TABLE 1.
Degree of leukocyte infiltration at day 28 postinfectiona
| Age (mo) | Inoculum (IFU) | Degree of infiltrationb
|
||
|---|---|---|---|---|
| Lung | Heart | Brain | ||
| 6 | 0 | − | − | − |
| 6 | 0 | − | − | − |
| 20 | 0 | − | − | − |
| 6 | 5 × 104 | + | + | − |
| 6 | 5 × 104 | + | ++ | − |
| 20 | 5 × 104 | ++ | ++ | − |
| 20 | 5 × 104 | + | ++ | − |
| 20 | 5 × 104 | ++ | +++ | +/− |
| 6 | 5 × 105 | + | + | − |
| 6 | 5 × 105 | + | ++ | − |
| 6 | 5 × 105 | − | − | − |
| 20 | 5 × 105 | − | + | − |
| 20 | 5 × 105 | ++ | +++ | − |
| 20 | 5 × 105 | +++ | ++ | − |
a
The perfusion fixed tissues of all mice examined by histology evaluation were examined by a pathologist in order to determine the extent of leukocytic infiltration. Tissues were stained with hematoxylin and eosin and scored based on the degree of leukocyte infiltration.
b
Scoring: −, normal appearance; +, limited, focal distribution of leukocytes present in several fields of view; ++, multiple foci of leukocytes; +++, diffuse accumulations of leukocytes. Four sections were evaluated for each tissue.