Prevalence of Hepatitis B Antigen and Antibody in Prostitutes

We investigated the prevalence of hepatitis B antigen (HBAg) and antibody (HBAb) in 293 prostitutes and in 379 pregnant women of similar age and of low socioeconomic level, who served as controls. HBAg was found in 4·4% of prostitutes and 3·4% of controls. The prevalence of HBAb was significantly higher (P <0·001) in prostitutes (56·7%) than in controls (24·5%). The prevalence of HBAb was clearly age-dependent in both groups. Evidence of hepatitis B virus infection significantly increased with the number of years in prostitution. The evidence of increased infection rates among prostitutes and their distribution support the hypothesis that hepatitis B infection is sexually transmitted.     

Human antibody immunosorption of hepatitis B surface antigen from blood and plasma

Removal of the Hepatitis B surface antigen (HBsAg) from whole blood and blood products, using human antibody (HBAb) immunosorbent, was studied and kinetics of complexing were monitored using radioimmunoassay (RIA). An intermittent complexing process was developed that minimizes damage to the cellular components of blood. HBsAg concentration in blood was reduced 1.5 to 2 logarithmic cycles in 3 hr with this system. Free HBsAg remaining in solution at equilibrium was further reduced by transferring the blood to a vessel containing unused immunosorbent. Through multiple stage treatment of a blood sample, it may be possible to reduce the probability of contamination with HBsAg to below the infectious level. This process may be applied to the selective removal of other proteins from blood and plasma.     

Monoclonal antibody purification using cationic polyelectrolytes: an alternative to column chromatography

The potential of cationic polyelectrolytes to precipitate host cell and process related impurities was investigated, to replace one or more chromatography steps in monoclonal antibody purification. The impact of antibody isoelectric point, solution properties (pH and ionic strength), and polyelectrolyte properties (structure, molecular weight and pK(a)) on the degree of precipitation was studied. At neutral pH, increasing solution ionic strength impeded the ionic interaction between the polyelectrolyte and impurities, reducing impurity precipitation. Increasing polyelectrolyte molecular weight and pK(a) enabled precipitation of impurities at higher ionic strength. PoIy(arginine) was selected as the preferred polyelectrolyte in unconditioned cell culture fluid. PoIy(arginine) precipitation achieved consistent host cell protein clearance and antibody recovery for multiple antibodies across a wider range of polyelectrolyte concentrations. Poly(arginine) precipitation was evaluated as a flocculant and as a functional replacement for anion exchange chromatography in an antibody purification process. Upstream treatment of cell culture fluid with poly(arginine) resulted in flocculation of solids (cells and cell debris), and antibody recovery and impurity clearance (host cell proteins, DNA and insulin) comparable to the downstream anion exchange chromatography step.     

A protein-stabilizing technology for enhanced antibody stability and antibody-binding profiles in a microchip array

The stability of therapeutic antibodies during downstream processing and storage is important for functionality and quality. To determine functional antibody performance, the UNIchip? high-density protein microarray with 384 recombinant antigenic targets was developed; this allows characterization of antibody specificity by generating standardized quantitative binding profiles. In this study, we used UNIchip? to test the efficacy of a novel protein stabilizing and protecting solution (SPS) to preserve the binding specificity and binding strength of a therapeutic anti-TNF-α antibody (Adalimumab; Humira). Our results show that reconstituted SPS-formulated and lyophilized Adalimumab elicits significantly less off-target activity after reconstitution and preserves binding strength even after six weeks of storage at 40°C compared with Adalimumab that underwent the same treatment with the original formulation. By means of UNIchip? , we were able to confirm the protein stabilizing effects of SPS as shown by preserved antibody functionality.     

Liquid-liquid phase separation of a monoclonal antibody and nonmonotonic influence of Hofmeister anions

Liquid-liquid phase separation was studied for a monoclonal antibody in the monovalent salt solutions of KF, KCl, and KSCN under different pH conditions. A modified Carnahan-Starling hard-sphere model was utilized to fit the experimental data, establish the liquid-liquid coexistence curve, and determine antibody-antibody interactions in the form of T_c (critical temperature) under the different solution conditions. The liquid-liquid phase separation revealed the complex relationships between antibody-antibody interactions and different solution conditions, such as pH, ionic strength, and the type of anion. At pH 7.1, close to the pI of the antibody, a decrease of T_c versus ionic strength was observed at low salt conditions, suggesting that the protein-protein interactions became less attractive. At a pH value below the pI of the antibody, a nonmonotonic relationship of T_c versus ionic strength was apparent: initially as the ionic strength increased, protein-protein interactions became more attractive with the effectiveness of the anions following the inverse Hofmeister series; then the interactions became less attractive following the direct Hofmeister series. This nonmonotonic relationship may be explained by combining the charge neutralization by the anions, perhaps with the ion-correlation force for polarizable anions, and their preferential interactions with the antibody.     

Human alpha-L-iduronidase. 1. Purification, monoclonal antibody production, native and subunit molecular mass

Human alpha-L-iduronidase from liver was purified about 20 000-fold with a new rapid three-step, five-column procedure which consisted of a Concanavalin-A-Sepharose/Blue-A-Agarose coupled step, a CM-Sepharose/Bio-Gel HT coupled step followed by a cupric-ion-chelating Sepharose 6B step. The behaviour of alpha-L-iduronidase on gel permeation chromatography was dependent upon both pH and ionic strength of the eluting buffer. The formation of species with enzyme activity which behaved as large-molecular-mass aggregates was favoured under conditions of low ionic strength and neutral pH. The amount of high-Mr species diminished as the pH decreased or the ionic strength increased to favour a single active species of Mr 65 000. A specific monoclonal antibody was generated against liver alpha-L-iduronidase. The antibody specifically immunoprecipitated enzyme activity from both crude and purified sources. The subunit Mr of liver alpha-L-iduronidase was estimated to be 65 000 using SDS-PAGE. Monoclonal antibody immunoprecipitation of radiolabelled enzyme was used to provide definitive confirmation of this subunit size.     

Selective antibody precipitation using polyelectrolytes: A novel approach to the purification of monoclonal antibodies

We evaluated the potential for polyelectrolyte induced precipitation of antibodies to replace traditional chromatography purification. We investigated the impact of solution pH, solution ionic strength and polyelectrolyte molecular weight on the degree of precipitation using the anionic polyelectrolytes polyvinylsulfonic acid (PVS), polyacrylic acid (PAA), and polystyrenesulfonic acid (PSS). As we approached the pI of the antibody, charge neutralization of the antibody reduced the antibody–polyelectrolyte interaction, reducing antibody precipitation. At a given pH, increasing solution ionic strength prevented the ionic interaction between the polyelectrolyte and the antibody, reducing antibody precipitation. With increasing pH of precipitation, there was an increase in impurity clearance. Increasing polyelectrolyte molecular weight allowed the precipitation to be performed under conditions of higher ionic strength. PVS was selected as the preferred polyelectrolyte based on step yield following resolubilization, purification performance, as well as the nature of the precipitate. We evaluated PVS precipitation as a replacement for the initial capture step, as well as an intermediate polishing step in the purification of a humanized monoclonal antibody. PVS precipitation separated the antibody from host cell impurities such as host cell proteins (HCP) and DNA, process impurities such as leached protein A, insulin and gentamicin, as well as antibody fragments and aggregates. PVS was subsequently removed from antibody pools to <1 µg/mg using anion exchange chromatography. PVS precipitation did not impact the biological activity of the resolubilized antibody. Biotechnol. Bioeng. 2009;102: 1141–1151. © 2008 Wiley Periodicals, Inc.     

抗脂多糖纳米抗体的筛选及其五聚体的制备

目的：筛选抗脂多糖（LPS）纳米单域抗体,并制备抗LPS纳米抗体五聚体。方法：以LPS为抗原,从驼源天然单域重链抗体库中筛选抗LPS纳米抗体,利用分子克隆技术将抗LPS单域抗体基因组装入志贺杆菌样毒素B亚基蛋白结构域（VTB）的五聚体特异性表达载体中进行可溶性表达,并用ELISA法鉴定所获抗体的抗原结合活性和特异性。结果：获得抗LPS纳米单域抗体及LPS纳米抗体五聚体;经鉴定,LPS纳米抗体五聚体的抗原结合活性优于抗LPS单域抗体。结论：利用驼源天然单域重链抗体库制备了抗LPS纳米单域抗体及抗LPS纳米抗体五聚体,为脓毒血症的分子诊断、预后判断及寻找生物治疗新靶点奠定了基础。     

Tailoring translational strength using Kozak sequence variants improves bispecific antibody assembly and reduces product-related impurities in CHO cells

Optimal production of bispecific antibodies (bsAb) requires efficient and tailored co-expression and assembly of two distinct heavy and two distinct light chains. Here, we describe a novel technology to modulate the translational strength of antibody chains via Kozak sequence variants to produce bsAb in a single cell line. In this study, we designed and screened a large Kozak sequence library to identify 10 independent variants that can modulate protein expression levels from approximately 0.2 to 1.3-fold compared with the wild-type sequence in transient transfection. We used a combination of several of these variants, covering a wide range of translational strength, to develop stable single cell Chinese hamster ovary bispecific cell lines and compared the results with those obtained from the wild-type sequence. A significant increase in bispecific antibody assembly with a concomitant reduction in the level of product-related impurities was observed. Our findings suggest that for production of bsAb it can be advantageous to modify translational strength for selected protein chains to improve overall yield and product quality. By extension, tuning of translational strength can also be applied to improving the production of a wide variety of heterologous proteins.     

The Glycoprotein of Vesicular Stomatitis Virus Is the Antigen That Gives Rise to and Reacts with Neutralizing Antibody

The glycoprotein, but no other virion protein, of vesicular stomatitis virus was solubilized by the nonionic detergent Triton X-100 in low ionic strength buffer. The solubilized viral glycoprotein induced the synthesis of antibody that formed a single precipitin line with the glycoprotein and that neutralized the infectivity of the virus. The neutralizing activity of the antibody was efficiently blocked by purified glycoprotein.     

Seropositivity for CMV and IL-6 levels are associated with grip strength and muscle size in the elderly

Background

Sarcopenia is an important cause of morbidity and mortality in older adults, with immunosenescence and inflammation being possible underlying mechanisms. We investigated the relationship between latent cytomegalovirus (CMV) infection, Interleukin 6 (IL-6) levels, muscle size and strength in a group of healthy older community-dwelling people.

Methods

Participants were healthy volunteers from the Lothian Birth Cohort 1936 study. Participants had IL-6 level and CMV antibody titre measured at age 70 years and grip strength and a volumetric T1-weighted MRI brain scan (allowing measurement of neck muscle cross-sectional area (CSA)) at age 73. Markers of childhood deprivation were adjusted for in the analysis due to correlations between childhood deprivation and latent CMV infection.

Results

866 participants were studied; 448 men (mean age 72.48 years, sd 0.70) and 418 women (mean age 72.51 years, sd 0.72). In men, CMV seropositivity was associated with smaller neck muscle CSA (p = 0.03, partial eta squared = 0.01), even after adjustment for IL-6 levels. Neck muscle CSA was not associated with CMV seropositivity in women, or CMV antibody titre or IL-6 level in either sex. Grip strength associated negatively with IL-6 level (right grip strength p<0.00001, partial eta squared 0.032 and left grip strength p<0.00001, partial eta squared 0.027) with or without adjustment for CMV serostatus or antibody titre. CMV status and antibody titre were not significantly associated with grip strength in either hand.

Conclusion

These findings support the hypothesis that there is a relationship between markers of immunosenescence (i.e. CMV serostatus and IL6 level) and low muscle mass and strength and longitudinal studies in older cohorts are now required to investigate these relationships further.

     

Production and characterization of a genetically engineered anti-caffeine camelid antibody and its use in immunoaffinity chromatography

This work demonstrates the feasibility of using a camelid single domain antibody for immunoaffinity chromatographic separation of small molecules. An anti-caffeine VHH antibody was produced by grafting the complementarity determining sequences of a previously generated antibody onto an anti-RNase A antibody scaffold, followed by expression in E. coli. Analysis of the binding properties of the antibody by ELISA and fluorescence-based thermal shift assays showed that it recognizes not only caffeine, but also theophylline, theobromine, and paraxanthine, albeit with lower affinity. Further investigation of the effect of environmental conditions, i.e., temperature, pH, and ionic strength, on the antibody using these methods provided useful information about potential elution conditions to be used in chromatographic applications. Immobilization of the VHH onto a high flow-through synthetic support material resulted in a stationary phase capable of separating caffeine and its metabolites.     

Diffusion-limited rates for monoclonal antibody binding to cytochrome c.

The kinetic and spectroscopic changes accompanying the binding of two monoclonal antibodies to the oxidized form of horse heart cytochrome c have been investigated. The two epitopes recognized by the antibodies are distinct and noninteracting: antibody 2B5 binds to native cytochrome c near a type II turn (residue 44) while antibody 5F8 binds on the opposite face of the protein near the amino terminus of an alpha-helical segment (residue 60). Antibody-cytochrome c binding obeys a simple bimolecular reaction mechanism with second-order rate constants approaching those expected for diffusion-limited protein-protein interactions. The association rate constants have small activation enthalpies and are inversely dependent on solvent viscosity, as expected for diffusion-controlled reactions. There is a moderate ionic strength dependence of the rate of association between the 2B5 antibody and cytochrome c, with the rate constant increasing about 4-fold as the ionic strength is varied between 0.14 and 0 M. Comparison of the rates for antibody-cytochrome c complex formation for binding to the reduced-native, oxidized-native, and alkaline conformations shows that for MAb 2B5 the forward rate constant depends slightly on cytochrome c conformation. Investigation of the pH-induced transition between the native and alkaline conformational states for free cytochrome c and for antibody-cytochrome c complexes shows that antibody binding stabilizes the native form of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of charged groups in haptens on adsorption equilibrium of hapten antibody

Antisera against charged (p-azobenzoate and p-azoben zenesulfonate) and uncharged (dinitrophenyl) haptenic groups were produced in rabbits, and the equilibrium characteristics of hapten-antibody were measured by use of immunoadsorbents. The antibody to the uncharged hapten formed a stable binding with the hapten to the changes in ionic strength and pH. On the other hand, the antibodies to the charged haptens showed affinities sensitive to the changes in pH and ionic strength. Therefore, the effect of the pK(a) of ionizable haptens on the pH dependence of the hapten-antibody binding was studied by comparing the interactions between a series of para-substituted benzoic acids and the anti-p-azobenzoate antibody. The pH dependence of the interactions was strongly affected by the pK(a) of ionizable groups in haptens. Furthermore, the equilibrium characteristics of anti-p-aminobenzoyl dipeptides were compared. The characteristics of interactions were affected by the features of amino acid residues.     

Differing accessibility in chromatin of the antigenic sites of regions 1-58 and 63-125 of histone H2B

Experiments with antibodies induced by separated fragments 1-58 and 63- 125 of H2B histone indicated that the 1-58 portion of the molecule is much more accessible in chromatin than is the 63-125 region. In immunoabsorption and immunoelectron microscopic assays with bovine and chicken chromatins, anti-1-58 antibodies reacted with sheared or unsheared chromatin both at low ionic strength (1 mM Tris-HCl) and in 0.14 M NaCl. Anti-63-125 antibodies were bound only weakly by chromatin at low ionic strength and not at all in 0.14 M NaCl. Antibodies to whole H2B showed intermediate reactivity with chromatin in both assays. In tests of immunofluorescence with unfixed calf liver nuclei in suspension, anti-1-58 caused nucleolar as well as nucleoplasmic fluorescence, whereas anti-63-125 did not lead to detectable fluorescence; anti-H2B showed intermediate staining intensity. In control experiments, anti-H1 antibody was bound by chromatin at low ionic strength but not in 0.14 M NaCl; anti-H3 antibody was bound poorly under either condition.     

Purification of human adult and foetal intestinal alkaline phosphatases by monoclonal antibody immunoaffinity chromatography.

We have used the technique of monoclonal antibody immunoaffinity chromatography to purify adult and foetal intestinal alkaline phosphatases. Pure adult intestinal enzyme was obtained from a crude tissue extract with a single immunoaffinity chromatographic step in yields exceeding 95%. An additional ion-exchange chromatographic step was necessary for purification of the foetal enzyme, but yields still exceeded 70%. Experiments to optimize the efficiency of the monoclonal antibody immunoaffinity chromatography procedure suggest that the relative strength of binding of an antibody to its antigen is the most important factor to consider when constructing such columns. A column made from an antibody of too low an avidity will not retain the enzyme, while one of too high an avidity will make elution of enzyme in the active state difficult. A scheme is suggested for the application of this technique to a general approach to enzyme purification.     

Immobilization of animal cells using photo-crosslinkable resin

A photo-crosslinkable resin, BIX12, was selected from among various photo-crosslinkable resins for the immobilization of animal cells. BIX12 had no cytotoxic effect on the growth of hybridoma cells and the production of monoclonal antibody, although other photo-crosslinkable resins had significant inhibitory effects. Using BIX12-alginate hybrid gel particles, hybridoma cells could grow in the resins and produce monoclonal antibody. For the continuous production of monoclonal antibody, perfusion culture using a fluidized-bed bioreactor with direct air bubbling was carried out. By this cultivation, monoclonal antibody could be produced stably for more than 50 d. A high viable cell density of more than 10⁷ cells/ml-gel was attained, and the antibody productivity was improved 8.5-fold compared with conventional suspension culture using a spinner flask. Anchorage-dependent cells were also immobilized in the resin particles by three immobilization procedures. Among these procedures, porous BIX12 formed by adding gelatin powder provided good support strength and allowed the cells to grow on the surface inside of the support.     

High-throughput analysis of concentration-dependent antibody self-association

Monoclonal antibodies are typically monomeric and nonviscous at low concentrations, yet they display highly variable associative and viscous behavior at elevated concentrations. Although measurements of antibody self-association are critical for understanding this complex behavior, traditional biophysical methods are not capable of characterizing such concentration-dependent self-association in a high-throughput manner. Here we describe a nanoparticle-based method, termed self-interaction nanoparticle spectroscopy, that is capable of rapidly measuring concentration-dependent self-interactions for three human monoclonal antibodies with unique solution behaviors. We demonstrate that gold nanoparticles conjugated with antibodies at low protein concentrations (<40 μg/mL) display self-association behavior (as measured by the interparticle distance-dependent plasmon wavelength) that is well correlated with static light-scattering measurements obtained at three orders of magnitude higher antibody concentrations. Using this methodology, we find that the antibodies display a complex pH-dependent self-association behavior that is strongly influenced by the solution ionic strength. Importantly, we find that a polyclonal human antibody is nonassociative for all solution conditions evaluated in this work, suggesting that antibody self-association is more specific than previously realized. We expect that our findings will guide rational manipulation of antibody phase behavior, and enable studies that elucidate sequence and structural determinants of antibody self-association.     

Enantiomer separation of amino acids in immunoaffinity micro LC-MS

Chiral immunoaffinity microbore columns were directly interfaced with MS detection, and the effect of column length and temperature on the enantiomer separation of a number of underivatized aromatic and aliphatic amino acids was investigated utilizing an antibody chiral stationary phase that had been prepared by immobilizing a monoclonal anti-D-amino acid antibody onto silica. The stronger affinity of the antibody towards aromatic and bulky amino acids allowed separation of such analytes in a 0.75 x 150 mm column, while an increase in column length enabled separation of more weakly bound compounds. The strength of interaction between chiral selector and analytes could be modulated conveniently by lowering the temperature. For the first time, simultaneous enantiomer separation of mixtures of amino acids was achieved on antibody-based chiral stationary phases using extracted ion chromatograms.