Kiyohiko Kurai

Typing hepatitis C virus by polymerase chain reaction with type-specific primers: application to clinical surveys and tracing infectious sources

Based on variation in nucleotide sequence within restricted regions in the putative C (core) gene of hepatitis C virus (HCV), four groups of HCV have been postulated in a panel of 44 HCV isolates. They were provisionally designated types I, II, III and IV. A method for typing HCV was developed, depending on the amplification of a C gene sequence by polymerase chain reaction using a universal primer (sense) and a mixture of four type-specific primers (antisense). HCV types were determined by the size of the products specific to each of them. Type II was found in HCV samples from 131 (82%) of 159 blood donors, more often than in those from 48 (60%) of 80 patients with non-A, non-B (NANB) liver disease in Japan (P less than 0.01). In 11 haemophiliacs who had received imported coagulation factor concentrates, type I was found in five, as against type II in four. Double infection with two different HCV types was found in two patients with chronic NANB liver disease (types I and II; II and III) and two haemophiliacs (types I and II; I and III). HCV types were identical in mother and baby in each of two examples of perinatal transmission, and were also identical in donor and recipient in a case of accidental needle exposure.

Changes of serum aminotransferase activities in relation to serum hepatitis Be antigen levels in chronic type B hepatitis

The purpose of this study was to determine the level of serum hepatitis Be antigen (HBeAg) during hepatitis B virus carriage and its clinical significance. The mean level of serum HBeAg, quantitated by solid‐phase enzyme immunoassay, was 5924 units in asymptomatic carriers (s.d. = 5534, n= 100), 3044 units in patients with chronic persistent hepatitis (s.d. = 4826, n= 34), 3599 units in chronic active hepatitis (s.d. = 4953, n= 45) 1348 units in liver cirrhosis (s.d. = 2379, n= 25) and 766 units in hepatocellular carcinoma (s.d. = 1257, n= 18). In the 10 HBeAg‐positive patients with chronic active hepatitis, the fluctuation in HBeAg level was followed by changes in alanine aminotransferase (ALT) activity. Among the 36 peaks of HBeAg and ALT, HBeAg peaks preceded ALT peaks in 22 and simultaneous peaks were present in 14. The changes of HBeAg level were closely related to increase in disease activity as estimated by ALT activities; therefore, HBeAg quantitation can be a useful predictor of disease activity in chronic hepatitis B.

Clinical utility of a simple quantitative determination of hepatitis B e antigen

The titre of serum hepatitis B e antigen (HBeAg) was determined by using a simple quantitative system which is a slight modification of a commercially available enzyme immunoassay, and the relationship of serum HBeAg titre, hepatitis B virus (HBV)‐associated DNA polymerase activity and HBV DNA level was evaluated. The HBeAg titre was found to have a significant correlation with DNA polymerase activity (r= 0.8153) and HBV DNA level (r= 0.8001). In 12 acute exacerbations of hepatitis in 10 patients with chronic type B hepatitis, these three parameters were found to be elevated either prior to or concurrent with the elevation of serum alanine aminotransferase, and the HBeAg titre peaked either simultaneously with or 1–4 weeks after the peaks of DNA polymerase activity and HBV DNA level, with average time lags of 1.00 weeks (s.d. = 1.29) and 1.08 weeks (s.d. = 1.25), respectively. Quantified HBeAg can be considered as a serum marker indicative of HBV replication, as is the case with DNA polymerase and HBV DNA. Furthermore, the HBeAg assay has the advantages of simplicity and low cost and it does not require special equipment. Therefore, quantification of HBeAg should be employed widely in clinical practice.