Funding global health product R&D: the Portfolio-To-Impact Model (P2I), a new tool for modelling the impact of different research portfolios.

Background: The Portfolio-To-Impact (P2I) Model is a novel tool, developed to estimate minimum funding needs to accelerate health product development from late stage preclinical study to phase III clinical trials, and to visualize potential product launches over time. Methods: A mixed methods approach was used. Assumptions on development costs at each phase were based on clinical trial costs from Parexel's R&D cost sourcebook. These were further refined and validated by interviews, with a wide variety of stakeholders from Product Development Partnerships, biopharmaceutical and diagnostic companies, and major funders of global health R&D. Results: the tool was used to create scenarios describing the impact, in terms of products developed, of different product portfolios with funding ranging from $1 million per annum through to $500 million per annum. These scenarios for a new global financing mechanism have been previously presented in a report setting out the potential for a new fund for research and development which would assist in accelerating product development for the diseases of poverty.  Conclusion: The P2I tool does enable a user to model different scenarios in terms of cost and number of health products launched when applied to a portfolio of health products.  The model is published as open access accompanied with a user guide.  The design allows it to be adapted and used for other health R&D portfolio analysis as described in an accompanying publication focussing on the pipeline for neglected diseases in 2017. We aim to continually refine and improve the model and we ask users to provide us with their own inputs that can help us update key parameters and assumptions.  We hope to catalyse users to adapt the model in ways that can increase its value, accuracy, and applications.

An internally modulated, thermostable, pH-sensitive Cys loop receptor from the hydrothermal vent worm Alvinella pompejana.

Cys loop receptors (CLRs) are commonly known as ligand-gated channels that transiently open upon binding of neurotransmitters to modify the membrane potential. However, a class of cation-selective bacterial homologues of CLRs have been found to open upon a sudden pH drop, suggesting further ligands and more functions of the homologues in prokaryotes. Here we report an anion-selective CLR from the hydrothermal vent annelid worm Alvinella pompejana that opens at low pH. A. pompejana expressed sequence tag databases were explored by us, and two full-length CLR sequences were identified, synthesized, cloned, expressed in Xenopus oocytes, and studied by two-electrode voltage clamp. One channel, named Alv-a1-pHCl, yielded functional receptors and opened upon a sudden pH drop but not by other known agonists. Sequence comparison showed that both CLR proteins share conserved characteristics with eukaryotic CLRs, such as an N-terminal helix, a cysteine loop motif, and an intracellular loop intermediate in length between the long loops of other eukaryotic CLRs and those of prokaryotic CLRs. Both full-length Alv-a1-pHCl and a truncated form, termed tAlv-a1-pHCl, lacking 37 amino-terminal residues that precede the N-terminal helix, formed functional channels in oocytes. After pH activation, tAlv-a1-pHCl showed desensitization and was not modulated by ivermectin. In contrast, pH-activated, full-length Alv-a1-pHCl showed a marked rebound current and was modulated significantly by ivermectin. A thermostability assay indicated that purified tAlv-a1-pHCl expressed in Sf9 cells denatured at a higher temperature than the nicotinic acetylcholine receptor from Torpedo californica.

An evaluation of emerging vaccines for childhood pneumococcal pneumonia.

BACKGROUND: Pneumonia is the leading cause of child mortality worldwide. Streptococcus pneumoniae (SP) or pneumococcus is estimated to cause 821,000 child deaths each year. It has over 90 serotypes, of which 7 to 13 serotypes are included in current formulations of pneumococcal conjugate vaccines that are efficacious in young children. To further reduce the burden from SP pneumonia, a vaccine is required that could protect children from a greater diversity of serotypes. Two different types of vaccines against pneumococcal pneumonia are currently at varying stages of development: a multivalent pneumococcal conjugate vaccine covering additional SP serotypes; and a conserved common pneumococcal protein antigen (PPA) vaccine offering protection for all serotypes. METHODS: We used a modified CHNRI methodology for setting priorities in health research investments. This was done in two stages. In Stage I, we systematically reviewed the literature related to emerging SP vaccines relevant to several criteria of interest: answerability; efficacy and effectiveness; cost of development, production and implementation; deliverability, affordability and sustainability; maximum potential for disease burden reduction; acceptability to the end users and health workers; and effect on equity. In Stage II, we conducted an expert opinion exercise by inviting 20 experts (leading basic scientists, international public health researchers, international policy makers and representatives of pharmaceutical companies). The policy makers and industry representatives accepted our invitation on the condition of anonymity, due to sensitive nature of their involvement in such exercises. They answered questions from CHNRI framework and their "collective optimism" towards each criterion was documented on a scale from 0 to 100%. RESULTS: The experts expressed very high level of optimism (over 80%) that low-cost polysaccharide conjugate SP vaccines would satisfy each of the 9 relevant CHNRI criteria. The median potential effectiveness of conjugate SP vaccines in reduction of overall childhood pneumonia mortality was predicted to be about 25% (interquartile range 20-38%, min. 15%, max 45%). For low cost, cross-protective common protein vaccines for SP the experts expressed concerns over answerability (72%) and the level of development costs (50%), while the scores for all other criteria were over 80%. The median potential effectiveness of common protein vaccines in reduction of overall childhood pneumonia mortality was predicted to be about 30% (interquartile range 26-40%, min. 20%, max 45%). CONCLUSIONS: Improved SP vaccines are a very promising investment that could substantially contribute to reduction of child mortality world-wide.

Progress with human H5N1 vaccines: a perspective from industry.

With the ongoing widespread circulation of avian H5N1 influenza viruses and the threat of pandemic influenza an ever-present reality, it is essential that those charged with protecting public health continue to focus intently on this urgent issue. As part of the response to this pandemic threat, research-based influenza vaccine manufacturers have made rapid progress with the research, development and testing of new vaccines and have greatly expanded their capacity to manufacture these products in the last few years. With the research and development phase now reaching completion, regulators have approved several prototype 'mock-up' pandemic vaccines and a number of 'prepandemic' H5N1 vaccines. As a consequence, the world is better prepared than it has ever been to counter an influenza pandemic. However, despite these advances, many policy, logistical and practical issues must be resolved for the population to benefit from these breakthroughs. In particular, the global community must establish the infrastructure required for population-wide immunization, secure appropriate vaccine supplies and undertake sufficient vaccine stockpiling to protect against the first wave of a pandemic.

Current challenges in implementing cell-derived influenza vaccines: implications for production and regulation, July 2007, NIBSC, Potters Bar, UK.

A meeting was held at NIBSC, UK in July 2007 to discuss the implications of progress in the use of cell culture systems for the manufacture of vaccines against influenza. Issues discussed included the effect of using eggs and different cell types in strain selection, development of seed viruses to be used in production and the nature of the reagents to be used in determining vaccine potency. Future studies to progress the field were reviewed.

Unexpected sensitivity of the human alpha7 neuronal nicotinic acetylcholine receptor to aminoglycosides.

The wide use of antibiotics and the development of resistance is a major health concern and, despite their relatively severe side effects, aminoglycoside antibiotics are still used in clinics. Effects of seven aminoglycosides were investigated at the human homomeric alpha7 and heteromeric alpha4beta2 neuronal nicotinic acetylcholine receptors. All aminoglycosides tested inhibited the acetylcholine-evoked responses with more pronounced effects at alpha7 than at alpha4beta2. Neomycin displayed higher blockade with a half inhibition in the nanomolar range at low calcium concentration and in the micromolar range in physiological calcium concentration but still exerted blockade below the concentration used in the clinic. These data suggest that some of their side effects may be attributable to their interactions with neuronal nicotinic acetylcholine receptors.

Gelsolin mediates calcium-dependent disassembly of Listeria actin tails.

The role of intracellular Ca2+ in the regulation of actin filament assembly and disassembly has not been clearly defined. We show that reduction of intracellular free Ca2+ concentration ([Ca2+]i) to <40 nM in Listeria monocytogenes-infected, EGFP-actin-transfected Madin-Darby canine kidney cells results in a 3-fold lengthening of actin filament tails. This increase in tail length is the consequence of marked slowing of the actin filament disassembly rate, without a significant change in assembly rate. The Ca2+-sensitive actin-severing protein gelsolin concentrates in the Listeria rocket tails at normal resting [Ca2+]i and disassociates from the tails when [Ca2+]i is lowered. Reduction in [Ca2+]i also blocks the severing activity of gelsolin, but not actin-depolymerizing factor (ADF)/cofilin microinjected into Listeria-infected cells. In Xenopus extracts, Listeria tail lengths are also calcium-sensitive, markedly shortening on addition of calcium. Immunodepletion of gelsolin, but not Xenopus ADF/cofilin, eliminates calcium-sensitive actin-filament shortening. Listeria tail length is also calcium-insensitive in gelsolin-null mouse embryo fibroblasts. We conclude that gelsolin is the primary Ca2+-sensitive actin filament recycling protein in the cell and is capable of enhancing Listeria actin tail disassembly at normal resting [Ca2+]i (145 nM). These experiments illustrate the unique and complementary functions of gelsolin and ADF/cofilin in the recycling of actin filaments.