Association of TNF-α gene promoter region polymorphisms in bovine leukemia virus (BLV)-infected cattle with different proviral loads

Abstract

Tumor necrosis factor alpha (TNF-a) is a pleiotropic cytokine involved in the immune response against viral and other infections. Its expression levels are affected by a polymorphism in the promoter region of the gene. Bovine leukemia virus is a retrovirus that infects cattle and develops two different infection profiles in the host. One profile is characterized by a high number of proviral copies integrated into the host genome and a strong immune response against the virus, while the most relevant property of the other profile is that the number of copies integrated into the host genome is almost undetectable and the immune response is very weak. We selected a population of cattle sufficiently large for statistical analysis and classified them according to whether they had a high or low proviral load (HPL or LPL). Polymorphisms in the promoter region were identified by PCR-RFLP. The results indicated that, in the HPL group, the three possible genotypes were normally distributed and that, in the LPL group, there was a significant association between the proviral load and a low frequency of the G/G genotype at position -824.

Relationship between polymorphism in the tumour necrosis factor-alpha gene and selected indices and cell subpopulations in naturally bovine leukaemia virus-infected and healthy cows

“…Similar results were reported by Lendez et al (2015) in whose study cows with the G/G genotype of TNFα polymorphism at position -824 (AG) were significantly more often classified as BLV + with HPL than BLV + with a low proviral load (LPL).…”

“…The correlation between TNFα gene polymorphism and resistance/susceptibility to mastitis (Ranjan et al 2015), tuberculosis (Cheng et al 2016) and EBL has been investigated in a limited number of studies (Konnai et al 2006;Bojarojc-Nosowicz et al 2015;Lendez et al 2015).…”

“…Most authors have analysed only the influence of the AG polymorphism at position -824 of the TNFα gene, which limits the significance of their findings (Konnai et al 2006;Bojarojc-Nosowicz et al 2015;Lendez et al 2015).…”

A novel association of BoLA DRB3 alleles in BLV infected cattle with different proviral loads

“…Moreover, a tendency toward an increased BLV provirus load in cattle with the TNF-α -824 G/G homozygote was observed when compared to the A/A homozygote or genotype A/G. Lendez et al (2015), analysing a large population of cattle with HPVL or LPVL, revealed a significant association between LPVL and a low frequency of the G/G genotype at position -824. That means that an animal carrying this polymorphism most probably belongs to the HPVL group.…”

“…It must be considered that expression of BoLA DRB3 might be influenced by polymorphisms in other surrounding genes. An important gene of the immune system that has been linked to the BoLA region is the promoter region of tumor necrosis factor-alpha (TNF-α): both genes are located in the q22 arm of the bovine chromosome 23 and in linkage disequilibrium (LENDEZ et al, 2015). Concerning BLV infection, TNF-α is closely related with the immune response against viral dissemination, stimulating the elimination of infected lymphocytes (KABEYA et al, 1999).…”