Ultrastructural study of a tetratrichomonad isolated from pig fecal samples

First Molecular Detection and Genetic Characterization of Tetratrichomonas buttreyi and Pentatrichomonas hominis in Donkeys in Shanxi Province, China

Two species of trichomonads, Tetratrichomonas buttreyi and Pentatrichomonas hominis, are common intestinal parasites that can impact animal health and productivity. Severe infection by these parasites can lead to diarrhea and wasting in affected animals. Notably, P. hominis is known to cause diarrhea and has the potential to be transmitted between animals and humans. Donkeys hold significant economic importance in China's agricultural sector. However, whether donkeys are infected with T. buttreyi and P. hominis remains unknown globally. To address this gap in knowledge, 815 fecal samples were collected from donkeys in three representative regions in Shanxi Province, North China. Then, the presence and genetic characteristics of T. buttreyi and P. hominis were examined using species-specific PCR primers amplifying the small subunit ribosomal RNA genes. The overall prevalence was detected to be 25.4% (207/815) for T. buttreyi and 0.7% (6/815) for P. hominis in donkeys in Shanxi Province. All obtained P. hominis sequences were identified as genotype CC1. Genetic analysis revealed that all P. hominis isolates from donkeys were clustered into the same branch with isolates detected in humans, suggesting possible zoonotic transmission. This study is the first to report the occurrence and prevalence of T. buttreyi and P. hominis in donkeys globally. These findings expand the host range of trichomonads and improve our understanding of their genetic diversity and zoonotic potential, providing essential baseline data for the prevention and control of these parasites in donkeys in the region.

Prevalence of Tetratrichomonas buttreyi and Pentatrichomonas hominis in yellow cattle, dairy cattle, and water buffalo in China

The trichomonad species Tetratrichomonas buttreyi and Pentatrichomonas hominis have been reported in the bovine digestive tract in only a few studies, and the prevalence and pathogenicity of these two protists in cattle herds remain unknown. In this study, the prevalence of T. buttreyi and P. hominis in yellow cattle, dairy cattle, and water buffalo in Anhui Province, China, was determined with a PCR analysis of the small subunit ribosomal RNA genes. The overall infection rates for T. buttreyi and P. hominis were 8.1% and 5.4%, respectively. Double infections were found in 15 (1.6%) samples from four farms. The prevalence of P. hominis in cattle with abnormal feces was significantly higher than that in cattle with normal feces (χ² = 13.0, p < 0.01), and the prevalence of T. buttreyi in the northern region of Anhui Province was also significantly higher than that in the mid region (χ² = 16.6, p < 0.01). Minor allelic variations were detected in the T. buttreyi isolates from cattle in this study, as in other hosts in previous studies. Morphological observations, together with the PCR analysis, demonstrated that the trichomonads isolated in this study were P. hominis. The presence of T. buttreyi and P. hominis indicated that cattle are natural hosts of these two trichomonads and could be a potential source of P. hominis infections in humans and other animal hosts.

Morphological, ultrastructural, and molecular characterization of intestinal tetratrichomonads isolated from non-human primates in southeastern Brazil

Non-human primates are our closest relatives and represent an interesting model for comparative parasitological studies. However, research on this topic particularly in relation to intestinal parasites has been fragmentary and limited mainly to animals held in captivity. Thus, our knowledge of host-parasite relationships in this species-rich group of mammals could be considered rudimentary. The current study combined morphological, ultrastructural, and molecular analyses to characterize isolates of intestinal tetratrichomonads recovered from the feces of three species of South American, non-human primates. Fecal samples were collected from 16 animals, representing 12 distinct species. Parabasalid-like organisms were evident in five samples (31%) of feces: two from Alouatta sara, two from Callithrix penicillata, and one from Sapajus apella. The five samples presented morphologies consistent with the description of Tetratrichomonas sp., with four anterior flagella of unequal length, a well-developed undulating membrane, and a long recurrent flagellum. Sequencing of the ITS1-5.8S rRNA-ITS2 region demonstrated that the isolates from A. sara, and C. penicillata were closely related and highly similar to isolates of Tetratrichomonas brumpti, recovered previously from tortoises (Geochelone sp.). The flagellate recovered from S. apella demonstrated a similar morphology to those of the other isolates, however, sequence analysis showed it to be identical to an isolate of Tetratrichomonas sp. recovered from white-lipped peccaries (Tayassu pecari). The findings of this study extend and enhance our knowledge of parasitism of non-human primates by members of the genus Tetratrichomonas and indicate that the host range of these parasites is broader than previously believed.

The prevalence of intestinal trichomonads in Chinese pigs

Intestinal infection of pigs with trichomonads, (Tritrichomonas suis, Tetratrichomonas buttreyi, and Pentatrichomonas hominis) has been reported in many countries, such as the Philippines, Belgium, and the Czech Republic. However, the prevalence of trichomonads infection of swine in China has not yet been investigated. In this study, we used small subunit ribosomal RNA genes to detect the prevalence of T. suis, T. buttreyi and P. hominis among 158 fecal specimens from healthy pigs. Infection rates were 12.03%(19/158), 14.57% (23/158), and 24.05% (38/158) for T. suis, T. buttreyi and P. hominis, respectively. Molecular evolutionary analysis showed minor allelic variation in T. buttreyi from China compared to T. buttreyi isolated from other hosts in different parts of the world.

Pentatrichomonas hominis: first isolation from the feces of a dog with diarrhea in China

A trichomonad-like parasite isolated from canine fecal samples in Changchun, China was successfully cultivated in vitro using RPMI1640 medium supplemented with 10% heat-inactivated calf serum and antibiotics. These were then subjected to scanning and transmission electron microscopy for ultrastructural study. This parasite has four anterior flagella of unequal length, one independent flagellum, and one recurrent flagellum. It exhibits an anterior nucleus, a Golgi complex, an axostyle, food vacuoles, and hydrogenosomes. These features are consistent with the ultrastructural characteristics of previously described Pentatrichomonas hominis. Polymerase chain reaction and sequence analysis of three genetic loci, including ITS1-5.8S rRNA-ITS2, 18S rRNA, and EF-1α, were also used to compare these samples with other trichomonad species. Molecular identification was also consistent with P. hominis. This is the first time that isolation of P. hominis has been isolated from dog in China, although several other strains of P. hominis have been isolated from human samples.

Molecular and morphologic identification of Pentatrichomonas hominis in swine

A marasmic pig with watery diarrhea was identified to harbor the human-pathogenic protist Pentatrichomonas hominis by PCR and sequence analysis of three genetic loci (ITS1-5.8S rRNA-ITS2, 18S rRNA, and EF-1α), electron microscopy, and infection experiments. DNA sequencing and phylogenetic analysis indicated the organism isolated in this study was most closely related to P. hominis. SEM and TEM observation of the ultrastructure demonstrated that it had a morphology identical to P. hominis. The result of experimental infections with P. hominis exhibited that the cells had the ability to propagate in the cecum of piglets and fecal-oral route might be the major way in which pigs became infected. The present study confirmed that swine could be a host for P. hominis and might serve as a reservoir for human trichomoniasis.

Molecular characterization of trichomonads isolated from animal hosts in the Philippines

Trichomonads are amitochondrial anaerobic flagellated protists that are either parasites or commensals, generally living in the digestive or genitourinary tract of humans and animals. It has been reported that these protozoa can migrate to other sites in their target host, can adapt to new hosts, and are capable of zoonotic transmission. In this study, 59 trichomonad isolates from different animal hosts in the Philippines were identified and characterized. Primer sets were designed and were successful in amplifying the 18S rRNA gene sequences of the isolates. Phylogenetic trees were constructed using neighbor-joining (NJ), maximum parsimony (MP), maximum-likelihood (ML) and Bayesian inference (BI) analyses. Results showed that BLAST analysis of the isolates corresponded to the clustering of the isolates together with reference sequences in the constructed ML tree. Cattle and pig isolates were most likely Tetratrichomonas buttreyi, which were observed to be commensal in both animals. All duck and rooster isolates were similar with Tetratrichomonas gallinarum. All dog isolates together with single isolates from boa, goat, and owl were identical to Pentatrichomonas hominis. Occurrence of P. hominis in Boa constrictor imperator (boa) and Otus megalotis (Philippine scops owl) suggested the adaptation of the trichomonad to new hosts. Reptile hosts were observed to harbor Trichomitus batrachorum or Hypotrichomonas acosta. Three reptile isolates (Igu2, Igu4, and Liz7) suggest novel species belonging to Class Hypotrichomonadea. Furthermore, iguanas were infected with T. batrachorum or H. acosta. Trichomonads in animal hosts are commensal and the mode of transmission is via fecal-oral route. They are capable of adaptation to new hosts and therefore, zoonotic transmission is possible as well as pathogenesis in host. Thus, trichomonads can pose threats to the health of humans and animals.

Morphological and molecular identification of Tetratrichomonas flagellates from the giant anteater (Myrmecophaga tridactyla)

A tetratrichomonad flagellate found in the diarrhoeic faeces of a 5 years-old male giant anteater (Myrmecophaga tridactyla) was characterised by morphological and genetic analysis. This protozoan presents four anterior flagella of unequal length and a recurrent flagellum attached to the undulating membrane without a free end portion, and a broad axostyle projection. Numerous vacuoles of different sizes containing bacteria and digestion products were found. The complete sequence of the DNA coding for the 16S rRNA-ITS1-5.8S rRNA-ITS2 region was also obtained in order to compare this isolate with other tetratrichomonad species. The sequence obtained was identical to others previously obtained by other researchers from bovines and turtles (Geochelone sp.). It is not easily explainable how the same organism could be found in such different hosts and locations; however these results indicate that some tetratrichomonad species could have a wide host range and could survive in a wide range of environmental conditions.

Molecular survey of Tritrichomonas suis (=T. foetus) 'cat' and 'cattle' genotypes in pigs in Japan

Tritrichomonas suis (=T. foetus) is a protozoan parasite of pigs, cattle and cats. Based on host range and genetic differences, T. suis has been divided into a 'cat genotype' and a 'cattle genotype', with the latter genotype capable of infecting both cattle and pigs. Since no information is currently available on the genetic characteristics of T. suis from pigs in Japan, we conducted a molecular survey of T. suis using fecal DNA from pigs in Japan. Of the 64 pigs examined, nested PCR revealed that 36 (56.3%) were positive for T. suis. Sequence analysis of 8 positive samples showed that 7 of the pig isolates belonged to the 'cattle genotype' and the remaining isolate belonged to the 'cat genotype'. The findings revealed that T. suis infection is common in pigs in Japan and that pigs can be infected by both genotypes.

First evidence of previously undescribed trichomonad species in the intestine of pigs?

Three different parasites of the phylum Parabasala (Tritrichomonas foetus, Trichomitus rotunda and Tetratrichomonas buttreyi) have been described in pigs. In a previous study (Mostegl et al., 2011) approximately 47% of 91 paraffin wax-embedded intestinal samples of pigs which were Trichomonas-positive by in situ hybridization using a probe with a broad reactivity spectrum contained other species than T. foetus. Out of these, intestinal trichomonads from three pigs (pigs 1–3) were further analyzed by gene sequencing of a part of the 18S ribosomal RNA (rRNA) gene using primer walking. Subsequently, the partial sequences achieved by the different primer pairs were combined to a sequence of about 1000 bp for each trichomonad. In all three pigs unique sequences were acquired which showed only moderate similarities to sequences available in the GenBank. Alignments and the BLAST analysis showed a high degree of homology between sequences of trichomonads from pig 1 and pig 3 with only 1% difference. These sequences were found to be 92% similar to Hypotrichomonas acosta, a trichomonad isolated from squamate reptiles. The trichomonad sequence detected in the intestine of pig 2 showed about 10% nucleotide differences compared to pigs 1 and 3. This sequence was 97% similar to two Trichomitus batrachorum (a frog symbiont) sequences. A phylogenetic analysis using the neighbor-joining and maximum likelihood methods supported the data of the BLAST analysis. These results suggest the presence of at least two as yet undescribed trichomonad species in the intestinal contents of pigs.

Investigations on the prevalence and potential pathogenicity of intestinal trichomonads in pigs using in situ hybridization

In pigs, three different trichomonad species (Tritrichomonas foetus, Tetratrichomonas buttreyi and Tritrichomonas rotunda) have been described as commensals in the large intestine. The aim of this study was to gain further knowledge on the prevalence and pathogenicity of trichomonads in pigs by using a morphology-based approach. Chromogenic in situ hybridization (ISH) is a technique which allows direct localization of the protozoa in the intestinal tissue and correlation of the infection with pathologic changes. In the present study paraffin-wax embedded colon and ileum samples of 192 pigs were analyzed with this method. Using a probe specific for all known members of the order Trichomonadida (OT) 100 of the 192 pigs were tested positive. Thereof, about 10% showed moderate to high-grade parasitic load with trichomonads invading the lamina propria. Partial 18S ribosomal RNA gene sequencing of six of those animals showed a 100% sequence identity with T. foetus sequences. The majority of these animals were also tested positive for other enteropathogenic agents, such as Brachyspira sp., Lawsonia intracellularis, Escherichia coli, and porcine circovirus type 2. All OT-positive samples were further examined with another probe complementary to all known Tritrichomonas species sequences including T. foetus, T. augusta, T. mobilensis and T. nonconforma resulting in only 48 positives. These results suggest that T. foetus may not only be considered as an intestinal commensal but rather a facultative pathogen of pigs with a tendency for tissue invasion in the presence of other agents. Furthermore, the existence of other – yet to be identified – trichomonad species in the colon of pigs was shown.

Design and validation of an oligonucleotide probe for the detection of protozoa from the order Trichomonadida using chromogenic in situ hybridization

Infections with protozoal parasites of the order Trichomonadida are often observed in veterinary medicine. Based on the trichomonad species involved these infections are either asymptomatic or can lead to sometimes serious disease. To further study protozoal agents of the order Trichomonadida the establishment of a method to detect trichomonads directly in the tissue, allowing parasite-lesion correlation, is necessary. Here we describe the design and evaluation of an oligonucleotide probe for chromogenic in situ hybridization, theoretically allowing detection of all hitherto known members of the order Trichomonadida. The probe was designed on a region of the 18S ribosomal RNA gene homologue for all representatives of the order Trichomonadida available in the GenBank. Functionality of the probe was proven using protozoal cultures containing different trichomonads (Monocercomonas colubrorum, Hypotrichomonas acosta, Pentatrichomonas hominis, Trichomitus batrachorum, Trichomonas gallinae, Tetratrichomonas gallinarum, Tritrichomonas foetus, and Tritrichomonas augusta). Furthermore, three different tissue sections containing either T. gallinae, T. foetus or Histomonas meleagridis were tested positive. Additionally, to rule out cross-reactivity of the probe a large number of different pathogenic protozoal agents, fungi, bacteria and viruses were tested and gave negative results. The probe presented here can be considered an important tool for diagnosis of all to date described relevant protozoal parasites of the order Trichomonadida in tissue samples.