Manufacturing a chimpanzee adenovirus-vectored SARS-CoV-2 vaccine to meet global needs

Manufacturing has been the key factor limiting rollout of vaccination during the COVID-19 pandemic, requiring rapid development and large-scale implementation of novel manufacturing technologies. ChAdOx1 nCoV-19 (AZD1222, Vaxzevria) is an efficacious vaccine against SARS-CoV-2, based upon an adenovirus vector. We describe the development of a process for the production of this vaccine and others based upon the same platform, including novel features to facilitate very large-scale production. We discuss the process economics and the "distributed manufacturing" approach we have taken to provide the vaccine at globally-relevant scale and with international security of supply. Together, these approaches have enabled the largest viral vector manufacturing campaign to date, providing a substantial proportion of global COVID-19 vaccine supply at low cost.

Prevention of Fab-arm exchange and antibody reduction via stabilization of the IgG4 hinge region

IgG4s are dynamic molecules that undergo a process called Fab-arm exchange. Disulfide bonds between heavy chains are transiently reduced, resulting in half antibodies that reform intact antibodies with other IgG4 half antibodies. In vivo, therapeutic IgG4s can recombine with endogenous IgG4s, resulting in a heterogeneous mixture of bispecific antibodies. A related issue that can occur for any therapeutic protein during manufacturing is interchain disulfide bond reduction. For IgG4s, this primarily results in high levels of half-mAb that persist through purification processes. The S228P mutation has been used to prevent half-mAb formation. However, we demonstrated that IgG4s with the S228P mutation are subject to half-mAb formation and Fab-arm exchange in reducing environments. We identified two novel mutations that stabilize the heavy-heavy chain interaction via incorporation of additional disulfide bonds in the hinge region. Individually, these mutations increase stability toward reduction and lessen Fab-arm exchange. Combination of all three mutations, Y219C, G220C, and S228P, has an additive benefit resulting in an IgG4 with ˃7-fold increase in stability toward reduction while preventing Fab-arm exchange. Importantly, the mutations do not affect antigen binding or Fc effector function. These mutations hold great promise for solving mAb reduction during manufacturing and preventing Fab-arm exchange in vivo.

Impact of Fc N-linked glycans on in vivo clearance of an immunoglobulin G1 antibody produced by NS0 cell line

The heterogeneity of glycosylation on therapeutic monoclonal antibodies (mAbs) may affect the safety and efficacy of these agents. In particular, glycans of nonhuman origin, such as galactose-alpha-1,3-galactose (gal-α-gal) and N-glycolylneuraminic acid (NGNA), in the Fc region of therapeutic mAbs produced from murine cell lines carry a risk of immunogenicity. Immunogenic glycan structures can have immune-mediated clearance, resulting in faster clearance from in vivo circulation than non-immunogenic structures. To demonstrate the impact of these Fc nonhuman glycans on in vivo clearance, we purified and analyzed the glycan profile of a monoclonal antibody (mAb1) from human serum samples collected from clinical study participants. We purified mAb1 in a three-step chromatographic separation process (protein A, immobilized anti-mAb1 antibody affinity, and weak cation exchange chromatography) and extracted and labeled its N-linked oligosaccharide structures with 2-aminobenzamide acid for analysis on ultrahigh-performance hydrophilic interaction liquid chromatography. A comparison of the glycan profile of mAb1 recovered from human serum on the same day and 4 weeks after dosing revealed no significant differences, indicating similar clearance of mAb1 with nonhuman gal-α-gal or NGNA glycan in the Fc region compared with the human glycans. The relative proportions of the glycans remained similar, and all patients who had already received multiple doses of mAb1 over the course of a year were negative for antidrug antibodies, suggesting that none of the glycans induced an immune response. Therefore, we concluded that mAb1 gal-α-gal and NGNA glycoforms represent a low risk of conferring immunogenicity.

Upper airway dimensions and sleep efficiency--three-dimensional imaging analysis and assessment of the nasopharyngeal appliance

BACKGROUND

Reduction of upper airway (UA) dimensions during sleep is contemplated to cause reduced sleep efficiency (SE) but a definitive association is not affirmed. Efficacy of nasopharyngeal appliance (NPA) in management of UA resistance syndrome (UARS) has not been compared with mandibular repositioning splint (MRS). This study intended to assess relation of UA dimensions to SE and effectiveness of NPA.

MATERIALS AND METHODS

Research had two phases: Case-control study to determine association between UA and SE; randomized control trial (with independent concurrent trial groups and double-blind design) to analyze treatment outcome with NPA. Subjects were categorized to three groups of 20 in each: A control group of healthy subjects (Group A); two "Randomly Assigned" sample groups of subjects with reduced SE (Groups B and C). Preliminary questionnaire for sleep analysis, Final data collection sheet (first and second case sheets) were recorded, cephalometric variables analyzed, and diagnostic overnight polysomnography was done to match and confirm selection criteria. Three-dimensional computed tomography was done to analyze airway dimensions before and after appliance placement. ANOVA and post-hoc tests were used for statistical analysis of results.

CONCLUSIONS

Reduced UA dimension during sleep is associated with reduced SE; NPA gives better improvement for UARS than MRS.

Assurance of monoclonality in one round of cloning through cell sorting for single cell deposition coupled with high resolution cell imaging

Regulatory authorities require that cell lines used in commercial production of recombinant proteins must be derived from a single cell progenitor or clone. The limiting dilution method of cell cloning required multiple rounds of low-density cell plating and microscopic observation of a single cell in order to provide evidence of monoclonality. Other cloning methods rely on calculating statistical probability of monoclonality rather than visual microscopic observation of cells. We have combined the single cell deposition capability of the Becton Dickinson Influx™ cell sorter with the microscopic imaging capability of the SynenTec Cellavista to create a system for producing clonal production cell lines. The efficiency of single cell deposition by the Influx™ was determined to be 98% using fluorescently labeled cells. The centrifugal force required to settle the deposited cells to the bottom of the microplate well was established to be 1,126g providing a 98.1% probability that all cells will be in the focal plane of the Cellavista imaging system. The probability that a single cell was deposited by the cell sorter combined with the probability of every cell settling into the focal plane of the imager yield a combined >99% probability of documented monoclonality.

Comprehensive analysis of repair/reinforcement materials for polymethyl methacrylate denture bases: mechanical and dimensional stability characteristics

Fracture of complete denture is a common problem as acrylic resins hold inherent limitations. This necessitates affirmation of a selection criterion by evaluating the critical requirements of repair materials. The study intended to evaluate mechanical properties and dimensional stability of common denture base repair and reinforcement materials under standard experimental protocol. Seven types of denture reinforcement materials were chosen. Forty cuboidal samples were made in accordance with ISO 178 for three point bending test and divided to eight groups of five samples each. One group acted as control and samples of seven groups were sectioned and repaired with chosen materials. Five mechanical properties-fracture load, deflection, flexural strength, fracture toughness and elastic modulus were evaluated for all groups. Forty mandibular complete denture specimens were utilized for evaluating fracture load and deflection under loading. Dimensional stability after repair with seven different repair materials was analyzed in two planes (Linear and curvilinear) utilizing separate set of denture samples. Heat cure polymethyl methacrylate with polyethylene fiber was affirmed as material of choice based on this study as it accomplishes the most critical norms of requirement.

An appraisal on increasing the occlusal vertical dimension in full occlusal rehabilitation and its outcome

Increasing the occlusal vertical dimension for gaining sufficient restoration space in the management of severely worn dentition is being practiced. This contentious belief has lead to challenging thoughts regarding its effects on the Odonto-stomatognathic system. There are basic uncertainties and existing erroneous thoughts regarding the perception of increasing the occlusal vertical dimension. This manuscript will review the bite raising concepts and its outcome on the stomatognathic system.

Structured internship orientation programme for undergraduate students: easy transition to clinical work

BACKGROUND

Internship is a phase of training when a new graduate is expected to acquire skills under supervision, so that he/she may become capable of functioning independently. Often, new graduates go through this period without a clear aim. We conducted an orientation programme before fresh graduates started their 1-year internship to familiarize them with their clinical tasks and their role in the community.

METHODS

Interns were invited to participate in a one-and-a-half day programme conducted by faculty members and administrators that included interactive lectures, structured panel discussions, group discussions and role plays. The participants provided feedback using a structured questionnaire and during informal group discussions. They were also evaluated by a pre-test and post-test questionnaire.

RESULTS

Of the 41 interns who attended the programme on day 1 and the 28 who completed it on day 2, 19 completed the post-test questionnaire. The post-test score (median 14.5; range 10-18) represented a significant improvement over the pre-test score (median 13, range 3-16). All participants felt that the workshop was successful in achieving its objectives.

CONCLUSION

A brief and structured orientation programme before internship offers a practical means of making the transition of new graduates from students to practising doctors smoother.

Development of a high permeability cored transintegumental power transformer

Circulatory support devices require 10-20 W. Currently, several devices are under development for the transmission of this power via transcutaneous transformers, with the secondary implanted subcutaneously and the primary worn externally. Because these devices are air cored, they have relatively large, bulky external appliances, poor coil to coil coupling, and result in significant stray fields passing through adjacent tissues. This article reports on the engineering design of a novel, high permeability cored transformer implanted in a transenteric configuration using an isolated intestinal pouch. Such an approach offers greater energy transmission efficiency, less heat dissipation, less stray electromagnetic energy, and greatly reduced device size. Two competing designs using this concept have been developed and tested. Each consists of the transformer, together with power interface electronics, forming a direct current (DC)/DC resonant converter. Operating frequencies are 90.2 and 14.7 kHz, respectively, with primary/secondary turns ratios of 10/10 and 11/14, respectively. In addition, data interface electronics allows communication across the transformer of up to four signals at a per channel sample rate of 10 Hz. Both designs are able to continuously transmit 25 W at an output level of 12 Vdc into a 5.8 omega load. Calorimetry tests indicate DC to DC efficiencies greater than 75% and coil to coil efficiencies greater than 96%. Total package size for the implantable portion of each device (including sensor internal interface electronics) is less than 40 ml, with a weight weight of less than 100 g. The results of short-term implantation studies have been favorable. Long-term implantation studies currently are under way.