Hepatitis B virus X gene variability in French-born patients with chronic hepatitis and hepatocellular carcinoma

Abstract

The polymorphism of the hepatitis B virus (HBV) X gene from patients born in Lorraine has been studied in serum samples from 22 HBV infected patients, 14 presenting with chronic hepatitis and 8 with hepatocellular carcinoma (HCC). Subtypes adw and ayw represented 21 of the 22 sequenced isolates. The sequence of the X gene of HBV strains from these patients differed from the ones of Far East origin by A to T(1678) and G to A(1759) changes for subtype ayw and C to T(1792) for adw. The expression of the preC region, as indicated by the detection of HBe antigen (HBeAg), was not observed in 11 patients. In 6 patients (3 HCC and 3 non HCC), the absence of HBeAg could be related to a stop codon at position 28. For the 5 remaining patients, the precore stop mutation at codon 28 was not evidenced but 3 out these 5 patients had mutations at nt 1764 and nt 1766 in the promoter of the preC/C gene. These two mutations were also observed in 2 patients with HBeAg, indicating that they are not implicated in the suppression of expression of this gene. Independently of the serotype, two main differences were noted between aminoacid (aa) sequences of chronic hepatitis and HCC related strains: first, twice as many aa changes were found in HCC patients than in chronic hepatitis B carriers (mean of aa changes per patient 4.1 vs. 2.0) and second, we found apparition of polar aa in HCC patients. Most mutations already described in patients from the Far East with HCC have been found in strains of patients from Lorraine. The changes K130M and V131I, considered as "hot spot mutations," were found in strains of HCC patients carrying an ayw subtype of the HBV genome but not in the ones of chronically infected patients. In contrast, strains of the adw subtype had these two changes in the two groups of patients. However when considering the 22 sequenced genes, these hot spot mutations were associated with HCC (P = 0.034).