Table 6.
Viral neutralization test results using PRRSV strains 3262 and 3267
| |
Nº of responding pigs; mean titre (log2) and standard deviation Range of titres (log2) for positive pigs |
|||||||
|---|---|---|---|---|---|---|---|---|
| |
Strain used in the viral neutralization test |
|||||||
| |
3262 |
3267 |
||||||
| Days post-inoculation | Days post-inoculation | |||||||
|
Challenge group† |
21 |
42 |
84 |
98 |
21 |
42 |
84 |
98 |
|
A + A |
0/4 |
0/4 |
0/4 |
0/4 |
0/4 |
3/4* |
4/4* |
4/4* |
|
(3262+3262) |
- |
- |
- |
- |
- |
1.7 ± 0.6a |
2.0 ± 0.8a |
4.25 ± 1.0b |
| (1–2) |
(1–3) |
(3–5) |
||||||
|
A + B |
0/4 |
0/4 |
0/4 |
0/4 |
0/4 |
2/4 |
2/4 |
4/4* |
|
(3262+3267) |
- |
- |
- |
- |
- |
1.0 ± 0.0a |
2.0 ± 0.0a |
5.3 ± 0.5b |
| (1–1) |
(2–2) |
(5–6) |
||||||
|
C1 + B |
0/2 |
0/2 |
0/2 |
0/2 |
0/2 |
0/2 |
0/2 |
2/2* |
|
(C+3267) |
- |
- |
- |
- |
- |
- |
- |
2.5 ± 0.5 |
| (2–3) |
||||||||
|
B + B |
0/4 |
2/4 |
4/4‡ |
4/4‡ |
4/4‡ |
4/4 |
4/4 |
4/4 |
|
(3267+3267) |
0/4 |
1.0 ± 0.0 |
2.2 ± 1.5 |
2.8 ± 1.7 |
2.0 ± 0.8a |
2.5 ± 1.0a |
4.8 ± 1.0b |
6.0 ± 0.8b¶ |
| |
- |
(1–1) |
(1–4) |
(1–5) |
(1–3) |
(2–4) |
(4–6) |
(5–7) |
|
B + A |
0/3 |
0/3 |
3/3‡ |
3/3‡ |
1/3 |
3/3 |
3/3 |
3/3 |
|
(3267+3262) |
2.0 ± 1.0 |
1.3 ± 0.6 |
1.0 ± 0.0 |
3.0 ± 1.0a |
4.0 ± 1.0a |
5.3 ± 0.6b |
||
| |
- |
- |
(1–3) |
(1–2) |
(1–1) |
(2–4) |
(3–5) |
(5–6) |
|
C2 + A |
0/3 |
0/3 |
0/3 |
0/3 |
0/3 |
0/3 |
0/3 |
0/3 |
| (C+3262) | - | - | - | - | - | - | - | - |
† Chronological sequence of strains used for inoculation is shown in parentheses.
* The asterisk show statistical differences (p < 0.05) for the proportion of responding pigs using one or the other PRRSV strain.
Superscript letters indicate statistical differences (p < 0.05; ¶ p = 0.08) in the average titres between different days using a given strain.
‡ The symbol indicates statistically significant differences for the proportion of responding pigs for similar groups between experiments (i.e. homologous A + A vs. homologous B + B) using the same strain.