Publikationsdatenbank

Exploring the genetic diversity of Toxoplasma gondii in Europe by molecular fine characterization (2024)

Art

Hochschulschrift

Autor

Joeres, Maike (WE 7)

Quelle

Berlin, 2024 — 121 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/44420

Kontakt

Institut für Mikrobiologie und Tierseuchen

Robert-von-Ostertag-Str. 7-13
14163 Berlin
+49 30 838 51843 / 66949
mikrobiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

T. gondii is a zoonotic protozoon that can infect virtually all warm-blooded species on all continents. The parasite has a complex population structure, including countries and continents dominated by only a few clonal lineages, while T. gondii populations in South America are highly diverse. The genetic diversity described in Central and South America is associated with higher virulence and more severe cases of toxoplasmosis in humans, making it important to detect the introduction of such genotypes into Europe. This work focused on genotyping of T. gondii in Europe where the clonal lineage type II is predominant. The predominance of T. gondii type II in Europe was described in the past as part of global studies on population genetics of T. gondii, but there were no studies that focused exclusively on Europe. Therefore, the available genotyping information on European T. gondii was summarized in a review and the distribution of circulating strains in Europe was mapped, revealing that there was little or no information available for some countries. Moreover, it was recognized that the application of genotyping methods was not consistent between different laboratories. A frequently used genotyping method for T. gondii is based on MS markers. It represents the current reference standard for genotyping and fingerprinting. To reach consistency in T. gondii MS typing, a ring trial among five European laboratories was organized and the results were published together with guidelines for a harmonized application of MS typing. On this basis, MS typing results may become more comparable in the future, which is necessary to combine larger data sets on T. gondii genotypes originating from different studies. Guidelines for MS typing may also encourage more laboratories in Europe to use the MS method, which may help to fill the identified gaps in genotyping data. MS typing and WGS analysis revealed genetic variability within T. gondii type II. To explore this further, an NGS-based typing method with a high typing resolution among T. gondii type II strains was established. This new Ion AmpliSeq method appears to be suitable to improve the understanding of transmission pathways of T. gondii, to trace infection sources in outbreaks or to detect recombination and the introduction of genotypes to new areas. Furthermore, the harmonized MS method was applied in a study for genotyping of T. gondii DNA extracted from tissue samples of red squirrels (Sciurus vulgaris) found dead in the Netherlands. This study identified genetic clusters based on the MS typing results, but without obvious regional association. In future studies, cluster analyses can be performed with large, combined datasets using the harmonized MS typing method or Ion AmpliSeq typing to obtain further insights into the population structure of T. gondii in Europe.