Identification of a novel antigen of pathogenic Leptospira spp. that reacted with convalescent mice sera

Area of Science:

• Infectious Diseases
• Microbiology
• Immunology
• Animal Models

Background:

• Leptospirosis is a significant zoonotic disease caused by pathogenic Leptospira bacteria.
• Understanding the virulence factors of Leptospira is crucial for developing effective diagnostics and treatments.
• C3H/HeJ mice are often used in infectious disease research, but their suitability as a model for severe leptospirosis required investigation.

Purpose of the Study:

• To evaluate the virulence of human-isolated Leptospira strains in C3H/HeJ mice.
• To establish an acute lethal mouse model for severe leptospirosis.
• To identify novel antigens of pathogenic Leptospira spp. involved in virulence.

Main Methods:

• Infection of C3H/HeJ mice with clinical isolates of Leptospira from severe human leptospirosis cases.
• Observation of survival rates and disease progression in infected mice.
• Screening of Leptospira antigens using convalescent mouse sera to identify immunogenic proteins.

Main Results:

• Infection with clinical Leptospira isolates proved lethal to C3H/HeJ mice, validating the model for severe leptospirosis.
• A novel 42 kDa inner-membrane protein, designated LAg42, was identified as reactive with convalescent sera.
• The gene encoding LAg42 is conserved in pathogenic Leptospira but absent in non-pathogenic strains, indicating its potential role in virulence.

Conclusions:

• C3H/HeJ mice serve as an effective acute lethal model for studying severe leptospirosis.
• LAg42 is a potential virulence factor of pathogenic Leptospira, with its immunogenic region located in the C-terminal domain.
• The identification of LAg42 provides a new target for understanding and potentially combating Leptospira infections.