Molecular and pathological characterization of teat papillomatosis in dairy cows in southern Brazil

Teat papillomatosis is caused by different bovine papillomavirus (BPV) types and is especially important for dairy cows, because it results in severe damage to the health and structure of the mammary gland. This work describes the molecular and pathological aspects of teat papillomatosis in dairy cows in southern Brazil. Samples of teat papillomas were collect from 73 slaughtered dairy cows. Fragments of the lesions were collected in individual pools per animal and subjected to PCR using the FAP primer pair and sequencing of the amplification products. Teats with the remaining lesions were fixed in 10% neutral buffered formalin, routinely processed for histopathology, and stained with hematoxylin and eosin (H&E). Papillomatous lesions were characterized by three macroscopic patterns, namely exophytic (5 [6.9%]), flat (29 [39.7%]), and mixed (39 [53.4%]). Histologically, all samples were identified as squamous papillomas. Partial sequencing of the L1 gene resulted in the detection of 8 classical BPV types (BPVs 4, 6, 7, 8, 9, 10, 11, and 12) in 27 samples, 6 previously reported putative BPV types in 17 samples, and 10 putative new BPV types in 15 samples. Four sequences could not be classified, and 10 were negative in the PCR. There was no correlation between the gross pattern and the BPV type identified, and all the samples were characterized by squamous papillomas under histological examination. However, 24 different BPV types were identified, demonstrating high genetic diversity among BPVs associated with teat papillomatosis in dairy cows in southern Brazil.