Biomedical subjects

H Attoui

Publications and source records attributed to H Attoui.

24 records · Page 2Linked to original sources

PubMed1999

Determination and phylogenetic analysis of partial sequences from TT virus isolates.

Sera from French in-patients were tested for the presence of the TT virus (TTV) genome using PCR and degenerate primers located in ORF1. Thirty-six sequences were determined and compared with those deposited in databases, revealing a high degree of genetic variability between TTV isolates (up to 47% for amino acid sequences). Phylogenetic analysis demonstrated the existence of three main groups corresponding to the previously described genotypes 1 and 2 and to a new genotype 3. Isolates could be assigned to distinct genotypes if their genetic distance was > 27%. No comparable genetic criteria were found for the definition of sub-types in the region studied. A 15-31 month follow-up of three haemodialysis patients proved the existence of chronic infection by TTV. In one patient, two strains belonging to different genotypes were detected at the same time. Sequences of both ORF1 and ORF2 remained unchanged for a given strain during the follow-up.

Amino Acid Sequence↗

PubMed1998

Comparative sequence analysis of American, European and Asian isolates of viruses in the genus Coltivirus.

In this study, the basis for the classification of virus isolates grouped within the genus Coltivirus, family Reoviridae, is discussed. Sequences of dsRNA segments from American (segments 9-12), European (segment 12) and Asian (segments 7-12) isolates were characterized and polythetic criteria were defined for their taxonomic classification. These criteria (including sequence analysis) permitted the different species to be distinguished and classified into two groups. In both groups, subgroups were defined according to the degree of homology between the genomic sequences. American and European isolates are classified within group A, which includes subgroups A1 (Colorado tick fever virus species) and A2 (Eyach virus species). Asian isolates are classified in group B, which includes subgroups B1 (JKT-7075 virus species) and B2 (JKT-6423 virus species). The proteins encoded by the sequenced genomic segments were analysed. This allowed the identification of dsRNA binding domains in the proteins encoded by segment 8 of subgroup B1 isolates and segment 12 of subgroup B2 isolates. A conserved pattern of amino acids in segment 7 of group B isolates matched sequences found in the catalytic domains of protein kinases.

Amino Acid Sequence↗

PubMed1998

Serologic and molecular diagnosis of Colorado tick fever viral infections.

Molecular and serologic methods usable for the biological diagnosis of Coltivirus infection are reported. We designed a multiplex reverse transcription-polymerase chain reaction system that allowed the simultaneous and specific amplification of three genomic segments from as little as 0.01 plaque-forming units. Another system in the S2 viral segment permitted the differential diagnosis of American and European viral isolates. We also discuss some improvements of previous ELISAs, and the results obtained with paired sera from Colorado tick fever (CTF) virus-infected individuals. Western blot analysis was developed that allowed the detection of antibodies to a 38-kD viral protein in all tested sera. It also enabled the detection of anti-CTF virus antibodies in ELISA-negative sera. Specific IgM antibodies against a synthetic viral peptide could be detected in sera at the acute stage of the infection. Together, these results should permit the diagnosis of Coltivirus infection at any stage of the pathology.

Amino Acid Sequence↗

PubMed1997

Evaluation of four PCR systems amplifying different genomic regions for molecular diagnosis of GB virus C infections.

Diagnosis of GB virus C (GBV-C) infection is based on RT-PCR methodology that detects genomic viral RNA. Four sets of primers located in different genomic regions were compared. These primers were used to amplify a reference panel of sera used by the French blood banks, including five positive sera, five negative sera and 10-fold serial dilutions of one positive serum. Three sets of primers located in the 5'UTR, NS3 and NS5a genomic regions gave comparable results with undiluted sera. When diluted sera were tested, the most sensitive protocol was that using a set of primers and a probe selected within the 5'UTR, together with a colorimetric detection based on DNA enzyme immunoassay.

Evaluation Studies as Topic↗

PubMed1997

Classification of hepatitis C virus variants in six major types based on analysis of the envelope 1 and nonstructural 5B genome regions and complete polyprotein sequences.

The phylogenetic status of recently described isolates of hepatitis C virus (HCV) from Vietnam, Thailand and Indonesia (previously classified as types 7, 8, 9, 10 and 11) was re-analysed by the neighbour-joining method instead of the unweighted pair-group method with arithmetic mean (UPGMA) that was first used by the discoverers of these strains. The analysis of complete amino acid sequences and of nucleotide sequences of the envelope 1 (672 nt) and nonstructural 5B (1092 nt) genomic regions permitted the re-assignment of the type 7, 8, 9 and 1 1 isolates to type 6, and that of type 10 strains to type 3. Finally, this study made possible the classification of the previously described HCV strains (including these South-East Asian isolates) in six major types and at least 30 subtypes. It confirms that analysis of the E 1 and NS5B genomic regions using the neighbour-joining method is a reliable tool for the assignment of most new isolates.

Genome, Viral↗

PubMed1997

Complete nucleotide sequence of Colorado tick fever virus segments M6, S1 and S2.

The nucleotide sequences of the tenth (M6), eleventh (S1) and twelfth (S2) dsRNA genomic segments of the Florio strain (N-7180) of Colorado tick fever virus were determined and found to be 675, 998 and 1884 bp, respectively, in length. A nonanucleotide motif and a hexanucleotide motif were found to be highly conserved in the 5' and 3' non-coding regions (NCRs), respectively, of the three segments. The first and last three nucleotides of each segment were of inverted complementarity, and segment-specific inverted terminal repeats were detected in the NCRs of the three segments. These findings suggest the occurrence of intracellular panhandle structures for the RNA transcripts. A readthrough phenomenon is suspected in segment M6. The environment surrounding the opal codon (position 1052-1054) of segment M6 conforms to that of leaky opal codons described in the literature.

Animals↗