Detection of Anti-LipL32 Antibodies in Serum Samples from Horses with Chronic Intraocular Infection with Leptospira spp.

Tobias Geiger,Bettina Wollanke,Hartmut Gerhards

doi:10.3390/pathogens10101325

Abstract

Equine recurrent uveitis (ERU) is typically caused by chronic intraocular leptospiral infection in warm-blooded horses in central Europe. The most effective therapy for leptospiral-induced ERU is the surgical removal of diseased vitreous (vitrectomy). Since vitrectomy is a highly specialized and invasive surgery, the indication must be determined very carefully. In order to obtain evidence of intraocular leptospiral infection by laboratory diagnostics in questionable leptospiral ERU-cases, sampling of aqueous humor is required, because serum tests using microscopic agglutination test (MAT) are too unspecific. The SNAP Lepto is a cross-species rapid test for the detection of anti-Lipl32 antibodies that has a high sensitivity (0.97) and specificity (1.00) for the detection of anti-leptospiral antibodies using aqueous humor or vitreous samples, which is comparable to MAT. To evaluate sensitivity and specificity of SNAP Lepto using serum, serum samples from 90 horses with confirmed leptospiral ERU and from 103 ocularly healthy horses were tested by both MAT and SNAP Lepto. Sensitivity was similar for both tests (0.82 vs. 0.79), but specificity was lower for MAT (0.52 vs. 0.95). Sensitivity and specificity are therefore lower in serum samples compared to intraocular samples, however, the SNAP Lepto is far superior to MAT and suitable as a screening method using equine serum.

Highlights

In the horses suffering from equine recurrent uveitis (ERU), aqueous humor had either been collected during preoperative diagnostics in order to confirm the indication for vitrectomy on the basis of laboratory tests, or vitrectomy had been performed on the basis of the history and ophthalmologic findings without first collecting aqueous humor
Horses were assigned to the ERU group if either in the aqueous humor samples or in the vitreous samples an antibody titer against a leptospiral serovar of 1:100 or higher was detectable by microscopic agglutination test (MAT), if the SNAP Lepto test was positive, or if the LipL32 gene was detectable in the intraocular samples by real-time PCR
In the sera in which no anti-Leptospira antibodies were detectable by MAT, no antiLipL32 antibodies were detectable by SNAP Lepto either in most cases (32/37 sera, 86.5%)

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. In central Europe, equine recurrent uveitis (ERU) with its classic symptoms is typically caused by a chronic intraocular leptospiral infection [1,2,3,4,5,6,7,8,9,10,11]. The term ”ERU” will be used for leptospiral induced recurrent uveitis in warm-blooded horses with painful episodes, and which has been demonstrated to be a chronic intraocular infection. It has been demonstrated that infectious leptospiral uveitis is accompanied by biofilm formation [12,13]

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