TABLE 1.
Serologic analysis of dogs naturally or experimentally infected with T. cruzi
| Weeks post-infection | ||||||
|---|---|---|---|---|---|---|
| T. cruzi infection | Week 0 | Week 1 | Week 2 | Week 3 | Week 4 | Week 10 |
| IHA | ||||||
| Natural (A) | + | + | + | + | + | + |
| Zump (B) | − | − | + | + | + | + |
| Sylvio (C) | − | − | + | + | + | ND |
| None (D) | − | − | − | − | − | − |
| ELISA—OD450nm ± SD | ||||||
| Natural (A) | 1.85 ± 0.07 | 1.81 ± 0.03 | 1.88 ± 0.05 | 1.89 ± 0.02 | 1.88 ± 0.02 | 1.92 ± 0.05 |
| Zump (B) | 0.11 ± 0.03 | 0.14 ± 0.01 | 0.16 ± 0.05 | 0.25 ± 0.04 | 0.38 ± 0.07 | 1.05 ± 0.61 |
| Sylvio (C) | 0.09 ± 0.03 | 0.18 ± 0.03 | 0.16 ± 0.04 | 0.28 ± 0.04 | 0.53 ± 0.2 | ND |
| None (D) | 0.13 ± 0.01 | 0.13 ± 0.02 | 0.17 ± 0.03 | 0.13 ± 0.003 | 0.14 ± 0.02 | 0.15 ± 0.01 |
| Cut-off (CV) | 0.23 (0.21–0.26) | 0.23 (0.28–0.25) | 0.27 (0.25–0.30) | 0.23 (0.28–0.25) | 0.24 (0.22–0.27) | 0.25 (0.22–0.27) |
Sera samples were collected from dogs with natural T. cruzi infection (Group A) and dogs that were experimentally infected with Zumpahuacan (Zump, Group B) or Sylvio-X10 (Sylvio, Group C) isolates of T. cruzi at 1, 2, 3, 4, and 10 weeks post-infection. Normal, uninfected dogs (none, Group D) were used as controls. The sera level of anti-T. cruzi antibodies was determined by IHA and ELISA. IHA: +, positive at least at a 1/8 serum dilution; −, negative. The + and − represent mean of triplicate observations from four dogs in each group. ELISA: cut-off = average of negative controls +0.1 (±10%). Absorbance (OD450nm) ± SD values are representative of mean of triplicate observations per dog, four dogs per group, with variation coefficient subtracted at 10% level.
CV = coefficient of variation; ND = not determined because dogs died, and no samples were available.