# Serum Proteomic Changes in Pet Rabbits with Subclinical and Clinical Encephalitozoonosis in Thailand

## TL;DR

This study identifies blood proteins that can help detect and differentiate early and advanced stages of a rabbit parasite infection.

## Contribution

The study discovers specific serum proteins as potential biomarkers for early and clinical detection of Encephalitozoon cuniculi in rabbits.

## Key findings

- 88 proteins were differentially expressed in infected rabbits compared to healthy controls.
- 12 proteins were consistently upregulated in both subclinical and clinical infections.
- Key proteins include beta-2-microglobulin, antithrombin-III, retinol-binding proteins, and actin-depolymerizing factor.

## Abstract

Encephalitozoon cuniculi is a microsporidian parasite that infects rabbits and other mammals, often affecting the nervous system and sometimes causing anemia, which can complicate a diagnosis, especially in asymptomatic cases. This study analyzed serum proteins in healthy, subclinical, and clinical rabbits using gel electrophoresis and mass spectrometry to identify biomarkers of infection. A total of 88 proteins were differentially expressed in infected rabbits, with 12 consistently upregulated in both subclinical and clinical groups. These proteins are involved in the immune response, coagulation, vitamin A transport, metabolism, and oxidative stress. Key markers included beta-2-microglobulin, antithrombin-III, retinol-binding proteins, and actin-depolymerizing factor. These findings suggest specific blood proteins that may serve as biomarkers for the early detection and clinical differentiation of E. cuniculi infection in pet rabbits.

Encephalitozoon cuniculi causes both clinical and subclinical infections in rabbits, complicating a diagnosis due to the limitations of conventional tools like ELISA. This study analyzes serum proteomic profiles across clinical, subclinical, and healthy rabbits to identify discriminatory biomarkers. Serum from 90 pet rabbits (30 per group) was pooled (10 samples per pool, 3 pools per group) and analyzed using one-dimensional gel electrophoresis and mass spectrometry. The proteomic analysis revealed 109, 98, and 74 proteins expressed in healthy, subclinical, and clinical groups, respectively. Of these, 50, 40, and 33 proteins were unique to the healthy, subclinical, and clinical groups, respectively, with only 10 proteins shared across all. A total of 88 proteins were differentially expressed in infected groups compared to healthy controls. Importantly, 12 proteins were consistently upregulated in both subclinical and clinical infections. These include markers related to the immune response (beta-2-microglobulin, alpha-2-HS-glycoprotein), coagulation (antithrombin-III, alpha-1-antiproteinase S-1), vitamin A transport (retinol-binding proteins), lipid metabolism (apolipoprotein C-III), cytoskeletal regulation (actin-depolymerizing factor), extracellular matrix integrity (fibrillin 2), and oxidative stress (monooxygenase DBH-like 1). Additionally, Gc-globulin and ER lipid-raft-associated 1 were linked to immune modulation and signaling. These findings identify specific serum proteins as promising biomarkers for distinguishing subclinical from clinical encephalitozoonosis in rabbits, enabling an early diagnosis and effective disease monitoring.