Abstract
Background: Papillomaviruses (PVs) infect animals and humans and are linked to 27%-30% of cancers. The L1 protein is a cornerstone in bovine PVs (BPVs), being the main components of the viral capsid and playing pivotal roles in infectivity and antigenicity. Objective: The current study aims to characterize the genetic variation in the L1 gene of the BPV, explore in silico the protein structure, predict epitopes, and evaluate the impact of mutation on the epitope conservancy. Methods: Fifty tumor samples were collected from cattle with papilloma lesions from Babylon, Wasit, and Al-Qadisiyah provinces, Iraq. Samples were submitted to PCR to amplify the complete L1 gene. Phylogeny was performed to assess the L1 gene. Various bioinformatics tools were utilized to analyze physicochemical properties, secondary structure of the deduced protein, and predict immunodominant epitopes for B and T cells. Results: BPV DNA was detected in 42 (84%) samples. Sequence analysis of 10 samples revealed that BPV-1 was the predominant type circulating in study regions. Phylogeny demonstrated that analyzed strains were aligned with a distance value of 1%-15% to strains of delta PVs. Amino acid characterization indicated two amino acid mutations compared with reference strain (X02346.1) including SER31/ASN and Ala 55/ASP. The 3D model revealed L1 that formed from hexameric subunits, each subunit with six loops. ALA 55/ASP substitutions are located in the Loop1. The predicted B- and T-cell epitopes showed that L1 protein has highly potent epitopes and can be a promising target for nucleic acid vaccine design to elicit an anti-BPV humeral and cellular immune response. Conclusions: The current investigation has provided crucial insights into BPV-1 type and diversity in the middle provinces of Iraq. These predominant strains have been identified and registered at NCBI for the first time. The amino acid mutations in the L1 protein have been highlighted. The conserved T- and B-cell epitopes that can detect BPV-1 type have been stablished. Finally, this project is the initial phase of creating a DNA-based vaccination for preventative and treatment purposes against BPV-related illnesses.