Multilocus Analysis Resolves the European Finch Epidemic Strain of Trichomonas gallinae and Suggests Introgression from Divergent Trichomonads

Abstract

In Europe, Trichomonas gallinae recently emerged as a cause of epidemic disease in songbirds. A clonal strain of the parasite, first found in the United Kingdom, has become the predominant strain there and spread to continental Europe. Discriminating this epidemic strain of T. gallinae from other strains necessitated development of multilocus sequence typing (MLST). Development of the MLST was facilitated by the assembly and annotation of a 54.7 Mb draft genome of a cloned stabilate of the A1 European finch epidemic strain (isolated from Greenfinch, Chloris chloris, XT-1081/07 in 2007) containing 21,924 protein coding genes. This enabled construction of a robust 19 locus MLST based on existing typing loci for Trichomonas vaginalis and T. gallinae. Our MLST has the sensitivity to discriminate strains within existing genotypes confidently, and resolves the American finch A1 genotype from the European finch epidemic A1 genotype. Interestingly, one isolate we obtained from a captive black-naped fruit dove Ptilinopsus melanospilus, was not truly T. gallinae but a hybrid of T. gallinae with a distant trichomonad lineage. Phylogenetic analysis of the individual loci in this fruit dove provides evidence of gene flow between distant trichomonad lineages at 2 of the 19 loci examined and may provide precedence for the emergence of other hybrid trichomonad genomes including T. vaginalis.

High‐throughput sequencing of faeces provides evidence for dispersal of parasites and pathogens by migratory waterbirds

“…Similarly, the large diversity of trichomonads predominantly associated with waterfowl samples (Figure 4), can also be related to other bird‐associated trichomonads, for example the high prevalence and diversity of Tetratrichomonas recently detected in geese (Falkowski et al, 2020), indicating a much larger diversity of these parasites than previously known. This is of particular interest given the emergence of diseases caused by Trichomonas gallinae and recent evidence of introgression between different trichomonad lineages (Alrefaei et al, 2019). The latter includes Tetratrichomonas causing typhlo‐hepatitis in three different duck species (Richter et al, 2010), and related parasites reducing condition in doves/pigeons and eagles (Martínez‐Díaz et al, 2015).…”

Molecular detection and genetic characterization of Trichomonas gallinae in falcons in Saudi Arabia

“…The four types of sequences detected in the current study correspond to four genotypes previously reported (Fig 1). These sequences, A, C, II and KSA11, are distinct lineages of T. gallinae, and all the sequences are commonly found in many species of birds, including columbids, raptors, chickens and finches, in various European countries, such as the UK, the USA, Canada, Brazil and Saudi Arabia [5,6,8,13,18,19,23,28,29]. However, the most important finding is that sequence II, originally reported in a racing pigeon in Austria (GenBank: FN433474) [26], was the most prevalent in the Saudi falcons.…”

Trichomonosis in Greenfinches (Chloris chloris) in the Netherlands 2009–2017: A Concealed Threat

“…To further elucidate the importance of this finding, other genes would need to be sequenced, preferably more variable than the SSU rRNA gene and the rpb1 gene, which are very conserved (21) and were therefore not used in this study. Primers have just been published for performing a parallel 19 locus multilocus sequence typing test that showed good discriminatory ability for distinguishing T. gallinae strains (31).…”