The incidence of the co-infection of hepatitis G virus (HGV) and hepatitis C virus (HCV) and its clinical implication was investigated and the difference in the positive rate of HGV RNA and HCV RNA between plasma and peripheral blood mononuclear cells (PBMCs) observed. By using reverse transcriptase polymerase chain reaction (RT-PCR) assay, HCV-RNA and HGV-RNA in plasma and PBMCs of 72 patients with hepatitis C was detected. It was showed that HGV RNA was positive in plasma of 11 patients, in PBMCs of 15 patients, and simultaneously in both of plasma and PBMCs of 10 patients with the co-infection rate being 22.2 %. Nine patients were both HGV RNA and HCV RNA positive in plasma, 11 patients were both HGV RNA and HCV RNA positive in PBMC, and 6 patients were both HGV RNA and HCV RNA positive in both plasma and PBMC with the positive rate being 12.4 %, 15.3% and 8.3 % respectively. The positive rate of both HGV RNA and HCV RNA in PBMCs was higher than in plasma. It was concluded that the HGV co-infection rate in the patients with hepatitis C was 22.2 %. Simultaneous examination of plasma and PBMC can improve clinically detectable rate.

To investigate the feasibility of using free fetal DNA from maternal plasma as the source of fetal material in non-invasive prenatal diagnosis, SRY gene of free DNA in maternal blood of 65 samples were analyzed by using primer extension preamplication (PEP) and probe microplate hybridization techniques. The results showed that the detection rate of SRY gene in maternal blood from women carrying male fetuses detected by probe microplate hybridization alone and probe microplate hybridization with PEP were 76. 09 % (35/46) and 95. 65 % (44/46) respectively, and there was a significant difference between them. The non-detection rate of SRY gene in blood samples from women carrying female fetus was 100 % (19/19). It is indicated that probe microplate hybridization was an effective method in detecting trace fetal DNA from maternal plasma and the sensitivity could be substantially improved by combined use of the two techniques. Analysis of fetal DNA in maternal plasma can serve as an alternative for non-invasive prenatal diagnosis.