstrated the relative overall structural stability of the VLPs, but were not predictive of the excellent long-term stability observed with the IVRP assay.