WHO/BS/2023.2449 WHO 1st IS for Rift Valley Fever

Overview

Rift Valley fever virus (RVFV) is a phlebovirus infecting primarily ruminants (sheep, cows, goats, camels, etc.) and humans. RVF has significant socio-economic impact due to livestock losses and human fatalities. The disease is endemic in sub-Sahara Africa, but outbreaks have been recorded in Africa and Arabia. RVF has been identified by the WHO R&D Blueprint as one of the top ten priority pathogens for its outbreak potential. Vaccines and treatments are in development and reliable assays are needed for their evaluation. The availability of an International Standard (IS) for antibody would facilitate the standardisation of RVFV serological assays and support the development of vaccines and therapeutics. In this report a pool of plasma from RVF recovered patients from Uganda was evaluated in 32 methods by 19 participants to serve as First WHO IS for anti-RVFV antibody. The methods included neutralisation assays using 3 RVFV isolates and a recombinant RVF virus, as well as binding assays.