Gene heterogeneity of hepatitis B virus isolates from patients with severe hepatitis B

BACKGROUND: The pathogenesis of severe hepatitis B remains unknown. Reports have indicated that hepatitis B virus (HBV) mutations are important factors in the pathogenesis of this disease. This study was to investigate the genetic heterogeneity of HBV strains from serum samples of patients with fulminant hepatitis B. METHODS: Full-length HBV genomes from 4 patients with severe hepatitis B were cloned and sequenced to observe mutations in every open reading-frame ( ORF). Serum samples of another 25 patients with severe hepatitis B, 30 patients with chronic hepatitis B, and 25 HBV carriers were collected for sequencing and comparison of mutations in preS2, preC and core promoter regions. RESULTS: Of 4 HBV full-length genome sequences, 3 had a G to A mutation at nucleotide A1896 in the preC region and 1 had double mutations of T1762-A1764 in the core promoter region. The 4 sequences showed mutations in the known B or T cell epitopes of the preS2 and C regions. For the other 3 groups, more mutations were seen in the preS2 region in the HBV isolates from the patients with severe hepatitis B than those from the patients with chronic hepatitis B and HBV carriers (P <0.01). There was a significant difference of mutations in the T cell epitope region of preS2 between the patients with severe hepatitis B and those with chronic hepatitis B or HBV carriers (P <0.01). In the preC and core promoter regions, the mutation frequencies of T1653 and C1753 were 48.0% and 24.0% respectively in the patients with severe hepatitis B, but none of these mutations were observed in the patients with chronic hepatitis B group or HBV carriers (P <0.01). The mutation frequency of T1762-A1764 was 76.0% in the patients with severe hepatitis B, 40.0% in the patients with chronic hepatitis B (P <0. 01) , and 16. 0% in the HBV carriers ( P < 0. 01). There was a significant difference in A1896 mutation between the patients with severe hepatitis B and the patients with chronic hepatitis B (P < 0. 05 ) or the HBV carriers (P<0.05). CONCLUSION: Our observations suggest that the accumulation and persistence of high frequency mutations or complex mutations may be associated with the development and deterioration of HBV infection.

Ambisense polarity of genome RNA of orthomyxoviruses and coronaviruses

Influenza viruses and coronaviruses have linear single-stranded RNA genomes with negative and positive sense polarities and genes encoded in viral genomes are expressed in these viruses as positive and negative genes,respectively.Here we consider a novel gene identified in viral genomes in opposite direction,as positive in influenza and negative in coronaviruses,suggesting an ambisense genome strategy for both virus families.Noteworthy,the identified novel genes colocolized in the same RNA regions of viral genomes,where the previously known opposite genes are encoded,a so-called ambisense stacking architecture of genes in virus genome.It seems likely,that ambisense gene stacking in influenza and coronavirus families significantly increases genetic potential and virus diversity to extend virus-host adaptation pathways in nature.These data imply that ambisense viruses may have a multivirion mechanism,like"a dark side of the Moon",allowing production of the heterogeneous population of virions expressed through positive and negative sense genome strategies.

Chevrier＇s Field Mouse(Apodemus chevrieri) and Père David＇s Vole(Eothenomys melanogaster) in China Carry Orthohepeviruses that form Two Putative Novel Genotypes Within the Species Orthohepevirus C

Hepatitis E virus(HEV)is the prototype of the family Hepeviridae and the causative agent of common acute viral hepatitis.Genetically diverse HEV-related viruses have been detected in a variety of mammals and some of them may have zoonotic potential.In this study,we tested 278 specimens collected from seven wild small mammal species in Yunnan province,China,for the presence and prevalence of orthohepevirus by broad-spectrum reverse transcription(RT)-PCR.HEV-related sequences were detected in two rodent species,including Chevrier’s field mouse(Apodemus chevrieri,family Muridae)and Père David’s vole(Eothenomys melanogaster,family Cricetidae),with the infection rates of 29.20%(59/202)and 7.27%(4/55),respectively.Further four representative full-length genomes were generated:two each from Chevrier’s field mouse(named Rd HEVAc14 and Rd HEVAc86)and Père David’s vole(Rd HEVEm40 and Rd HEVEm67).Phylogenetic analyses and pairwise distance comparisons of whole genome sequences and amino acid sequences of the gene coding regions showed that orthohepeviruses identified in Chinese Chevrier’s field mouse and Père David’s vole belonged to the species Orthohepevirus C but were highly divergent from the two assigned genotypes:HEV-C1 derived from rat and shrew,and HEV-C2 derived from ferret and possibly mink.Quantitative real-time RT-PCR demonstrated that these newly discovered orthohepeviruses had hepatic tropism.In summary,our work discovered two putative novel genotypes orthohepeviruses preliminarily named HEVC3 and HEV-C4 within the species Orthohepevirus C,which expands our understanding of orthohepevirus infection in the order Rodentia and gives new insights into the origin,evolution,and host range of orthohepevirus.