P2RY12 and viral infectious disease: Interestingly, clusters of microglia observed in the brain at sites of virus infection in P2Y12−/− mice were located in the close vicinity of degenerated, PRV-immunopositive neurons, suggesting that P2Y12 deficiency markedly impairs microglial responses to signals released from infected neurons and compromises phagocytic responses, but does not fully block microglial migration to already disintegrated cells.