Nucleotide sequence analysis of the precore region in patients with spontaneous reactivation of chronic hepatitis B

The role of HBV precore mutations in the spontaneous reactivation of chronic hepatitis B (CHB) is currently unknown. We studied 10 patients with CHB; five were HBeAg⁺ (group I) and five were anti-HBe⁺ (group II). All 10 had spontaneous reactivation of CHB as defined by the appearance of clinical symptoms along with an increase of serum ALT activity at least 5× above baseline values, in the absence of any other known causes of liver disease or CHB reactivation. The precore (87 nt) and proximal core (81 nt) regions were sequenced after PCR amplification. From each patient three serum samples were studied: one 3-12 months before, one during, and one six months after reactivation. Prior to reactivation, none of the group I patients harbored an HBV strain having a mutation that prevented HBeAg synthesis; however, 2/5 developed such a mutation during reactivation (G to A transition at nt 1896). Among the group II patients, three harbored an HBeAg defective mutant both before and during reactivation; after six months, two of these three patients were HBV DNA negative in serum by PCR. Several other sequence polymorphisms, some of which changed the predicted amino acid sequence, were either present initially or developed during reactivation. In conclusion, in this small group of CHB patients who were HBeAg⁺ spontaneous reactivation was accompanied in some cases by a shift to an HBeAg defective mutant, while in patients who were anti-HBe⁺, such mutations were frequently present prior to reactivation. In patients already harboring precore defective mutants, spontaneous reactivation may precede an attenuation of viral replication.