[8] Rayner's research interests encompass the origins of Plasmodium parasites, and how their invasion of red blood cells cause all the symptoms of malaria.

Working with collaborators such as Beatrice Hahn, he has demonstrated that Plasmodium falciparum is likely to have originated in gorillas, rather than chimpanzees or ancient humans.

[9] Together with colleagues at the Sanger Institute, Rayner has identified a key ligand which is essential for erythrocyte invasion by P. falciparum and therefore has significant anti-malarial potential.

[11] Rayner used the prize money to create compact disc versions of the interactive game Malaria Challenge[12] and distributed copies freely to schools in the UK.

[14] In 2022 Rayner was elected as a Fellow of EMBO, the European Molecular Biology Organization.