Compositions and methods related to protein A (SpA) variants
The present invention concerns methods and compositions for treating or preventing a bacterial infection, particularly infection by a Staphylococcus bacterium. The invention provides methods and compositions for stimulating an immune response against the bacteria. In certain embodiments, the methods and compositions involve a non-toxigenic Protein A (SpA) variant.
1. A recombinant nucleic acid molecule comprising a nucleic acid sequence encoding a Staphylococcus aureus Protein A (SpA) D domain segment having (a) at least one amino acid substitution that disrupts Fc binding and (b) at least one amino acid substitution that disrupts VH3 binding and (c) an amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 2, wherein the amino acid substitutions correspond to amino acids at position 9, 10, 36 and/or 37 of SEQ ID NO: 2; and wherein the substitutions at amino acids corresponding to positions 9 and 10 are with a glycine residue and the substitutions at amino acids corresponding to positions 36 and 37 are with a serine residue; or wherein the substitutions at amino acids corresponding to positions 9 and 10 are with a lysine residue and the substitutions at amino acids corresponding to positions 36 and 37 are with an alanine residue.
2. The nucleic acid molecule of claim 1 , wherein the SpA D domain segment is at least 90% identical to the amino acid sequence of SEQ ID NO: 2.
3. The nucleic acid molecule of claim 1 , further comprising a nucleic acid sequence encoding one or more SpA E domain, A domain, B domain or C domain.
4. The nucleic acid molecule of claim 1 , further comprising a nucleic acid sequence encoding a non-Protein A segment.
5. The nucleic acid molecule of claim 1 , further comprising a nucleic acid sequence encoding a second antigen segment, wherein the second antigen segment is a staphylococcal antigen segment selected from Emp, EsxA, EsxB, EsaC, Eap, Ebh, EsaB, Coa, vWbp, vWh, Hla, SdrC, SdrD, SdrE, IsdA, IsdB, IsdC, ClfA, ClfB, and/or SasF segment.
6. The nucleic acid molecule of claim 1 , wherein the (SpA) D domain segment has glycine substitutions at amino acids corresponding to positions 9 and 10 and serine substitutions at amino acids corresponding to positions 36 and 37 of SEQ ID NO:2.
7. The nucleic acid molecule of claim 1 , wherein the (SpA) D domain segment has lysine substitutions at amino acids corresponding to positions 9 and 10 and alanine substitutions at amino acids corresponding to positions 36 and 37 of SEQ ID NO:2.
8. A host cell comprising the nucleic acid molecule of claim 1 .
9. A method of making an isolated polypeptide comprising expressing the recombinant nucleic acid molecule of claim 1 in a host cell.
10. The method of claim 9 , wherein the host cell is a bacterial cell or eukaryotic cell.
11. The method of claim 9 , wherein the method comprises culturing the host cell.
12. The method of claim 11 , wherein the host cell is induced to express the polypeptide.
13. The method of claim 9 , wherein the (SpA) D domain segment has glycine substitutions at amino acids corresponding to positions 9 and 10 and serine substitutions at amino acids corresponding to positions 36 and 37 of SEQ ID NO:2.
14. The method of claim 9 , wherein the (SpA) D domain segment has lysine substitutions at amino acids corresponding to positions 9 and 10 and alanine substitutions at amino acids corresponding to positions 36 and 37 of SEQ ID NO:2.