P2RY4 and infection: Similar reductions in the infection index (82%) that were observed in UTP treatment were observed in infected macrophages treated with 2Thio-UTP at the concentrations of 0.05 and 0.1 μM, which trigger P2Y2 activation only, and at the concentrations of 0.5 and 1 μM, which activate both P2Y2 and P2Y4 (Fig 9A).