A prototype diagnostic test for Rift Valley Fever virus must prove it can detect all 15 known genetic lineages of the virus before it can be deployed in the field. This matters because Rift Valley Fever causes periodic large outbreaks across more than 20 countries in Africa and the Middle East, with high mortality in severe cases. Current diagnostics rely on sending samples to reference laboratories for RT-PCR or ELISA testing, causing delays that allow transmission to spread and fatalities to mount. A rapid test that works at the point of care could change that, but the prototype developed at the Liverpool School of Tropical Medicine has only been tested against a single lineage. Without evidence that it detects all widely circulating lineages, its real-world utility remains uncertain. If this evaluation succeeds, the project becomes viable for larger funding and eventual regulatory approval. The result would be a simple lateral flow test—similar to a pregnancy test—that healthcare workers in endemic regions can use on the spot, without sending samples away. That would speed outbreak detection, improve patient management, and reduce transmission. The test is being manufactured in ISO 13485-accredited facilities to ensure it meets future regulatory standards.
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Rift Valley Fever (RVF) is a WHO-listed priority disease due to the lack of therapeutics, vaccines, diagnostics and high risk of causing epidemics. RVFV causes periodic large outbreaks, which pose a large public health threat to humans due to high mortality rates in severe cases and high socio-economic burden. RVF is endemic in more than 20 countries in Africa and the Middle East, with an increased number of cases and outbreaks in recent years. RVF is a viral haemorrhagic fever (VHF) with a mortality rate of 18% to 50% in severe cases. Like other VHFs, RVF has nonspecific symptoms, and laboratory confirmation is needed for patient and outbreak management. Current diagnostics are delayed as they rely on sending samples to reference laboratories for RT-PCR and/or ELISA testing. The diagnostic delay leads to late outbreak detection and prevents appropriate care and patient management, increasing the risk of transmission and the number of fatalities. The Liverpool School of Tropical Medicine (LSTM) has developed a lateral flow assay (LFA) prototype to detect RVF virus (RVFV) nucleoprotein antigen. Pilot data shows a limit of detection of 0.2 ng/mL (˜1 x106 virus/mL) using the KEN/MAL-032/07 isolate of RVFV lineage C. This data is encouraging; however, RVFV is genetically diverse and has 15 lineages (named A to O). The ultimate aim of this programme is the development of a pan-lineage RVFV LFA to be used in all endemic countries for real-world impact. Without demonstration of the utility of the LFA with all widely circulating lineages, the project is at risk, as the diagnostic utility of the device is uncertain. This GAP fund aims to evaluate the LFA prototype with all RVFV lineages to demonstrate inclusivity, de-risk the project, and make it more attractive for larger funding opportunities. We will use a mixed approach of testing, combining clinical patients' samples and recombinant nucleoprotein to ensure that all lineages are included in the evaluation. We will manufacture the LFA devices in the ISO 13485-accredited facilities of our subcontractor Global Access Diagnostics to ensure results from this grant are compatible with future regulatory standards. In collaboration with the Institute Pasteur Dakar (IPD) in Senegal, the Biomedical Research Centre (RBC) in Rwanda and the International Livestock Research Institute (ILRI) in Kenya the LFA will be evaluated in a panel of 386 biobanked patients' samples from Burundi, Kenya, Mali, Mauritania, Niger, Rwanda, Senegal and Uganda; and at LSTM, we will express the RVFV nucleoprotein antigen to determine the limit of detection of the device in all lineages. Upon completion of this project and production of key evidence data on the utility of the device, we will apply for follow-up funding to continue the development of this prototype.
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