A Cytopathogenic, Apoptosis-Inducing Variant of Hepatitis A Virus

Abstract

A cytopathogenic variant of hepatitis A virus (HAVcyt/HB1.1) was isolated from persistently infected BS-C-1 cells by serial passages in FRhK-4 cells. This virus shows a rapid replication pattern and high final titers are obtained, which are main characteristics of cytopathogenic HAVs. Sequencing of the nontranslated regions and the coding regions for 2ABC and 3AB revealed that mutations are distributed all over these regions and that certain mutated sites correspond to those in other cytopathogenic HAV variants. Investigating the mechanisms causing the cytopathic effect in FRhK-4 cells infected with this variant, we found that an apoptotic reaction takes place.

Apoptosis induced by a cytopathic hepatitis A virus is dependent on caspase activation following ribosomal RNA degradation but occurs in the absence of 2′–5′ oligoadenylate synthetase

“…Previous investigations have demonstrated that a cp strain of HAV, HAVcyt/HB1.1, derived from the cc strain HM175, induced apoptosis in 2-5% of the cells by 120 h post-infection (pi), increasing to 37.5% by 14 days pi (Brack et al, 1998). Similar slowly developing cpe and apoptosis were reported in cells infected with another cp strain, HM175/24a (Gosert et al, 2000).…”

“…ing virus, viral genomic RNA was amplified using primers directed to the 5 NTR (Panel E). The results clearly show the presence of undiminished amount of viral genome in clone 1 cells after several months of cultivation, with no indication that the virus has acquired the 14 base repeat present in the genome of 18f and other cp strains (Brack et al, 1998;Zhang et al, 1995).…”

“…Cell pellets of uninfected or virus infected cells were resuspended in 10 mM Tris-HCl, 20 mM EDTA, pH 8.0 and lysed by the addition of Triton X-100 to 0.5% (Brack et al, 1998). Cell lysates were kept on ice for 20 min with intermittent vortex mixing, followed by centrifugation at 12,000 × g for 10 min.…”

“…This is in contrast to in vivo infection, where persistence is restricted to a few weeks (Lemon, 1985;Vallbracht et al, 1989), although sporadic cases of chronic infection have been reported (Fagan et al, 1990;Inoue et al, 1996). Several laboratories have isolated rapidly replicating cytopathogenic (cp) strains that produce visible morphological changes primarily in continuous cell lines of monkey kidney origin (Divizia et al, 1986;Venuti et al, 1986;Anderson, 1987;Cromeans et al, 1987;Nasser and Metcalf, 1987;Zhang et al, 1995;Brack et al, 1998). The mechanism of the cytopathogenic effect (cpe) produced by the rapidly replicating HAV strains has been intensely investigated during the past few years to understand why wild type (wt) and cell culture adapted (cc) strains replicate slowly and are unable to induce cpe in these cell lines.…”

“…The mechanism of the cytopathogenic effect (cpe) produced by the rapidly replicating HAV strains has been intensely investigated during the past few years to understand why wild type (wt) and cell culture adapted (cc) strains replicate slowly and are unable to induce cpe in these cell lines. These studies have revealed that the genome of the cpe-inducing (cp) strains contain point mutations, compared to the wt strains from which they were derived, scattered throughout the genome, as well as a 14-bp repeat in the 5 non-translated region (NTR), which harbors the internal ribosomal entry site or IRES (Lemon et al, 1991;Brack et al, 1998). The biological significance of these mutations for the rapid replication phenotype of the cp strains is not completely understood.…”