Purification process development of a recombinant monoclonal antibody expressed in glycoengineered Pichia pastoris.

A robust and scalable purification process was developed to quickly generate antibody of high purity and sufficient quantity from glycoengineered Pichia pastoris fermentation. Protein A affinity chromatography was used to capture the antibody from fermentation supernatant. A pH gradient elution was applied to the Protein A column to prevent antibody precipitation at low pH. Antibody from Protein A chromatography contained some product related impurities, which were the misassembling of cleaved heavy chain, heavy chain and light chain. It also had some process related impurities, including Protein A residues, endotoxin, host cell DNA and proteins. Cation exchange chromatography with optimal NaCl gradient at pH 4.5-6.0 efficiently removed these product and process related impurities. The antibody from glycoengineered P. pastoris was comparable to its commercial counterpart in heterotetramer folding, physical stability and binding affinity.

Multiplexed analysis of peptide antigen-specific antibodies.

Many experiments require the simultaneous measurement of more than one parameter at a time. These protocols describe a multiplex method that can be used to detect two or more analytes simultaneously in the same sample preparation. Our example detects antibodies directed against peptide antigens but is amenable to most typical EIA format configurations to allow measurement of alternative analytes. We chose to use the LumAvidin bead-based assay system due to the simplicity of coupling synthesized biotin-peptides to the spectrally distinct bead types. The coupled beads were stored at 4 degrees C. Using unlabeled beads as a negative control posed a significant risk of antigen migration from other labeled beads in the multiplex format. Therefore, labeled beads should be mixed immediately prior to performing the assay. Peptide-specific units were assigned to a polyclonal standard control allowing for quantitation of sample responses. The assay has proven to be quite robust.

Production of monoclonal antibodies by glycoengineered Pichia pastoris.

The growing antibody market and the pressure to improve productivity as well as reduce cost of production have fueled the development of alternative expression systems. The therapeutic function of many antibodies is influenced by N-linked glycosylation, which is affected by a combination of the expression host and culture conditions. This paper reports the generation of a glycoengineered Pichia pastoris strain capable of producing more than 1 g l(-1) of a functional monoclonal antibody in a robust, scalable and portable cultivation process with uniform N-linked glycans of the type Man(5)GlcNAc(2). N-linked glycan uniformity and volumetric productivity have been maintained across a range of cultivation process conditions including pH (5.5-7.5), temperature (16-24 degrees C), dissolved oxygen concentration (0.85-3.40 mg l(-1)) and specific methanol feed rate (9-19 mg g(-1) h(-1)) as well as across different cultivation scales (0.5, 3.0, 15 and 40 l). Compared to a marketed CHO-produced therapeutic antibody, the glycoengineered yeast-produced antibody has similar motilities on SDS-PAGE, comparable size exclusion chromatograms (SEC) and antigen binding affinities. This paper provides proof of concept that glycoengineered yeast can be used to produce functional full-length monoclonal antibodies at commercially viable productivities.

Design and optimization of a multiplex anti-influenza peptide immunoassay.

Current flu vaccines are based on killed or attenuated virus vaccines that must be altered each year to include the hemagglutinin and neuraminidase genes from a strain of virus predicted to predominate in the coming year. A vaccine that could protect against multiple strains of influenza A and B would be a major asset in the fight against flu-related mortality and morbidity. To support development of such a vaccine, we have developed a Flu Multiplex Assay based on a Luminex platform to assess serum antibody levels to two conserved peptides derived from influenza A (M2 protein) and influenza B (hemagglutinin protein). The peptides were synthesized with a biotin label and subsequently coupled to two different LumAvidin microspheres. We then tested various sera against both types of peptide in the multiplex assay format. The data show that sera from Rhesus macaques immunized with a single peptide react only with the homologous peptide while Rhesus macaques immunized with both peptides respond well to both peptides. Additionally, we were able to specifically compete reactivity to both peptides. We have tested serial bleeds from 100 pediatric patients at ages ranging from 16 to 56 weeks as well as single bleeds from over 100 healthy adults. No overall trend in titer relative to pediatric age was detected. Both demographics exhibited a minimal response to either the A/M2 or B/HA0 peptides. However, the average titer for the pediatric serum samples was significantly lower than that found in the adult population. The adult population exhibited a higher prevalence of low reactive samples. Assay reagents and parameters have been optimized and the assay is shown to be repeatable and robust. The assay will be used to support clinical vaccine trials of a bivalent peptide vaccine.

Effects of the potency and composition of the multivalent human-bovine (WC3) reassortant rotavirus vaccine on efficacy, safety and immunogenicity in healthy infants.

BACKGROUND: Rotavirus gastroenteritis, which causes substantial infant mortality and morbidity worldwide, is a vaccine-preventable disease. The purpose of this study was to evaluate different compositions and potencies (vaccine virus titers) of a live multivalent human-bovine (WC3) reassortant rotavirus vaccine in order to select the potency and composition of the vaccine for further development. METHODS: The efficacy, safety, and immunogenicity of a G1, G2, G3, G4, and P1A pentavalent composition at three different potencies, a G1, G2, G3, G4 quadrivalent composition, and a P1A monovalent composition of an oral human-bovine (WC3) reassortant rotavirus vaccine were compared in a blinded, placebo-controlled trial conducted between 1998 and 2001 enrolling 1,946 healthy Finnish infants 2-8 months of age. RESULTS: All potencies of the pentavalent and quadrivalent vaccines were efficacious (58-74%) against wild-type rotavirus gastroenteritis of any severity and 100% protective against severe rotavirus disease caused by vaccine G-serotypes through the first rotavirus season post-vaccination. The monovalent P1A vaccine was 53% efficacious against moderate-and-severe rotavirus gastroenteritis. Protection against rotavirus gastroenteritis of any severity was demonstrated through two and three rotavirus seasons for all vaccine compositions. After the third dose, the percentage of infants with >or=3-fold rise in baseline serum neutralizing antibody titers against G1 ranged from 62% to 86% for recipients of the pentavalent vaccine, depending on the potency. The incidence of fever, irritability, vomiting, and diarrhea did not significantly differ between vaccine and placebo groups. A 7-month-old male developed intussusception 9 days after the first dose of the low-potency pentavalent vaccine. CONCLUSIONS: Based on the results of this trial, a pentavalent composition (G1, G2, G3, G4, and P1A) of human-bovine (WC3) reassortant rotavirus vaccine with a potency similar to that of the middle-potency pentavalent vaccine ( approximately 8 x 10(6) plaque-forming units/dose) was selected for further development.

HDV 16 antibody prevalence in Jamaica and the United States reflects differences in cervical cancer rates

Human papillomavirus (HPV) is widely accepted as the primary etiologic agent in the development of cervical cancer. DNA of a particular HPV type, HPV 16, is found in about half of tumors tested. Inconsistent with this causal relationship, however, population-based studies of HPV DNA prevalence have often failed to find high rates of anogenital HPV infection in countries with high cervical cancer rates. To examine this issue, we used serology to compare HPV 16 exposure in healthy volunteer blood donors in the United States (n = 278) and similar subjects from a country with 3-fold higher cervical cancer rates, Jamaica (n = 257). Jamaican sexually transmitted disease (STD) patients (n = 831) were also studied to examine in detail the relation of HPV 16 antibodies with sexual history. Serology was conducted using an ELISA employing HPV 16 virus-like particles (VLPs). Age-adjusted seroprevalence rates were greatest among male (29 percent) and female (42 percent) STD patients, intermediate in male (19 percent) and female (24 percent) Jamaican blood donors and lowest among male (3 percent) and female (12 percent) U.S. blood donors. The higher seroprevalence in women was significant, and prevalence tended to increase with age. In multivariate logistic regression, controlling for age and gender, Jamaican blood donors were 4.2-fold (95 percent CI 2.4 - 7.2) and STD patients 8.1-fold (95 percent CI 5.0 - 13.2) more likely to have HPV 16 VLP antibodies than U.S. blood donors. Among STD patients, HPV 16 antibodies were associated with lifetime number of sex partners and years of sexual activity, as well as other factors. Our data suggest that HPV 16 VLP antibodies are strongly associated with sexual behavior. Moreover, exposure to HPV 16 appears to be much greater in Jamaica than in the United States, consistent with the high rate of cervical cancer in Jamaica (Au)

Detection of early human T-cell lymphotropic virus type I antibody patterns during seroconversion among transfusion recipients

From a cohort of human T-cell lymphotropic virus type I (HTLV-I) exposed transfusion recipients (N=71) enrolled in the Jamaican Transfusion Study, 11 were selected for detailed laboratory evaluation. All recipients were followed at monthly intervals for 6 months and then bimonthly up to 1 year for evidence of HTLV-I seroconversion. Without regard to results on screening assays, pretransfusion and posttransfusion samples were tested with two licensed HTLV-I whole-virus screening enzyme immunoassays (EIAs), recombinant EIAs for antibody against tax (p40x) and p21e envelope, standard whole virus Western blot (WB), WB enhanced with recombinant p21e, and radioimmunoprecipitation assay (RIPA). In the early period post transfusion, antibody to gag core protein was predominant with anti-p24 generally appearing before anti-p19. Recombinant anti-p21e envelope protein, in EIA and WB format, was frequently the earliest envelope reactively detected, while anti-gp46 in WB and anti-gp61/68 in RIPA system appeared later. Anti-tax antibodies appeared later in the time course of seroconersion. The whole-virus EIAs were less sensitive than the confirmatory assays. The combination of WB and RIPA or WB enhanced with recombinant p21e appeared equally effective in confirming samples as positive by the Public Health Service two gene group confirmatory algorithm. However specificity of this assay approach could not be addressed in this study.(AU)

Human T lymphotropic virus type I antibody patterns: evidence of difference by age and risk group

Detection of human T lymphotropic virus type I (HTLV-I) antibody was assessed on 368 sera from subjects with different clinical features and from different parts of the world. Enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay for purified p24 antibodies (p24-RIA) used as screening tests agreed in 88.7 percent of the sera. The results from 247 selected sera were compared with western blot (WB). WB was reactive in sera five to 25 times more dilute than the last positive ELISA or p24-RIA, but different WB batches varied in sensitivity. ELISA was more sensitive than p24-RIA, and p24-RIA was more specific than ELISA. Indeterminate WB interpretations were common (25.5 percent). Most seropositive intravenous drug abusers had unusually strong p24 bands by WB. Among healthy individuals, positive WB reactivity increased with age, whereas indeterminate reactivity declined (P=.034). Thus more sensitive and -specific HTLV-I antibody tests are needed. (AU)