ABSTRACT
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. On the other hand, 4 alleles had a non-synonymous substitution other than synonymous substitutions, resulting in the substitution of a single amino acid. The distribution of each allele was generally emm genotype-specific. Only sdaB7 was found in both emm2 and emm4. The promoter region was highly conserved and DNase B protein was similarly expressed in all alleles.
Subject(s)
Antigens, Bacterial/genetics , Bacterial Outer Membrane Proteins/genetics , Carrier Proteins/genetics , Deoxyribonucleases/genetics , Genes, Bacterial , Streptococcus pyogenes/genetics , Alleles , Amino Acid Substitution , Blotting, Western , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Deoxyribonucleases/analysis , Gene Expression , Genotype , Molecular Sequence Data , Mutation , Phylogeny , Promoter Regions, Genetic , Sequence Analysis, DNA , Sequence Homology, Nucleic Acid , Statistics as Topic , Streptococcus pyogenes/enzymologyABSTRACT
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. In addition, these T11 isolates may have obtained the tet(M) gene after the 1990s, because resistance to tetracycline in T11 isolates was rarely found before then. These results strongly suggested that the T4 and T11 GAS isolates acquired tetracycline-resistance via different molecular mechanisms.
Subject(s)
Bacterial Proteins/genetics , Carrier Proteins/genetics , Streptococcus pyogenes/drug effects , Tetracycline Resistance/genetics , DNA Transposable Elements , Electrophoresis, Gel, Pulsed-Field , Genotype , Humans , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Sequence Analysis, DNA , Serotyping , Streptococcus pyogenes/classification , Streptococcus pyogenes/genetics , Streptococcus pyogenes/isolation & purificationABSTRACT
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. RESULTS: In 2002, we isolated a total of 50 Echo13 strains, which had not been detected from 1981 until 2001 in Japan. The antibody positive rate was higher (57.2-62.0%) in subjects 50 years or over than in those under 50 years (0-14.4%). CONCLUSIONS: Serological study suggested that Echo13 had been present in Yamagata until around 1960, at which time the antibody positive persons were exposed to Echo13 in their childhood. Furthermore, results of virus isolation demonstrated that Echo13 re-emerged in around 2002 after a hiatus of several decades.
Subject(s)
Echovirus Infections/epidemiology , Enterovirus B, Human/isolation & purification , Adolescent , Adult , Antibodies, Viral/blood , Child , Child, Preschool , Echovirus Infections/blood , Enterovirus B, Human/classification , Female , Humans , Infant , Infant, Newborn , Japan/epidemiology , Male , Middle Aged , Seroepidemiologic StudiesABSTRACT
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. RESULTS: During the period, we isolated 40 Coxsackie A2 (CoxA2), 13 CoxA4, 16 CoxA16, 1 CoxB2, 11 CoxB3, 2 CoxB5, 54 echo16, 2 entero71 and 1 polio2. By observing a cell sensitivity pattern with HEF, HEp-2, Vero, RD-18S, and GMK, we could finally differentiate five enterovirus groups: CoxA except for CoxA16, CoxA16/entero71, CoxB, echovirus, and poliovirus. CONCLUSIONS: With this system, the RD-18S cell line enabled us to isolate CoxA virus, except for CoxA16, for the first time. Differentiation of five enterovirus groups by cell sensitivity simplified the specific identification by neutralization test as a presumptive identification. A modified microplate method may be an appropriate cell combination for virus isolation, especially for enteroviruses, and is expected to be used routinely for virologic diagnosis and to clarify the epidemiology of ARI in children.
Subject(s)
Enterovirus Infections/diagnosis , Enterovirus/isolation & purification , Respiratory Tract Infections/diagnosis , Respiratory Tract Infections/virology , Virus Cultivation/methods , Adolescent , Animals , Cell Line , Child , Enterovirus/classification , Female , Humans , Male , Serial Passage , Time FactorsABSTRACT
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. These results suggest that a reassortment to produce A(H1N2) does not readily occur even when A(H1N1) and A(H3N2) co-circulate in a community such as Yamagata.