Does the precore mutant of hbv cause fulminant hepatitis?
Authors: Thomas Howard C. 
Published: March 2007

Background.

A nosocomial outbreak of fulminant hepatitis B occurred in five patients in Haifa, Israel. Previous investigations identified the suspected source as a carrier of hepatitis B surface antigen who was positive for antibodies to hepatitis B e antigen and had chronic liver disease. We examined the strain of hepatitis B virus (HBV) that caused this epidemic, in order to identify specific mutations in the precore or core region.

Methods.

The presence of HBV was identified by polymerase-chain-reaction amplification of viral DNA in serum from the source patient, the five patients with fulminant hepatitis B, and five controls with acute, self-limited hepatitis B. The amplified viral HBV DNA samples were then cloned and sequenced.

Results.

Sequence analysis of viral DNA established that the same HBV mutant with two mutations in the precore region was present in the source patient and the five patients with fulminant hepatic failure. This HBV mutant had significant sequence divergence from other known HBV subtypes in the X, precore, and core regions. Cloned HBV DNA derived from a hospitalized patient who had subclinical hepatitis B at the same time as the outbreak and from four other control subjects with acute, self-limited hepatitis B all contained the wild-type sequence in the precore region.

Conclusions.

In the outbreak we studied, a mutant hepatitis B viral strain was transmitted from a common source to five patients who subsequently died of fulminant hepatitis B infection. Naturally occurring viral mutations in the HBV genome may predispose the infected host to more severe liver injury.

Background.

The presence of the hepatitis B e antigen (HBeAg) in serum is known to be a marker of a high degree of viral infectivity. However, fulminant hepatitis may occur in persons who are negative for HBeAg. A single point mutation has been reported to produce a stop codon in the precore region of hepatitis B virus DNA and prevent the formation of the precore protein required to make HBeAg. To determine whether a precore-mutant virus is causally related to severe liver injury, we analyzed the entire precore region in viral strains isolated from patients with fatal cases and uncomplicated cases of hepatitis B.

Methods.

Serum was obtained from 9 patients with fatal hepatitis B (5 with fulminant and 4 with severe exacerbations of chronic hepatitis) and 10 patients with acute, self-limited hepatitis B. Serum samples from a sex partner implicated as the source of the virus in one case of fulminant hepatitis were also studied. The 87 nucleotides in the precore region of the hepatitis B virus were amplified by the polymerase chain reaction and then directly sequenced.

Results.

Of the nine patients with fatal hepatitis, seven had retrievable hepatitis B DNA. In all seven there was a point mutation from G to A at nucleotide 1896 of the precore region, converting tryptophan (TGG) to a stop codon (TAG). In contrast, this mutation was not found in the 10 patients with acute, self-limited hepatitis B. The hepatitis B DNA from the implicated source contained a sequence with the stop-codon mutation that was identical to the sequence in her partner, who had fulminant hepatitis.

Conclusions.

The presence of a mutant viral strain is associated with and may be involved in the pathogenesis of fulminant hepatitis B and severe exacerbations of chronic hepatitis B.