Detection of Leptospira Interrogans DNA and Antigen in Fixed Equine Eyes Affected with End-Stage Equine Recurrent Uveitis

Abstract

Abstract. Equine recurrent uveitis (ERU) is the most frequent cause of blindness in horses worldwide. Leptospira has been implicated as an etiologic agent in some cases of ERU and has been detected in fresh ocular tissues of affected horses. The objective of this study was to determine the presence of Leptospira antigen and DNA in fixed equine ocular tissues affected with end-stage ERU. Sections of eyes from 30 horses were obtained. Controls included 1) 10 normal equine eyes and 2) 10 equine eyes with a nonrecurrent form of uveitis. The experimental group consisted of 10 eyes diagnosed with ERU based on clinical signs and histologic lesions. Sections were subjected to immunohistochemical staining with an array of rabbit antiLeptospira polyclonal antibodies. DNA extractions were performed by using a commercial kit designed for fixed tissue. Real-time PCR analysis was completed on extracted DNA. The target sequence for PCR was designed from alignments of available Leptospira 16S rDNA partial sequences obtained from GenBank. Two of 10 test samples were positive for Leptospira antigen by immunohistochemical assay. Zero of 20 controls were positive for Leptospira antigen. All test samples and controls were negative for Leptospira DNA by realtime PCR analysis. Leptospira was detected at a lower frequency than that previously reported for fresh ERUaffected aqueous humor and vitreous samples. Leptospira is not frequently detectable in fixed ocular tissues of horses affected with ERU when using traditional immunohistochemical and real-time PCR techniques.

A study of leptospirosis in South African horses and associated risk factors

“…PCR has also been used to make a definitive diagnosis of horses with Equine recurrent uveitis (ERU), and it was found more reliable than culture for detecting the presence of leptospires in the aqueous humor (Faber et al 2000). However in one study, PCR could not detect leptospiral DNA in fixed equine ocular tissues affected with end-stage ERU (Pearce et al 2007). PCR does not identify the infecting serovar, although some primer sets may permit further identification to the species or strain level when the PCR amplicons are sequenced (OIE.…”

“…The pathogenesis of leptospiral-induced inflammation in equine recurrent uveitis is still unknown, but there is evidence that both persistent infection and autoimmune mechanisms may play a role (Pearce et al 2007). …”

Ophthalmic alterations in horses with leptospirosis by serovar Icterohaemorrhagiae in Rio de Janeiro, Brazil

“…In horses, it has a wide spectrum of effects, ranging from no apparent clinical signs to death (Gilger 2005, Pinna et al 2007. Infection with these organisms commonly results in impaired reproductive function in mares, as well as uveitis (Lilenbaum 1998, Faine et al 2000, Hartskeerl et al 2004, Gilger 2005, Pearce et al 2007.…”

“…Equine recurrent uveitis (ERU), also known as moon blindness or periodic ophthalmia, is the most common cause of blindness in horses worldwide (Faber et al 2000, Pearce et al 2007. It is characterized by recurring episodes of intense intraocular inflammation in one or both eyes (Brandes et al 2007).…”

“…In horses, it has a wide spectrum of effects, ranging from no apparent clinical signs to death (Gilger 2005, Pinna et al 2007. Infection with these organisms commonly results in impaired reproductive function in mares, as well as uveitis (Lilenbaum 1998, Faine et al 2000, Hartskeerl et al 2004, Gilger 2005, Pearce et al 2007.Equine recurrent uveitis (ERU), also known as moon blindness or periodic ophthalmia, is the most common cause of blindness in horses worldwide (Faber et al 2000 The objective of the study was to determine the association between clinical ophthalmic alterations and seroreactivity to leptospirosis by serovar Icterohaemorrhagiae in horses in Rio de Janeiro, Brazil. A total of 199 horses were studied.…”