Letters in Applied Microbiology, 2023, 76, 1–6 https://doi.org/10.1093/lambio/ovad066 Advance access publication date: 7 June 2023 Review Article Protothecosis in Veterinary Medicine: a minireview Valessa Lunkes Ely 1 , Julia Pires Espindola 1 , Bibiana Martins Barasuol 1 , Luís Antônio Sangioni 1 , Daniela Brayer Pereira 2 , Sônia de Avila Botton 1,* 1 Universidade Federal de Santa Maria (UFSM), Centro de Ciências Rurais (CCR), Departamento de Medicina Veterinária Preventiva (DMVP), Programa de Pós-graduação em Medicina Veterinária (PPGMV), Av. Roraima, 1000, Prédio 44 (CCRII), Sala 5132, Campus Sede – Camobi, Santa Maria, Rio Grande do Sul (RS), CEP 97105-900, Brasil 2 Universidade Federal de Pelotas (UFPel), Instituto de Biologia (IB), Departamento de Microbiologia e Parasitologia, Programa de Pós-graduação em Microbiologia e Parasitologia (PPGMPAR). Travessa André Dreyfus, s/n, Prédios 18 e 25, Campus Universitário do Capão do Leão, Capão do Leão, RS, CEP 96010-900, Brasil ∗ Corresponding author. Universidade Federal de Santa Maria (UFSM), Centro de Ciências Rurais (CCR), Departamento de Medicina Veterinária Preventiva (DMVP). Av. Roraima, 1000, Prédio 44 (CCRII), Sala 5132, Campus Sede, Camobi, Santa Maria, RS, CEP 97105-900, Brazil. E-mail: sabott20@gmail.com Abstract Protothecosis is an important infection caused by Prototheca spp., an alga that affect humans and animals. Prototheca spp. infections determine losses of production and quality of life for the affected animals. In this disease, prevention and early diagnosis are essential to avoid the spread of the agent to susceptible hosts. This review aimed to assemble the reported cases of protothecosis in Veterinary Medicine, highlighting Pro- totheca species involved in the infections, the main animal species affected, as well as the clinical manifestations, diagnosis, and treatment. Our fndings showed that protothecosis has been reported in various domestic and wild animal species, presenting diverse clinical manifestations, including mastitis in cows, respiratory manifestations in goats and cats, and a wide range of clinical signs in dogs. The clinical diagnosis and treatment of Prototheca spp. infections are dif fcult and infected animals are frequently discarded or euthanized. Due to the importance of this infection, protothecosis must be considered an important differential diagnosis in routine clinical Veterinary Medicine. Signifcance and impact of the study Protothecosis is an important infection caused by algae that affect humans and animals, causing great damage to animal production systems, as well as to the quality of life of affected animals. In this disease, prevention and early diagnosis are essential to avoid the spread of the agent, since there is no effective treatment protocol for the cure of affected animals. Thus, this work seeks to inform about the main clinical manifestations of protothecosis, demonstrating the importance of investigating this agent in the clinical routine of Veterinary Medicine. Keywords: Prototheca spp., protothecosis, veterinary disease, alga, eukaryotic agent Introduction Since its discovery in 1894 by Krüger, the taxonomic clas- sifcation of Prototheca spp. has been discussed, and in re- cent decades, based on molecular analyses, these microorgan- isms have been classifed as algae closely related to the mi- croorganism Chlorella spp. (Irrgang et al. 2015). When it was initially described, the Prototheca genus was not listed as a cause of illness. In 1952, Lerche performed the frst descrip- tion of protothecosis in bovine mastitis, and subsequently in 1964, Davies reported the frst human infection caused by Prototheca spp. (Todd et al. 2018). Since then, numerous re- ports of infections caused by Prototheca spp. have been found in the literature, a summary is listed in Table 1. Prototheca spp. are unicellular algae achlorophylls. These algae freely occurring in nature and reproduce asexually by endosporulation (Sudman and Kaplan 1973). These eukary- otic organisms are organized in an oval or spherical cell called the mother cell (sporangium), which can produce 2–16 daugh- ter cells, known as endospores (Camboim et al. 2010b). Pro- totheca spp. have a wide environmental spread and prefer moist places with the presence of organic matter (Pore et al. 1983). They are isolated from feces, sea and lake waters, trees, and several other biomes, facilitating the exposure of suscep- tible hosts to the pathogen in different environments (Sudman and Kaplan 1973). Since the frst reports of the occurrence of these microor- ganisms, many changes have been made regarding their clas- sifcations. A total of seven species of Prototheca had been recognized, including P. stagnora, P. ulmea, P. wickerhamii, P. blaschkeae, P. zopfi, P. cutis, and P. miyajii (Pore et al. 1983, Roesler et al. 2006, Satoh et al. 2010); P. moriformis was not considered a distinct species because it was geneti- cally and biochemically similar to P. zopfi and with great het- erogeneity between strains (Roesler et al. 2006, Severgnini et al. 2018). Jagielski et al. (2019a) proposed a new classifcation for the genus based on the evaluation of the mitochondrial cy- tochrome B (cytB) gene by including six new species, totaling 14 species. Thus, the genus was grouped into two main lin- eages: the triad formed by P. ciferrii sp. nov, P. zopfi, P. bovis sp. nov, and P. wickerhamii cluster. Nevertheless, three new species (i.e. P. cookei sp. nov., P. cerasi sp. nov., and P. pring- sheimii sp. nov.) were related to the aforementioned triad but with important differences. Furthermore, P. wickerhamii, P. cutis, P. miyajii, and the newly proposed species P. xanthoriae sp. nov. have been reported as the closest related species to the photosynthetic genera Chlorella and Auxenochlorella. Ac- cording to the taxonomy proposed by Jagielski et al. (2019a), Received: July 4, 2022. Revised: March 3, 2023. Accepted: May 20, 2023 C  The Author(s) 2023. Published by Oxford University Press on behalf of Applied Microbiology International. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com Downloaded from https://academic.oup.com/lambio/article/76/6/ovad066/7191846 by guest on 21 June 2023