Antigenic and genetic variation in cytopathic hepatitis A virus variants arising during persistent infection: evidence for genetic recombination

Abstract

Variants of hepatitis A virus (pHM175 virus) recovered from persistently infected green monkey kidney (BS-C-1) cells induced a cytopathic effect during serial passage in BS-C-1 or fetal rhesus kidney (FRhK-4) cells. Epitope-specific radioimmunofocus assays showed that this virus comprised two virion populations, one with altered antigenicity including neutralization resistance to monoclonal antibody K24F2, and the other with normal antigenic characteristics. Replication of the antigenic variant was favored over that of virus with the normal antigenic phenotype during persistent infection, while virus with the normal antigenic phenotype was selected during serial passage. Viruses of each type were clonally isolated; both were cytopathic in cell cultures and displayed a rapid replication phenotype when compared with the noncytopathic passage 16 (p16) HM175 virus which was used to establish the original persistent infection. The two cytopathic virus clones contained 31 and 34 nucleotide changes from the sequence of p16 HM175. Both shared a common 5' sequence (bases 30 to 1677), as well as sequence identity in the P2-P3 region (bases 3249 to 5303 and 6462 to 6781) and 3' terminus (bases 7272 to 7478). VP3, VP1, and 3CPr0 contained different mutations in the two virus clones, with amino acid substitutions at residues 70 of VP3 and 197 and 276 of VP1 of the antigenic variant. These capsid mutations did not affect virion thermal stability. A comparison of the nearly complete genomic sequences of three clonally isolated cytopathic variants was suggestive of genetic recombination between these viruses during persistent infection and indicated that mutations in both 5' and 3' nontranslated regions and in the nonstructural proteins 2A, 2B, 2C, 3A, and 3DPo' may be related to the cytopathic phenotype.

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

“…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.…”

Pathogen evolution within host individuals as a primary cause of senescence

“…Some variants of measles virus in persistent infections are resistant to interferon (Carrigan & Knox, 1990). Variants of hepatitis A virus isolated from persistently-infected monkey cells were cytophatic (Lemon et al, 1991). The appearance of variants which evade immune surveillance has been reported for visna view of sheep (Stanley et al, 1988) and for equine infectious anaemia virus (Salinovich et al, 1986).…”

“…Righthand (1991) showed that persistent non-lytic variants of echovirus 6 replicate. Lemon et al (1991) measured the rate of replication of hepatitis A virus in cultured cells.…”

“…Persistent strains of Theiler's virus are less abundant and have lower rates of replication than virulent strains (Lipton et al, 1991). Variant forms of hepatitis A virus which appear during persistent infections and which have altered antigenicity, including neutralization resistance to antibody, have lower rates of replication than forms with normal antigenic characteristics (Lemon et al, 1991). A causal relationship between persistence and reduced replication was established by J. S. , who showed that a mutant of duck hepatitis B virus with a reduced rate of replication established a persistent infection when inoculated experimentally.…”

Evolutionary biology of human hepatitis viruses

“…For all human hepatitis viruses, recombination has been exhaustively described. [78][79][80][81][82][83] The plethora of recently discovered viruses has enabled revisiting the occurrence of recombination events during the genealogy of human hepatitis viruses and their animal homologues.…”