Eyedrop Inoculation Causes Sublethal Leptospirosis in Mice

Area of Science:

• Infectious Diseases
• Immunology
• Microbiology

Background:

• Leptospirosis is a zoonotic disease caused by Leptospira bacteria.
• Transmission occurs through contact with contaminated soil and water.
• The conjunctival route is a potential, less-studied mode of infection.

Purpose of the Study:

• To investigate the pathogenesis of Leptospira interrogans serovar Copenhageni infection via the conjunctival route in mice.
• To compare disease progression kinetics with the standard intraperitoneal route.
• To analyze the host immune response and kidney pathology.

Main Methods:

• C3H/HeJ mice were infected conjunctivally with L. interrogans.
• Spirochete dissemination, bacterial load in blood, urine, and kidney were quantified.
• Leptospira-specific IgM and IgG antibody responses were measured.
• Kidney histology and proinflammatory cytokine levels were analyzed.

Main Results:

• Conjunctival infection led to weight loss, dissemination to blood, urine, and kidneys.
• Spirochetes were detected in blood and urine simultaneously.
• Kidney infection showed interstitial nephritis and upregulated inflammatory mediators.
• Disease progression was slower compared to intraperitoneal infection.

Conclusions:

• The conjunctival route is a viable infection pathway for L. interrogans, leading to systemic dissemination and kidney pathology.
• Delayed disease kinetics may be due to host defenses at the ocular surface.
• Understanding this route is crucial for leptospirosis prevention and treatment strategies.