The decision to pursue a CDP in which licensure is based on a single CRT or to pursue a CDP relying on analytical endpoints (described above) to secure accelerated approval will significantly impact the level of development needed for such functional assays. As of 2010, the two major areas of focus for feeding assays were their reproducibility (in relation to their ability to be qualified), and the correlation between lab and field assays (outcomes of the 2010 MALVAC meeting and malERA

consultations have been detailed elsewhere in the literature [13], [15] and [16]). Standard membrane feeding assay (SMFA): Laboratory-based assay where lab-reared mosquitoes feed on cultured P. falciparum gametocytes through a membrane,

as depicted below. Direct membrane feeding assay (DMFA): Field-based assays (carried out in endemic Abiraterone areas) where progeny of wild-caught Cyclopamine solubility dmso mosquitoes feed on a blood meal from a malaria-infected host through a membrane. Direct feeding assay (DFA): Field-based assays (carried out in endemic areas) where progeny of wild-caught mosquitoes feed directly through the skin of a malaria-infected host. For a week following a feed, all mosquitoes are kept alive to allow ingested parasites to develop into oocysts. Mosquitoes are then dissected and the number of oocysts counted in the mid-guts. (MVI is supporting efforts to develop higher throughput, less labor-intensive methods for determining the number of oocysts in the mosquito mid-gut.) For the SMFA, the results are reported as a percent reduction in the number of oocysts compared to a pre-immune control. The SMFA readout, reduction in oocyst intensity, can be understood as oocyst reducing/inhibiting activity. For the field assays, results can be reported in a binary fashion, where mosquitoes are scored as having oocysts or not (oocyst prevalence). This readout can be referred to found as transmission-blocking activity, and indicates whether or not the mosquito

was infected and had the potential to transmit disease. In the context of a malaria program reaching elimination, this is the most relevant readout. How the lab- and field-based assays relate to one another, and how a vaccine candidate that performs well (strong oocyst reducing activity) in the SMFA will perform in a field-based feeding assay (DMFA or DFA), is not well understood. Following the review described under “Assays and Correlates,” MVI-funded efforts on bridging the assays are underway with the hope to have clearer understanding of the relationship between the lab and field assays in the coming year or two. How robust the feeding assays need to be will depend on the clinical development path chosen (see Fig.