Abstract
BackgroundToxoplasma gondii is a major cause of abortion in small ruminants and presents a zoonotic risk when undercooked meat containing cysts is consumed. The aim of the present study was to investigate the genetic diversity among the T. gondii strains circulating in ovine livestock in Spain.MethodsSelected samples collected from abortion outbreaks due to toxoplasmosis (n = 31) and from chronically infected adult sheep at slaughterhouses (n = 50) in different Spanish regions were bioassayed in mice, aiming at parasite isolation. In addition, all original clinical samples and the resulting isolates were genotyped by multi-nested PCR-RFLP analysis of 11 molecular markers and by PCR-DNA sequencing of portions of the SAG3, GRA6 and GRA7 genes.ResultsAs a result, 30 isolates were obtained from 9 Spanish regions: 10 isolates from abortion-derived samples and 20 isolates from adult myocardial tissues. Overall, 3 genotypes were found: ToxoDB#3 (type II PRU variant) in 90% (27/30) of isolates, ToxoDB#2 (clonal type III) in 6.7% (2/30), and ToxoDB#1 (clonal type II) in 3.3% (1/30). When T. gondii-positive tissue samples (n = 151) were directly subjected to RFLP genotyping, complete restriction profiles were obtained for 33% of samples, and up to 98% of the specimens belonged to the type II PRU variant. A foetal brain showed a clonal type II pattern, and four specimens showed unexpected type I alleles at the SAG3 marker, including two foetal brains that showed I + II alleles as co-infection events. Amplicons of SAG3, GRA6 and GRA7 obtained from isolates and clinical samples were subjected to sequencing, allowing us to confirm RFLP results and to detect different single-nucleotide polymorphisms.ConclusionsThe present study informed the existence of a predominant type II PRU variant genotype (ToxoDB#3) infecting domestic sheep in Spain, in both abortion cases and chronic infections in adults, coexisting with other clonal (ToxoDB#1 and ToxoDB#2), much less frequent genotypes, as well as polymorphic strains as revealed by clinical sample genotyping. The use of multilocus sequence typing aided in accurately estimating T. gondii intragenotype diversity.
Highlights
Toxoplasma gondii is a major cause of abortion in small ruminants and presents a zoonotic risk when undercooked meat containing cysts is consumed
This paper presents the genetic characterization of T. gondii ovine isolates and clinical samples obtained from abortion tissues and chronically infected adult animals, providing a picture of the genetic population of T. gondii infecting sheep in Spain
Aiming to maximize the geographical extension covered within Spain and hypothesizing higher probabilities to describe genetic diversity among isolates, 2 types of tissue samples were collected for parasite isolation: (i) tissues derived from suspected Toxoplasma-related abortion outbreaks; and (ii) myocardial tissues from adult animals collected in authorized slaughterhouses
Summary
Toxoplasma gondii is a major cause of abortion in small ruminants and presents a zoonotic risk when undercooked meat containing cysts is consumed. The aim of the present study was to investigate the genetic diver‐ sity among the T. gondii strains circulating in ovine livestock in Spain. A risk assessment study estimated that the consumption of undercooked ovine meat is responsible for 14% of meat-related T. gondii infections in the Dutch population [18]. Despite the importance of the ovine industry in Europe, information about T. gondii strains circulating in European ovine livestock is scarce (Table 1); while most ovine isolates and genotyping descriptions in Europe are clonal [21], some specific findings of novel genotypes [22] and non-clonal isolates [23], along with mixed infections [24], deserve attention.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
