Variation in the N-terminal region of an M-like protein of Streptococcus equi and evaluation of its potential as a tool in epidemiologic studies.
OBJECTIVE
To develop a method for typing Streptococcus equi on the basis of the DNA sequence of the genes that produce an M-like protein and to compare isolates among the United States, Japan, and other countries.


METHODS
S equi strains CF32, Hidaka/95/2, and NCTC9682 as well as 82 other isolates from the United States, Japan, and other countries obtained during 1975 to 2001.


METHODS
DNA sequences of the structural genes ( SeM and SzPSe) that produce M-like proteins were determined for 3 representative strains to find a variable region. Variability in this region of SeM was then determined for the other isolates. Amino acid sequences were deduced and analyzed phylogenetically by use of the neighbor-joining method.


RESULTS
Sequence diversity was detected in the N-terminal region of SeM but not in SzPSe of the 3 representative strains. Base substitutions in the variable region of SeM varied in a nonsynonymous manner, resulting in variation in the amino acid sequence. Eighty-five isolates were categorized as 32 types of SeM on the basis of differences in the deduced amino acid sequences.


CONCLUSIONS
This study documented a region in the N-terminal portion of SeM that varies in a nonsynonymous manner. This information should be useful in molecular epidemiologic studies of S equi.
Anzai
Toru
T
Epizootic Research Center, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Kokubunji-machi, Shimotsuga-gun, Tochigi 329-0412, Japan.
Kuwamoto
Yasushi
Y
Wada
Ryuichi
R
Sugita
Sigeo
S
Kakuda
Tsutomu
T
Takai
Shinji
S
Higuchi
Tohru
T
Timoney
John F
JF
D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D016000:Cluster Analysis; D017931:DNA Primers; D014644:Genetic Variation; D006736:Horses / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D018502:Streptococcus equi / Q000235:genetics*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D017931:DNA Primers; C107891:SeM protein, Streptococcus equi