| Across the world, there are about 170,000,000 people afflicted with hepatitis C virus, and most of them are chronic carriers. And moreover, hepatitis C uausually developes to cirrhosis and carcinoma of liver. 3% people of our country also afflicted this disease. The typical transmission way of HCV is through blood or blood product. After 1991, screening of donators largely decreases the transmission of HCV through blood However, the way of HCV transmission is changing now. Increasing children suffered with HCV don't inflected through blood. It is becoming an important issue that the transmission of HCV in uterus, during delivery or after delivery. Recently, many studies showed that HCV could be transmitted to the foetus through the plancent, and infected in uterus was one important way of HCV transmission.The trophoblast is the first line of defence of HCV transmitting to foetus. Recent years, some studies introduced the conception of antibody depended enhancement of virus infection. This phenomenon was found in many kinds of virus, such as human immunodeficiency virus (HIV), influenzaviruses A, coxsackie virus, feline infection peritonitis virus, and Dengue virus (DV). The antibody dependent enhancement (ADE) also play an important role inthe mother-to-infant transmission of HTV. At present, there is no report about whether HCV can be infected through the way of ADE.In order to investigate the mechanisim of HCV transmitted in uterus, we have done some works as follows:Firstly, Isolate and culture the trophoblasts in vitro. To isolate cytotrophoblasts from human placentae and observe their biological characteristics, cytotrophoblasts have been prepared from human term placentae digested with trypsin, and centrifuged on two layers (35% and 45%) of Percoll gradient. Biological characteristics were observed by the way of immunofluorescence and transmission electron microscope. More than 90% trophoblasts were obtained through our improved method. Under transmission electron microscopy, we have observed three-diffirent mature stage of cytotrophoblast Higher purity trophoblasts could be obtained by this improved method. This is the cytologyic experimental basis of study the mechanism of HCV mother-to-infant tramsmission.Secondly, detect the IgG FcR of trophoblasts. IgG FcR is the essential condition of cells infected by virus through the way of ADE. To detect whether there is FcR on the surface of trophoblasts, we stained the placent villous and trophoblasts cultured in vitro. CD16 (FcRIII) positive stain was observed on trophoblasts, the outside layer of the placenta, and those trophoblasts cultured in vitro. This receptor is the key molecul of the way of ADE.Thirdly, infecting the trophoblasts with HCV positive serum. Infecting the cells with HCV positive serum is the most commonly used way. So,trophoblastic cells were incubated in HCV positive serum, and then the HCV infection of syncytiotroblasts was detected with qualitative and quantitive RT-PCR. Ultrastructure characteristics were observed with transmission electron microscope. The HCV RNA was intermittentiy detected in the supematent of the culture medium during the 16 days culture. After infected by hepatitis c virus, the ultrastructure of throphotoblast cells is very different from the control cells. The main manifestations were hyperplasia of lysosomes and rough endoplasmic, decrease of lipid droplets, presentation of vacuoles, and virus-like particles were observed. With indirect immumofluorescence and confocal microscopy detection, we find the positive stain of anti-HCV NS5. Positive particles mainly located in the perinuclear region of infected cells.. This result shows that trophoblastic cells can be infected by HCV, and the infection probably lead to the ultrastructure alteration of trophoblastic cells. However, there are still many studied should be do, such as to confirm the virus like particle by immunoelectron microscopic method or in situ hybridization,to answer whether HCV can replicate in trophoblasts and produce...
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