In vitro interactions of cytokines and bovine viral diarrhea virus in phytohemagglutinin-stimulated bovine mononuclear cells

Effect of interleukin-1 receptor antagonist on concanavalin A response of peripheral blood mononuclear cells from newborn calves

The coexistence of interleukin (IL)-1beta with IL-1 receptor antagonist (ra) in bovine colostrum and the possibility of simultaneous transfer of these cytokines to neonates via colostrum have been demonstrated. In the present study, we investigated the effect of IL-1ra on the mitogenic response of calf peripheral blood mononuclear cells (PBMC) stimulated by concanavalin A (ConA), which was mediated by IL-1. Pretreatment of PBMC with recombinant bovine (rb) IL-1ra alone significantly suppressed the proliferation of ConA-stimulated cells. However, in the presence of rbIL-1beta, the suppressive activity of rbIL-1ra was counteracted. These results suggest that coexistence of IL-1ra with IL-1 in colostrum may have no effect on the activation of the neonatal immune system by IL-1beta.

Detection of bovine viral diarrhea virus in the ovaries of cattle acutely infected with bovine viral diarrhea virus

Bovine viral diarrhea virus (BVDV) is recognized worldwide as a major cause of economic loss in cattle. Infection with BVDV can result in several clinical outcomes. However, the reproductive consequences may be the most important. Infertility, early embryonic death, abortion, and congenital anomalies have all been reported following acute infection with BVDV. The cause of infertility following acute BVDV infection is not known. BVDV has been isolated from the bovine ovary and has been associated with chronic oophoritis. The purpose of this study was to identify the ovarian cell types infected with BVDV following acute infection. Twelve heifers were acutely infected with noncytopathic BVDV, and ovariectomies were performed between 4 and 60 days postinfection. BVDV was isolated on days 6 and 8 postinfection. Viral antigen was detected in macrophage-like cells and stromal cells in the ovarian cortex and oophoritis was evident from 6 to 60 days postinfection. These findings indicate that acute infection with BVDV may result in changes in ovarian function that could lead to reduced fertility.

Immunology of bovine viral diarrhea virus

Often persistent and primary postnatal infections with BVDV result in immunosuppression in cattle, thereby enhancing the vulnerability of the latter to secondary infections. The evidence for and nature of impaired immunity in these animals is reviewed. Our knowledge of the extent and nature of protective immunity induced by natural BVDV infections and vaccines is still in its infancy. Significant new information on the bovine immune response to BVDV antigens, however, has been identified in recent years. These data are reviewed and related to prospects for improved immunoprophylaxis against diseases caused by the virus.

Control of bovine viral diarrhea infection by use of vaccination

Vaccination with either inactivated or modified live virus vaccines is beneficial for control of BVD in cattle. The advantages and/or disadvantages of each type of vaccine often influence vaccine selection. The frequency of vaccination depends on the herd management system, regional prevalence of BVDV, and required duration of protection. Vaccines for BVD likely will change in content as knowledge of BVDV increases and as new technologies are adapted for vaccine production.

Lymphocyte responses to viral antigens and phytohaemagglutinin in persistently viraemic sheep and lambs experimentally infected with Border disease virus

Lymphocytes obtained from lambs 5 to 21 days after experimental infection with Border disease virus (BDV) showed significant blastogenic responses to live or inactivated BDV. Live virus stimulated significantly higher lymphocyte transformation (LT) responses than inactivated virus. Lymphocytes obtained from uninfected control and persistently infected lambs had no significant response to live or inactivated antigen. Lymphocyte responses to phytohaemagglutinin were significantly higher in control lambs than in experimentally infected lambs in samples obtained 5 to 10 days post-inoculation.

Replication of border disease virus in ovine lymphocytes and monocytes in vitro

Adherent and non-adherent mononuclear cells obtained from the peripheral blood of normal sheep supported the in vitro replication of a non-cytopathic and a cytopathic strain of Border disease virus (BDV) with no apparent cytopathic effects. There was a significant rise in virus titres in adherent mononuclear cells (monocyte) and non-adherent (lymphocyte) cultures infected with both non-cytopathic and cytopathic strains of BDV 24 hours after inoculation. Peak virus titres of 5.36 log10 TCID50 ml-1 were recorded in adherent samples incubated for 48 hours while peak titres of 6.17 log10 TCID50 ml-1 were recorded in lymphocyte culture after 72 hours of incubation. Both the non-cytopathic and the cytopathic strains of BDV produced significantly higher titres in non-adherent (lymphocyte) cultures than in adherent (monocyte) cultures (P < 0.001) but the replication in adherent cells was faster than in nonadherent cell cultures. The addition of virus on both types of mononuclear cell cultures had no effect on cell viability but it had a significant inhibitory effect on the blastogenic responses of lymphocytes to phytohaemagglutinin.

Effects of recombinant human cytokines on mitogen-induced bovine peripheral blood mononuclear cell proliferation

The effects of interleukin 1 alpha (IL-1 alpha), IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, and insulin growth factor-1 (IGF-1) on proliferation of mitogen-stimulated bovine peripheral blood mononuclear cells (PBMC) were determined. Four concentrations of each cytokine were incubated 48 or 96 h with PBMC alone or with PBMC and three concentrations of three different mitogens. The mitogens included concanavalin A (Con A) phytohemagglutinin (PHA), and Escherichia coli 055:B5 lipopolysaccharide (LPS). Proliferation of unstimulated PBMC was not affected by IL-1 alpha, IL-1 beta, IL-3, IL-5, IL-6, IL-8, and IGF-1 whereas IL-2, IL-4, and IL-7 increased proliferation. Incubation of PBMC with Con A plus IL-1 alpha, IL-2, IL-4, IL-7 or IL-8 increased proliferation when compared to PBMC that were incubated with either Con A or the cytokine alone. Interleukin-1 beta, IL-3, IL-5, IL-6 and IGF-1 did not influence proliferation of Con A-stimulated PBMC. Proliferation of PHA-stimulated PBMC was increased when PBMC were cultured with IL-2, IL-4 or IL-7, but not when cultured with IL-1 alpha, IL-1 beta, IL-3, IL-5, IL-6, IL-8 or IGF-1. Similar results occurred with LPS-stimulated PBMC in that proliferation induced by LPS was enhanced by IL-2 or IL-7, but not by any of the other cytokines.(ABSTRACT TRUNCATED AT 250 WORDS)

Immune mechanisms in the pathogenesis of viral diseases: a review

Three immunopathological mechanisms may determine the pathogenesis of viral diseases in animals. (1) A variety of viruses causes transient or prolonged immunosuppression by infecting lymphoreticular tissues and interacting with components of the immune system. (2) In persistent viral infections effective immune responses may result in tissue damage. The mechanisms involved are T-cell-mediated destruction of infected cells and delayed-type hypersensitivity. (3) In a number of viral diseases pathogenic immune complexes are formed when antibodies are produced and react with viral antigen molecules persisting in the host. The selected examples of immune dysfunction are the focus of this review.

Bovine virus diarrhoea virus induces in vitro a proliferative response of peripheral blood mononuclear cells from cattle immunized by infection

The ability of bovine peripheral blood mononuclear cells (PBMC) to mount a proliferative response to bovine virus diarrhoea virus (BVDV) in vitro was examined. After culturing PBMC in the presence of a non-cytopathic strain of BVDV for 6 days, the magnitude of PBMC proliferation was measured as incorporation of radiolabelled thymidine, present during the last 18 h. Live, but not heat-inactivated, BVDV evoked a proliferative response of PBMC obtained from cattle seropositive to the virus. However, PBMC from seronegative or persistently BVDV-infected animals were not stimulated by BVDV. The presence of live BVDV did not alter the proliferative response of PBMC to stimulation with concanavalin A.

In vitro inhibition of 5-lipoxygenase metabolite, leukotriene B4, in bovine mononuclear cells by bovine viral diarrhea virus

Bovine viral diarrhea (BVD) virus inhibited phytohemagglutinin (PHA)-, PHA plus phorbol-12-myristate-13 acetate (PMA)- or PHA plus calcium ionophore (A23187)-stimulated bovine peripheral blood mononuclear cell (PBMC) proliferation. Further, BVD-virus inhibited A23187-stimulated leukotriene B4 (LTB4) synthesis into the culture supernatants. Presence of exogenous LTB4 failed to reverse the BVD virus-induced immunosuppression. Our results suggest that BVD virus-induced immunosuppression is due to a factor that may be necessary to induce LTB4 synthesis for normal mononuclear cell proliferation.

Effect of infection by bovine viral diarrhea virus (BVDV) in vitro on interleukin-1 activity of bovine monocytes

The effect of bovine viral diarrhea virus (BVDV) infection in vitro on the interleukin-1 (IL-1) activity of bovine monocytes was studied. Supernatants from BVDV-infected monocytes suppressed IL-1-stimulated proliferation of mouse thymocytes and masked lipopolysaccharide-stimulated IL-1 activity of bovine monocytes in the mouse comitogen thymocyte assay. Suppression of mouse thymocyte proliferation was restored by the addition of IL-1. IL-1 inhibitory activity was induced both by the prototype variants BVDV/NADL cytopathic and BVDV/NY-1 noncytopathic and by BVDV variants isolated from persistently infected cattle. Suppressed IL-1 activity was also found in supernatants from monocytes from persistently infected cattle following infection with BVDV in vitro. No differences in levels of IL-1 mRNA synthesis were detected between BVDV-infected and uninfected monocytes by RNA-cDNA hybridization. These results suggest that infection of bovine monocytes with BVDV results in the production and/or activation of a soluble inhibitor of IL-1 activity.