Epidemiology Of Hepatitis E Virus In Pregnant Women And The Mechanism Of Adverse Pregnancy Outcomes

Hepatitis E virus(HEV)is the main pathogen of acute viral hepatitis worldwide.It is extremely harmful for pregnant women with HEV infection during the third trimester of pregnancy,and the mortality is up to 30%.HEV infection can also lead to stillbirth,abortion,premature delivery and many other adverse pregnancy outcomes.Many adverse pregnancy outcomes reported were caused by HEV genotype 1 or 2infections.The most prevalence of HEV in China is genotype 4,but its prevalence in pregnant women and adverse pregnancy outcomes are still unknown.In addition,the inflammatory response,pathological damage and immune alternation caused by HEV infection in pregnant women remain unclear.This study mainly investigated the epidemiology and the mechanism of adverse pregnancy outcome caused by HEV infection,including the following six parts:(1)Epidemiology of HEV infection and determination of HEV genotype in pregnant women.A total of 19,762 pregnant women participated in the epidemiological investigation of HEV in Yunnan province,China.The seropositive of HEV was 11.62%(2,297/19,762;95%CI:11.18%–12.07%),of which 11.37%(2,247/19,762;95%CI:10.93%–11.81%)were positive for HEV Ig G antibody,0.11%(22/19,762;95%CI:0.06%–0.16%)were positive for HEV Ig M antibody,and 0.14%(28/19,762;95%CI:0.09%–0.19%)were positive for both HEV Ig M and Ig G antibodies.HEV RNA was detected in 61 out of 2,297 HEV antibody-positive sera.Phylogenetic analysis revealed that all HEV isolates from pregnant women belong to genotype 4.(2)Risk factors for HEV infection in pregnant women.Characteristics of 19,762 pregnant women were analyzed to found that age,gravidity and parity were risk factors for HEV infection in pregnant women.(1)With the increased age,Ig G positive rate increased from 2.92%to 19.04%;Ig M positive rate increased from 0 to 0.42%.Older pregnant women(≥35 years old)were more susceptible to HEV than younger pregnant women(<35 years old).(2)With the increased gravidity,Ig G positive rate increased from 6.90%to 15.79%;Ig M positive rate increased from 0.21%to 0.36%,HEV RNA positive rate increased from 0.05%to0.43%.(3)With the increased parity,Ig G positive rate increased from 7.11%to 15.62%;Ig M positive rate increased from 0.15%to 0.35%;HEV RNA positive rate increased from 0.16%to 0.45%.(4)In addition,the incidence of adverse pregnancy history in Ig G positive women was significantly higher than in the uninfected group(c OR=1.50,95%CI:1.37-1.65;a OR=1.16,95%CI:1.05-1.29).(3)Adverse pregnancy outcomes caused by HEV infection.(1)Ig G-positive pregnant women had a higher risk of adverse maternal outcomes(c OR=1.29,95%CI:1.16-1.43;a OR=1.40,95%CI:1.25-1.55),including gestational diabetes mellitus(c OR=2.54,95%CI:2.14-3.01;a OR=3.31,95%CI:2.76-3.98)and pregnancy-induced hypertension syndrome(c OR=2.35,95%CI:1.95-2.85;a OR=2.26,95%confidence interval:1.84-2.76).(2)Ig M-positive pregnant women also had higher adverse maternal pregnancy outcomes(c OR=1.38,95%CI:1.02-1.86;a OR=1.43,95%CI:1.05-1.95),including gestational diabetes mellitus(c OR=1.80,95%CI:1.13-2.86;a OR=2.30,95%CI:1.41-3.75)and pregnancy-induced hypertension syndrome(c OR=1.73,95%CI:1.04-2.90;a OR=1.74,95%CI:1.01-3.00).(3)In addition,HEV RNA-positive pregnant women had a higher risk of developing gestational diabetes(c OR=1.37,95%CI:1.01-1.87;a OR=1.68;95%CI:1.23 2.30).(4)Ig G positive pregnant women had a higher incidence of adverse fetal outcomes(c OR=1.80,95%CI:1.61-2.01;a OR=1.77,95%CI:1.57-1.99),including fetal distress(c OR=1.20,95%CI:0.99-1.44;a OR=1.26,95%CI:1.03-1.53),and spontaneous abortions(c OR=2.37,95%CI:1.82-3.09;a OR=2.28,95%CI:1.69-3.07),fetal deformity or death(c OR=1.49,95%CI:1.07-2.07;a OR=2.82,95%CI:2.00-3.99).(4)HEV can be transmitted vertically from mother to child.HEV Ig G and Ig M antibodies were detected in 13 samples of maternal plasma and umbilical cord blood.Besides,HEV RNA can be detected in maternal plasma,umbilical cord blood,amniotic fluid,placenta,fetal membrane and umbilical cord tissues.In addition,results showed that the virus titers of maternal blood,umbilical cord blood,amniotic fluid,placenta,fetal membrane and umbilical cord were 1.02×10~6,1.17×10~6,2.02×10~6,1.63×10~6,1.73×10~6 and 1.32×10~6 copies/ml by RT-q PCR,respectively.HEV ORF2 antigen can also be detected in placenta,fetal membrane and umbilical cord tissue by IHC.Results indicated that HEV can be transmitted vertically from mother to child.(5)HEV infection resulted in maternal inflammation responses and pathological damages.HEV infection were accompanied by inflammation.The expressions of F4/80,CD45,apoptosis and autophagy in placenta,fetal membrane and umbilical cord were significantly increased of HEV-infected pregnancy women.HEV infection can cause histopathological changes in placenta of pregnant women,including fibrinoid necrosis and pathological calcification.However,there was no obvious pathological damage in fetal membrane and umbilical cord tissues.(6)The study on the mechanism of adverse pregnancy outcomes caused by HEV infection.The expressions of interferon-stimulated genes(ISGs)were suppressed in HEV-infected mothers and fetuses.The expressions of 23 maternal cytokines/chemokines were increased in HEV-infected pregnancy women by using MILLIPLEX.VIP scores of IFN-γ,VEGF,MCP-1,G-CSF,s CD40L,IL-13 and IL-8 were higher than 1,suggesting these seven cytokines/chemokines play important roles in HEV infection.