TI - Effects of human parvovirus B19 VP1 unique region protein on macrophage responses . AB - Background Activity of secreted phospholipase A ( sPLA2 ) has been implicated in a wide range of cellular responses . However , little is known about the function of human parvovirus B19-VP1 unique region ( VP1u ) with sPLA2 activity on macrophage . Methods To investigate the roles of B19-VP1u in response to macrophage , phospholipase A2 activity , cell migration assay , phagocytosis activity , metalloproteinase assay , RT-PCR and immunoblotting were performed . Results In the present study , we report that migration , phagocytosis , IL-6 , IL-1beta mRNA and MMP9 activity are significantly increased in RAW264.7 cells by B19-VP1u protein with sPLA2 activity , but not by B19-VP1uD175A protein that is mutated and lacks sPLA2 activity . Additionally , significant increases of PHOSphorylated ERK1/2 and JNK proteins were detected in macrophages that were treated with B19-VP1u protein , but not when they were treated with B19-VP1uD175A protein . Conclusion Taken together , our experimental results suggest that B19-VP1u with sPLA2 activity affects production of IL-6 , IL-1beta mRNA and MMP9 activity , possibly through the involvement of ERK1/2 and JNK signaling pathways . These findings could provide clues in understanding the role of B19-VP1u and its sPLA2 enzymatic activity in B19 infection and B19-related diseases .