New Genetic Material from Group B Streptococcus
Identified By Laura
McGinnis August 5, 2009
Streptococcus agalactiae (also called Group B
Streptococcus, or GBS) is a versatile pathogen that affects a variety
of animals. Now studies by Agricultural
Research Service (ARS) scientists and their university colleagues are
revealing new information about this pathogen.
The symptoms of GBS vary from animal to animal. In cattle, GBS is
associated with mastitis, a painful udder inflammation that costs the U.S.
cattle industry about $2 billion annually. In farmed and wild fish, the
bacteria can cause meningo-encephalitis, which is accompanied by swimming
difficulty and hemorrhaging.
To learn more about the emergence and transmission of GBS, scientists
with the ARS
Animal Health Research Unit in Auburn, Ala., and Chestertown, Md., compared
GBS samples, or "isolates," collected from infected fish, dolphins, cattle and
humans. The study was led by ARS aquatic pathologist
Evans in Chestertown.
The scientists collected the genetic material from several fish
species in the United States, Latin America and the Middle East; a bottlenose
dolphin in Kuwait; humans and cattle in North America, and humans in Japan.
The scientists used a technique known as multilocus sequence typing
(MLST) to examine similarities and differences between the genes of the GBS
isolates. This was the first study to apply the technology to GBS isolates from
During characterization of the GBS isolates, the scientists discovered
a previously unknown serotype in fish isolates from Kuwait, Brazil, Israel and
the United States. This particular serotype had been found in some cattle and
human GBS isolates, although it had never before been observed in fish or
dolphin GBS isolates.
Using MLST data, Evans and her colleagues also discovered five
previously unknown sequence types that were genetically unrelated to any known
GBS sequence types. These novel genetic, serotypic and phenotypic strains will
be explored for genes, unique antigens or virulence factors that may be
involved in inducing protective immunity, and therefore could be potential
candidates for superior vaccine efficacy against GBS in cattle and fish.
This research was published in several scientific journals between
2006 and 2009, most recently in the November 2008 issue of the
Journal of Medical
Microbiology and the May 2009 issue of
about this research in the August 2009 issue of Agricultural Research
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture.