Figure 6

Anti-PfHRP2 antibody impairs the ability of three PfHRP2-detecting RDTs to detect cultured P. falciparum . Three brands of RDT (SD, ICT and First Response) were tested with P. falciparum-parasitized red cells pre-incubated with normal plasma (NP) or plasma from a subject with high titre anti-PfHRP2 antibody level (S14). Blood was serially diluted using normal human blood maintaining a 50% haematocrit to parasite densities of 100,000, 30,000, 10,000, 3,000, 1,000, 300, 100, and 30 parasites/μL (1–8). The experiment was undertaken before (A) and after (B) the blood was washed to remove any residual PfHRP2 present in the culture medium.