Author:
CHANTER N.,COLLIN N.,HOLMES N.,BINNS M.,MUMFORD J.
Abstract
The 16S-23S RNA gene intergenic spacers of isolates of Streptococcus
equi (n=5), S.
zooepidemicus (n=5), S. equisimilis (n=3)
and
S. dysgalactiae (n=2) were sequenced and
compared. There were distinct regions within the spacer, arranged in the
order
1–9 for all S.
equi and one S. zooepidemicus isolate and 1,2 and 4–9
for
the remaining isolates. Region 4 was identical to the tRNAala
gene found in the 16S-23S intergenic spacers of other streptococci.
Regions 1, 5, 6 and 7 had distinct variations, each conserved in different
isolates. However,
amongst the intergenic spacers there were different combinations of variant
regions,
suggesting
a role for DNA recombination in their evolution. The intergenic spacer
of all
isolates of S.
equi and one S. zooepidemicus isolate were almost identical.
Primers derived from the variant
sequences of regions 1 and 5 to 6 were used to group all S. zooepidemicus
(n=17) and S. equi
(n=5) into 1 of 8 types by polymerase chain reaction; three S.
zooepidemicus isolates typed
the same as S. equi. S. equi and S. zooepidemicus
were
clearly distinguishable from
S. equisimilis and S. dysgalactiae which had shorter
regions
5 and 6 and no region 7. Most
homology for the group C sequences was found in previously published sequences
for the
16S-23S intergenic spacers of S. anginosis, S. constellatus,
S. intermedius, S. salivarius and
S. agalactiae. A 75-90 nucleotide length shared with S. anginosus
and S. intermedius in opposite
orientations in the two main variants of region 6 supported the role for
DNA
recombination
in the evolution of the spacer. The 16S-23S intergenic spacers indicate
that
S. zooepidemicus
was the archetypal species for S. equi and that both are genetically
more distant from
S. equisimilis and S. dysgalactiae. The intergenic spacer
can be used to identify specifically
the group C. streptococci and as an epidemiological marker for
S.
zooepidemicus.
Publisher
Cambridge University Press (CUP)
Subject
Infectious Diseases,Epidemiology
Cited by
66 articles.
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