Vertical transmission of hepatitis E virus in pregnant rhesus macaques.

Hepatitis E virus (HEV) is the major pathogen of viral hepatitis. HEV causes high mortality in pregnant women. Its infection during pregnancy usually leads to fulminant hepatic failure, spontaneous abortions, premature delivery, or stillbirth. Vertical transmission of HEV has been reported, but the pathogenesis during pregnancy remains largely elusive. Pregnant rhesus macaques were infected with HEV to explore the pathogenesis of genotype 4 HEV infection during pregnancy. Active HEV infections were established with shedding viruses in the feces and blood, and elevated liver enzymes. Notably, higher viral titers and longer durations of HEV infection were found in HEV-infected pregnant rhesus macaques than in non-pregnant macaques. Premature delivery and fetal death occurred in one of the HEV-infected pregnant rhesus macaques. HEV RNA was detected in the liver, spleen, kidneys, and intestines of the dead fetus. This result strongly indicated vertical HEV transmission from mother to fetus. Maternal-transferred antibodies were observed in one of the babies with poor protection. The expressions of interferon-stimulated genes (ISGs) related to HEV infection were completely different between pregnant and non-pregnant rhesus macaques. During pregnancy, impaired innate immune responses, reduced progesterone levels, and shifts in immune states may aggravate HEV infection and result in adverse pregnancy outcomes.