Molecular basis of variation in protective SzP proteins of Streptococcus zooepidemicus.
OBJECTIVE
To characterize, on a molecular basis, variable regions of the SzP proteins of the Moore and Bryans serovars of Streptococcus zooepidemicus and specificity of opsonic responses.


METHODS
14 Moore and Bryans serovars of S zooepidemicus.


METHODS
Using polymerase chain reaction analysis and primers from the 5' and 3' sequences of the prototype gene SzPW60, the SzP genes of each Moore and Bryans serovar were sequenced and translated, then the amino acid sequences were compared.


RESULTS
Comparison of the amino acid sequences revealed 2 variations at the N terminus; a hypervariable (HV) region from residue 106 to 166, approximately; and proline-glutamic acid-proline-lysine repeats in the carboxy terminus that ranged in number from 7 to 12. Five distinct motifs, HV 1 to 5, which varied independently of the N termini were found in the internal HV region. All serovars were opsonized by antiserum to the prototype SzPW60 protein, indicating that opsonogenic epitopes are on the conserved regions of the protein.


CONCLUSIONS
Variant motifs may be valuable in epizootiologic and pathogenesis studies of S zooepidemicus infections of the respiratory tract of young horses and in determining whether there are populations of S zooepidemicus unique to specific animal hosts. It is also clear from the opsonic responses to SzP that at least a portion of the protective responses are probably not serovar specific.
Walker
J A
JA
Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington 40546-0099, USA.
Timoney
J F
JF
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D015139:Blotting, Southern; D003001:Cloning, Molecular; D014644:Genetic Variation; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D018502:Streptococcus equi / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins