Five newly identified proteins are key to the survival of the louse-borne relapsing fever pathogen.
A research team led by Professor Peter Kraiczy at Universitätsmedizin Frankfurt and Goethe University, in collaboration with Justus Liebig University Giessen, has identified and characterized five homologous Chi proteins crucial for the survival of Borrelia recurrentis, the causative agent of louse-borne relapsing fever.
"These Chi proteins have dual functions," Professor Kraiczy explained. "They inhibit the complement system and bind plasminogen, a strategy used by other pathogens to aid tissue invasion."
The findings, funded by the LOEWE Center DRUID (2018-2024), open new avenues for diagnostics and vaccine development.
Key Survival Mechanisms
Chi proteins give Borrelia recurrentis distinct advantages after entering the human body:
- Complement Inhibition: They bind to human blood proteins, preventing activation of the complement system—a critical component of innate immunity.
- Plasminogen Binding: They also bind plasminogen, converting it to active plasmin, which may assist the bacteria in invading tissues and spreading throughout the body.
Background on the Disease
- Cause: Louse-borne relapsing fever, first described by Hippocrates, is caused by Borrelia recurrentis and transmitted by body lice.
- Symptoms: The disease is characterized by recurrent episodes of high fever.
- Treatment: It is treatable with antibiotics. Untreated cases can be fatal in up to 20% of patients.
- Status: Considered a poverty-related neglected disease. Major outbreaks occurred in Europe in the last century; currently, outbreaks are reported in countries around the Horn of Africa. In 2015, increased cases among refugees in Europe drew attention. Infected body lice are not currently found in Europe.
Implications for the Future
Based on these proteins, diagnostic tests have been developed, and potential vaccine targets may be derived.
"Pathogen-specific tests help quickly initiate appropriate antibiotic treatment," Professor Kraiczy noted. "Vaccines could play a role in preparing for potential larger epidemics, should infected individuals or lice introduce the pathogen to Europe."
Current Research
Serological tests developed in the laboratory are currently being studied in Kenya and Nigeria.
Funding
This research was funded by the State of Hesse through the LOEWE Center DRUID (Novel Drug Targets against Poverty-related and Neglected Tropical Infectious Diseases) from 2018 to 2024.