Table 2.
Histopathological changes in the gastro-intestinal tract of 4-day-old CDCD piglets inoculated with different passages of PEDV PC22A.
| PC22A passage | Villous atrophy A, B, C | VH:CD ratios (Sampling time, dpi) A, B |
Infection Sites in intestines |
Intra-cellular PEDV N protein staining pattern | |||
|---|---|---|---|---|---|---|---|
| Vertical (location) B |
Longitudinal (extent) |
||||||
| Villous D | Crypt | D, J, I | C | ||||
| P3 | Severe | 0.99–2.80 (1–3) | +++ (entire) | + | D (patchy), J, I (cont.) | + | diffuse |
| P95C13 (CCL81) | Moderate to severe | 3.73 (2), 2.17 (3), 1.19 (6) | +++ (entire) | – | D (patchy), J, I (cont.) | + | diffuse |
| P100C4 | Moderate | 2.34 (6), 2.54–3.91 (10) | +/++ (entire) | – | D (patchy), J, I (cont.) | – | diffuse |
| P100C6 | Moderate to severe | 6.32 (6), 5.02–6.33 (10), 0.74 (10) |
+/++ (entire) | – | J, I (patchy) | – | diffuse |
| P100C4 + P10 | Moderate | 7.71 (6), 4.76 (9) | +/++ (entire) | – | J, I (patchy) | – | diffuse |
| P120 | Moderate | 3.59 (9) | + (entire/top) | – | J, I (patchy) | – | stippled E |
| P140 | Mild | 4.99 (9) | – | – | – | – | – |
| P160 | No to mild | 5.21 (9) | – | – | – | – | – |
| Mock | No | 9.01 (3), 7.31 (6), 6.80 (9) | |||||
dpi: days post-inoculation, VH:CD: villous height: crypt depth, D: duodenum, J: jejunum, I: ileum, C: colon; cont.: continuous.
Only piglets dead/euthanized near onset of clinical signs and/or peak of fecal PEDV RNA shedding, if presented, are reported.
In jejunum.
Severe, moderate or mild villous atrophy was interpreted when VH:CD ratios <1/3, 1/3 to 2/3 and >2/3 of their age-matched controls.
−, +, ++, and +++ denotes none, less than 30%, 30% to 60% and more than 60% of villous enterocytes showing PEDV N protein positive cells, respectively.
Diffuse: positive signal presented in whole cytoplasm except nucleus. Stippled: pinpoint signal scattered in the cytoplasm.