At the peak of infection, the proportion of NK cells expressing the early activation marker CD69+ was significantly increased in all patients and reached 72±35% in DENV-2, 58±21% in CHIKV+ and 42±5% in CHIKV/DENV-2 co-infected patients, as compared to 15±6% in healthy Gabonese controls (Fig 1B) [14,17]. This evidence concerns the gene CD69 and infection.