Toxoplasma gondii Genotypes Circulating in Serbia—Insight into the Population Structure and Diversity of the Species in Southeastern Europe, a Region of Intercontinental Strain Exchange

Abstract

In Europe, Toxoplasma gondii lineage II is dominant, and ToxoDB#1 the most frequently occurring genotype. The abundance of lineage III genotypes varies geographically and lineage I are rare, yet present in several regions of the continent. Data on the T. gondii population structure in southeastern Europe (SEE) are scarce, yet necessary to appreciate the diversity of the species in Europe. To help fill this gap, we genotyped 67 strains from nine species of intermediate hosts in Serbia by MnPCR-RFLP, determined the population structure, and identified the genotypes using ToxoDB. A neighbor-joining tree was also constructed from the isolates genotyped on nine loci. While 42% of the total genotype population consisted of ToxoDB#1 and ToxoDB#2, variant genotypes of both lineages comprised 46% of the population in wildlife and 28% in domestic animals and humans. One genotype of Africa 4 lineage was detected in a human sample. Interestingly, the findings include one lineage III variant and one II/III recombinant isolate with intercontinental distribution, which appear to be moderately related to South American genotypes. Based on these findings, SEE is a region of underappreciated T. gondii genetic diversity and possible strain exchange between Europe and Africa.

Toxoplasma gondii Genotyping: A Closer Look Into Europe

“…Clonal type III-related strains were also highlighted, mainly detected in animal hosts. Some authors claimed that type III alleles are more frequently detected in southern Europe compared to other parts of the continent ( Kuruca et al., 2019 ; Uzelac et al., 2021 ), but the reality is that France, Italy, and Portugal are the countries that have published the most T. gondii genotyping studies, with a lower contribution from northern countries ( Figure 2D ), implying large areas without information. Type I alleles are particularly underrepresented in Europe.…”

An African perspective on the genetic diversity of Toxoplasma gondii: A systematic review

“…The Africa 4 variant was isolated from a chicken in Benin and ToxoDB#137, which is the RFLP equivalent to the Africa 4 variant, was isolated from a chicken in Ghana (Dubey et al ., 2008 ; Hamidović et al ., 2021 ). This genotype has also been described in Serbia from the amniotic fluid of an immunocompromised patient with no history of travel and in a congenitally infected case from Bulgaria (Uzelac et al ., 2021 ).…”

“…The land and maritime trade between Northeast Africa, Asia and Europe via the Silk Road may have contributed to the dissemination of T. gondii genotypes (Chaichan et al ., 2017 ; Galal et al ., 2019 b ). Seasonal migration of wild birds between Africa and Europe may also play a role in the accrual of African genotypes in European countries (Uzelac et al ., 2021 ). Every year 5 billion wild birds of 187 species migrate from Europe and Asia to Africa (Parin et al ., 2018 ).…”

“…Migratory birds can spread a variety of diseases to resident bird populations and poultry during stopovers along their flyways (Parin et al ., 2018 ). It is feasible that Toxoplasma -infected migratory birds may en route to their destination introduce new genotypes into an environment, via predation or succumbing to disease and being eaten by scavengers (Uzelac et al ., 2021 ).…”

A Pork Industry in the Backyard: An Analysis of Toxoplasma gondii Infection in Serbia’s Pigs

“…Genotyping was performed as previously described in [ 38 ] using the markers Alt.SAG2, SAG3, GRA6, BTUB, C-22, PK1, CS3, L358, C29-2 and APICO. The reaction and digestion mixtures were prepared as described in [ 39 ]. PCR was performed in a Veriti thermal cycler (Applied Biosystems, Foster City, CA, USA) and the PCR and RFLP products were separated by electrophoresis in 2.5% agarose gels stained with ethidium bromide and visualized with a BioDocAnalyze instrument (Biometra, Göttingen, Germany).…”