Leptospiral VM Protein Antigen Detection for Rapid Diagnosis of Leptospirosis

Summary
Pathogenic members of the genus, Leptospira, in particular L. interrogans, cause leptospirosis, a zoonotic
bacterial disease of global importance, which affects more than 1 million people annually with a conservatively
estimated 5-20% case fatality rate. Early diagnosis of leptospirosis leading to specific antimicrobial treatment is
thought to prevent progression to severe disease, which is characterized by fever, refractory shock, pulmonary
(and other) hemorrhage, and acute oliguric renal failure. Because the initial manifestations of leptospirosis -
acute undifferentiated fever — are non-specific, the diagnosis of this disease is often missed or delayed. The
potential market for a diagnostic test that identifies early, acute leptospirosis is substantial and an unmet need,
both in terms of clinical care as well as for quantifying the burden of leptospirosis disease that is of prime
interest to public health authorities. In the developing tropical world, leptospirosis affects large swaths of
endemic populations as well as those subject to major weather-related events such as flooding in large urban
settings that occur with predictable regularity. Clinically-actionable tests to diagnose acute leptospirosis remain
unavailable. This proposal aims to address this gap by developing tests capable of rapid, point-of-care,
actionable diagnosis. The premise of this application is that tests based on leptospiral antigen in body fluids
(whole blood, serum, urine) will rapidly and specifically diagnose leptospirosis, leading to improved clinical care
and providing more precise public health data related to burden of disease policymaking. The hypothesis
underlying this proposal is that detecting abundant leptospiral antigens including Virulence Modifying proteins
(VMP) (based on new preliminary data), pathogenic Leptospira-specific LipL32, and Icterohaemorrhagiae
serogroup lipopolysaccharide (LPS) in patient blood will lead to actionable therapeutic interventions and
enable burden of disease studies to justify further leptospirosis product development such as vaccines and
biologics. Specific Aims: 1) Optimize and validate solid phase VMP-based antigen-detection leptospirosis
diagnostic tests. 2) Determine sensitivity and specificity of multiplex antigen-detection solid phase assays,
adding LipL32 and LPS antigen-detection leptospirosis diagnostic tests. The performance of new ELISA and
lateral flow assay prototypes will be determined using in vitro spiked specimens using normal human
blood, serum and urine matrices, ex vivo specimens from acute and chronic animal models, and endemic
country-obtained de-identified leptospirosis human samples. This Phase I STTR project will yield intellectual
property and prototypes of solid phase leptospiral antigen-detecting assays for diagnosis of human
leptospirosis. In a Phase II project, we will scale-up manufacturing for ELISA kits and LFA devices, and expand
field-based clinical testing in humans in established leptospirosis-endemic regions and at US-based clinical
reference laboratories.

Grant Number: 5R41AI181135-02
NIH Institute/Center: NIH
Principal Investigator: Reetika Chaurasia