Production of a Shigella sonnei Vaccine Based on Generalized Modules for Membrane Antigens (GMMA), 1790GAHB.

Recently, we developed a high yield production process for outer membrane particles from genetically modified bacteria, called Generalized Modules of Membrane Antigens (GMMA), and the corresponding simple two step filtration purification, enabling economic manufacture of these particles for use as vaccines. Using a Shigella sonnei strain that was genetically modified to produce penta-acylated lipopolysaccharide (LPS) with reduced endotoxicity and to maintain the virulence plasmid encoding for the immunodominant O antigen component of the LPS, scale up of the process to GMP pilot scale was straightforward and gave high yields of GMMA with required purity and consistent results. GMMA were formulated with Alhydrogel and were highly immunogenic in mice and rabbits. In mice, a single immunization containing 29 ng protein and 1.75 ng of O antigen elicited substantial anti-LPS antibody levels. As GMMA contain LPS and lipoproteins, assessing potential reactogenicity was a key aspect of vaccine development. In an in vitro monocyte activation test, GMMA from the production strain showed a 600-fold lower stimulatory activity than GMMA with unmodified LPS. Two in vivo tests confirmed the low potential for reactogenicity. We established a modified rabbit pyrogenicity test based on the European Pharmacopoeia pyrogens method but using intramuscular administration of the full human dose (100 µg of protein). The vaccine elicited an average temperature rise of 0.5°C within four hours after administration, which was considered acceptable and showed that the test is able to detect a pyrogenic response. Furthermore, a repeat dose toxicology study in rabbits using intramuscular (100 µg/dose), intranasal (80 µg/dose), and intradermal (10 µg/dose) administration routes showed good tolerability of the vaccine by all routes and supported its suitability for use in humans. The S. sonnei GMMA vaccine is now in Phase 1 dose-escalation clinical trials.

Simplified low-cost production of O-antigen from Salmonella Typhimurium Generalized Modules for Membrane Antigens (GMMA).

The Novartis Vaccines Institute for Global Health is developing vaccines using outer membrane particles, known as Generalized Modules for Membrane Antigens (GMMA). These are blebs of outer membrane and periplasm, shed from the surface of living Gram-negative bacteria following the targeted deletion of proteins involved in maintaining the integrity of the inner and outer membranes. The current study investigates the use of GMMA as starting material for extraction of membrane components, focusing on the O-antigen polysaccharide portion of lipopolysaccharide from Salmonella Typhimurium. We show that the amount of O-antigen extracted from GMMA by acid hydrolysis is comparable to the quantity extracted from whole wild type bacteria, but with less protein and DNA contaminants. Compared to conventional purification, GMMA enabled a reduction in the number of purification steps required to obtain the O-antigen polysaccharide with the same purity. Purification processes from GMMA and bacteria were characterised by similar final yields. Use of GMMA as starting material provides the possibility to simplify the purification process of O-antigen, with a consequent decrease in manufacturing costs of O-antigen-based glyconjugate vaccines against Salmonella strains and potentially other Gram-negative bacteria.

High yield production process for Shigella outer membrane particles.

Gram-negative bacteria naturally shed particles that consist of outer membrane lipids, outer membrane proteins, and soluble periplasmic components. These particles have been proposed for use as vaccines but the yield has been problematic. We developed a high yielding production process of genetically derived outer membrane particles from the human pathogen Shigella sonnei. Yields of approximately 100 milligrams of membrane-associated proteins per liter of fermentation were obtained from cultures of S. sonnei ΔtolR ΔgalU at optical densities of 30-45 in a 5 L fermenter. Proteomic analysis of the purified particles showed the preparation to primarily contain predicted outer membrane and periplasmic proteins. These were highly immunogenic in mice. The production of these outer membrane particles from high density cultivation of bacteria supports the feasibility of scaling up this approach as an affordable manufacturing process. Furthermore, we demonstrate the feasibility of using this process with other genetic manipulations e.g. abolition of O antigen synthesis and modification of the lipopolysaccharide structure in order to modify the immunogenicity or reactogenicity of the particles. This work provides the basis for a large scale manufacturing process of Generalized Modules of Membrane Antigens (GMMA) for production of vaccines from gram-negative bacteria.

Characterization of Citrobacter sp. line 328 as a source of Vi for a Vi-CRM(197) glycoconjugate vaccine against Salmonella Typhi.

INTRODUCTION: Salmonella enterica serovar Typhi is the causative agent of typhoid fever with over 22 million cases and over 200,000 deaths reported annually. A vaccine is much needed for use in young children and the Novartis Vaccines Institute for Global Health (NVGH) is developing a conjugate vaccine which targets S. Typhi Vi capsular polysaccharide. METHODOLOGY: Here we describe a method suitable for industrial scale production of the Vi antigen based on expression by a Citrobacter line. We optimized the production of Vi by selecting a suitable Citrobacter strain (Citrobacter 328) that yields high and stable expression of Vi in chemically defined medium under industrial-scale fermentation conditions. RESULTS: Vi-CRM197 made using Vi from Citrobacter 328 elicited high anti-Vi antibody levels in mice and rabbits. CONCLUSIONS: Citrobacter 328 is a suitable strain for production of Vi for conjugate anti-Typhi vaccines. Being a BSL-1 organism, which grows in defined medium and stably produces high yields of Vi, it offers excellent potential for safe production of inexpensive vaccines for populations at risk of typhoid fever.

Safety, immunogenicity and dose ranging of a new Vi-CRM197 conjugate vaccine against typhoid fever: randomized clinical testing in healthy adults.

BACKGROUND: Typhoid fever causes more than 21 million cases of disease and 200,000 deaths yearly worldwide, with more than 90% of the disease burden being reported from Asia. Epidemiological data show high disease incidence in young children and suggest that immunization programs should target children below two years of age: this is not possible with available vaccines. The Novartis Vaccines Institute for Global Health developed a conjugate vaccine (Vi-CRM197) for infant vaccination concomitantly with EPI vaccines, either starting at 6 weeks with DTP or at 9 months with measles vaccine. We report the results from a Phase 1 and a Phase 2 dose ranging trial with Vi-CRM197 in European adults. METHODOLOGY: Following randomized blinded comparison of single vaccination with either Vi-CRM197 or licensed polysaccharide vaccines (both containing 25·0 µg of Vi antigen), a randomised observer blinded dose ranging trial was performed in the same center to compare three concentrations of Vi-CRM197 (1·25 µg, 5·0 µg and 12·5 µg of Vi antigen) with the polysaccharide vaccine. PRINCIPAL FINDINGS: All vaccines were well tolerated. Compared to the polysaccharide vaccine, Vi-CRM197 induced a higher incidence of mild to moderate short lasting local pain. All Vi-CRM197 formulations induced higher Vi antibody levels compared to licensed control, with clear dose response relationship. CONCLUSIONS: Vi-CRM197 did not elicit safety concerns, was highly immunogenic and is therefore suitable for further clinical testing in endemic populations of South Asia. TRIAL REGISTRATION: ClinicalTrials.gov NCT01123941 NCT01193907.

Conversion of murine antibodies to human antibodies and their optimization for ovarian cancer therapy targeted to the folate receptor.

We previously developed murine and chimeric antibodies against a specific epithelial ovarian carcinoma (EOC) marker, named folate receptor (FR), and promising results were obtained in phase II trials. More recently, we successfully generated a completely human Fab fragment, C4, by conversion of one of the murine anti-FR antibodies to human antibody using phage display and guided selection. However, subsequent efforts to obtain C4 in a dimer format, which seems especially desirable for EOC locoregional treatment, resulted in a highly heterogeneous product upon natural dimerization and in a very poor production yield upon chemical dimerization by a non-hydrolyzable linker to a di-Fab-maleimide (DFM). We therefore designed, constructed and characterized a large Fab dual combinatorial human antibody phage display library obtained from EOC patients and potentially biased toward an anti-tumor response in an effort to obtain new anti-FR human antibodies suitable for therapy. Using this library and guiding the selection on FR-expressing cells with murine/human antibody chains, we generated four new human anti-FR antibody (AFRA) Fab fragments, one of which was genetically and chemically manipulated to obtain a chemical dimer, designated AFRA-DFM5.3, with high yield production and the capability for purification scaled-up to clinical grade. Overall affinity of AFRA-DFM5.3 was in the 2-digit nanomolar range, and immunohistochemistry indicated that the reagent recognized the FR expressed on EOC samples. (131)I-AFRA-DFM5.3 showed high immunoreactivity, in vitro stability and integrity, and specifically accumulated only in FR-expressing tumors in subcutaneous preclinical in vivo models. Overall, our studies demonstrate the successful conversion of murine to completely human anti-FR antibodies through the combined use of antibody phage display libraries biased toward an anti-tumor response, guided selection and chain shuffling, and point to the suitability of AFRA5.3 for future clinical application in ovarian cancer.

2-Arylpropionic CXC chemokine receptor 1 (CXCR1) ligands as novel noncompetitive CXCL8 inhibitors.

The CXC chemokine CXCL8/IL-8 plays a major role in the activation and recruitment of polymorphonuclear (PMN) cells at inflammatory sites. CXCL8 activates PMNs by binding the seven-transmembrane (7-TM) G-protein-coupled receptors CXC chemokine receptor 1 (CXCR1) and CXC chemokine receptor 2 (CXCR2). (R)-Ketoprofen (1) was previously reported to be a potent and specific noncompetitive inhibitor of CXCL8-induced human PMNs chemotaxis. We report here molecular modeling studies showing a putative interaction site of 1 in the TM region of CXCR1. The binding model was confirmed by alanine scanning mutagenesis and photoaffinity labeling experiments. The molecular model driven medicinal chemistry optimization of 1 led to a new class of potent and specific inhibitors of CXCL8 biological activity. Among these, repertaxin (13) was selected as a clinical candidate drug for prevention of post-ischemia reperfusion injury.

Noncompetitive allosteric inhibitors of the inflammatory chemokine receptors CXCR1 and CXCR2: prevention of reperfusion injury.

The chemokine CXC ligand 8 (CXCL8)/IL-8 and related agonists recruit and activate polymorphonuclear cells by binding the CXC chemokine receptor 1 (CXCR1) and CXCR2. Here we characterize the unique mode of action of a small-molecule inhibitor (Repertaxin) of CXCR1 and CXCR2. Structural and biochemical data are consistent with a noncompetitive allosteric mode of interaction between CXCR1 and Repertaxin, which, by locking CXCR1 in an inactive conformation, prevents signaling. Repertaxin is an effective inhibitor of polymorphonuclear cell recruitment in vivo and protects organs against reperfusion injury. Targeting the Repertaxin interaction site of CXCR1 represents a general strategy to modulate the activity of chemoattractant receptors.

Key role of proline-rich tyrosine kinase 2 in interleukin-8 (CXCL8/IL-8)-mediated human neutrophil chemotaxis.

The signalling pathways leading to CXCL8/IL-8-induced human neutrophil migration have not been fully characterized. The present study demonstrates that CXCL8 induces tyrosine phosphorylation as well as enzymatic activity of proline-rich tyrosine kinase 2 (Pyk2), a non-receptor protein tyrosine kinase (PTK), in human neutrophils. Induction of Pyk2 tyrosine phosphorylation by CXCL8 is regulated by Src PTK activation, whereas it is unaffected by phosphatidylinositol 3-kinase activation. Inhibition of Pyk2 activation by PP1, a Src PTK inhibitor, is paralleled by the inhibition of CXCL8-mediated neutrophil chemotaxis. Among CXCL8 receptors, Src protein tyrosine kinase activation selectively regulates CXCR1-mediated polymorphonuclear neutrophil (PMN) chemotaxis. Overexpression of PykM, the kinase-dead mutant of Pyk2, blocks CXCL8-induced chemotaxis of HL-60-derived PMN-like cells, thus pinpointing the key role of Pyk2 in CXCL8-induced chemotaxis.

Glycosylation enhances functional stability of the chemotactic cytokine CCL2.

The human chemokine CCL2 gene was expressed in the yeast P.pastoris and gave rise to a mixture of differently glycosylated recombinant proteins. In comparison to non-glycosylated E.coli-derived CCL2, glycosylated yeast CCL2L was 4-20 times less active in a chemotactic assay in vitro. However, CCL2L could maintain full activity upon prolonged incubation at 37 degrees C, whereas the non-glycosylated chemokine readily lost activity. It could be hypothesized that glycosylation is a mechanism used by the organism to modulate CCL2 stability. The partial loss of specific activity due to glycosylation is balanced by the advantage of prolonging the effectiveness of chemokine. Thus, differential glycosylation allows one to obtain highly effective short-lived CCL2 or less-effective long-lived CCL2 and may thus represent a novel mechanism of adaptation to pathological versus physiological conditions.