Close correlation of streptococcal DNase B (sdaB) alleles with emm genotypes in Streptococcus pyogenes.

DNase B is a major nuclease and a possible virulence factor in Streptococcus pyogenes. The allelic diversity of streptococcal DNase B (sdaB) gene was investigated in 83 strains with 14 emm genotypes. Of the 15 alleles identified, 11 alleles carried only synonymous nucleotide substitutions.

Molecular mechanisms of high level tetracycline-resistance in group A streptococcal isolates, T serotypes 4 and 11.

The molecular mechanism of high level tetracycline resistance in T serotypes 4 and 11 group A streptococcal (GAS) isolates was examined in 61 tetracycline-resistant isolates in Japan. PCR and sequencing analyses revealed that the T serotype/emm genotype, T4/4 isolates carried tet(O) genes, which were genetically homogenous. The T11/11 and T11/89 isolates carried different subtypes of tet(M) genes, which were present on transposons Tn916 and Tn1545, respectively.

Re-emergence of echovirus type 13 infections in 2002 in Yamagata, Japan.

Objectives: To analyze the prevalence of echovirus type 13 (Echo13) in Yamagata, Japan.

Methods: Virus isolation was performed from 6514 clinical specimens using six cell lines between January 1999 and December 2002. We also carried out a seroepidemiological study against Echo13, using 234 serum samples collected in 2001.

Enterovirus isolation from children with acute respiratory infections and presumptive identification by a modified microplate method.

Objective: To evaluate a modified microplate method, utilizing HEF, HEp-2, Vero, MDCK and newly introduced RD-18S and GMK cell lines, for virus isolation.

Methods: From June to October 2001, 723 throat swab specimens taken from children with acute respiratory infections (ARIs) were inoculated onto these cells. To analyze cell sensitivity, we also inoculated 20 serotypes of stocked enteroviruses.

A rare appearance of influenza A(H1N2) as a reassortant in a community such as Yamagata where A(H1N1) and A(H3N2) co-circulate.

To find a new influenza subtype A(H1N2), 383 isolates identified as H1 by hemagglutination inhibition test between the 1998-1999 and 2001-2002 seasons in Yamagata, Japan, were screened by reverse transcription polymerase chain reaction. As a result, 3 strains from the 1999-2000 season were identified as possibly being A(H1N2). Although several of their clones were found to be A(H1N2), A(H1N1) and A(H3N2), we could not confirm the origin of the A(H1N2) clones without the original specimens.