Table 2.
Experimental doses and measured response variables for virulence (percent morality and median day to death) and success (myxospores per actinospore and total myxospores per fish). Juvenile Chinook salmon were exposed to genotypes I (“I”) and/or II (“II”), or specific-pathogen free well water (“W”). Exposures were conducted either concurrently on day 0 or sequentially on days 0 and 6. “.” indicates separation between dose dates (e.g., I.W = exposed to genotype-I on day 0, exposed to water on day 6). Values are means ± 1 S.E. Target doses were as follows: 5 actinospores fish−1 administered in a single exposure (positive controls), 10 actinospores fish−1 administered in a single exposure (concurrent treatments), and 10 actinospores fish−1 administered over two exposure periods (5 per exposure, sequential treatments). Actual doses varied from target doses.
| Treatment type | Treatment | Dose per fish | Percent Mortality | Median Day to Death | Myoxspores per actinospore | Total myxospores per fish |
|---|---|---|---|---|---|---|
| Negative controls |
– |
0 |
0 |
N/A |
. |
0 |
| Positive controls (target dose 5 actinospores fish−1) | I.W | 2.9 | 100 ± 0 | 23 ± 0 | 3249 ± 1690 | 5800 ± 402 |
| W.I | 2.2 | 100 ± 0 | 23 ± 0 | 1939 ± 181 | 4264 ± 795 | |
| II.W | 3.0 | 58 ± 6 | 40 ± 1 | 18795 ± 3792 | 59166 ± 16189 | |
| W.II |
5.3 |
56 ± 11 |
43 ± 2 |
23042 ± 20572 |
68705 ± 52379 |
|
| Concurrent (target dose 10 actinospores fish−1; 5 each per genotype, in a single exposure) | I + I.W | 5.6 | 93 ± 7 | 21 ± 0 | 715 ± 105 | 3872 ± 576 |
| I + II.W | 3.6(I), 2.4(II) | 98 ± 2 | 22 ± 0 | 747 ± 398(I), 646 ± 284(II) | 2538 ± 1196(I), 1445 + 597(II) |
|
| II + II.W |
2.9 |
40 ± 15 |
36 ± 5 |
8548 ± 4122 |
20896 ± 7260 |
|
| Sequential (target dose 10 actinospores fish−1; 5 each per genotype, administered over 2 exposures) | I.I | 10.1 (7.3 + 2.8) | 100 ± 0 | 22 ± 1 | 617 ± 191 | 6237 ± 2071 |
| I.II | 4.8(I), 3.7(II) | 98 ± 2 | 23 ± 0 | 1137 ± 275(I), 43 ± 17(II) |
5161 ± 1045(I), 183 ± 84(II) |
|
| II.I | 1.7(I), 4.0(II) | 100 ± 0 | 30 ± 0 | 2620 ± 1816(I), 5859 ± 2544(II) |
2843 ± 1079(I), 17821 ± 10356(II) |
|
| II.II | 7.0 (2.3 + 4.7) | 40 ± 4 | 40 ± 1 | 4024 ± 2952 | 31579 ± 23953 |