Sequence-based genotyping clarifies conflicting historical morphometric and biological data for 5 Eimeria species infecting turkeys

Abstract

Unlike with Eimeria species infecting chickens, specific identification and nomenclature of Eimeria species infecting turkeys is complicated, and in the absence of molecular data, imprecise. In an attempt to reconcile contradictory data reported on oocyst morphometrics and biological descriptions of various Eimeria species infecting turkey, we established single oocyst derived lines of 5 important Eimeria species infecting turkeys, Eimeria meleagrimitis (USMN08-01 strain), Eimeria adenoeides (Guelph strain), Eimeria gallopavonis (Weybridge strain), Eimeria meleagridis (USAR97-01 strain), and Eimeria dispersa (Briston strain). Short portions (514 bp) of mitochondrial cytochrome c oxidase subunit I gene (mt COI) from each were amplified and sequenced. Comparison of these sequences showed sufficient species-specific sequence variation to recommend these short mt COI sequences as species-specific markers. Uniformity of oocyst features (dimensions and oocyst structure) of each pure line was observed. Additional morphological features of the oocysts of these species are described as useful for the microscopic differentiation of these Eimeria species. Combined molecular and morphometric data on these single species lines compared with the original species descriptions and more recent data have helped to clarify some confusing, and sometimes conflicting, features associated with these Eimeria spp. For example, these new data suggest that the KCH and KR strains of E. adenoeides reported previously represent 2 distinct species, E. adenoeides and E. meleagridis, respectively. Likewise, analysis of the Weybridge strain of E. adenoeides, which has long been used as a reference strain in various studies conducted on the pathogenicity of E. adenoeides, indicates that this coccidium is actually a strain of E. gallopavonis. We highly recommend mt COI sequence-based genotyping be incorporated into all studies using Eimeria spp. of turkeys to confirm species identifications and so that any resulting data can be associated correctly with a single named Eimeria species.

Re-description of a genetically typed, single oocyst line of the turkey coccidium, Eimeria adenoeides Moore and Brown, 1951

“…In a recent study (El-Sherry et al 2014) using sequence-based genotyping using mtCOI, E. adenoeides Guelph strain had a COI sequence that was identical to the E. adenoeides KCH strain, and the mtCOI sequence of E. meleagridis USAR97-01 matched that of E. adenoeides KR strain isolated by Poplstein and Vrba (2011).…”

Complete mitochondrial genome sequences from five Eimeria species (Apicomplexa; Coccidia; Eimeriidae) infecting domestic turkeys

“…Six single oocyst-derived lines of five Eimeria species were used in this study. A description of the origins of the original isolates from which each line was derived is provided by El Sherry et al [ 25 ]. The resulting lines used were as follows: 1) Eimeria adenoeides Guelph strain [ 26 ] in submission, for biological features of the line), 2) Eimeria dispersa Briston strain; 3) E. meleagrimitis USMN08-01 strain see [ 27 , 28 ] for biological features); 4) E. meleagridis USAR97-01 strain see [ 29 ], for biological features); 5) E. gallopavonis Weybridge strain see [ 30 ] for biological features); and 6) E. gallopavonis USKS06-01 strain.…”

PCR identification and prevalence of Eimeria species in commercial turkey flocks of the Midwestern United States

“…This information could help evaluate potential need for inclusion of additional species in future commercially available live oocyst vaccines or to make informed decisions about species inclusions in flock-specific autogenous vaccines in order to enhance disease protection. Original characterization of Eimeria species relied on phenotypic characteristics such as host specificity, intestinal localization and lesions, oocyst morphology, cross-immunity, prepatent period, and pathogenicity ( Joyner and Long, 1974 ; El-Sherry et al, 2015 ). While these parameters are still useful today, overlap between species can lead to inconclusive or incorrect identification, especially in cases of mixed species infection ( McDougald and Jeffers, 1976 ; Long and Joyner, 1984 ).…”