A high molecular weight polysaccharide intracellular adhesin (SAE) antigen having the general structure of poly-1,6,β-2-amidoglucopyranoside, which is variable substituted with N-acetyl and O-succinyl substituents is described. Also, a method is given for isolating this antigen from Staphylococcus aureus . The SAE can be used in a vaccine, either alone, conjugated to an immunogenic protein, and/or with an immunogenic adjuvant.
1. An isolated Staphylococcus aureus exopolysaccharide (SAE) having the formula
wherein 40–60% of R 1 is H and the remainder of R 1 is COCH 3; and 75–95% of R 2 is H and the remainder of R 2 is an O-linked succinate and n is such that the molecular weight is at least about 300,000 Da.
2. A SAE according to claim 1 wherein 45–55% of R 1 is H, and 85–95% of R 2 is H.
3. A SAE according to claim 2 wherein 50% of R 1 is H, and 85–95% of R 2 is H.
4. An immunogenic composition comprising a SAE according to claim 1 .
5. A composition according to claim 4 in a physiologically acceptable salt solution.
6. An immunogenic composition comprising a SAE according to claim 1 covalently coupled to an immunogenic protein carrier.
7. A composition according to claim 6 further comprising an immunostimulatory adjuvant.
8. A method of inducing an immune response in an animal comprising administering an immunogenic composition of claim 4 .
9. A method of inducing an immune response in an animal comprising administering an immunogenic composition of claim 6 .
10. A method of making a SAE compound according to claim 1 , comprising the steps of:
a) concentrating medium obtained from a S. aureus culture to obtain a concentrated medium;
b) filtering the concentrated medium to obtain a retentate; and
c) digesting the retentate with a protease to obtain the SAE compound.
11. A method according to claim 10 , further comprising the steps of:
d) concentrating the SAE using diafiltration.
12. A method of making a SAE compound according to claim 10 , wherein step a) comprises concentrating medium obtained from a S. aureus culture using tangential flow filtration.
13. A method of making a SAE compound according to claim 10 , wherein step b) comprises a diafiltration step.