TGFB1 and systemic lupus erythematosus: Taken together, this study firstly demonstrated an aggravated effects of B19 NS1 protein on hepatic fibrosis in NZB/W F1 mice through enhancing the TGF-β/Smad fibrotic signaling and could provide a possible explanation in exacerbating the hepatic fibrosis in SLE patients with B19 infection.