Studies On The Vertical Transmission Of Hepatitis C Virus

Chronic hepatitis C virus (HCV) infection is a major cause of chronic liver disease and death throughout the world. HCV is transmitted mainly through contact with blood and blood products, such as blood transfusion. With the advent of routine blood screening for HCV antibodies in 1990s and the implement of the new blood donation law, transfusion-related HCV transmission decreased significantly. Mother-to-infant vertical transmission has been a major pathway of HCV transmission. However, the transmission rate shows great difference in reference. The reported rate varies from 0 to 100 percent. Therefore, new evidences are needed to evaluate the real transmission rate, especially the direct intrauterine transmission evidence.A study here was carried out to observe the HCV vertical transmission using 1506 samples from couples and their unconstraint-aborted fetus with more than 3 months pregnancy, which were collected in 4 county hospitals in the south of China.Through blood screening for HCV antibodies, the infection rate of HCV in pregnant women in south of China is 1.33% (20/1506). Using nested RT-PCR, 80% (16/20) of the anti-HCV positive pregnant women are HCV RNA positive. Sixteen pairs of "mother and fetus" are anti-HCV positive, among them, 12 pregnant women are HCV RNA positive, and 6 of their aborted fetus are also HCV RNA positive. It indicated that intrauterine transmission of HCV exists and the transmission rate is 50% (6/12). If using HCV RNA positive in white blood cell (WBC) as criterion, the intrauterine transmission rate is 58% (712). The nucleotide sequences of HCV genome spanning core and envelope gene region (HCV C/El) were determined and compared. The homology of HCV in mothers and their own fetus is above 99%, and the homology of mother-fetus was significantly higher than that of mother-mother or fetus-fetus. It strongly indicated that the HCV intrauterinetransmission is vertical transmission. The HCV serotypes and genotypes of the six regarded intrauterine transmission "mother-fetus" cases were consistent. Five pairs (83.3%) were of genotype II and serotype 1, the left 1 pair was of genotype III and serotype 2. In contrast, a total sample of 1230 detection showed no HCV transmission from fathers and fetus, which means the vertical transmission of HCV in father to fetus need more evidence to testify.In conclusion, relative large-scale samples from couples and their unconstraint-aborted fetus were used for the first time to detect the HCV vertical transmission. Using immunological and genetic method, we have testified that during the phase of pregnancy (intrauterine), HCV vertical transmission is in existance. This study is useful for prevention and intervention of mother-to-fetus HCV vertical transmission under the situation of good control of blood and blood products safety.