Table 1.
Protection conferred by immunization with vaccines in hamsters.
| Vaccine Formulation a | % Protection b | Endpoint Day | Kidney Positive Detection c | ||
|---|---|---|---|---|---|
| Antigen | Adjuvant | Culture | qPCR | ||
| PBS | LMQ | 0 | 7, 8, 9, 10, 11 | 0/5 | 5/5 |
| Heat-killed Leptospira | Freund’s | 100 ** | 28, 28, 28, 28, 28 | 0/5 | 5/5 |
| LigAc | LMQ | 60 ** | 11, 11, 28, 28, 28 | 0/5 | 5/5 |
| LenA | LMQ | 40 | 8, 8, 9, 28, 28 | 0/5 | 5/5 |
| LcpA | LMQ | 20 | 7, 7, 8, 8, 28 | 0/5 | 5/5 |
| Lsa23 | LMQ | 20 | 7, 7, 8, 10, 28 | 0/5 | 5/5 |
| LigAc + LenA + LcpA + Lsa23 | LMQ | 60 * | 9, 10, 28, 28, 28 | 0/5 | 5/5 |
a PBS: phosphate buffered saline; LMQ: a combination of neutral liposome, monophosphoryl lipid A, and Quillaja saponaria fraction 21. LigAc, LenA, LcpA, Lsa23: recombinant factor H binding protein subunit vaccines. The final volume ratio of LMQ or Freund’s adjuvants to immunogen was 6:4 or 1:1, respectively. b % Protection was calculated by the number of survivors/total challenged hamsters ×100 (n = 5/group). Statistical values of survival rate between adjuvant control group and other vaccination groups were analyzed by log-rank test; * represents p < 0.05 and ** represents p < 0.01. c Positive detection was evaluated in all hamsters by culture and/or real-time PCR techniques. The results showed the number of positive detection/total challenged hamsters. The PCR negative detection for leptospires was assigned in a sample whose threshold cycle value was greater than 40 cycles.