TABLE 2.
Conjugation method/immunogenicity relationships of conjugates prepared with a 10-mer of γDPGA bound to rPAa
| Conjugate | γDPGA (mol)/ protein (mol) | Protein/γDPGA (wt/wt) | Anti-γDPGA (EU)
|
Anti-rPA (μg/ml)
|
||
|---|---|---|---|---|---|---|
| 2nd injection | 3rd injection | 2nd injection | 3rd injection | |||
| Thioether linkage | ||||||
| rPA-SH/Br-Gly3-γDPGA10 | 14 | 1:0.22 | 4,400 | 7,200 | 0.3 | 66 |
| rPA-Br/Cys-Gly3-γDPGA10 | 22 | 1:0.35 | 2,200 | 5,800 | 2 | 210 |
| rPA-ITL/Br-Gly3-γDPGA10 | 8 | 1:0.13 | 2,300 | 3,700 | 4.7 | 61 |
| Oxime linkage | ||||||
| rPA-CONH2/CHO-Gly3-γDPGA10 | 20 | 1:0.32 | 2,000 | 4,300 | 0.4 | 25 |
| Hydrazone linkage | ||||||
| rPA-CHO/AH-γDPGA15 | 15 | 1:0.36 | 2,200 | 3,000 | 0.2 | 6 |
| rPA-AH/CHO-Gly3-γDPGA10 | 22 | 1:0.34 | 1,000 | 2,500 | 0.3 | 28 |
a
Five- to 6-week-old NIH general-purpose mice (n = 10) were injected subcutaneously with 2.5 μg of γDPGA as a conjugate 2 weeks apart and exsanguinated 7 days after the second or third injection. IgG anti-γDPGA and anti-rPA were measured by ELISA, and the results are expressed as the geometric means.