On hepatitis C virus evolution: the interaction between virus and host towards treatment outcome.

BACKGROUND: Hepatitis C is a disease spread throughout the world. Hepatitis C virus (HCV), the etiological agent of this disease, is a single-stranded positive RNA virus. Its genome encodes a single precursor protein that yields ten proteins after processing. NS5A, one of the non-structural viral proteins, is most associated with interferon-based therapy response, the approved treatment for hepatitis C in Brazil. HCV has a high mutation rate and therefore high variability, which may be important for evading the immune system and response to therapy. The aim of this study was to analyze the evolution of NS5A quasispecies before, during, and after treatment in patients infected with HCV genotype 3a who presented different therapy responses. METHODS: Viral RNA was extracted, cDNA was synthesized, the NS5A region was amplified and cloned, and 15 clones from each time-point were sequenced. The sequences were analyzed for evolutionary history, genetic diversity and selection. RESULTS: This analysis shows that the viral population that persists after treatment for most non-responder patients is present in before-treatment samples, suggesting it is adapted to evade treatment. In contrast, the population found in before treatment samples from most end-of-treatment responder patients either are selected out or appears in low frequency after relapse, therefore changing the population structure. The exceptions illustrate the uniqueness of the evolutionary process, and therefore the treatment resistance process, in each patient. CONCLUSION: Although evolutionary behavior throughout treatment showed that each patient presented different population dynamics unrelated to therapy outcome, it seems that the viral population from non-responders that resists the treatment already had strains that could evade therapy before it started.

Occurrence and phylogenetic characterization of a baculovirus isolated from Culex quinquefasciatus in São Paulo State, Brazil.

The aim of this study was to assess the occurrence of baculovirus infections in mosquitoes and characterize them by using molecular tools. Fortnightly collections were made of mosquito larvae in the city of Caraguatatuba. Six larvae of Culex quinquefasciatus were isolated that had white cysts (nodules) in epithelia cells of the posterior midgut, indicative of infection by a baculovirus. These larvae were subjected to DNA extraction. DNA was amplified, producing a fragment of around 600 nt of the lef-8 gene and 400 nt of Pif-2 gene. The sequences were aligned, using ClustalX 2.0, with partial sequences of lef-8 genes of baculoviruses isolated from members of other insect orders taken from the GenBank database and edited, and phylogenetic analysis was performed. Phylogenetic analysis performed with the lef-8 and pif-2 genes demonstrated that the baculovirus identified in Culex quinquefasciatus in the Caraguatatuba region is most closely related to the deltabaculovirus Culex nigripalpus nucleopolyhedrovirus.

Molecular evidence of horizontal transmission of hepatitis C virus within couples.

Hepatitis C virus (HCV) transmission has decreased with the adoption of universal blood donor screening and social policies to reduce the risk of infection in intravenous drug users, but remains a worldwide health problem. The objective of this study was to evaluate the phylogenetic relationships among sequences from different HCV genomic regions from sexual partners of infected patients. Nine couples with a stable relationship and without other risk factors for HCV infection and 42 control patients were selected, and the NS3 and NS5B regions were analysed. Phylogenetic analysis showed that viruses from five of the couples had a common origin, clustering in the same monophyletic group, with bootstrap values greater than 70. For the other couples, monophyletic groups were observed, but without bootstrap support. Thus, using two different viral genome regions, a common source of infection was observed in both members of five couples. These data strongly support HCV transmission within couples.

A phylogenetic study of hepatitis B virus in chronically infected Brazilian patients of Western and Asian descent.

BACKGROUND: Hepatitis B virus (HBV) causes one of the most important chronic viral infections worldwide. HBV is classified into eight genotypes whose epidemiology varies geographically. In Brazil, genotypes A, D, and F are more frequent, while in East Asia, genotypes B and C predominate. Several studies showed that immigrants retain the HBV infection pattern of their ancestral country. PURPOSE: To identify HBV genotypes infecting chronic carriers in Brazilian families of Western and Asian descent by Hepatitis B surface antigen gene sequencing and analyze the route of viral transmission by phylogenetic analysis of viral sequences. METHODS: Eighty-seven people chronically infected with HBV were separated into two groups: Western descent (27) and Asian descent (60). Surface and pre-core/core genes were amplified from serum HBV-DNA and sequences were subjected to phylogenetic analysis. RESULTS: HBV genotype A was found in 74% of Western subjects, while genotype C was found in 94% of Asian patients. Thirty-eight percent of Western families were infected with HBV with similar pre-core/core sequences, while only 25% of Asian families showed similarity in these sequences. CONCLUSIONS: Phylogenetical analysis of pre-core/core HBV gene suggested intra-familial transmission of HBV in 38% of Western families and 25% of Asian families. Analysis of HBsAg gene sequences helped to define the HBV genotype but did not allow inferring route of transmission as its sequences showed a smaller phylogenetic signal than pre-core/core sequences. Chronic HBV carriers of Asian descent born in or living in Brazil were infected with the same HBV genotype predominant in their ancestral country.

Differences in viral kinetics between genotypes 1 and 3 of hepatitis C virus and between cirrhotic and non-cirrhotic patients during antiviral therapy.

AIM: To evaluate the impact of hepatitis C virus (HCV) infection with genotype 1 or 3 and the presence or absence of liver cirrhosis (LC) in the early viral kinetics response to treatment. METHODS: Naive patients (n = 46) treated with interferon-alpha (IFN-alpha) and ribavirin and followed up with frequent early HCV-RNA determinations were analysed. Patients were infected with genotype 1 (n = 28, 7 with LC) or 3 (n = 18, 5 with LC). RESULTS: The first phase decline was larger in genotype 3 patients than in genotype 1 patients (1.72 vs 0.95 log IU/mL, P < 0.001). The second phase slope decline was also larger in genotype 3 patients than in genotype 1 patients (0.87 vs 0.15 log/wk, P < 0.001). Differences were found in both cirrhotic and non-cirrhotic patients. Genotype 1 cirrhotic patients had a slower 2nd phase slope than non-cirrhotic patients (0.06 vs 0.18 log/wk, P < 0.02). None of genotype 1 cirrhotic patients had a 1st phase decline larger than 1 log (non-cirrhotic patients: 55%, P < 0.02). A similar trend toward a slower 2nd phase slope was observed in genotype 3 cirrhotic patients but the 1st phase slope decline was not different. Sustained viral response was higher in genotype 3 patients than in genotype 1 patients (72% vs 14%, P < 0.001) and in genotype 1 non-cirrhotic patients than in genotype 1 cirrhotic patients (19% vs 0%). A second phase decline slower than 0.3 log/wk was predictive of non-response in all groups. CONCLUSION: Genotype 3 has faster early viral decline than genotype 1. Cirrhosis correlates with a slower 2nd phase decline and possibly with a lower 1st phase slope decline in genotype 1 patients.