Table 2.
Detection of parasite DNA and histopathological changes in foetal and maternal tissues of immunised and non-immunised cattle after challenge infection with the Nc-1 isolate in early gestation
| Group | Time of foetal death (dpc) a |
Foetal |
Serology |
Tissues from foetus/calf |
Maternal placenta |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| crown-rump length (cm) | in progeny (IFAT) c |
Brain |
Liver |
Heart |
|||||||||||
| HP d | DNA e | MS f | HP d | DNA e | MS f | HP d | DNA e | MS f | HP d | DNA e | MS f | ||||
| 2 (Immunised/70-challenged) |
26 |
14 |
- |
+ |
3/3 |
Nc-1 |
++ |
3/3 |
Nc-1 |
++ |
3/3 |
Nc-1 |
++ |
1/3 |
Nc-1 |
| 97b |
15 |
nd |
+ |
0/3 |
- |
++ |
0/3 |
- |
++ |
0/3 |
- |
++ |
1/3 |
na |
|
| Alive |
nd |
- |
- |
0/12 |
- |
- |
0/3 |
- |
- |
0/3 |
- |
- |
0/3 |
- |
|
| Alive |
nd |
- |
- |
0/12 |
- |
- |
0/3 |
- |
- |
0/3 |
- |
- |
0/3 |
- |
|
| Alive |
nd |
- |
- |
0/12 |
- |
- |
0/3 |
- |
- |
0/3 |
- |
- |
0/3 |
- |
|
| 3 (Non-immunised/70-challenged) | 26 |
17 |
- |
+ |
1/9 |
na |
- |
0/3 |
- |
- |
0/3 |
- |
- |
0/3 |
- |
| 26 |
16 |
- |
+ |
3/3 |
Nc-1 |
++ |
3/3 |
Nc-1 |
++ |
3/3 |
Nc-1 |
++ |
2/3 |
na |
|
| 77 |
18 |
1:32 |
* |
1/3 |
na |
* |
0/3 |
- |
* |
1/3 |
na |
++ |
2/3 |
na |
|
| 83 |
30 |
- |
* |
1/3 |
na |
++ |
2/3 |
na |
++ |
2/2 |
na |
++ |
2/3 |
na |
|
| Alive | nd | - | - | 0/12 | - | - | 0/3 | - | - | 0/3 | - | - | 0/3 | - | |
a Day post-challenge when foetal death was detected by transrectal ultrasonography. The remaining foetuses lived until the end of the experiment.
b This foetus was mummified but probably died two months before (around 33 dpc) as indicated by its foetal crown-rump length. The poor quality of the samples from this mummified foetus most likely made the detection of parasite DNA unfeasible. Foetal abdominal fluid for serological analysis could not be collected.
c Mean IFAT IgG antibody titres in foetal body fluids and in pre-colostral serum collected after birth in calves born alive.
d Histopathological lesion severity: none detected (-), consistent with (+), and characteristic of (++) N. caninum infection; * Autolysed.
e Fractions represent number of samples positive by nested PCR/number of samples examined.
f Microsatellite analysis was performed using one sample per nested-PCR-positive tissue. Microsatellite markers could not be amplified from all of the PCR-positive tissues analysed (na). The microsatellite profiles of the tissues from which the microsatellite markers could be amplified corresponded to that of the challenge isolate (Nc-1).