IgG antibodies from dourine infected horses identify a distinctive Trypanosoma equiperdum antigenic pattern of low molecular weight molecules.

This research paper explores the development and analysis of a new technique, called chemiluminescent immunoblotting (cIB), to identify infection in horses by the Trypanosoma equiperdum parasite, which causes the disease dourine.

Objective of the Research

• The main goal of the study was to enhance the understanding of the humoral (blood fluid) response of horses to dourine infection and to identify a specific antigenic pattern that would signify the presence of the disease.
• To achieve this, the researchers developed a new testing method – chemiluminescent immunoblotting (cIB) assay – that allowed for a better characterization of the T. equiperdum antigen pattern recognised by horses’ IgG (an antibody type) during dourine infection. The researchers were particularly interested in the difference in patterns between healthy and infected horses.

Methodology

• The research team recruited a study group of 8 naturally infected horses that had survived Italian outbreaks and additional 2 experimentally infected ones.
• They collected blood serum samples from these horses, as well as from 10 healthy control animals sourced from dourine-free regions – although 8 of them were positive to another unrelated test (CFT), they were negative to a test for dourine (IFA).
• All these serums were subjected to a series of three tests: complement fixation test (CFT), indirect immune fluorescence (IFA) and the newly developed cIB assay.

Findings

• The researchers’ cIB assay revealed that serum IgG from dourine-infected horses, unlike those from healthy horses, specifically recognized a T. equiperdum antigenic profile comprising of low molecular weight bands ranging from 16 to 35 kDa.
• This unique antigenic profile indicative of dourine infection wasn’t discernible until approximately 17 days post-infection, as observed from a time series experiment.
• Furthermore, all the horses that were known to be infected tested positive by cIB, while all control horses tested negative for dourine, confirming the effectiveness of this new technique.

Conclusion and Potential impact

• Overall, the study’s findings suggest that the cIB assay can provide accurate confirmation of trypanosome infection in horses, thereby making it a viable confirmatory serological test for dourine infection.
• This advancement may significantly strengthen the diagnosis and control attempts against dourine, as the current understanding of the disease’s serological evidence is limited.