Development of a pan-lineage lateral flow assay for the detection of Rift Valley Fever Virus

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.