Mosaic quadrivalent influenza vaccine single nanoparticle characterization.

Recent work by our laboratory and others indicates that co-display of multiple antigens on protein-based nanoparticles may be key to induce cross-reactive antibodies that provide broad protection against disease. To reach the ultimate goal of a universal vaccine for seasonal influenza, a mosaic influenza nanoparticle vaccine (FluMos-v1) was developed for clinical trial (NCT04896086). FluMos-v1 is unique in that it is designed to co-display four recently circulating haemagglutinin (HA) strains; however, current vaccine analysis techniques are limited to nanoparticle population analysis, thus, are unable to determine the valency of an individual nanoparticle. For the first time, we demonstrate by total internal reflection fluorescence microscopy and supportive physical-chemical methods that the co-display of four antigens is indeed achieved in single nanoparticles. Additionally, we have determined percentages of multivalent (mosaic) nanoparticles with four, three, or two HA proteins. The integrated imaging and physicochemical methods we have developed for single nanoparticle multivalency will serve to further understand immunogenicity data from our current FluMos-v1 clinical trial.

The Joint Effect of Body Mass Index and Serum Lipid Levels on Incident Dementia among Community-Dwelling Older Adults.

OBJECTIVES: This study aimed to explore the joint effect of body mass index (BMI) and serum lipids levels on incident dementia. METHODS: We prospectively followed up with 1,627 dementia-free community residents aged ≥60 for 5.7 years on average. At baseline, weight, and height were measured, and total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were detected in serum. Demographic characteristics were collected through questionnaires. Dementia was based on consensus diagnosis of neurologists and neuropsychologists using DSM-IV criteria. Additive Cox proportional model was used to assess the exposure-response relationship between BMI and serum lipid levels and dementia risk. Interactions and further classifications of BMI and serum lipid levels were further presented by bivariate surface models and decision-tree models. RESULTS: The joint effects of TC with BMI, TG with BMI, and LDL-C with BMI on the risk of incident dementia shared a similar pattern, different from their independent exposure-response curves. The joint effect of HDL-C with BMI showed an S-surface but without statistical significance. Participants with TC<5.4 mmol/L and BMI<21 kg/m2 (Hazard Ratio(HR) 1.93, 95% Confidence Interval (CI) 1.05-3.53), TC<5.4 mmol/L and BMI≥21 kg/m2 (HR 1.73, 95% CI 1.09-2.72), and TC≥5.4 mmol/L and BMI<21 kg/m2 (HR 4.02, 95% CI 2.10-7.71) were identified to have the increased risk of incident dementia compared to those with TC≥5.4 mmol/L and BMI≥21 kg/m2. Participants with TG<1.7 mmol/L and BMI<21 kg/m2 had an increased risk of incident dementia compared to those with TG≥1.7 mmol/L and BMI≥21 kg/m2 (HR 1.98, 95%CI 1.17-3.3). Participants with LDL-C≥3.3 mmol/L and BMI<21 kg/m2 were identified to have an increased risk of incident dementia compared to those with LDL-C≥3.3 mmol/L and BMI≥21 kg/m2 (HR 3.33, 95%CI 1.64-6.78). CONCLUSIONS: Our study showed that low BMI combined with low or high levels of serum lipids may increase the risk of dementia among older adults. This finding suggests the potential impacts of these two metabolic indexes on the risk of dementia.

Soluble prefusion-closed HIV-envelope trimers with glycan-covered bases.

Soluble HIV-1-envelope (Env) trimers elicit immune responses that target their solvent-exposed protein bases, the result of removing these trimers from their native membrane-bound context. To assess whether glycosylation could limit these base responses, we introduced sequons encoding potential N-linked glycosylation sites (PNGSs) into base-proximal regions. Expression and antigenic analyses indicated trimers bearing six-introduced PNGSs to have reduced base recognition. Cryo-EM analysis revealed trimers with introduced PNGSs to be prone to disassembly and introduced PNGS to be disordered. Protein-base and glycan-base trimers induced reciprocally symmetric ELISA responses, in which only a small fraction of the antibody response to glycan-base trimers recognized protein-base trimers and vice versa. EM polyclonal epitope mapping revealed glycan-base trimers -even those that were stable biochemically- to elicit antibodies that recognized disassembled trimers. Introduced glycans can thus mask the protein base but their introduction may yield neo-epitopes that dominate the immune response.

Quantitation of strain-specific hemagglutinin trimers in mosaic quadrivalent influenza nanoparticle vaccine by ELISA.

An enzyme linked immunosorbent assay (ELISA) method was developed to analyze the assembly of a tetravalent mosaic influenza nanoparticle (NP) vaccine, Flumos-v1, consisting of hemagglutinin trimers (HAT) from H1 (A/Idaho/07/2018), H3 (A/Perth/1008/2019), HBV (Vic-B/Colorado/06/2017) and HBY (Yam-B/Phuket/3073/2013) strains. The sandwich ELISA assay used lectin from Galanthus nivalis as a universal capture reagent for all HAT strains and specific monoclonal antibody (mAb) to detect corresponding hemagglutinin antigen. The mAb binding of HATs incorporated into NPs diverged from those for single HAT solutions, resulting in inaccurate quantitation of assembled HATs. An optimized zwittergent treatment was used to fully dissociate the influenza NP and aligned binding activities in each pair of single HAT and dissociated HAT from NP. The dissociated HATs were then quantified against their corresponding HAT standard solutions for three development lots of FluMos-v1 vaccine and the assembly ratio of all four HATs was calculated. The molar ratio of different HATs incorporated into this quadrivalent NP vaccine was consistent and determined as H3:H1: HBV: HBY âˆ¼ 1.00:0.92:0.96:0.87, which was close the expected 1:1:1:1 ratio and confirmed a proper assembling of multivalent NP.

High-field magnetization and electronic spin resonance study in the twisted honeycomb latticeα-Mn2V2O7.

We report the single-crystal growth of Mn2V2O7and the results of magnetic susceptibility, high-field magnetization up to 55 T and high-frequency electric spin resonance (ESR) measurements for its low-temperatureαphase. Two antiferromagnetic (AFM) ordering at 17.5 K and 3 K and obvious magnetic anisotropy are observed inα-Mn2V2O7upon cooling. In pulsed high magnetic fields, the compound reaches the saturation magnetic moment of ∼10.5µBfor each molecular formula at around 45 T after two undergoing AFM phase transitions atHc1≈ 16 T,Hc2≈ 34.5 T forH//[11-0] andHsf1= 2.5 T,Hsf2= 7 T forH//[001]. In these two directions, two and seven resonance modes are detected by ESR spectroscopy, respectively. Theω1andω2modes ofH//[11-0] can be well described by two-sublattice AFM resonance mode with two zero-field gaps at 94.51 GHz and 169.28 GHz, indicating a hard-axis feature. The seven modes forH//[001] are partially separated by the critical fields ofHsf1andHsf2, displaying the two signs of spin-flop transition. The fittings ofωc1andωc2modes yield zero-field gaps at 69.50 GHz and 84.73 GHz forH//[001], confirming the axis-type anisotropy. The saturated moment and gyromagnetic ratio indicate the Mn2+ion inα-Mn2V2O7is in a high spin state with orbital moment completely quenched. A quasi-one-dimensional magnetism with a zig-zag-chain spin configuration is suggested inα-Mn2V2O7, due to the special neighbor interactions caused by a distorted network structure with honeycomb layer.

Site-Specific Fluorescent Labeling of Hemagglutinin-Specific Antigen Binding Fragment through Amine Chemistry Revealed by Mass Spectrometry.

To capture the structure of assembled hemagglutinin (HA) nanoparticles at single-particle resolution, HA-specific antigen binding fragments (Fabs) were labeled by fluorescent (FLR) dyes as probes to highlight the HA trimers displayed on the assembled tetravalent HA nanoparticles for a qualitative localization microscopic study. The FLR dyes were conjugated to the Fabs through N-hydroxysuccinimide (NHS) ester mediated amine coupling chemistry. The labeling profile, including labeling ratio, distribution, and site-specific labeling occupancy, can affect the imaging results and introduce inconsistency. To evaluate the labeling profile so as to evaluate the labeling efficiency, a combination of intact mass measurement by MALDI-MS and peptide mapping through LC-MS/MS was implemented. At the intact molecular level, the labeling ratio and distribution were determined. Through peptide mapping, the labeled residues were identified and the corresponding site-specific labeling occupancy was measured. A systematic comparative investigation of four different FLR-labeled 1H01-Fabs (generated from H1 strain HA specific mAb 1H01) allowed accurate profiling of the labeling pattern. The data indicate that the labeling was site-specific and semiquantitative. This warrants the consistency of single-particle fluorescent imaging experiments and allows a further imaging characterization of the single nanoparticles.

Characterization of Flu MOSAIC nanoparticle vaccine candidate using high performance size-exclusion chromatography to support vaccine process development.

This report describes an application of analytical high performance size exclusion chromatography with UV and Fluorescent detection (HPSEC-UV/FLR) method that enabled a bridging from research vaccine candidate discovery (His-tagged model) to clinical product development (Non-His-tagged molecules). HPSEC measurement can accurately determine the total trimer-to-pentamer molar ratio by either titration evaluation during the nanoparticle being assembled or dissociation during a well-formed nanoparticle being dis-assembled. Through experimental design with small sample consumptions, HPSEC can provide a quick determination on the nanoparticle assembling efficiency which can therefore guide the buffer optimization for an assembly, from His-tagged model nanoparticle, to non-His-tagged clinical development product. HPSEC has also discovered a difference in assembling efficiencies for various strains of HAx-dn5B with Pentamer-dn5A components, and different efficiencies for monovalent assembly vs. multivalent assembly. The present study demonstrates HPSEC as a pivotal tool to support the Flu Mosaic nanoparticle vaccine development from research to clinical production.

Development and validation of a mass spectrometry based analytical method to quantify the ratios in hemagglutinin trimers in quadrivalent influenza nanoparticle vaccine - FluMos-v1.

A quadrivalent influenza nanoparticle vaccine (FluMos-v1) offers long-lasting protection against multiple influenza virus strains and is composed of four strains of hemagglutinin trimer (HAT) assembled around a pentamer core. Here we report an LC-MS/MS analytical development and validation method to measure the percentage of each HAT component in FluMos-v1.

Engineering of HIV-1 neutralizing antibody CAP256V2LS for manufacturability and improved half life.

The broadly neutralizing antibody (bNAb) CAP256-VRC26.25 has exceptional potency against HIV-1 and has been considered for clinical use. During the characterization and production of this bNAb, we observed several unusual features. First, the antibody appeared to adhere to pipette tips, requiring tips to be changed during serial dilution to accurately measure potency. Second, during production scale-up, proteolytic cleavage was discovered to target an extended heavy chain loop, which was attributed to a protease in spent medium from 2-week culture. To enable large scale production, we altered the site of cleavage via a single amino acid change, K100mA. The resultant antibody retained potency and breadth while avoiding protease cleavage. We also added the half-life extending mutation LS, which improved the in vivo persistence in animal models, but did not impact neutralization activity; we observed the same preservation of neutralization for bNAbs VRC01, N6, and PGDM1400 with LS on a 208-virus panel. The final engineered antibody, CAP256V2LS, retained the extraordinary neutralization potency of the parental antibody, had a favorable pharmacokinetic profile in animal models, and was negative in in vitro assessment of autoreactivity. CAP256V2LS has the requisite potency, developability and suitability for scale-up, allowing its advancement as a clinical candidate.

Analytical characterization of broadly neutralizing antibody CAP256LS heavy chain clipping during manufacturing development.

Broadly neutralizing antibody (bNAb) CAP256-VRC26.25 (abbreviated CAP256LS), a human IgGI monoclonal antibody targeting the V1V2 site of the HIV-1 envelope, has demonstrated high therapeutic potential as a broadly neutralizing monoclonal antibody against HIV-1. During the process development, a heavy chain fragmentation (clipping) was observed, that led to a relative potency reduction. In this report, we highlighted a series of process and product mitigation strategies deployed to advance this product. We have detailed how analytical characterization tools, especially the microchip reduced capillary gel electrophoresis (CGE-SDS), played a pivotal role in identifying the development issues and in providing measurements to guide implementation of mitigation strategies.

Tyrosine O-sulfation proteoforms affect HIV-1 monoclonal antibody potency.

CAP256V2LS, a broadly neutralizing monoclonal antibody (bNAb), is being pursued as a promising drug for HIV-1 prevention. The total level of tyrosine-O-sulfation, a post-translational modification, was known to play a key role for antibody biological activity. More importantly, here wedescribe for the first time the significance of the tyrosine-O-sulfation proteoforms. We developed a hydrophobic interaction chromatography (HIC) method to separate and quantify different sulfation proteoforms, which led to the direct functionality assessment of tyrosine-sulfated species. The fully sulfated (4-SO3) proteoform demonstrated the highest in vitro relative antigen binding potency and neutralization efficiency against a panel of HIV-1 viruses. Interestingly, highly variable levels of 4-SO3 were produced by different clonal CHO cell lines, which helped the bNAb process development towards production of a highly potent CAP256V2LS clinical product with high 4-SO3 proteoform. This study presents powerful insight for any biotherapeutic protein development where sulfation may play an important role in product efficacy.

Quantification of prefusion conformation for HIV vaccine using size-exclusion chromatography.

A closed prefusion conformation or an open (non-prefusion) conformational state of a protein vaccine candidate molecule can determine if it effectively elucidates a desired immunity. A quick and reliable method to monitor conformational state is important during vaccine development. In addition to our existing immunoassays, we have developed a unique physicochemical approach using size-exclusion chromatography to assess binding between antibody and the structurally desired antigen protein. Through the bound monoclonal antibody protein vaccine peak shift in the size-exclusion chromatography profile, this method determines the percent closed (prefusion) conformation present in a sample. Since only the closed prefusion conformation binds to the specific antibody, the population of the closed versus the open conformation of the vaccine molecule can be monitored without the need for a reference calibrator. This new method can be applied broadly to vaccine development, as well as for antibody selection during antibody drug discovery. The mAb CAP256V2LS (250 µg/mL) specific to prefusion conformation was mixed with HIV trimer (250 µg/mL) at 2:1 volume ratio, incubated at 37 °C for 30 mins and injected onto HPLC column. The percent of non-prefusion conformation was calculated based on ratio of peak area of unbound trimer and total area of control trimer sample (without mAb).

[The effect of HOXC10 gene on biological behaviors of glioma cells and mechanism in tumor microenvironment].

Objective: To study the effects of Homeobox C10 (HOXC10) on biological characteristics such as migration, invasion and proliferation of glioma cancer cells and to explore the role of HOXC10 gene in glioma microenvironment. Methods: The expression level of HOXC10 in high grade glioma (glioblastoma) and low grade glioma and its effect on patient survival were analyzed by using The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) database. Hoxc10-siRNA-1, HOXC10-siRNA-2 and siRNA negative control (NC) were transfected into U251 cells according to the operation instructions of HOXC10-siRNA transfection. 100 ng/ mL recombinant protein chemokine ligand 2 (reCCL2) was added into the transfection group, and was labeled as HOXC10-siRNA-1+ reCCL2 and HOXC10-siRNA-2+ reCCL2 groups. The expressions of HOXC10 mRNA and target protein in each group was detected by real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) and western blot. The proliferation ability of cells in each group was detected by cell counting kit 8 (CCK8) method. The migration ability of cells was detected by Transwell assay and Nick assay, and cell apoptosis was detected by flow cytometry. The expression of chemokines in each group was detected by multiple factors. Co-incubation assays were performed to determine the role of HOXC10 and chemokine ligand 2 (CCL2) in recruiting and polarizing tumor-associated macrophages (M2-type macrophages). Results: The median expression level of HOXC10 in high grade gliomas was 8.51, higher than 1.00 in low grade gliomas (P<0.001) in TCGA database. The median expression level of HOXC10 in high grade gliomas was 0.83, higher than 0.00 in low grade gliomas (P=0.002) in CGGA database. The 5-year survival rate of patients with high HOXC10 expression in TCGA database was 28.2%, lower than 78.7% of those with low HOXC10 expression (P<0.001), and the 5-year survival rate of patients with high HOXC10 expression in CGGA database was 20.3%, lower than 58.0% of those with low HOXC10 expression (P<0.001). The numbers of cell migration in HOXC10-siRNA-1 group and HOXC10-siRNA-2 group were (45±3) and (69±4) respectively, lower than (159±3) in NC group (P<0.05). The cell mobility of HOXC10-siRNA-1 group and HOXC10-siRNA-2 group at 48 hours were (15±2)% and (28±4)% respectively, lower than (80±5)% of NC group (P<0.05). The expressions of vimentin in HOXC10-siRNA-1 group and HOXC10-siRNA-2 group were (141 740.00±34 024.56) and (94 655.00±5 687.97), N-cadherin were (76 810.00±14.14) and (94 254.00±701.45), ß-catenin were (75 786.50±789.84) and (107 296.50±9 614.53), lower than (233 768.50±34 114.37), (237 154.50±24 715.50) and (192 449.50±24 178.10) of NC group (P<0.05). The A value of HOXC10-siRNA-1 group and HOXC10-siRNA-2 group were (0.44±0.05) and (0.32±0.02) at 96 hours, lower than 0.92±0.12 of NC group (P<0.05). The apoptosis rates of HOXC10-siRNA-1 group and HOXC10 siRNA-2 group were (10.23±1.24)% and (13.81±2.16)%, higher than (4.60±0.07)% of NC group (P<0.05). The expression levels of CCL2 in U251 cells in HOXC10-siRNA-1 and HOXC10-siRNA-2 groups were (271.63±44.27) and (371.66±50.21), lower than (933.93±29.84) in NC group (P<0.05). The expression levels of CCL5 (234.81±5.95 and 232.62±5.72), CXCL10 (544.13±48.14 and 500.87±15.65) and CXCL11 (215.75±15.30 and 176.18±16.49) in HOXC10-siRNA-1 and HOXC10-siRNA-2 groups were higher than those in NC group (9.98±0.71, 470.54±18.84 and 13.55±0.73, respectively, P<0.05). The recruited numbers of CD14(+) THP1 in HOXC10-siRNA-1 and HOXC10-siRNA-2 groups were (159.33±1.15) and (170.67±1.15), respectively, lower than (360.00±7.81) in NC group (P<0.05), while addition of reCCL2 promoted the recruitment of CD14(+) THP1 cells (287.00±3.61 and 280.67±2.31 in HOXC10-siRNA-1+ reCCL2 group and HOXC10-siRNA-2+ reCCL2 group, respectively, P<0.05). The expressions level of M2-type macrophage-related gene TGF-ß in HOXC10-siRNA-1 group and HOXC10-siRNA-2 group were (0.30±0.02) and (0.28±0.02), respectively, lower than (1.06±0.10) in NC group (P<0.05). The expressions level of M1-related gene NOS2 in HOXC10-siRNA-1 and HOXC10-siRNA-2 were (11 413.95±1 911.85) and (5 894.00±945.21), respectively, higher than (13.39±4.32) in NC group (P<0.05). Conclusions: The expression of HOXC10 in glioma is high and positively correlated with the poor prognosis of glioma patients. Knockdown of HOXC10 can inhibit the proliferation, migration and metastasis of human glioma U251 cells. HOXC10 may play an immunosuppressive role in glioma microenvironment by promoting the expression of CCL2 and recruiting and polarizing tumor-associated macrophages (M2 macrophages).

Development and application of an analytical approach to assess an antibody's potential for disulfide reduction.

Monoclonal antibody (mAb) interchain disulfide bond reduction has been observed in a recent large-scale clinical manufacturing operation. A massive reduction/precipitation at post-clarification steps has occurred. This note presents the development of a novel analytical approach to identify the "potential reduction"-a unique approach to predict the propensity of a monomeric-profiled mAb to be reduced in the post-harvest stage, such as harvest clarification and/or purification steps. The core of this new approach includes comparing the non-reducing capillary electrophoresis profiles of pre- and post-vacuum treated mAb in harvest cell culture fluid (HCCF). Using this approach, the potential reductions of two in-house mAbs in the unclarified and clarified cell culture harvest were assessed.

Streamlining Peptide Mapping LC-MS Approach for Studying Fusion Peptide-Conjugated Vaccine Immunogens.

A newly introduced HIV-1 vaccination utilizes a fusion peptide (FP)-based immunogen-carrier conjugate system, where the FP is coupled to a protein carrier via a bifunctional linker. Such heterogeneous materials present a challenge for the routine product quality assessment. Peptide mapping LC-MS analysis has become an indispensable tool for assessing the site-specific conjugation ratio, estimating site occupancy, monitoring conjugation profiles, and analyzing post-translational modifications (PTMs) and disulfide bonds as well as high-order protein structures. To streamline the peptide mapping approach to match the needs of a fast-paced conjugate vaccine product characterization, a selection of signature fragment ions generated by MSE fragmentation was successfully applied to assess the product quality at the different stages of a conjugates' manufacturing process with an emphasis on monitoring the amount of a reactive linker. This technique was employed in different conjugation studies of the protein carriers, linkers, and FP compositions as well as the cross-linked species formed during stress-degradation studies. Multiple derivatives of the intermediate and final conjugated products formed during a multistaged synthesis were monitored by means of the sensitive extracted-ion chromatogram (XIC) profiling and were included in the estimation of the site-specific conjugation loads. Differentiation of the conjugates with various FP compositions was demonstrated. The conjugation site occupancy was evaluated with respect to the solvent exposure of Lys residues. The findings of these LC-MS studies greatly aided in choosing the best conjugation strategy to ensure that the final recombinant tetanus toxoid heavy chain (rTTHc) product is chemically inert and represents a safe vaccine candidate for clinical evaluation.

[Evaluation on applicationof virtual reality technology in dental implant process training].

Objective: To explore the application effect and evaluation of virtual reality technology in oral implant therapy training. Methods: In November 2018, one adult patient (female, 36 years old) with missing right mandibular first molar was treated in the Department of Implantology, School and Hospital of Stomatology, Fujian Medical University. The three-dimensional virtual models of mandible and implant surgery tools were established, and the virtual reality software (Unity 3D 5.5.1) was imported. Combined with the virtual reality head mounted display, a virtual reality training system simulating the dental implant treatment process was independently developed. Ten refresher doctors and 20 graduate students in Department of Implantology, School and Hospital of Stomatology, Fujian Medical University from September 2018 to December 2019 were recruited as the experimental objects (no clinical experience was found). According to the level and seniority of doctors, they were randomly divided into virtual training group and conventional training control group, which made the two groups comparable, with 15 in each group. Subjective scores (including anatomical structure, surgical field of vision, cavity preparation, implant placement and process mastery) were given after the corresponding training in the two groups, and the virtual reality training system was used to test. The mesial and distal direction, buccolingual direction, depth and angle deviation of implants before and after the training were analyzed, and the differences between the two groups were compared. Results: The subjective scores of five dimensions in the virtual training group were significantly higher than those in the conventional training control group (P<0.05). In the virtual training group, the mesial and distal, buccolingual, depth and angle deviation of implants were (0.73±0.33), (0.78±0.41), (0.61±0.32) mm and 6.66°±3.87°. All of them were significantly lower than those in the control group [(0.85±0.32), (1.12±0.38), (0.89±0.24) mm and 9.68°±3.74°] (P<0.05). Conclusions: The self-developed virtual reality system of oral implant has good application effect, good operability and predictability. It can be effectively carried out in implant education and training, and it can strengthen skills of doctors, and is conducive to the practical operation.

Structures of HIV-1 Neutralizing Antibody 10E8 Delineate the Mechanistic Basis of Its Multi-Peak Behavior on Size-Exclusion Chromatography.

Antibody 10E8 is capable of effectively neutralizing HIV through its recognition of the membrane-proximal external region (MPER), and a suitably optimized version of 10E8 might have utility in HIV therapy and prophylaxis. However, 10E8 displays a three-peak profile on size-exclusion chromatography (SEC), complicating its manufacture. Here we show cis-trans conformational isomerization of the Tyr-Pro-Pro (YPP) motif in the heavy chain 3rd complementarity-determining region (CDR H3) of antibody 10E8 to be the mechanistic basis of its multipeak behavior. We observed 10E8 to undergo slow conformational isomerization and delineate a mechanistic explanation for effective comodifiers that were able to resolve its SEC heterogeneity and to allow an evaluation of the critical quality attribute of aggregation. We determined crystal structures of single and double alanine mutants of a key di-proline motif and of a light chain variant, revealing alternative conformations of the CDR H3. We also replicated both multi-peak and delayed SEC behavior with MPER-antibodies 4E10 and VRC42, by introducing a Tyr-Pro (YP) motif into their CDR H3s. Our results show how a conformationally dynamic CDR H3 can provide the requisite structural plasticity needed for a highly hydrophobic paratope to recognize its membrane-proximal epitope.

Investigation of Cysteine Modifications in Recombinant Protein Tetanus Toxoid Heavy Chain Fragment C.

For conjugated HIV-1 fusion peptide vaccine development, recombinant Tetanus toxoid heavy chain fragment C (rTTHC) was applied as a carrier protein to boost peptide immunogenicity. Understanding the characteristics of rTTHC is the first step prior to the peptide conjugation. A comprehensive mass spectrometry (MS) characterization was performed on E. coli expressed rTTHC during its purification process. Intact mass along with peptide mapping analysis discovered the existence of three cysteine modification forms: glutathionylation, trisulfide bond modification, and disulfide bond shuffling, in correlation to a three-peak profile during a hydrophobic interaction chromatography (HIC) purification step. Coexistence of these multiple oxidative forms indicated that the active thiols underwent redox reaction in the rTTHC material. Identity confirmation of the rTTHC carrier protein by MS analysis provided pivotal guidance to assess the purification step and helped ensure that vaccine development could proceed.

Protein and glycan molecular weight determination of highly glycosylated HIV-1 envelope trimers by HPSEC-MALS.

High Performance Size-Exclusion Chromatography coupled with Multi-Angle Light Scattering detection (HPSEC-MALS) is an important tool to provide a reliable molecular weight measurement for a large complex biomolecule. A recent HIV-1 soluble envelope trimer vaccine candidate, BG505 DS-SOSIP.664, is among the most glycosylated proteins to enter a clinical trial to date, and determination of its protein and glycan molecular weight is one of the key attributes in pre-clinical characterization. However, protein and glycans possess disparate dndcvalues making molecular weight measurement inaccurate in conventional SEC-MALS. To overcome these challenges, a simple mathematically guided experiment was explored, and a composite dndcvalue was established by utilizing protein and glycan mass contributions for the HIV-1 envelope trimer. This establishment was further verified by an orthogonal mass spectrometry analysis. This innovative, simple, and quick analytical approach can be applied broadly to measuring the molecular weight of various composite molecular structures, such as complex glycoconjugates.