Antigen-Specific Urinary Immunoglobulin in Reservoir Hosts of Leptospirosis.

Jarlath E Nally,David P Alt,Richard L Hornsby

doi:10.3390/vetsci8090178

Abstract

Domestic and wildlife animal species act as reservoir hosts of leptospirosis, a global zoonotic disease affecting more than 1 million people annually and causing significant morbidity and mortality in domestic animals. In contrast to incidental hosts which present with an array of clinical manifestations, reservoir hosts are typically asymptomatic and can shed leptospires from chronically infected kidneys via urine for extended periods of time. Renal excretion of leptospires occurs despite evidence of a humoral and cellular immune response and is reflective of the unique biological equilibrium that exists between certain animal species and specific serovars of Leptospira. Here, we demonstrate that urinary excretion of leptospires is accompanied by the presence of antigen-specific urinary immunoglobulin. In rats experimentally infected with L. interrogans serovar Copenhageni using the intraperitoneal or conjunctival route of inoculation, urinary immunoglobulin (Ig) G specific for protein antigens was detectable within 1 week. Rat urinary IgG was not bound to urinary-derived leptospires. In cattle that were naturally exposed to, and infected with, L. borgpetersenii serovar Hardjo, urinary IgA specific for protein antigens was detected. Collectively, these results demonstrate that urinary excretion of immunoglobulin specific for leptospires is a hallmark of reservoir hosts of infection.

Highlights

Disease transmission is maintained by domestic and wildlife animal species which act as reservoir hosts of infection and excrete leptospires colonizing the renal tubules via urine into the environment where they can persist in suitable moist conditions [2]
Though reservoir hosts are generally asymptomatic, animal leptospirosis in domestic animal species can result in significant morbidity and mortality; bovine leptospirosis causes reproductive failure, abortion, stillbirth, and loss of milk production [3]
In rat 18, for which both IgG heavy and light chain was readily detected by immunoblot in Figure 1B, urinary IgG specific for leptospires was present by post-infection week (PIW) 4 and increased at PIW8 and PIW12

Summary

Introduction

Pathogenic leptospires of the genus Leptospira are the causative agent of leptospirosis, a global zoonotic disease infecting more than 1 million people annually [1]. Disease transmission is maintained by domestic and wildlife animal species which act as reservoir hosts of infection and excrete leptospires colonizing the renal tubules via urine into the environment where they can persist in suitable moist conditions [2]. Serologic reactivity detected using the microscopic agglutination test (MAT) is most often used to establish exposure of an animal to pathogenic leptospires, but this is of limited value in identifying reservoir hosts of infection since active shedding of leptospires can occur in the absence of a detectable MAT titer [4,5]

Methods

Results

Conclusion