Evaluation of genotoxic and cytogenetic effects of saponins and aluminum
hydroxide adjuvant on viral vaccine
Abstract
Bovine papillomavirus (BPV) is the etiological agent of bovine
papillomatosis, infectious disease characterized by the presence of
benign tumors that can progress to malignancy. The phylogenetic
classification of the PVs is performed based on the sequence homology of
the Open Reading Frame L1, the most conserved among different viral
serotypes. Given the immunogenicity of saponins, its has been used as a
candidate as adjuvant use. For this reason, the safety of using saponin
as an adjuvant has to be better determined to human or veterinary
vaccine use. So, this study aimed to evaluate the mutagenic and
genotoxic effect of saponins in comparison with the adjuvant widely used
aluminum hydroxide using an isolated and purified L1 protein from BPV as
model. In this study, genomic lesions, which after processed without
repair can result in mutations, were detected by comet assay. Possible
damages to genetic material caused by structural chromosomal changes
(clastogenesis), as well as chromosomal losses were evaluated by the
micronucleus test. Both tests were done on polychromatic erythrocytes
and Vero cells. The evaluation of apoptosis and necrosis of treated Vero
cells was made by Annexin V / PI staining and flow cytometry. The two
vaccine products (L1 +Saponin and L1 + Aluminum Hydroxide) showed
damages compatible with the positive control in the comet assay and both
slightly elevated the micronucleus levels, in the Cell Viability Assay
the results with Aluminum Hydroxide were satisfactory, characterizing
Aluminum Hydroxide as a safer adjuvant according to the proposed tests,
better than the saponins.