Ultrastructural Study of Bovine Papillomavirus During Outbreaks in Brazil

Abstract

SUMMARY:Papillomaviruses, belonging to the Papillomaviridae family, are small oncogenic viruses, causing papillomas and fibropapillomas in the mucosal and cutaneous epithelia of several animals. In bovine species, thirteen types (BPV 1-13) were characterized to date. In this study, the occurrence of papillomatosis in four outbreaks in cattle herds, coming from Brazilian states were registered. The papillomatous lesions were found located in the teats, udders, head and neck. Under the transmission electron microscope, by the negative staining technique, it was possible to visualized rounded-format papillomavirus, with icosahedral symmetry, characterized as "full" and "empty" particles, measuring on average 60 nm in diameter, in all the 40 samples observed of skin lesion fragments. The ultrathin sections revealed the presence of groups of viral, intranuclear, rounded particles measuring 35 nm in diameter and tubular particles with a diameter of 35-39 nm. At immunoelectron microscopy technique, positivity obtained was marked by the presence of aggregates of viral particles formed by the antigen-antibody interaction. In the immunocytochemistry technique, the antigen-antibody reaction showed colloidal gold particles evenly distributed over the surface of the virus. These results showed the importance of the transmission electron microscopy techniques in the diagnosis of bovine papillomatosis that can be used in routine procedures to identify viral agent of this important disease.

Pathological and immunohistochemical evaluation of skin and teat papillomas in cattle

“…The present study was undertaken to evaluate the histopathology and immunohistochemistry of warts from the skin and teats, and diagnosis of the lesions depended on the pathological results with BPV-specific immunolabeling. BPV-induced skin warts were seen on the neck, shoulders, and ventral abdomen, and the masses exhibited circumscribed aspects, pedunculated, cornified, black or grayish in color, as reported by others (5,8,(12)(13)(14)(15)(16)(17)(18). The reason for the predominant occurrence of warts on the neck might be due to the traumatized skin induced by metal chains used for stabilization of cattle during the winter season in this region.…”

“…Outbreaks can reach serious proportions and teats often become secondarily infected, and sometimes the invasion of tumors can be so severe that milking becomes impossible (3,5,8,22). Teats revealed grossly flat-and-round type, frond-like, and rice grain-like growths, usually multiple in numbers on all teat skin.…”

“…However, six types of the virus have been well characterized. BPV 1, BPV 2, and BPV 5 commonly cause cutaneous fibropapillomas, while BPV 3, BPV 4, and BPV 6 induce squamous papillomas in both the skin and upper gastrointestinal system (2,4,5,(7)(8)(9). Teat papillomatosis has often been identified in dairy herds as a cattle health problem resulting in economic losses.…”

“…Papillomatosis is considered to be contagious in cattle, in which it naturally occurs, and in some cattle extensive papillomas might develop, resulting in debilitated animals that may succumb (1,6). Cattle with warts are usually less than 2 years old and the masses regress spontaneously within 1-14 months (2,5,7,8). Bovine papilloma virus (BPV) is common in cattle herds around the worldwide and is recognized as the cause of the disease associated with many forms of benign tumors, e.g., skin fibropapillomas, genital fibromas, and tumors of the urinary bladder, as well as benign fibroplasia in teats and the esophagus (3,4,8).…”

“…The disease is regarded as either hyperproliferative lesion or benign neoplasms since they do not metastasize (1)(2)(3)(4)(5). Papillomatosis is considered to be contagious in cattle, in which it naturally occurs, and in some cattle extensive papillomas might develop, resulting in debilitated animals that may succumb (1,6).…”