PARP1 and infection: Given that infection of many pathogens, including ZIKV virus13 and Streptococcus pyogenes34 induces PARP1 activation and PAR formation in host cells, we initially explored whether the infection of E. piscicida results in the accumulation of intracellular PAR mainly synthesized by PARP1 in macrophage J774A.1 cells.