Ewa Kaczmarczyk

Polymorphism and expression of the tumour necrosis factor-alpha (TNF-alpha) gene in non-infected cows and in cows naturally infected with the bovine leukaemia virus (BLV).

The objective of this study was to determine the influence of TNF-alpha gene polymorphism at position -824 A > G on TNF-alpha gene expression in BLV-positive animals with aleukaemic (AL) and persistent lymphocytosis (PL) forms of enzootic bovine leukosis (EBL) and in BLV-negative cows. Polymorphism of the TNF- alpha gene at position -824 A > G had a complex influence on TNF-alpha gene expression in cows infected with BLV. In animals with various TNF-alpha genotypes, mRNA levels were stable and similar, but significant differ - ences were noted in the percentages of PBMCs expressing membrane TNF-alpha (mTNF-alpha) protein (PBMCs that were positive for mTNF-alpha). In healthy cows, significant differences in TNF-alpha gene expression were not noted at any of the analysed levels. BLV infection and EBL progression resulted in differential TNF-alpha gene expression at both mRNA and protein levels, but the differences in the amount of the transcript and the percentages of mTNF-alpha+ cells exhibited a reverse trend. The lowest mRNA levels and the highest percentage of PBMCs expressing mTNF-alpha protein were determined in BLV-positive cows. These complex results regard- ing TNF-alpha gene expression in BLV-positive cows could be attributed to the presence of virus or viral protein/ proteins modifying the expression of the TNF-alpha gene.

Polymorphism and expression of the tumor necrosis factor receptor II gene in cows infected with the bovine leukemia virus.

A single T>C nucleotide polymorphism (rs42686850) of bovine tumor necrosis factor receptor type II gene (TNF-RII) is located within a sequence with allele-specific affinity to bind E2F transcription factors, considered pivotal in the regulation of cell cycle and cell proliferation. The objective of the study was to determine the effect of this SNP and BLV infection on the TNF-RII gene expression at the mRNA and protein levels in peripheral blood mononuclear cells (PBMC). We noted that analyzed TNF-RII gene polymorphism influenced the expression of the TNF-RII gene at the mRNA level but only in BLV-positive cows. Concurrently, no statistically significant association was found between gene polymorphism and TNF-RII expression at the protein level. However, we found a significant effect of BLV infection status on the amount of TNF-RII mRNA and the percentage of PBMC expressing TNF-RII. These results show an unclear effect of considered T>C polymorphism on TNF-RII gene expression in bovine leukocytes and they suggest the involvement of BLV in modifying the TNF-RII expression in BLV-infected cows potentially implying the EBL (Enzootic Bovine Leukosis) associated pathogenesis.

Tumor necrosis factor-alpha (TNFα) gene polymorphism and expression of membrane-bound TNFα protein on CD11b+ and IgM+ cells in cows naturally infected with bovine leukemia virus

The aim of this study was to determine whether SNP at position -824 (promoter region) of the TNFα gene significantly differentiates the size of IgM+, CD5+ and CD11b+ cell subpopulations and affects the expression of membrane-bound TNFα protein (mTNFα) on these cells and their susceptibility to BLV infections. In this study, significant differences were determined for the first time between TNFα genotypes and the percentage of cells with the CD11b+TNFα+p24+ immunophenotype. Furthermore, greater expansion of lymphocytes with the IgM+TNFα+p24+ immunophenotype was reported in cows with the G/G genotype than in A/A homozygotes. Cells with the above immunophenotype were more frequently observed in cows with persistent leukocytosis than in aleukemic cattle. Our results suggest that polymorphism of the TNFα-824 A>G gene and mTNFα protein expression play an important role in the pathogenesis of enzootic bovine leukosis.

Polymorphism in the region of bovine prion protein gene and selected haematological indices in cows naturally infected with bovine leukaemia virus

Abstract The objective of this study was to determine whether insertion-deletion (indel) 23 bp polymorphism of the bovine prion protein (PRNP) gene differentiates the total number of leukocytes and lymphocytes and the number of virus-infected lymphocytes. The experimental materials comprised 119 Black-and-White Polish Holstein-Friesian cows. Bovine leukosis was diagnosed by an indirect immunofluorescence based on the detection of viral protein p24 in bovine lymphocytes infected with leukaemia virus (BLV). Indel23 polymorphism was determined by PCR. Blood haematological parameters (total leukocyte counts, total lymphocyte counts, and their percentages) were determined at a specialist haematological laboratory. The examined indices were analysed in three replications, at one-month intervals. It was found that indel23 polymorphism significantly differentiated blood leukocyte counts and the total number and percentage of lymphocytes. Cows with the 23 bp del/del genotype showed significantly higher leukocyte and lymphocyte counts than animals with the remaining two genotypes. Higher values of the analysed haematological parameters noted in homozygotes with 23 bp deletion are similar to the values reported in cows affected by persistent lymphocytosis, thus pointing to an adverse effect of this genotype on the haemopoiesis process. The variations between indel23 genotypes and the number and percentage of BLV-infected lymphocytes are less obvious and more difficult to interpret.