A novel high throughput plate-based method for 2-PE quantification in novel multidose vaccines (R21 malaria, Covishield and Covovax) and combination vaccines (Hexavalent).

Multidose presentation of vaccines is the most preferred choice, for mass immunization particularly during pandemics. WHO also recommends multidose containers of fill finished vaccines for programmatic suitability and global immunizations programmes. However, multidose vaccine presentations requires inclusion of preservatives to prevent contaminations. 2-Phenoxy ethanol (2-PE) is one such preservative which is being used in numerous cosmetics and many vaccines recently. Estimation of 2-PE content in multidose vials is a crucial quality control parameter to ensure in use stability of the vaccines. Presently available conventional methods, have their own limitation in terms of being time consuming, requiring sample extraction, large sample volume requirement etc. Therefore, a robust, simple, high-throughput method with a low turnaround time was required, which can quantitate 2-PE content in the conventional combination vaccines as well as new generation complex VLP based vaccines. In order to address this issue, a novel absorbance-based method has been developed. This novel method specifically detects 2-PE content in Matrix M1 adjuvanted R21 malaria vaccine, nano particle and viral vector based covid vaccines and combination vaccines like Hexavalent vaccine. The method has been validated for parameters such as linearity, accuracy and precision. Importantly, this method works even in presence of high amounts of proteins and residual DNA. Considering the advantages associated with method under study, this method can be used as an important in process or release quality parameter to estimate the 2-PE content in various vaccines containing 2-PE in multidose presentations.

Rapid, high throughput protein estimation method for saponin and alhydrogel adjuvanted R21 VLP Malaria vaccine based on intrinsic fluorescence.

Protein content estimation of recombinant vaccines at drug product (DP) stage is a crucial lot release and stability indicating assay in biopharmaceutical industries. Regulatory bodies such as US-FDA and WHO necessitates the quantitation of protein content to assess process parameters as well as formulation losses. Estimation of protein content at DP stage in presence of adjuvants (e.g AlOOH, AlPO4, saponin and squalene) is quite challenging, and the challenge intensifies when the target protein is in Virus like particles (VLP) form, owing to its size and structural complexity. Methods available for protein estimation of adjuvanted vaccines mostly suffer from inaccuracy at lower protein concentrations and in most cases require antigen desorption before analysis. Present research work is based on the development of a rapid plate-based method for protein estimation through intrinsic fluorescence by using Malaria vaccine R21 VLP as a model protein. Present method exhibited linearity for protein estimation of R21, in the range of 5-30 µg/mL in Alhydrogel and 4-20 µg/mL for Matrix M adjuvant. The method was validated as per ICH guidelines. The limit of quantification was found to be 0.94 µg/mL for both Alhydrogel and Matrix M adjuvanted R21. The method was found specific, precise and repeatable. This method is superior in terms of less sample quantity requirement, multiple sample analysis, short turnaround time and is non-invasive. This method was found to be stability indicating, works for other proteins containing tryptophan residues and operates well even in presence of host cell proteins. Based on the study, present method can be used in vaccine industries for routine in-process sample analysis (both inline and offline), lot release of VLP based drug products in presence of Alhydrogel and saponin based adjuvant systems.

Application of a protein domain as chaperone for enhancing biological activity and stability of other proteins.

Chaperones are a diverse class of molecules known for increasing thermo-stability of proteins, preventing protein aggregation, favoring disaggregation, increasing solubility and in some cases imparting resistance to proteolysis. These functions can be employed for various biotechnological applications including point of care testing, nano-biotechnology, bio-process engineering, purification technologies and formulation development. Here we report that the N-terminal domain of Pyrococcus furiosusl-asparaginase, (NPfA, a protein chaperone lacking α-crystallin domain) can serve as an efficient, industrially relevant, protein additive. We tested the effect of NPfA on substrate proteins, ascorbate peroxidase (APX), IgG peroxidase antibodies (I-HAbs) and KOD DNA polymerase. Each protein not only displayed increased thermal stability but also increased activity in the presence of NPfA. This increase was either comparable or higher than those obtained by common osmolytes; glycine betaine, sorbitol and trehalose. Most dramatic activity enhancement was seen in the case of KOD polymerase (∼ 40 % increase). NPfA exerts its effect through transient binding to the substrate proteins as discerned through isothermal titration calorimetry, dynamic light scattering and size exclusion chromatography. Mechanistic insights obtained through simulations suggested a remodeled architecture and emergence of H-binding network between NPfA and substrate protein with an effective enhancement in the solvent accessibility at the active site pocket of the latter. Thus, the capability of NPfA to engage in specific manner with other proteins is demonstrated to reduce the concentration of substrate proteins/enzymes required per unit operation. The functional expansion obtained through our finding establishes NPfA as a novel class of ATP-independent molecular chaperone with immense future biotechnological applications.

Malaria vaccine candidate based on Duffy-binding protein elicits strain transcending functional antibodies in a Phase I trial.

Reticulocyte invasion by Plasmodium vivax requires interaction of the Duffy-binding protein (PvDBP) with host Duffy antigen receptor for chemokines (DARCs). The binding domain of PvDBP maps to a cysteine-rich region referred to as region II (PvDBPII). Blocking this interaction offers a potential path to prevent P. vivax blood-stage growth and P. vivax malaria. This forms the rationale for development of a vaccine based on PvDBPII. Here we report results of a Phase I randomized trial to evaluate the safety and immunogenicity of recombinant PvDBPII formulated with glucopyranosyl lipid adjuvant-stable emulsion (GLA-SE). Thirty-six malaria-naive, healthy Indian male subjects aged 18-45 years were assigned into three cohorts corresponding to doses of 10, 25 and 50 µg of PvDBPII formulated with 5 µg of GLA-SE. Each cohort included nine PvDBPII/GLA-SE vaccinees and three hepatitis B control vaccine recipients. Each subject received the assigned vaccine intramuscularly on days 0, 28 and 56, and was followed up till day 180. No serious AE was reported and PvDBPII/GLA-SE was well-tolerated and safe. Analysis by ELISA showed that all three doses of PvDBPII elicited antigen-specific binding-inhibitory antibodies. The 50 µg dose elicited antibodies against PvDBPII that had the highest binding-inhibitory titres and were most persistent. Importantly, the antibody responses were strain transcending and blocked receptor binding of diverse PvDBP alleles. These results support further clinical development of PvDBPII/GLA-SE to evaluate efficacy against sporozoite or blood-stage challenge in controlled human malaria infection (CHMI) models and against natural P. vivax challenge in malaria endemic areas.

Heterologous expression of an engineered protein domain acts as chaperone and enhances thermotolerance of Escherichia coli.

Heat shock proteins (HSPs) are known to confer protection to the stressed cells by rescuing vital host cell proteins. In the present study we have demonstrated that heterologous expression of N-terminal domain of hyperthermophilic L-asparaginase (NPfA) confers thermotolerance to E. coli. The recombinant expression of NPfA enabled E. coli to demonstrate typical growth behavior at 52°C and survive a thermal shock up to 62°C, both being the highest reported temperatures for growth and heat shock survival. To understand the basis of protection proteome analysis of these cells was carried out which showed that NPfA guards a battery of proteins, especially related to gene regulations and repair, providing definite survival advantage to the stressed cells. Thus NPfA a non-canonical, non-natural chaperone has been shown to render E. coli cells with selective growth advantage under extremes of conditions. We propose that such modified, heat stabilized hosts could be utilized in developing heat-induced expression systems as well for the recombinant expression of thermophilic proteins.

Modes of Degradation and Impurity Characterization in rhPTH (1-34) during Stability Studies.

During storage of recombinant human parathyroid hormone (rhPTH) (amino acid residues 1-34) at 25 ± 2 °C, several impurities were obtained, which were detected by the tricine sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and reversed-phase high-performance liquid chromatography (RP-HPLC) methods. To characterize the impurities generated, forceful chemical oxidation and deamidation was done. The oxidized positions were characterized by cyanogen bromide (CNBr) cleavage followed by liquid chromatography/mass spectrometry (LCMS) and further confirmed through N-terminal sequencing. Three oxidized variants were observed: sulfoxide of Met8 and Met18 and a variant comprising sulfoxide forms of both the methionine residues. LCMS results confirmed the presence of deamidated (+1 Da) and succinimide (-17 Da) variants. The low molecular weight impurities observed by tricine SDS-PAGE was confirmed to be peptide fragments by N-terminal sequencing and LCMS, resulting from cleavage at the C-terminal of asparagine (Asn)16, Asn33, and Asp30. Studies showed that rhPTH (1-34) undergoes oxidation, deamidation, and peptide bond cleavage during storage at pH 4.0 in acetate buffer. LAY ABSTRACT: Unlike currently licensed therapies to manage osteoporosis, parathyroid hormone (PTH) and its analogs represent a new class of anabolic agents, which act primarily to inhibit bone resorption and remodeling. The hormone's recombinant form is a bioactive peptide, 1-34 residues, which is inherently very unstable. Prior understanding of the molecular degradation pathway will help in development of a process that will yield a better product with respect to its quality and stability. The current work focuses on detailed characterization of the product-related impurities generated during storage of recombinant human PTH. The study depicted the various routes through which the molecule can degrade during its shelf life. Through a combination of forced degradation and accelerated study, it was established that the impurities were generated owing to oxidation, deamidation, and peptide bond cleavage of/at various amino acid residues. Until this study, it was presumed that oxidation is the primary route of degradation in PTH and most of the published reports were on native (1-84) forms of the hormone. The present research confirms that the recombinant hormone (1-34) degraded not only because of oxidation but that deamidation and peptide bond cleavage are also prominent modes of degradation. Therefore, owing to the unstable nature of the molecule it is suggested that stringent conditions should be maintained during manufacturing to obtain a stable molecule with fewer impurities.