Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-3 (of 3 Records) |
Query Trace: Yokosawa J[original query] |
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Hepatitis C virus antigenic convergence.
Campo DS , Dimitrova Z , Yokosawa J , Hoang D , Perez NO , Ramachandran S , Khudyakov Y . Sci Rep 2012 2 267 Vaccine development against hepatitis C virus (HCV) is hindered by poor understanding of factors defining cross-immunoreactivity among heterogeneous epitopes. Using synthetic peptides and mouse immunization as a model, we conducted a quantitative analysis of cross-immunoreactivity among variants of the HCV hypervariable region 1 (HVR1). Analysis of 26,883 immunological reactions among pairs of peptides showed that the distribution of cross-immunoreactivity among HVR1 variants was skewed, with antibodies against a few variants reacting with all tested peptides. The HVR1 cross-immunoreactivity was accurately modeled based on amino acid sequence alone. The tested peptides were mapped in the HVR1 sequence space, which was visualized as a network of 11,319 sequences. The HVR1 variants with a greater network centrality showed a broader cross-immunoreactivity. The entire sequence space is explored by each HCV genotype and subtype. These findings indicate that HVR1 antigenic diversity is extensively convergent and effectively limited, suggesting significant implications for vaccine development. |
Efficient error correction for next-generation sequencing of viral amplicons.
Skums P , Dimitrova Z , Campo DS , Vaughan G , Rossi L , Forbi JC , Yokosawa J , Zelikovsky A , Khudyakov Y . BMC Bioinformatics 2012 13 Suppl 10 S6 BACKGROUND: Next-generation sequencing allows the analysis of an unprecedented number of viral sequence variants from infected patients, presenting a novel opportunity for understanding virus evolution, drug resistance and immune escape. However, sequencing in bulk is error prone. Thus, the generated data require error identification and correction. Most error-correction methods to date are not optimized for amplicon analysis and assume that the error rate is randomly distributed. Recent quality assessment of amplicon sequences obtained using 454-sequencing showed that the error rate is strongly linked to the presence and size of homopolymers, position in the sequence and length of the amplicon. All these parameters are strongly sequence specific and should be incorporated into the calibration of error-correction algorithms designed for amplicon sequencing. RESULTS: In this paper, we present two new efficient error correction algorithms optimized for viral amplicons: (i) k-mer-based error correction (KEC) and (ii) empirical frequency threshold (ET). Both were compared to a previously published clustering algorithm (SHORAH), in order to evaluate their relative performance on 24 experimental datasets obtained by 454-sequencing of amplicons with known sequences. All three algorithms show similar accuracy in finding true haplotypes. However, KEC and ET were significantly more efficient than SHORAH in removing false haplotypes and estimating the frequency of true ones. CONCLUSIONS: Both algorithms, KEC and ET, are highly suitable for rapid recovery of error-free haplotypes obtained by 454-sequencing of amplicons from heterogeneous viruses.The implementations of the algorithms and data sets used for their testing are available at: http://alan.cs.gsu.edu/NGS/?q=content/pyrosequencing-error-correction-algorithm. |
Detection of all four human metapneumovirus subtypes in nasopharyngeal specimens from children with respiratory disease in Uberlandia, Brazil
Carneiro BM , Yokosawa J , Arbiza J , Costa LF , Mirazo S , Nepomuceno LL , Oliveira TF , Goulart LR , Vieira CU , Freitas GR , Paula NT , Queiroz DA . J Med Virol 2009 81 (10) 1814-8 The human metapneumovirus (hMPV) is a pathogen of the respiratory tract identified first in the Netherlands in 2001 and since then it has been detected worldwide. The purpose of this study was to identify and characterize hMPV in samples collected from children <5 years presenting with acute respiratory disease (ARD) seen at a public hospital in Uberlandia, in Southeastern Brazil. One hundred fourteen nasopharyngeal aspirates (NPAs) samples that were negative for the presence of nine other respiratory viruses were tested by reverse transcription polymerase chain reaction (RT-PCR) for the presence of hMPV RNA. Fourteen out of 114 (12.3%) samples were positive for presence of hMPV RNA. PCR products, obtained by the amplification of partial nucleotide sequence of gene N, were sequenced and compared with sequences deposited in GenBank. Sequences from eight samples were obtained and all four subtypes were identified. Also, the recently proposed sublineages "a" and "b" of subtype A2 were found; mean age was 21 months old; upper respiratory tract infection (URTI) was the most common clinical symptom; the virus was detected in samples collected from March to November, a period that corresponds to late summer to mid-spring in Brazil. This is the first study to describe the circulation of all hMPV subtypes in Minas Gerais state. |
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