What Should Vaccine Developers Ask? Simulation of the Effectiveness of Malaria Vaccines

A number of different malaria vaccine candidates are currently in pre-clinical or clinical development. Even though they vary greatly in their characteristics, it is unlikely that any of them will provide long-lasting sterilizing immunity against the malaria parasite. There is great uncertainty about what the minimal vaccine profile should be before registration is worthwhile; how to allocate resources between different candidates with different profiles; which candidates to consider combining; and what deployment strategies to consider.We use previously published stochastic simulation models, calibrated against extensive epidemiological data, to make quantitative predictions of the population effects of malaria vaccines on malaria transmission, morbidity and mortality. The models are fitted and simulations obtained via volunteer computing. We consider a range of endemic malaria settings with deployment of vaccines via the Expanded program on immunization (EPI), with and without additional booster doses, and also via 5-yearly mass campaigns for a range of coverages. The simulation scenarios account for the dynamic effects of natural and vaccine induced immunity, for treatment of clinical episodes, and for births, ageing and deaths in the cohort. Simulated pre-erythrocytic vaccines have greatest benefits in low endemic settings (<EIR of 10.5) where between 12% and 14% of all deaths are averted when initial efficacy is 50%. In some high transmission scenarios (>EIR of 84) PEV may lead to increased incidence of severe disease in the long term, if efficacy is moderate to low (<70%). Blood stage vaccines (BSV) are most useful in high transmission settings, and are comparable to PEV for low transmission settings. Combinations of PEV and BSV generally perform little better than the best of the contributing components. A minimum half-life of protection of 2–3 years appears to be a precondition for substantial epidemiological effects. Herd immunity effects can be achieved with even moderately effective (>20%) malaria vaccines (either PEV or BSV) when deployed through mass campaigns targeting all age-groups as well as EPI, and especially if combined with highly efficacious transmission-blocking components.We present for the first time a stochastic simulation approach to compare likely effects on morbidity, mortality and transmission of a range of malaria vaccines and vaccine combinations in realistic epidemiological and health systems settings. The results raise several issues for vaccine clinical development, in particular appropriateness of vaccine types for different transmission settings; the need to assess transmission to the vector and duration of protection; and the importance of deployment additional to the EPI, which again may make the issue of number of doses required more critical. To test the validity and robustness of our conclusions there is a need for further modeling (and, of course, field research) using alternative formulations for both natural and vaccine induced immunity. Evaluation of alternative deployment strategies outside EPI needs to consider the operational implications of different approaches to mass vaccination

Tailoring high-temperature radiation and the resurrection of the incandescent source

In solar cells, the mismatch between the Sun's emission spectrum and the cells’ absorption profile limits the efficiency of such devices, while in incandescent light bulbs, most of the energy is lost as heat. One way to avoid the waste of a large fraction of the radiation emitted from hot objects is to tailor the thermal emission spectrum according to the desired application. This strategy has been successfully applied to photonic-crystal emitters at moderate temperatures but is exceedingly difficult for hot emitters (>1,000 K). Here, we show that a plain incandescent tungsten filament (3,000 K) surrounded by a cold-side nanophotonic interference system optimized to reflect infrared light and transmit visible light for a wide range of angles could become a light source that reaches luminous efficiencies (∼40%) surpassing existing lighting technologies, and nearing a limit for lighting applications. We experimentally demonstrate a proof-of-principle incandescent emitter with efficiency approaching that of commercial fluorescent or light-emitting diode bulbs, but with exceptional reproduction of colours and scalable power. The ability to tailor the emission spectrum of high-temperature sources may find applications in thermophotovoltaic energy conversion and lighting.United States. Army Research Office (W911NF-13-D-0001)United States. Dept. of Energy. Office of Basic Energy Sciences (DE-SC0001299)United States. Dept. of Energy. Office of Basic Energy Sciences (DE-FG02-09ER46577

Two different and functional nuclear rDNA genes in the abalone Haliotis tuberculata : tissue differential expression

International audienceAnalysis of the 18S rDNA sequences of Haliotis tuberculata tuberculata and H. t. coccinea subtaxa identified two different types of 18S rDNA genes and ITS1 regions. These two different genes were also detected in H. marmorata, H. rugosa and H. diversicolor that are separated from H. tuberculata by 5–65 mya. The mean divergence value between type I and type II sequences ranged from 7.25% for 18S to 80% for ITS1. ITS1 type II is homologous with the ITS1 consensus sequences published for many abalone species, whereas ITS1 type I presented only minor homology with a unique database entry for H. iris ITS1. A phylogenetic analysis makes a clear separation between type I and type II ITS1 sequences and supports grouping H. t. tuberculata, H. t. coccinea and H. marmorata together. The two subtaxa do not show any significant differences between the homologous 18S rDNA sequences. A general structure of the ITS1 transcript was proposed, with four major helices for the two types. The two genes were expressed and, for the first time, a putative differential expression of ITS1 type I was detected in the gills, digestive gland and gonads whereas ITS1 type II was expressed in all tissues