Frequency of association of noncytopathic bovine viral diarrhea virus with mononuclear leukocytes from persistently infected cattle.

All mononuclear leukocytes and T lymphocyte-enriched and B lymphocyte-enriched subpopulations of mononuclear leukocytes collected from 8 cows persistently infected with 1 of 3 isolates of noncytopathic bovine viral diarrhea virus were tested for association with virus. For all persistently infected cows, approximately 4.4% of all mononuclear leukocytes, 5.4% of T lymphocyte-enriched, and 2.1% of B lymphocyte-enriched subpopulations of mononuclear leukocytes were associated with virus. Differences between leukocyte populations in percentages of leukocytes associated with virus were real (P less than 0.05). Among virus isolates, significant differences in percentages of leukocytes associated with virus were not detected.