RESUMO
BACKGROUND: The emergence of new strains in RNA viruses is mainly due to mutations or intra and inter-genotype homologous recombination. Non-homologous recombinations may be deleterious and are rarely detected. In previous studies, we identified HCV-1b strains bearing two tandemly repeated V3 regions in the NS5A gene without ORF disruption. This polymorphism may be associated with an unfavorable course of liver disease and possibly involved in liver carcinogenesis. Here we aimed at characterizing the origin of these mutant strains and identifying the evolutionary mechanism on which the V3 duplication relies. METHODS: Direct sequencing of the entire NS5A and E1 genes was performed on 27 mutant strains. Quasispecies analyses in consecutive samples were also performed by cloning and sequencing the NS5A gene for all mutant and wild strains. We analyzed the mutant and wild-type sequence polymorphisms using Bayesian methods to infer the evolutionary history of and the molecular mechanism leading to the duplication-like event. RESULTS: Quasispecies were entirely composed of exclusively mutant or wild-type strains respectively. Mutant quasispecies were found to have been present since contamination and had persisted for at least 10 years. This V3 duplication-like event appears to have resulted from non-homologous recombination between HCV-1b wild-type strains around 100 years ago. The association between increased liver disease severity and these HCV-1b mutants may explain their persistence in chronically infected patients. CONCLUSIONS: These results emphasize the possible consequences of non-homologous recombination in the emergence and severity of new viral diseases.
Assuntos
Evolução Molecular , Duplicação Gênica , Hepacivirus/genética , Recombinação Genética , Proteínas não Estruturais Virais/genética , Teorema de Bayes , Carcinoma Hepatocelular/virologia , Estudos de Coortes , Loci Gênicos , Hepatite C/virologia , Interações Hospedeiro-Patógeno , Humanos/virologia , Neoplasias Hepáticas/virologia , Mutação , Filogenia , Polimorfismo Genético , Proteínas do Envelope Viral/genéticaRESUMO
BACKGROUND: Hepatitis C virus non-structural protein 5A is known to play a role in development of hepatocellular carcinoma (HCC) via interactions with host cell pathways. OBJECTIVES: Hepatitis C virus genotype 1b strains presenting a wide insertion of 31 amino acids in the non-structural protein 5A V3 domain (V3 DI) were studied to determine whether this V3-like additional domain (V3 DII) was associated with HCC occurrence. STUDY DESIGN: Seventy-four patients' sera were screened for V3 DII presence regarding clinical status. RESULTS: Three strains with duplicated V3 were detected among patients with progression to HCC (n=28), two strains among patients with liver cirrhosis (Ci, n=27) and none among patients with chronic hepatitis (Chr, n=19). Phylogenetic trees built from V3 DI and V3 DII sequences indicated that the latter clustered separately. In between-group clonal analysis, V3 DII sequences from the HCC group were found to be more distant from HCV-J than V3 DI sequences (p<0.0001). Between-group comparisons showed significant differences in genetic distances from HCV-J, in HCC V3 DI and HCC V3 DII compared to Ci V3 DI and Ci V3 DII sequences (p<0.0001). HCC V3 DII domain and its junction with V3 DI exhibited higher Shannon entropy values and enrichment in disorder-promoting residues. CONCLUSIONS: Taken together, our results suggest that V3 DII evolution may differ in strains associated with HCC occurrence. The presence of an intrinsically "disordered" V3 duplicate may alter the NS5A protein network. Further investigations are necessary to elucidate the potential impact of V3 duplication in the context of carcinogenesis.
Assuntos
Carcinoma Hepatocelular/epidemiologia , Carcinoma Hepatocelular/virologia , Duplicação Gênica , Hepacivirus/genética , Proteínas não Estruturais Virais/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Hepacivirus/patogenicidade , Humanos , Pessoa de Meia-Idade , Mutagênese Insercional , Estudos ProspectivosRESUMO
Nineteen E. faecium strains isolated from chicken caecum samples, collected in slaughterhouses and highly resistant to vancomycin or gentamicin, were coresistant to erythromycin, and/or tetracyclines, and/or streptogramins, and/or avilamycin. Multiple antibiotic resistance was related to the presence in various combinations of aac(6')-aph(2"), erm(B), emtA, mef(A), tet(L), tet(M), and vanA genes.