The eradication experience of enzootic bovine leukosis from Lithuania.

Before 1985 the situation regarding enzootic bovine leukosis (EBL) in Lithuanian cattle was described only haphazardly. In 1986 serological investigations were initiated together with an eradication programme. The EBL bovine leukosis virus (BLV) situation was monitored by the Institute of Immunology Vilnius University, national and regional veterinary laboratories. Starting in 1986 all EBL-positive cattle were separated from negative cattle into BLV-infected and BLV-free herds. To create the latter, calves were fed pasteurized milk. The seroprevalence in 1990 was 7.29%, but it steadily declined to 0.32% in 2006.

The distribution of Salmonella serovars in chicken and humans in Lithuania.

We studied serovars of Salmonella strains isolated from chicken and humans in Lithuania over the period from 2000 to 2004. Salmonella strains were isolated and identified according to the techniques recommended by International Organisation for Standardization (Microbiology of Food and Animal Feeding Stuff--Horizontal Method for the Detection of Salmonella, 1998, ISO, Geneva). The per cent of infected flocks with Salmonella in separate years was between 1.01% and 3.2% during the period of investigation. The contamination rate of broiler legs and breasts was higher (2.36% and 4.25%) than that of wings (0.82%). Eighteen serovars of Salmonella were identified from the total 300 isolated samples. The most prevalent serovars in chicken were Salmonella Enteritidis, Salmonella Infantis and Salmonella Typhimurium. Other serovars such as Salmonella Montevideo, Salmonella Djugu, Salmonella Isangi, Salmonella Bovismorbificans, Salmonella Mbankada, Salmonella Hadar were detected only in one to two samples. In general, similar serovars of Salmonella were found in humans and chicken (S. Enteritidis and S. Typhimurium), although distinct serovars were found only in humans or only in chicken. Analysis of the distribution of Salmonella serovars in humans during the seasons of the year indicated that the highest incidence of Salmonella was in Summer and in the beginning of Autumn. Analysis of the distribution of serovars during the study period indicated that there is a shift over time in both humans and chicken.

Alpha-1-acid glycoprotein inhibits phorbol ester-induced but not Fc-receptor-induced generation of reactive oxygen species in bovine peripheral blood neutrophils.

Alpha-1-acid glycoprotein (AGP) is an acute-phase protein with anti-inflammatory and immunomodulating properties. AGP is described as a potent inhibitor of the production of reactive oxygen species (ROS) in human neutrophils. However, published reports about the mechanism of inhibition are conflicting. The influence of bovine AGP on the production of ROS by bovine peripheral blood polymorphonuclear leucocytes (PMN) was studied using a highly sensitive method approaching its inhibitory mechanism. ROS production in PMN was induced with phorbol 12-myristate 13-acetate (PMA) or opsonized Staphylococcus aureus bacteria. ROS generation was quantified and evaluated by flow cytometry. AGP efficiently suppressed PMA, but did not opsonize bacteria-induced ROS generation in vitro. The suppressive effect was concentration-dependent and adversely proportional to PMA concentration. The selective inhibitory potential of AGP in comparison with ovalbumin (OVA) and bovine serum albumin (BSA) showed that ROS inhibition was not a mere protein effect. ROS production was suppressed only if AGP and PMA were simultaneously present with PMN. Pre-incubation of PMN with AGP did not alter the PMN response to PMA. Moreover, AGP could not suppress ROS production after pre-stimulation of PMN with PMA. Human and bovine AGP did not differ in their inhibitory potential to the PMA-induced ROS production in bovine, human and equine PMN. The results show that AGP does not modulate bovine neutrophil functions directly, but acts as a scavenger of PMA.

Obtaining immunologically active bovine viral diarrhea virus (BVDV) proteins for enzyme linked immunosorbent assay (ELISA).

We report here the preparation of BVDV antigen (Ag) to obtain adequate quantities of pure active viral proteins from Madin Darby Bovine kidney (MDBK) cell culture infected with BVDV cytophatic Oregon C24V strain. SDS-PAGE, Immunodot, ECL-Western blot and ELISA showed the best specificity and activity of BVDV Ag obtained from infected cells only by mild experimental conditions. BVDV Ag preparations showed the peculiar BVDV sensitivity to proteases, nonionic surfactants and tend for protein degradation and irreversible loss of conformational antigenic determinants with subsequent inability to detect antibodies against viral Ag in hyperimmune sera. The widest panel of immunologically active and specific polypeptides, that elicit Ab production in hyperimmune sera, was obtained by ultrasonication and subsequent purification on 20%-50% sucrose cushion. We observed that BVDV tend to remain in the infected cells, to associate with components of serum and cellular origin--this is of crucial importance towards the specificity of ELISA. BVDV antigenic properties are determined by the labile conformational antigenic epitopes.

T mu- and T gamma-cell subsets in normal and leukemic cattle.

T-cell subsets in the peripheral blood and lymphoid organs of normal and chronic lymphocytic leukemia (CLL) cattle were studied. Purified T lymphocytes were examined for the numbers of cells with the receptors for IgM (T mu) and IgG (T gamma). The expression of surface receptors on T mu- and T gamma-cell subsets was determined according to their capacity to bind different numbers of erythrocyte antibody complexes EAM or EAG. During the various times of preincubation of T cells at 37 degrees C, an increased release of receptors on the surface of T mu and partly T gamma cells was observed. For the optimal detection of bovine T mu cells, preincubation at 4 degrees C fro 24 h was necessary. The number of T gamma cells in the peripheral blood (P less than 0.001) and spleen (P less than 0.001) of CLL cattle was higher in comparison with controls. A considerably reduced number of T mu cells in the peripheral blood (P less than 0.001) and lymph nodes (P less than 0.02) of CLL cattle was observed. With the exception of thymus, T gamma cells from the lymphoid organs of CLL cattle had a higher expression of receptors than normal T gamma cells.

Immunochemical and biochemical study of an abnormal heavy chain of bovine IgG1.

An abnormal heavy chain (HC) protein of IgG1 was isolated from the serum of a leukemic cow by gel filtration on a Sephadex G-200 column with the following ion-exchange chromatography. The HC protein migrated electrophoretically in the anodic region. The molecular weight of the untreated HC protein was about 48,000. Enzymatic treatment with papain and reduction with beta-mercaptoethanol showed no effect on the protein. Antigenic analysis of the HC protein using a specific rabbit antiserum against bovine IgG1 showed a complete identity with the Fc fragment and a partial identity with the intact bovine IgG1. Antigenic determinants of the light-chain were not found. The HC protein consisted of only one polypeptide chain.