ARTIGO ACESSO ABERTO
Evaluation of the in vitro infection of Trypanosoma theileri and Trypanosoma theileri-like in a monolayer of embryonic cells of Rhipicephalus microplus (Canestrini) (Acari: Ixodidae)
Ingridi Braz de Oliveira Manhães, Renata Tonhosolo, Leidiane Lima-Duarte, Jaciara de Oliveira Jorge Costa, Ryan Emiliano da Silva, Pablo Henrique Nunes, Fernanda Aparecida Nieri-Bastos, Thamiris Nascimento dos Santos, Darci Moraes Barros-Battesti e Arlei Marcili
Vol. 1, Número 2, 2026


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DOI: 10.70061/2763-955X.2026.05
Abstract

The genus Trypanosoma infects a wide range of domestic and wild animals, with Trypanosoma theileri being a highly prevalent parasite in cattle worldwide. Members of the subgenus Megatrypanum are typically host-specific, infecting ungulates and ruminants. Experimental studies have shown that cattle-derived T. theileri does not infect sheep, indicating the absence of cross-species transmission. In water buffaloes (Bubalus bubalis), distinct T. theileri-like lineages occur, with no evidence of cross-infection between cattle and buffalo parasites. Tabanids and hippoboscids are recognized as natural vectors of this parasite. Rhipicephalus microplus is a one-host tick whose primary host is cattle. In this study, the growth and differentiation of T. theileri and T. theileri-like were evaluated in a monolayer of embryonic cells (RBME-6) of R. microplus. Amastigote forms were analyzed by fluorescence microscopy and confocal microscopy using DAPI and Phalloidin staining. Cultures of both T. theileri and T. theileri-like developed successfully in the RBME-6 cell line. The parasites invaded and remained active within the tick cells. These findings demonstrate that this cell line can be used to investigate parasite adaptation to the invertebrate host and to improve the understanding of parasite-host interactions. Furthermore, R. microplus embryonic cells constitute a rapid and low-cost in vitro model for the cultivation of trypanosomatids.

Keywords: bovine trypanosomatid, experimental infection, monoxenous tick, tick cell line.


Resumo

O gênero Trypanosoma infecta uma ampla variedade de animais domésticos e silvestres, sendo Trypanosoma theileri um parasita altamente prevalente em bovinos em todo o mundo. Membros do subgênero Megatrypanum são tipicamente específicos de hospedeiro, infectando ungulados e ruminantes. Estudos experimentais demonstram que T. theileri proveniente de bovinos não infecta ovinos, indicando ausência de transmissão entre espécies. Em búfalos (Bubalus bubalis) ocorrem linhagens distintas semelhantes a T. theileri, sem evidências de infecção cruzada entre parasitas de bovinos e búfalos. Tabanídeos e hipoboscídeos são reconhecidos como vetores naturais da enfermidade. Rhipicephalus microplus é um carrapato monoxeno cujo principal hospedeiro é o bovino. Neste estudo, avaliou-se o crescimento e a diferenciação de T. theileri e T. theileri-like em monocamada de células embrionárias (RBME-6) de R. microplus. As formas amastigotas foram avaliadas por microscopia de fluorescência e microscopia confocal utilizando coloração por DAPI e Faloidina. As culturas de T. theileri e T. theileri-like apresentaram crescimento satisfatório na linhagem celular RBME-6. Os parasitas invadiram e permaneceram ativos nas células de carrapato. Os resultados demonstram que essa linhagem celular pode ser utilizada para avaliar a adaptação ao hospedeiro invertebrado e ampliar o conhecimento sobre a interação parasito-hospedeiro, além de representar um modelo in vitro rápido e de baixo custo para o cultivo de tripanossomatídeos.

Palavras-chave: carrapato monoxeno, células embrionárias de carrapato, infecção experimental, tripanossomatídeo bovino.



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