Chlamydia research group - Borel Laboratory

About the lab

The different scientific backgrouns of the group members (biologists, biotechnologists, lab technicians, veterinarians) create a fruitful and inspiring environment. The group is working in the One Health setting on basic and applied research projects. We collaborate with veterinarians, scientists and physicians in an interdisciplinary environment. Our research targets animal and human diseases, in particular zoonotic infections.

Keyword: ChlamHealth

Featured research (197)

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) cause most bacterial sexually transmitted infections (STIs) worldwide. CT/NG co-infection is more common than expected due to chance, suggesting CT/NG interaction. However, CT/NG co-infection remains largely unstudied. Obligate intracellular CT has a characteristic biphasic developmental cycle consisting of two bacterial forms, infectious elementary bodies (EBs) and non-infectious, replicating reticulate bodies (RBs), which reside within host-derived, membrane-bound intracellular inclusions. Diverse stressors cause divergence from the normal chlamydial developmental cycle to an aberrant state called chlamydial persistence. Persistence can be induced by host-specific factors such as intracellular nutrient deprivation or cytokine exposure, and exogenous factors such as beta-lactam exposure, which disrupts RB to EB conversion. Persistent chlamydiae are atypical in appearance and, as such, are called aberrant bodies (ABs), but remain viable. The primary hallmark of persistence is reversibility of this temporary non-infectious state; upon removal of the stressor, persistent chlamydiae re-enter normal development, and production of infectious EBs resumes. The beta-lactam amoxicillin (AMX) has been shown to induce chlamydial persistence in a murine vaginal infection model, using the mouse pathogen C. muridarum (CM) to model human CT infection. This remains, to date, the sole experimentally tractable in vivo model of chlamydial persistence. Recently, we found that penicillinase-producing NG (PPNG) can alleviate AMX-induced CT and CM persistence in vitro. We hypothesized that PPNG vaginal co-infection would also alleviate AMX-induced CM persistence in mice. To evaluate this hypothesis, we modified the CM/AMX persistence mouse model, incorporating CM/PPNG co-infection. Contradicting our hypothesis, and recent in vitro findings, PPNG vaginal co-infection failed to alleviate AMX-induced CM persistence.
Water-filtered infrared A (wIRA) alone or in combination with visible light (VIS) exerts anti-chlamydial effects in vitro and in vivo in acute infection models. However, it has remained unclear whether reduced irradiation duration and irradiance would still maintain anti-chlamydial efficacy. Furthermore, efficacy of this non-chemical treatment option against persistent (chronic) chlamydial infections has not been investigated to date. To address this knowledge gap, we evaluated 1) irradiation durations of 5, 15 or 30 min in genital and ocular Chlamydia trachomatis acute infection models, 2) irradiances of 100, 150 or 200 mW/cm² in the acute genital infection model and 3) anti-chlamydial activity of wIRA and VIS against C. trachomatis serovar B and E with amoxicillin (AMX)- or interferon γ (IFN-γ)-induced persistence. Reduction of irradiation duration reduced anti-chlamydial efficacy. Irradiances of 150 to 200 mW/cm², but not 100 mW/cm², induced anti-chlamydial effects. For persistent infections, wIRA and VIS irradiation showed robust anti-chlamydial activity independent of the infection status (persistent or recovering), persistence inducer (AMX or IFN-γ) or chlamydial strain (serovar B or E). This study clarifies the requirement of 30 min irradiation duration and 150 mW/cm² irradiance to induce significant anti-chlamydial effects in vitro, supports the use of irradiation in the wIRA and VIS spectrum as a promising non-chemical treatment for chlamydial infections and provides important information for follow-up in vivo studies. Notably, wIRA and VIS exert anti-chlamydial effects on persistent chlamydiae which are known to be refractory to antibiotic treatment.
Chlamydia trachomatis (Ct) and Neisseria gonorrhoeae (Ng) are the most common bacterial sexually transmitted infections (STIs) worldwide. The primary site of infection for both bacteria is the epithelium of the endocervix in women and the urethra in men; both can also infect the rectum, pharynx and conjunctiva. Ct/Ng co-infections are more common than expected by chance, suggesting Ct/Ng interactions increase susceptibility and/or transmissibility. To date, studies have largely focused on each pathogen individually and models exploring co-infection are limited. We aimed to determine if Ng co-infection influences chlamydial infection and development and we hypothesized that Ng-infected cells are more susceptible to chlamydial infection than uninfected cells. To address this hypothesis, we established an in vitro model of Ct/Ng co-infection in cultured human cervical epithelial cells. Our data show that Ng co-infection elicits an anti-chlamydial effect by reducing chlamydial infection, inclusion size, and subsequent infectivity. Notably, the anti-chlamydial effect is dependent on Ng viability but not extracellular nutrient depletion or pH modulation. Though this finding is not consistent with our hypothesis, it provides evidence that interaction of these bacteria in vitro influences chlamydial infection and development. This Ct/Ng co-infection model, established in an epithelial cell line, will facilitate further exploration into the pathogenic interplay between Ct and Ng.
The Chlamydiae are a phylum of obligate intracellular, Gram-negative bacteria with a biphasic lifecycle [...]
Lateral gene transfer (LGT) facilitates many processes in bacterial ecology and pathogenesis, especially regarding pathogen evolution and the spread of antibiotic resistance across species. The obligate intracellular chlamydiae, which cause a range of diseases in humans and animals, were historically thought to be highly deficient in this process. However, research over the past few decades has demonstrated that this was not the case. The first reports of homologous recombination in the Chlamydiaceae family were published in the early 1990s. Later, the advent of whole-genome sequencing uncovered clear evidence for LGT in the evolution of the Chlamydiaceae , although the acquisition of tetracycline resistance in Chlamydia (C.) suis is the only recent instance of interphylum LGT. In contrast, genome and in vitro studies have shown that intraspecies DNA exchange occurs frequently and can even cross species barriers between closely related chlamydiae, such as between C. trachomatis , C. muridarum , and C. suis . Additionally, whole-genome analysis led to the identification of various DNA repair and recombination systems in C. trachomatis , but the exact machinery of DNA uptake and homologous recombination in the chlamydiae has yet to be fully elucidated. Here, we reviewed the current state of knowledge concerning LGT in Chlamydia by focusing on the effect of homologous recombination on the chlamydial genome, the recombination machinery, and its potential as a genetic tool for Chlamydia.

Lab head

Nicole Borel
  • Institut für Veterinärpathologie
About Nicole Borel
  • CHLAMHEALTH - Chlamydial diseases in humans and animals

Members (3)

Hanna Marti
  • University of Zurich
Theresa Pesch
  • University of Zurich
Efe Altuntaş
  • university of zurcih
Barbara Prähauser
Barbara Prähauser
  • Not confirmed yet

Alumni (27)