Electron microscopy and phylogenetic analysis of Bovine papillomavirus infection in cattle from four Egyptian governorates.

Cutaneous warts are the common clinical feature of infection with Bovine papillomavirus (BPV), and it is commonly known as bovine papillomatosis. It causes significant economic losses, especially in the dairy sector. The aim of this study was surveillance of the circulating strains of BPV in four Egyptian governorates and characterization by electron microscopy. Warts skin lesions and whole blood from seventy-eight native breed cattle were obtained. Molecular detection using two different sets of primers, phylogenetic analysis, and electron microscopy were carried out. The obtained results showed that using FAP59/FAP64 primer set is more sensitive than the MY09/My11 primer set in the detection of the papilloma L1 gene either in the blood or in the skin lesion. Sequence analysis of the partially amplified L1 gene revealed 4 different strains belonging to Deltapapillomavirus 4. Only Alfayoum_Deltapapillomavirus_2018 (accession no: MW018705) was found to be closely related to the strain previously isolated in different Egyptian governorates in 2017, and 2 strains were closely related to an isolate of equine origin. Electron microscopy examination of the skin lesions showed the presence of negatively stained rounded, non-enveloped virus particles with a size of 60 nm in diameter. In conclusion, continuous surveillance and characterization of the circulating strains using multiple sets of primers are important. Efficient biosecurity measures must be applied to decrease transmission of papillomavirus between the different animal species, especially in the mixed management system.