Persistence of Hepatitis B Virus DNA and the Tempos between Virion Secretion and Genome Maturation in a Mouse Model

Abstract

Chronic infection with human hepatitis B virus (HBV) could lead to cirrhosis and hepatoma. At present, there is no effective treatment to eradicate the virus from patients. HBV in chronic carriers does not exist as a single homogeneous population. The most frequent naturally occurring mutation in HBV core protein occurs at amino acid 97, changing an isoleucine to leucine (I97L). One dogma in the field is that only virions containing a mature genome are preferentially secreted into the medium. Here, we demonstrated that mutant I97L can secrete immature genome in mice. Although viral DNA of mutant I97L with immature genome is less persistent than wild-type HBV in time course experiments, viral DNA of mutant P130T with genome hypermaturation, surprisingly, is more persistent. Therefore, virion secretion regulated by genome maturity could influence viral persistence. It remains an open issue whether virion secretion could be a drug target for HBV therapy.

In Silico Analysis of Genetic Diversity of Human Hepatitis B Virus in Southeast Asia, Australia and New Zealand

“…Mutations within the PC region acquired after HBeAg seroconversion (c.1896G>A and p.P130T) can lead to defective HBV replication, decreased or lost secretion of HBeAg, HBeAg-negative CHB and even HCC with poorer prognosis [5,7,[45][46][47]. The two HBcAg mutations p.I/F97L and p.P130T are frequently observed concurrently in CHB patients [44], leading to the secretion of virions containing immature genomes and hypermaturations, respectively [48]. Meanwhile, double mutations c.1762A>T / c.1764G>A in the BCP region and mutation c.1613G>A within NRE, are associated with the suppressed expression of HBeAg, increased viral load in HBV carriers and increased risk of liver carcinogenesis [6,49,50].…”

Virion Secretion of Hepatitis B Virus Naturally Occurring Core Antigen Variants

“…One important unknown here is whether both genome-free and genome-containing virions are really secreted by the same route. Neither the classic genome maturation model [ 16 ] nor the revised single-strand blocking model, are consistent with the immature secretion of virions containing single-strand DNA [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. The temporal relationship between genome maturation and virion secretion deserves further investigation in the future.…”

“…Consistent with the previous results based on cell culture and transfection [ 17 ], mutant I97L in mice exhibited pleiotropic phenotypes. Extracellularly, the serum samples contained an excessive amount of HBV virions with immature genomes (left panel, Figure 10 ) [ 23 ]. Intracellularly, the liver samples presented significantly reduced amounts of intracellular RC and SS DNAs ( Figure 10 ) [ 23 ].…”

“…Extracellularly, the serum samples contained an excessive amount of HBV virions with immature genomes (left panel, Figure 10 ) [ 23 ]. Intracellularly, the liver samples presented significantly reduced amounts of intracellular RC and SS DNAs ( Figure 10 ) [ 23 ]. This intracellular deficiency in viral DNA synthesis of mutant I97L in mice is more consistent with the results of mutant F97L in HuH-7 cells [ 17 ], and less consistent with the result of mutant I97L in HepG2 cells [ 18 ].…”

“…Using a lower dose amount of DNA (1–2 μg) in liposome-mediated transfection, we also observed reduced intracellular viral DNA replication of mutant I97L in HepG2 cell culture (Szu-Yao Wu and Chiaho Shih, unpublished results). Overall, these pleiotropic phenotypes in vivo were observed in both immune-competent and immunodeficient mice [ 23 ]. Interestingly, an unexpected phenotype of mutant I97L in the mouse model is the less persistent intrahepatic and serum HBV DNAs than the wild type HBV ( Figure 10 ).…”