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Prototheca zopfii infections are becoming global concerns in humans and animals. Bovine protothecal mastitis is characterized by deteriorating milk quality and quantity, thus imparting huge economic losses to dairy industry. Previous published studies mostly focused on the prevalence and characterization of P. zopfii from mastitis. However, the ultrastructural pathomorphological changes associated with apoptosis in bovine mammary epithelial cells (bMECs) are not studied yet. Therefore, in this study we aimed to evaluate the in vitro comparative apoptotic potential of P. zopfii genotype-I and -II on bMECs using flow cytometry, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed fast growth rate and higher adhesion capability of genotype-II in bMECs as compared with genotype-I. The viability of bMECs infected with P. zopfii genotype-II was significantly decreased after 12 h ( p < 0.05) and 24 h ( p < 0.01) in comparison with control cells. Contrary, genotype-I couldn't show any significant effects on cell viability. Moreover, after infection of bMECs with genotype-II, the apoptosis increased significantly at 12 h ( p < 0.05) and 24 h ( p < 0.01) as compared with control group. Genotype-I couldn't display any significant effects on cell apoptosis. The host specificity of P. zopfii was also tested in mouse osteoblast cells, and the results suggest that genotype-I and -II could not cause any significant apoptosis in these cell lines. SEM interpreted the pathomorphological alterations in bMECs after infection. Adhesion of P. zopfii with cells and further disruption of cytomembrane validated the apoptosis caused by genotype-II under SEM. While genotype-1 couldn't cause any significant apoptosis in bMECs. Furthermore, genotype-II induced apoptotic manifested specific ultrastructure features, like cytoplasmic cavitation, swollen mitochondria, pyknosis, cytomembrane disruption, and appearance of apoptotic bodies under TEM. The findings of the current study revealed that genotype-II has the capability to invade and survive within the bMECs, thus imparting significant damages to the mammary cells which result in apoptosis. This study represents the first insights into the pathomorphological and ultrastructure features of apoptosis in bMECs induced by P. zopfii genotype-II.

Prototheca zopfii is an important bovine mastitis pathogen, which could result in severe mammary infection. However, the innate immune response in bovine mastitis associated with P. zopfii was not clear. Therefore, the aim of this study is to investigate in vitro innate immune responses implicated by P. zopfii. Bovine mammary epithelial cells (bMECs) were infected with 5.0 × 10 4 cells/ml P. zopfii genotypes I and II independently, and the mRNA expression of TLR-2, TLR-4, TNF-α, IL-1β, IL-8, NOD-1, NOD-2 and β-defensin-5 was determined by real-time polymerase chain reaction (RT-PCR) over a time course of 1, 3, 6, 12 and 24 h. The detection of the NF-κB p65 protein in nucleus and cytoplasm of infected bMECs over the same time course was evaluated. Results showed that P. zopfii genotype II has ability to up-regulate the expression of TLR-2, TLR-4, TNF-α, IL-1β, IL-8, NOD-1, NOD-2 and β-defensin-5 'more strongly than genotype I. Western blot results showed that when bMECs were challenged by P. zopfii genotype II, the expression of NF-κB p65 protein in the nucleus was up-regulated, while in cytoplasm it appeared to be repressed, which indicated that bMECs partly regulate the innate immune responses and inflammation by the NF-κB signaling pathway while being infected by P. zopfii genotype II. It was concluded that adhesion of genotype II was stronger than genotype I, and therefore the genotype II regulatory ability is more robust than that of the genotype I, which causes inflammation of bovine mammary tissue.

La prototecosis es una enfermedad causada por algas saprófitas, no clorofílicas, unicelulares y oportunistas del género Prototheca, que afecta, principalmente, a animales con inmunodeficiencias. En caninos, con la forma intestinal, se puede presentar inicialmente como diarrea sanguinolenta, pudiendo progresar a un cuadro sistémico; mientras que en felinos, generalmente, genera lesiones cutáneas. En Costa Rica, P. zopfii es la especie que se ha identificado con mayor frecuencia, y P. wickerhamii, una vez. El diagnóstico de esta enfermedad se puede realizar mediante distintas técnicas como: citología, histopatología, endoscopía, cultivo, reacción en cadena de polimerasa (PCR), método bioquímico, entre otros. El tratamiento recomendado es anfotericina B e itraconazol, los cuales son efectivos, principalmente, en felinos. Sin embargo, en caninos, con presentación sistémica, no existe un tratamiento efectivo. En caso de lesiones cutáneas, se recomienda la resección quirúrgica.

Foram revisados dados de etiologia, epidemiologia, patogenia, sinais clínicos, procedimentos diagnósticos, conduta terapêutica e ações de controle e profilaxia da prototecose em cães e gatos, além de aspectos da doença no homem e em bovinos.Etiology, epidemiology, pathogeny, clinical signs, diagnosis, therapeutic, control and preventive measures in protothecosis in dogs and cats were reviewed, besides aspects of disease in human and bovines.