Genetic characterisation of Toxoplasma gondii in wildlife from North America revealed widespread and high prevalence of the fourth clonal type

Abstract

a b s t r a c tLittle is known of the genetic diversity of Toxoplasma gondii circulating in wildlife. In the present study wild animals, from the USA were examined for T. gondii infection. Tissues of naturally exposed animals were bioassayed in mice for isolation of viable parasites. Viable T. gondii was isolated from 31 animals including, to our knowledge for the first time, from a bald eagle (Haliaeetus leucocephalus), five gray wolves (Canis lupus), a woodrat (Neotoma micropus), and five Arctic foxes (Alopex lagopus). Additionally, 66 T. gondii isolates obtained previously, but not genetically characterised, were revived in mice. Toxoplasma gondii DNA isolated from these 97 samples (31 + 66) was characterised using 11 PCR-restriction fragment length polymorphism (RFLP) markers (SAG1, 5 0 -and 3 0 -SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico). A total of 95 isolates were successfully genotyped. In addition to clonal Types II, and III, 12 different genotypes were found. These genotype data were combined with 74 T. gondii isolates previously characterised from wildlife from North America and a composite data set of 169 isolates comprised 22 genotypes, including clonal Types II, III and 20 atypical genotypes. Phylogenetic network analysis showed limited diversity with dominance of a recently designated fourth clonal type (Type 12) in North America, followed by the Type II and III lineages. These three major lineages together accounted for 85% of strains in North America. The Type 12 lineage includes previously identified Type A and X strains from sea otters. This study revealed that the Type 12 lineage accounts for 46.7% (79/169) of isolates and is dominant in wildlife of North America. No clonal Type I strain was identified among these wildlife isolates. These results suggest that T. gondii strains in wildlife from North America have limited diversity, with the occurrence of only a few major clonal types. Ó

New Insights into Clonality and Panmixia in Plasmodium and Toxoplasma

“…Clonality in Toxoplasma has been confirmed by numerous papers (Boothroyd, 2009;Dubey et al, 2011;Khan et al, 2009Khan et al, , 2011Sibley and Ajioka, 2008;Sibley and Boothroyd, 1992;Smith, 2009;Su et al, 2003;Wendte et al, 2010). It is preponderant in Europe, North America, and Africa, while recombination has a greater impact in South America (Lehman et al, 2004(Lehman et al, , 2006Mercier et al, 2011;Su et al, 2006Su et al, , 2010.…”

The Life Cycle of Toxoplasma gondii in the Natural Environment

“…These three major lineages accounted for 85% of strains from wildlife in North America [148]. The strains isolated from wildlife in North America are thus more diverse, but may also be more different from strains found in the domestic environment than in Europe.…”

“…This could explain the widespread occurrence of only a few well adapted clonal lineages (types II and III) even in wild animals. In other temperate or cold countries, such as the U.S.A. or Canada where large territories are non-anthropized, the genotypic diversity of T. gondii in the wild animals is present [148,149,172]. The diversity is maximal in tropical areas, due to high host diversity and large non-anthropized areas.…”

Qualitative risk assessment of impact of Toxoplasma gondii on health of beluga whales, Delphinapterus leucas from the Eastern Beaufort Sea, Northwest Territories

“…Studies based primarily on samples from humans and domestic animals indicated that Type II strains represent more than 60% of infections in warm-blooded vertebrates, followed by Type I or III (Howe and Sibley 1995;Howe et al 1997). The three clonal lineages are sporadically reported in marine mammals but other genotypes (atypical, Type A, Type X, and Type 12) dominate (Miller et al 2004b;Conrad et al 2005;Honnold et al 2005;Dubey et al 2007Dubey et al , 2008aDubey et al , 2009Dubey et al , 2011. Multiple genotypes have been reported in marine invertebrates (Shapiro et al 2015).…”