Study On Molecular Mechanism Of Mother-to-infant Transmission Of Hepatitis C

Hepatitis C virus (HCV) is the causative agent of hepatitis C. About180million people are infected with hepatitis C virus worldwide, according to theWorld Health Organization. The majority of HCV-infected individuals willbecome chronically infected. No effective method is found to prevent thetransmission. In China, the major transmission route of HCV is through bloodor blood products. With the enhancement of the detection of blood products,transmission incidence by blood transfusion of blood products has beengreatly reduced. Mother-to-infant transmission of HCV has been identifieduntil now, and it has became an important issue which deserves furtherexploration. To date little is known about the transmission mechanisms.Trophoblast cells compose the first layer of placental barrier. HCV need tobreak through trophoblast cells to infect the infant. The HCV envelopeglycoproteins (E1and E2) are involved in receptor binding, virus-cell fusion, and entry into the host cell. The process and mechanism of HCV binding totarget cell through specific receptor are still unclear in perinatal transmission ofHCV. And it is urgent to study the specific receptor and coreceptor in theprocess of HCV infection.Studies have shown that the mechanisms by which DC function wasregulated during HCV infection. The dendritic cell-specific-intercellular-adhesion-molecule-3grabbing nonintegrin (CLEC4L) can combine with theHCV envelope glycoprotein E1/E2in order to mediate virus internalization andinfect the target cells. Infection of trophoblastic cells in vertical transmission ofHCV may be related with the mechanism of CLEC4L mediated HCV entry. Yetmechanistic details of HCV infection-CLEC4L remain incompletely understood.To explore possible mechanisms of vertical transmission of HCV, we havedone the following work in this study:Firstly, the trophoblastic cells were obtained by improved separation andpurification methods, which were incubated in HCV positive. The infected cellswere lysed. HCV RNA in HCV infected trophoblast cells was quantitated byRT-PCR. The antigen of HCV NS5could be detected at48hours after infectionby Immunolfluorescence. The HCV RNA was detected in the supernatant of theculture medium at24,48,72,96,120hours after infection respectively. Thetrophoblastic cells cultured in vitro can be infected by HCV. The replication ofHCV in trophoblastic cells was detected, which supplied morphological featurein HCV vertical transmission.Secondly, the expression of CLEC4L placenta in different pregnancy andtrophoblast cells was detected by immunohistochemical method andImmunofluorescence. This provided some basic morphologic information forfurther study of molecular mechanisms of mother-to-infant transmission. Thirdly, to investigate HCV infection of human placental trophoblast cellsmediated by CLEC4L, cells were randomly divided into three groups includingCLEC4L monoclonal antibody, mannan and control group. HCV RNA in HCVinfected trophoblast cells was quantitated by RT-PCR. The results showed thatthe level of HCV RNA in CLEC4L monoclonal antibody group was less thanthat in control group. Compared with control group, the mannan showed thesimilar effect. Hepatitis C virus cell entry was mediated by CLEC4L, thereforeCLEC4L monoclonal antibody and mannan could help to block the cell entry ofHCV infection.