Table 1.
Outline of examined BLV-infected but clinically normal cattle
| Cattle | Age (years) | WBC (/μl) | Lymphocyte (/μl) (%) | Clinical stagea | ELISAb |
Proviral loadc (Copies/1 × 105cells) |
Syncytium assayd (Number/5 × 106cells) |
|---|---|---|---|---|---|---|---|
| BLV-free normal cattle | |||||||
| N790 |
2.5 |
9,540 |
6,382 (66.9) |
- |
- |
0 |
0 |
| N791 |
2.5 |
8,260 |
4,956 (60.0) |
- |
- |
0 |
0 |
| BLV-infected cattle | |||||||
| 1) Cattle with < 100 proviral load | |||||||
| N818 |
2.0 |
9,410 |
5,147 (54.7) |
AL |
+ |
8 |
0 |
| N789 |
2.5 |
5,472 |
5,472 (60.2) |
AL |
+ |
26 |
1 |
| 2) Cattle with > 100 proviral load | |||||||
| N787 N733 |
2.5 |
8,730 |
4,487 (51.4) |
AL |
+ |
294 |
250 |
| 2.5 |
8,230 |
6,313 (68.4) |
AL |
+ |
1,614 |
400 |
|
| N823 |
2.0 |
9,340 |
6,239 (66.8) |
AL |
+ |
11,112 |
11,000 |
| N788 |
2.5 |
9,620 |
5,435 (56.5) |
AL |
+ |
18,094 |
17,500 |
| O10 | 15.0 | 12,200 | 7,900 (64.8) | PL | + | 10,689 | 9,086 |
aThe clinical stage of BLV infection was evaluated according to the lymphocyte count (per 1 μl), the detection of atypical mononuclear cells, and the age of the animal [19]. AL, BLV-infected but clinically and hematologically normal cattle; PL, BLV-infected but clinically normal cattle showing an increase in the number of apparently normal B lymphocytes. In the latter case, three separate lymphocyte counts were performed at different times and all yielded the same results.
bELISA was performed using an anti-BLV ELISA kit according to the manufacturer’s instructions (JNC Inc., Tokyo, Japan). +, positive for anti-BLV antibodies; -, negative for anti-BLV antibodies.
cThe proviral load (expressed as the copy number per 105 peripheral blood mononuclear cells [PBMCs]) was evaluated by BLV-CoCoMo-qPCR as previously described [19].
dPBMCs were mixed with CC81 cells and 4 μg/ml polybrene (Sigma, St. Louis, MO) and used in the syncytium formation assay [19]. Syncytia were counted under a light microscope.