Open Access
Research (Published online: 13-05-2023)
13. Histopathology and virulence of an in vitro-adapted Trypanosoma evansi TEDC 953 strain (Thailand isolate) in mice
Wallaya Phongphaew, Charuwan Wongsali, Thanisorn Boonyakong, Theerawat Samritwatchasai, Wissanuwat Chimnoi, and Ketsarin Kamyingkird
Veterinary World, 16(5): 1008-1017

Wallaya Phongphaew: Department of Pathology, Faculty of Veterinary Medicine, Kasetsart University, Lad Yao, Chatuchak, Bangkok 10900, Thailand.
Charuwan Wongsali: Veterinary Diagnostic Center, Faculty of Veterinary Medicine, Kasetsart University, Lad Yao, Chatuchak, Bangkok 10900, Thailand.
Thanisorn Boonyakong: Laboratory Animal Unit, Research Support Center, Faculty of Veterinary Medicine, Kasetsart University, Lad Yao, Chatuchak, Bangkok 10900, Thailand.
Theerawat Samritwatchasai: Laboratory Animal Unit, Research Support Center, Faculty of Veterinary Medicine, Kasetsart University, Lad Yao, Chatuchak, Bangkok 10900, Thailand.
Wissanuwat Chimnoi: Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University, Lad Yao, Chatuchak, Bangkok 10900, Thailand.
Ketsarin Kamyingkird: Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University, Lad Yao, Chatuchak, Bangkok 10900, Thailand.

doi: 10.14202/vetworld.2023.1008-1017

Article history: Received: 31-01-2023, Accepted: 19-04-2023, Published online: 13-05-2023

Corresponding authors: Ketsarin Kamyingkird

E-mail: ketsarinkamy@hotmail.com

Citation: Phongphaew W, Wongsali C, Boonyakong T, Samritwatchasai T, Chimnoi W, and Kamyingkird K (2023) Histopathology and virulence of an in vitro-adapted Trypanosoma evansi TEDC 953 strain (Thailand isolate) in mice, Veterinary World, 16(5): 1008-1017.
Abstract

Background and Aim: Trypanosoma evansi is a blood and tissue protozoan parasite affecting domestic and wild animals. The T. evansi Thai strain, namely, T. evansi from dairy cattle number 953 (TEDC 953) strain, has been successfully isolated from dairy cattle and cultivated in vitro. The in vitro-cultivated parasite is useful for biological studies, evaluation of novel chemotherapeutic agents, and production of antigens for diagnostic tests. This study aimed to observe the histopathology and virulence of an in vitro-adapted T. evansi TEDC 953 strain in vivo.

Materials and Methods: The histopathology and virulence of the TEDC 953 strain were clarified in mice. Six mice were infected with 1 × 105 trypomastigotes of TEDC 953 strain intraperitoneally, and four mice were in the negative control. Parasitemia was monitored daily, and the mice were euthanized on 30 days post-infection (DPI). Internal organs were collected for histopathological examination using hematoxylin and eosin staining.

Results: Histopathological lesions were found in the liver, lung, heart, kidney, spleen, and brain of the inoculated mice. The main histopathological feature was lymphoplasmacytic inflammation in parenchyma and perivascular areas of multiple organs, and the severity of histopathological changes was related to the presence of trypomastigotes in the regional vessels. Granulomatous inflammation was seen in meninges, pleura, renal capsule, renal pelvis, and spleen of some infected mice. Four mice died at 17, 24, 26, and 27 DPI with an average parasitemia of 4.05 × 1011 trypomastigotes/mL. The average survival time was 23.5 DPI (mice = 4).

Conclusion: This study confirmed that the TEDC 953 strain is infectious and pathogenic in mice after the continuously cultivated in vitro. To replace the use of experimental animals, the in vitro-cultivated parasite can be used instead in further studies.

Keywords: experimentally infected mice, histopathology, in vitro, in vivo, Trypanosoma evansi Thai strain, virulence.