Fig. 2

Mechanisms underlying severe liver injury due to HEV infection in pregnancy. The altered status of immunity, hormone levels and viral factors may be related to the severity of the disease. Viral factors include HEV genome heterogeneity and variants, as well as viral proteins, such as MFP, encoded by HEV ORF3, may be associated with the severity of the disease. Host immune factors, such as CD8+ T cells, NK and NKT cells, may be involved in the pathogenicity of HEV during pregnancy. In addition, some cytokines, such as TNF-α, IL-6, IFN-γ, and TGF-β1, may also be involved in this process. The dramatically elevated levels of hormonal factors, including progesterone, estrogen and HCG, in pregnancy may also contribute to liver injury. Other host factors, such as nutritional status, may also influence the severity of HEV infection in pregnant women