The primary objective of this effort is to develop qualified circumsporozoite (CS) antibody subclass binding avidity assays that can be used for the testing of clinical samples from  controlled human malaria infection (CHMI) studies of CS-based experimental vaccines. The three assays that are being developed and qualified are (1) a subclass binding antibody multiplex assay (BAMA), (2) a subclass avidity assay by biolayer interferometry (BLI), and (3) surface plasmon resonance (SPR). Initial testing will focus on samples from the RTS,S-AS01 delayed fractional dose CHMI study conducted by the Walter Reed Army Institute of Research in 2013–2014.  The work is funded by a Global Health Vaccine Accelerator Platform (GH-VAP) grant from the Bill & Melinda Gates Foundation.