Bovine leukemia virus (BLV) infection is a chronic viral infection of cattle and endemic in many countries, including Japan. Our previous study demonstrated that PGE 2 , a product of cyclooxygenase (COX) 2, suppresses Th1 responses in cattle and contributes to the progression of Johne disease, a chronic bacterial infection in cattle. However, little information is available on the association of PGE 2 with chronic viral infection. Thus, we analyzed the changes in plasma PGE 2 concentration during BLV infection and its effects on proviral load, viral gene transcription, Th1 responses, and disease progression. Both COX2 expression by PBMCs and plasma PGE 2 concentration were higher in the infected cattle compared with uninfected cattle, and plasma PGE 2 concentration was positively correlated with the proviral load. BLV Ag exposure also directly enhanced PGE 2 production by PBMCs. Transcription of BLV genes was activated via PGE 2 receptors EP2 and EP4, further suggesting that PGE 2 contributes to disease progression. In contrast, inhibition of PGE 2 production using a COX-2 inhibitor activated BLV-specific Th1 responses in vitro, as evidenced by enhanced T cell proliferation and Th1 cytokine production, and reduced BLV proviral load in vivo. Combined treatment with the COX-2 inhibitor meloxicam and anti-programmed death-ligand 1 Ab significantly reduced the BLV proviral load, suggesting a potential as a novel control method against BLV infection. Further studies using a larger number of animals are required to support the efficacy of this treatment for clinical application.

ABSTRACT. In this study, we investigated whether ozonated autohemoadministration (OAHA) influences leukocyte populations in cows with clinical inflammatory disease. Eleven cows with inflammatory disease (Inflammatory Group) and three healthy cows (Control Group) were used for this study. The CD4 + /CD8 + ratio in the Inflammatory Group increased significantly compared to that in the Control Group 3 to 4 days after OAHA treatment. In the Inflammatory Group, the number of CD14 + cells decreased gradually after OAHA, but CD14 + levels remained stable in the Control Group. The number of MHC class-II + cells decreased gradually in the Inflammatory Group, but increased gradually in the Control Group, and the difference between the groups was significant on day 14 after OAHA. These findings suggest a possible difference in the activation of immune response after OAHA in infected cows compared to healthy cows. KEY WORDS: dairy cow, leukocyte population, ozonated autohemoadministration.

ABSTRACT. The effects of chlorpromazine (CPZ), pentoxifylline (PTX) and dexamethasone (DEX) on mRNA expression of lipopolysaccharide (LPS)-induced proinflammatory cytokines were examined in bovine peripheral blood mononuclear cells (PBMCs) in vitro. The expression of inflammatory cytokine mRNAs was analyzed by RT-PCR and Southern blot hybridization in bovine PBMCs. CPZ and DEX decreased the expression of cytokine mRNA (such as interleukin-1β and tumor necrosis factor-α) after stimulation with LPS in a dose-dependent manner. However, pretreatment with PTX had no inhibitory effect on the mRNA expression of proinflammatory cytokines. These results indicated that pretreatment with CPZ and DEX might be effective to reduce the production of LPS-induced inflammatory cytokines in bovine PBMCs in vitro.

ABSTRACT. Changes in subsets of peripheral blood mononuclear cells and lymphocyte blastogenesis reaction were observed after ozonated autohemoadministration (OAHA) in calves. Ten healthy calves were used in this study. After OAHA, CD8 + cells, CD14 + cells and WC1 + cells increased (p<0.05). The level of lymphocyte blastogenesis stimulated by PHA decreased after OAHA. A significant increase in serum IL-6 activity was observed in OAHA calves. These results suggested that OAHA induced immunological changes in calves. KEY WORDS: calf, immunological response, ozonated autohemoadministration.