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Published on: January 24, 2025
Virulence and Adhesion of the Treponema pallidum Nichols Strain Simultaneously Decrease in a Continuous-Infection New
Jialin Huang1, Yinbo Jiang1, Weiqiang Lin1
1Molecular Diagnosis and Treatment Center for Infectious Diseases, Dermatology Hospital, Southern Medical University, Guangzhou 510091, P. R. China.
Abstract:
Syphilis is a sexually transmitted disease caused by T. pallidum, and the T. pallidum Nichols strain is widely used with the New Zealand white rabbit model for evaluating drug and vaccine protection. However, changes in the virulence of T. pallidum during transmission are still unknown. Herein, we explored the virulence of T. pallidum in the rabbit model of continuous infection through phenotype observation and further investigated the relationship between virulence and adhesion. During the construction of the syphilis rabbit model, the optimal dose of 104/site of T. pallidum was determined to effectively observe the depiction of syphilis lesions and immune responses for further virulence evaluation. Its virulence was gradually weakened during the interaction with host cells or the testicular passage, which was also proven using the pathological phenotype of the syphilis rabbit model. In addition, the adhesive ability of T. pallidum was reduced with increasing generation, which was verified via the co-incubation of the pathogen with Sf1Ep cells. This study provides insight into the relationship by which the virulence and adhesion of T. pallidum were decreased in a New Zealand white rabbit model of continuous infection and contributes to our knowledge regarding the development of syphilis.
Insights
Syphilis virulence and adhesion of Treponema pallidum (T. pallidum) decrease with continuous infection in rabbits. This study reveals how T. pallidum weakens over time in a rabbit model, impacting syphilis development.
Area of Science:
- Infectious Diseases
- Microbiology
- Immunology
Background:
- Syphilis is a sexually transmitted infection caused by Treponema pallidum (T. pallidum).
- The T. pallidum Nichols strain in New Zealand white rabbits is a standard model for drug and vaccine efficacy studies.
- The impact of continuous transmission on T. pallidum virulence is not well understood.
Purpose of the Study:
- To investigate the changes in T. pallidum virulence during continuous infection in a rabbit model.
- To explore the relationship between T. pallidum virulence and its adhesion properties.
- To understand the implications for syphilis development and treatment.
Main Methods:
- Established a syphilis rabbit model using the T. pallidum Nichols strain.
- Determined the optimal infectious dose (10^4/site) for observing lesions and immune responses.
- Assessed virulence changes through pathological phenotypes and host cell interactions (Sf1Ep cells).
Main Results:
- T. pallidum virulence gradually decreased during host cell interaction and testicular passage in rabbits.
- The adhesive ability of T. pallidum diminished with increasing generations of infection.
- Pathological observations confirmed the weakening virulence in the continuously infected rabbit model.
Conclusions:
- Virulence and adhesion of T. pallidum are reduced during continuous infection in the New Zealand white rabbit model.
- Findings provide insights into T. pallidum adaptation and potential implications for syphilis pathogenesis.
- This research contributes to understanding syphilis development and informs future therapeutic strategies.
