Estradiol administration
To evaluate the effects of exogenous estradiol in vivo , estradiol
administration was performed using BLV-infected cattle (animals
#6–#10, Table 1). 2.5 mg/100 kg of estradiol benzoate (OVAHORMON
INJECTION; Aska Animal Health, Tokyo, Japan) was inoculated
intramuscularly, and peripheral blood samples were collected from these
cattle before inoculation (Day 0) and at 1 and 6 hours and 1, 2, 3, 4,
and 7 days after inoculation. PGE2 and estradiol
concentrations in serum were measured by ELISA, as described above.
Whole-blood culture and PBMC culture were conducted to evaluate
BLV-nonspecific and BLV-specific Th1 responses, respectively.