Bovine Papillomavirus Clastogenic Effect Analyzed in Comet Assay

Abstract

Bovine papillomavirus (BPV) is an oncogenic virus related to serious livestock diseases. Oncoproteins encoded by BPV are involved in several steps of cellular transformation and have been reported as presenting clastogenic effects in peripheral lymphocytes and primary culture cells. The aim of this study was to evaluate the clastogenic potential of BPV types 1, 2, and 4 by comet assay. Peripheral blood was collected from 37 bovines, 32 infected with different levels of papillomatosis (12 animals have no affection) and five calves, virus free (negative control). The viral identification showed presence of more than one virus type in 59.375% of the infected animals. Comet assay was performed according to alkaline technique. The Kruskal-Wallis test showed statistical difference between the negative control group and infected animals (P = 0.0015). The Dunn post hoc test showed difference comparing the infected animals with calves. Mann-Whitney U test verified no difference between animals infected with only one viral type and animals presenting more than one viral type. The comet assay is considered an efficient tool for assessment of damage in the host chromatin due to viral action, specifically highlighting viral activity in blood cells.

Bos taurus papillomavirus activity in peripheral blood mononuclear cells: demonstrating a productive infection

“…Although current studies have shown the expression of E5 and L1 of BPV-1 and -2 in CD4+ and CD8+ cells (Roperto et al 2008(Roperto et al , 2011, as well as BPV activity in PBMCs by comet assay in both symptomatic and asymptomatic cattle (Araldi et al, 2013a), the presence of BPV virions in PBMCs have not been identified. In this study, PCR results showed the co-infection of BPV-1, -2 and -4 in PBMCs, which has already been described in peripheral blood (Carvalho et al, 2013;Araldi et al, 2014a).…”

“…The same authors also suggest that the peripheral blood could act as a viral disseminator (Král et al, 2015). Recent studies have reinforced the role of peripheral blood mononuclear cells (PBMCs) as virus carriers, showing that BPV is present in CD4+ and CD8+ lymphocytes (Roperto et al, 2008;Araldi et al, 2014a) and the detection of BPV activity in PBMCs by the comet assay (Araldi et al, 2013a) and flow cytometry (Roperto et al, 2011).…”

“…E7 promotes the phosphorylation of retinoblastoma protein (pRb), leading to S phase entry (White and Howley, 2013), and is related to centrosome duplication and numeric aberrations (Duensing et al, 2000). The combined action of oncoproteins E5, E6, and E7 leads to genomic instability and malignancy (Araldi et al, 2013a;Araldi et al, 2015b).…”

Mutagenic potential of Cordia ecalyculata alone and in association with Spirulina maxima for their evaluation as candidate anti-obesity drugs

“…According to Ribeiro et al (2003) and Frieauff et al (2013), for the MNT in polychromatic erythrocytes, analysis of 2000 cells is recommended, whereas for the MNT in binucleated lymphocytes, 1000 cells are recommended for analysis. In the comet assay, only 100 cells need to be analyzed because of the high sensitivity of this assay in detecting free DNA fragments (Araldi et al, 2013). These values for cells analyzed are based on statistical considerations.…”

“…Micronuclei are chromosomal fragments or whole chromosomes that are lost during cell division, which can be detected as extra-chromosomal particles (Frieauff et al, 2013), indicating chromosome breakage (clastogenicity), which can lead to genomic instability, an indicator of oncogenic processes (Fenech, 2000;Araldi et al, 2013).…”