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Infection and Immunity, January 2001, p. 392-399, Vol. 69, No. 1
Institute for Animal Health, Compton
Laboratory, Compton, Berkshire RG20 7NN, United Kingdom,1
and Laboratoire de Genetique Microbienne, Institut National de
la Recherche Agronomique, Jouy en Josas, France2
Received 24 May 2000/Returned for modification 31 July
2000/Accepted 9 October 2000
The hyaluronic acid capsule of Streptococcus uberis has
been implicated in conferring resistance to phagocytosis by bovine neutrophils. Construction of a bank of random insertion mutants of
S. uberis (strain 0140J) was achieved using the
pGh9::ISS1 mutagenesis system (22). Phenotypic
screening of approximately 5,000 clones enabled the isolation of 11 acapsular mutants. Southern hybridization indicated that two mutants
carried a lesion within a group of genes similar to those involved in
the assembly of the hyaluronic acid capsule found in the group A
Streptococcus (GAS) has operon. The DNA
sequence flanking the points of insertion confirmed the presence of
homologues of GAS hasA and hasB in S. uberis. The DNA sequence flanking the ISS1 insertion
in another mutant identified a homologue of hasC in
S. uberis. The GAS hasABC operon structure was
not conserved in S. uberis, and two discrete loci
comprising homologues of either hasAB or hasC
were identified. Disruption of S. uberis hasA or
hasC resulted in the complete cessation of hyaluronic acid
capsule production. Correspondingly, these mutants were found to have
lost their resistance to phagocytosis by bovine neutrophils. The
bactericidal action of bovine neutrophils on S. uberis
0140J was shown unequivocally to depend upon the capsule status of the bacterium.
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.1.392-399.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Identification and Disruption of Two Discrete Loci
Encoding Hyaluronic Acid Capsule Biosynthesis Genes
hasA, hasB, and hasC in
Streptococcus uberis
*
Corresponding author. Mailing address: Institute for
Animal Health, Compton Laboratory, Compton, Berkshire RG20 7NN, United Kingdom. Phone: 44 (0) 1635 578411. Fax: 44 (0) 1635 577243. E-mail: james.leigh{at}bbsrc.ac.uk.
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