Biology subjects

Pesch, T.

Publications and source records attributed to Pesch, T..

4 recordsLinked to original sources

bioRxiv2023

Longitudinal study of Chlamydia pecorum in a healthy Swiss cattle population

Chlamydia pecorum is a globally endemic livestock pathogen but prevalence data from Switzerland has so far been limited. The present longitudinal study aimed to get an insight into the C. pecorum prevalence in Swiss cattle and investigated infection dynamics. The study population consisted of a bovine herd (n = 308) located on a farm in the north-eastern part of Switzerland. The herd comprised dairy cows, beef cattle and calves all sampled up to five times over a one-year period. At each sampling timepoint, rectal and conjunctival swabs were collected resulting in 782 samples per localization (total n = 1564). Chlamydiaceae screening was performed initially, followed by C. pecorum-specific real-time qPCR on all samples. For C. pecorum-positive samples, bacterial loads were determined. During this study, C. pecorum was the only chlamydial species found. Animal prevalences included 5.2%-11.4%, 38.1%-61.5% and 55%-100% in dairy cows, beef cattle and calves, respectively. In all categories, the number of C. pecorum-positive samples was higher in conjunctival (n = 151) compared to rectal samples (n = 65), however, the average rectal load was higher. At a younger age, the chlamydial prevalence and the mean bacterial loads were significantly higher. Of all sampled bovines, only 9.4% (29/308) were high shedders (number of copies per {micro}l >1000). Calves, which tested positive multiple times, either failed to eliminate the pathogen between sampling timepoints or were reinfected, whereas dairy cows were mostly only positive at one timepoint. In conclusion, C. pecorum was found in healthy Swiss cattle. Our observations suggested that infection takes place at an early age and immunity might develop over time. Although the gastrointestinal tract is supposed to be the main infection site, C. pecorum was not present in rectal samples from dairy cows.

microbiology↗

bioRxiv2022

Murine Vaginal Co-infection with Penicillinase-Producing Neisseria gonorrhoeae Fails to Alleviate Amoxicillin-Induced Chlamydial Persistence

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.

microbiology↗

bioRxiv2020

Experimental Reptarenavirus Infection of Boa constrictor and Python regius

Boid inclusion body disease (BIBD) causes losses in captive constrictor snake populations globally. BIBD associates with formation of cytoplasmic inclusion bodies (IB) which mainly comprise reptarenavirus nucleoprotein (NP). In 2017, BIBD was reproduced by cardiac injection of boas and pythons with reptarenaviruses, thus demonstrating a causative link between reptarenavirus infection and the disease. Herein, we report experimental infections of pythons (N=16) and boas (N=16) with three reptarenavirus isolates. First, we used pythons (N=8) to test two virus delivery routes: intraperitoneal injection and tracheal instillation. Independent of the delivery route, we detected viral RNA but no IBs in tissues two weeks post inoculation. Next, we inoculated pythons (N=8) via the trachea. During the four month following the infection snakes showed transient central nervous system (CNS) signs but lacked detectable IB at the time of euthanasia. One of the snakes developed severe CNS signs and we succeeded in re-isolating the virus from the brain of this individual, and could demonstrate viral antigen in neurons. In a third attempt, we tested co-housing, vaccination, and sequential infection with multiple reptarenavirus isolates on boas (N=16). At 10 months post inoculation all except one snake tested positive for viral RNA but none exhibited the characteristic IB. Analysis of the antibody responses demonstrated lower neutralizing but higher anti-reptarenavirus NP titers in experimentally versus naturally reptarenavirus infected boas. Our findings suggest that in addition to reptarenavirus infection, other factors, e.g. the antibody response, contribute to BIBD pathogenesis. IMPORTANCEA 2017 study demonstrated cardiac reptarenavirus injection to induce boid inclusion body disease (BIBD) in pythons and boas. In the present study, we experimentally infected pythons and boas with reptarenavirus via either intraperitoneal injection or tracheal instillation. We found both virus delivery routes to result in infection; though the latter could reflect the natural route of infection. In the experimentally infected snakes, we did not find evidence of inclusion body (IB) formation, characteristic to BIBD, in pythons or in boas. Most of the snakes (11/12) studied were reptarenavirus infected after ten-month follow up, which suggests that they could eventually have developed BIBD. We further found differences between the antibody responses of experimentally and naturally reptarenavirus infected snakes, which could indicate that the pathogenesis of BIBD involves factors additional to reptarenavirus infection. As snakes are poikilotherm, also the housing conditions could have an effect.

microbiology↗

bioRxiv2019

Molecular design, optimization and genomic integration of chimeric B cell receptors in murine B cells

Immune cell therapies based on the integration of synthetic antigen receptors provide a powerful strategy for the treatment of diverse diseases, most notably retargeting T cells engineered to express chimeric antigen receptors (CAR) for cancer therapy. In addition to T lymphocytes, B lymphocytes may also represent valuable immune cells that can be engineered for therapeutic purposes such as protein replacement therapy or recombinant antibody production. In this article, we report a promising concept for the molecular design, optimization and genomic integration of a novel class of synthetic antigen receptors, chimeric B cell receptors (CBCR). We initially optimized CBCR expression and detection by modifying the extracellular surface tag, the transmembrane regions and intracellular signaling domains. For this purpose, we stably integrated a series of CBCR variants into immortalized B cell hybridomas using CRISPR-Cas9. Subsequently, we developed a reliable and consistent pipeline to precisely introduce cassettes of several kilobases size into the genome of primary murine B cells, again via CRISPR-Cas9 induced HDR. Finally, we were able to show the robust surface expression and antigen recognition of a synthetic CBCR in primary B cells. We anticipate that CBCRs and our approach for engineering primary B cells will be a valuable tool for the advancement of future B cell-based immune therapies.

immunology↗