Humoral immune response and delayed-type hypersensitivity in rabbits infected with Trypanosoma equiperdum

Tiziana Di Febo,Barbara Bonfini,Manuela Tittarelli,Emanuela Rossi,Gianluca Orsini,Osvaldo Matteucci,Ivanka Krasteva,Diamante Rodomonti,Mirella Luciani,Michele Podaliri Vulpiani,Luigi Iannetti

doi:10.1038/s41598-020-71992-x

Tiziana Di Febo, Barbara Bonfini + Show 9 more

Open Access

https://doi.org/10.1038/s41598-020-71992-x

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Abstract

Trypanosoma equiperdum is the causative agent of dourine, a parasitic venereal disease of equids. In this work, rabbits were infected with T. equiperdum strain OVI; serological tests (complement fixation test, ELISA and immunoblotting), used for the diagnosis of dourine in horses, were applied to study rabbit humoral immune response and to characterise T. equiperdum antigen pattern recognised by antibodies from infected rabbits. Moreover a protein extract of T. equiperdum strain OVI was produced and tested in skin tests on infected rabbits to detect the cell-mediated response induced by T. equiperdum, in order to evaluate its use in the field diagnosis of dourine. Sera of infected rabbits recognized in immunoblotting Trypanosoma protein bands with molecular weight below 37 kDa, providing a serological response comparable with that already observed in dourine infected horses. Moreover the trypanosome protein extract was capable to produce in vivo delayed-type hypersensitivity (DHT Type IV) in rabbits and proved itself to be non-toxic and non-sensitizing.

Highlights

Trypanosoma equiperdum is the causative agent of dourine, a parasitic venereal disease of equids
No vaccines for dourine are available and pharmaceutical therapy is not recommended; the eradication strategy currently applied imposes slaughtering of seropositive a nimals[4]
All the nine rabbits infected with OVI T. equiperdum became positive after 7 days from inoculation (T7) (CFT titres ≥ 1:40) and maintained high antibody titers (CFT titres ≥ 1:320) for the entire duration of the experiment (Table 1)

Summary

Introduction

Trypanosoma equiperdum is the causative agent of dourine, a parasitic venereal disease of equids. Dourine is a sexually transmitted disease affecting equids and caused by the protozoan Trypanosoma equiperdum (Kinetoplastida, subgenus Trypanozoon). No vaccines for dourine are available and pharmaceutical therapy is not recommended; the eradication strategy currently applied imposes slaughtering of seropositive a nimals[4]. This policy, is not economically feasible to be applied in developing countries, where horses are extensively used for transport and a griculture[5]. T. evansi, because the two parasites are genetically and antigenically related and the clinical outcome of the two diseases in horses is very similar[3]

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