For first strand synthesis we used the SuperScript III First Strand Synthesis kit (Invitrogen). == qRT-PCR assay optimization == Amplification of the correct target sequence was confirmed by gel electrophoresis and melt curve analysis using SYBR Green (BioRad). available from expression arrays, targeting one sentinel marker per stage. The model as learned can be applied to any new microarray or qRT-PCR transcriptional measurement. We illustrate its usein vitroin inferring changes in stage distribution following stress and drug treatment andin vivoin identifying immature and mature sexual stage carriers within patient cohorts. We believe this approach will be a useful resource for staging lab and field samples alike and will have wide applicability in epidemiological studies of malaria transmission. == Author Summary == The human malaria parasitePlasmodium falciparumis transmitted through a mosquito vector and causes over half a million deaths per year. The microorganism cycles through asexual and sexual life cycle stages, and its successful transmission relies on cells in the sexual stage. These stages are, however, present only at low levels during infection; most infecting cells are asexually reproduced. It can be challenging to assign biomolecular activity to particular parasite life cycle stages from common gene expression profiles, given the mixed stage composition of most samples. We developed a deconvolution model to identify components ofPlasmodiumtranscriptional activity contributed by sexual and asexual life cycle stages, initially using samples of known composition. From these, we optimized a small set of stage-specific genes with highly informative expression patterns and trained an inference model to predict the stage composition of new samples. The model successfully inferred the parasite’s transition from asexual to sexual development over time under laboratory conditions and identified WYE-687 a subset of patient samples harboring transmissible sexual stages. The system presented here can WYE-687 aid in epidemiological or laboratory perturbation in which stage composition is an important step in understanding and WYE-687 preventing malaria transmission. == Introduction == One of the tenets of the recently released Malaria Eradication Research Agenda (malERA) is the development of new diagnostics specifically addressing transmission reduction[1]. Individuals harboring thePlasmodium falciparumtransmissible parasite stage, or gametocyte, are the primary reservoir for malaria transmission, and thus proper surveillance of gametocyte carriers is critical to transmission reduction. Surveillance is difficult, however, because gametocytes comprise only a small fraction of the total body parasite load during active contamination and are only observed in the bloodstream in their mature form, while developing stages are sequestered in tissues[2]. For these WYE-687 reasons, quantifying gametocytes in mixed parasite populations has been an ongoing challenge ever since they were first identified more than a century ago. Gametocytes do execute substantially different transcriptional programs from asexual parasite stages, however, as has been well-studiedin vitro[3]. Like the sequential dynamics of the asexualPlasmodiumlife cycle[4],[5], gametocytes develop in a staged progression from immature (young and intermediate stages) to mature transmission-competent cells in preparation for meiosis and further development in the mosquito vector. The NOTCH2 switch between asexual replication and sexual development does not occur ubiquitouslyin vivoorin vitro, as even the most synchronized gametocyte induction protocols result in partially asynchronous and mixed gametocyte stages[3],[6]. This problem is usually compoundedin vivo, WYE-687 as blood sampled during contamination is likely to contain both gametocyte and asexual parasite populations, leading to a highly convolved transcriptional mixture. In addition to the need to dissect these signatures for analysis of microarray data, it is also of interest to develop a field-friendly approach for detecting and quantifying both immature (indication of conversion to sexual development) and mature (indication of infectiousness to mosquito vector) gametocyte stages. Transcriptional approaches such as RT-PCR, QT-NASBA and RT-LAMP have been developed[7],[8],[9]using the established mature gametocyte markerPfs25and the putative immature gametocyte markerPfs16. While these approaches enable sensitive detection of these transcripts, it is unclear how the detection of these transcripts.