LruA and LruB, Novel Lipoproteins of PathogenicLeptospira interrogansAssociated with Equine Recurrent Uveitis

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Abstract
Recurrent uveitis as a sequela toLeptospirainfection is the most common infectious cause of blindness and impaired vision of horses worldwide. Leptospiral proteins expressed during prolonged survival in the eyes of horses with lesions of chronic uveitis were identified by screening a phage library ofLeptospira interrogansDNA fragments with eye fluids from uveitic horses. Inserts of reactive phages encoded several known leptospiral proteins and two novel putative lipoproteins, LruA and LruB. LruA was intrinsically labeled during incubation ofL. interrogansin medium containing [14C]palmitic acid, confirming that it is a lipoprotein.lruAandlruBwere detected by Southern blotting in infectiousLeptospira interrogansbut not in nonpathogenicLeptospira biflexa. Fractionation data from culturedLeptospiraindicate that LruA and LruB are localized in the inner membrane. Uveitic eye fluids contained significantly higher levels of immunoglobulin A (IgA) and IgG specific for each protein than did companion sera, indicating strong local antibody responses. Moreover, LruA- and LruB-specific antisera reacted with equine ocular components, suggesting an immunopathogenic role in leptospiral uveitis.