Analysis of intraspecific sequence variation among eight isolates of the rumen symbiont, Isotricha prostoma (Ciliophora), from two continents

The Phylogenetic Characterization of Balantioides coli Isolated in the Pavlova Culture Medium Supplemented with Coconut Water and Animal Serum

Balantioides coli is a ciliated protist that can cause dysentery in humans, pigs and nonhuman primates and may have the potential for zoonotic transmission. Its diagnosis is routinely performed through conventional parasitological techniques, and few studies have used culturing techniques to isolate it, applying molecular tools for the characterization of this protozoan. Thus, the objective of this study was to confirm B. coli diagnosis using molecular tools and to characterize the genetic variants of this parasite isolated from pigs kept on family farms in Brazil using three different culture media that differed in the serum added. Fecal samples from pigs were inoculated in Pavlova medium plus coconut water (PC), fetal bovine serum (PB) and horse serum (PH). Of the 127 samples positive for forms compatible with the phylum Ciliophora, 31 were selected for isolation. The most successful medium for isolation was PB 19/31 (61.3%), followed by PH 18/31 (58.1%) and PC 11/31 (35.5%). Of the nucleotide sequences generated, 20 were classified as genetic variant type B0, two as A1 and 15 as A0. The results indicated that PC, despite having allowed the isolation of B. coli for a short period, was not an adequate medium for the maintenance of this parasite in vitro, therefore requiring improvement.

Morphometric and Molecular Analysis of Five-Spine Epidinium Morphotypes Taken from the Rumen of European Bison, Bison bonasus

An important feature of ruminal ciliates is their phenotypic plasticity, which makes their identification difficult. The common manifestation of the phenotypic plasticity in rumen ciliates is a change in their cell size and caudal spination. We analyzed various morphotypes of Epidinium with five caudal processes (spines) taken from the rumen of European bison (Bison bonasus). In the study, the cluster analysis and K-means analysis of morphometric data could not distinguish very similar morphotypes of Epidinium with five caudal processes. However, the morphotype of E. parvicaudatum prevailed (70%). The DNA of four individual E. parvicaudatum was isolated successfully from formaldehyde-preserved samples. The partial 18S rDNA gene sequences (about 350-400 bp) were identical to Epidinium sequences in GenBank (E. caudatum, a one-spine morphotype, and E. cattanei, a five-spine morphotype). It can be assumed that these short sequences cannot distinguish the differences between the Epidinium morphospecies. Complete gene sequences from various hosts and various molecular markers are necessary to reveal the validity of the Epidinium five-spine species. In conclusion, classical morphology should be supplemented with molecular data when more morphotypes of the rumen ciliate species are present in samples.

First molecular characterization of Balantioides coli (Malmsten, 1857) isolates maintained in vitro culture and from feces of captive animals, Rio de Janeiro, Brazil

Ciliate protozoa of the genus Balantioides can parasitize a variety of animals. The morphology of the evolutionary forms of the parasite and the host species affected have long been the only characteristics used to taxonomically identify the species of these protozoa, but these variables are not very precise. To confirm species identity, molecular biology tools are currently used. In this context, this study aimed to analyze protozoan isolates maintained in culture medium and from fecal samples from captive animals in Rio de Janeiro, Brazil, by means of molecular tools. Forty isolates maintained in Pavlova modified medium (30 were isolated from feces of pigs and 10 from feces of cynomolgus macaques) were analyzed. In addition, 34 fecal samples (8 from pigs, 8 from cynomolgus macaques and 18 from rhesus macaques) containing Balantioides coli-like cysts were analyzed. All samples were subjected to DNA extraction and the polymerase chain reaction (PCR) to amplify the fragment ITS1 - 5.8s rRNA - ITS2, and the PCR products were purified and sequenced. All samples (100%) presented sequences that were grouped in the Balantioides coli cluster. The type A0 variant predominated. These sequences were 96% to 99% identical to those deposited in GenBank, including a B. coli sequence that had been obtained from human fecal material in Bolivia. It seems that the culturing system did not select variants, because this variant was also seen in the amplified sequences of fecal samples containing cysts. The isolate sequences in the cultures showed few ambiguities and substitutions, thus generating reliable chromatograms. This was the first study to identify B. coli in captive animals in Brazil, through molecular biology. In addition, it was the first to evaluate a large panel of isolates of the parasite through culturing.

Methods for taxonomic studies of rumen ciliates (alveolata: ciliophora): a brief review

This review presents the principal methods used in taxonomic studies of rumen ciliates: live observation, Lugol staining, fixation and staining with methyl-green formalin saline (MFS) solution, protargol staining, silver carbonate impregnation, scanning electron microscopy and molecular techniques. Mastering these techniques is essential for successful research on the taxonomy of rumen ciliates. No single technique reveals all of the characteristics required for a complete description of a rumen ciliate; therefore, it is necessary to combine the use of these techniques as appropriate to the rumen ciliate group under study. Tables are provided to summarize: 1) morphological methods more appropriate for revealing morphological structures of interest, 2) morphological methods indicated for each group of rumen ciliates, and 3) main primers used for PCR amplification of the 18S rDNA of rumen ciliates.

Novel insights into the genetic diversity of Balantidium and Balantidium-like cyst-forming ciliates

Balantidiasis is considered a neglected zoonotic disease with pigs serving as reservoir hosts. However, Balantidium coli has been recorded in many other mammalian species, including primates. Here, we evaluated the genetic diversity of B. coli in non-human primates using two gene markers (SSrDNA and ITS1-5.8SDNA-ITS2). We analyzed 49 isolates of ciliates from fecal samples originating from 11 species of captive and wild primates, domestic pigs and wild boar. The phylogenetic trees were computed using Bayesian inference and Maximum likelihood. Balantidium entozoon from edible frog and Buxtonella sulcata from cattle were included in the analyses as the closest relatives of B. coli, as well as reference sequences of vestibuliferids. The SSrDNA tree showed the same phylogenetic diversification of B. coli at genus level as the tree constructed based on the ITS region. Based on the polymorphism of SSrDNA sequences, the type species of the genus, namely B. entozoon, appeared to be phylogenetically distinct from B. coli. Thus, we propose a new genus Neobalantidium for the homeothermic clade. Moreover, several isolates from both captive and wild primates (excluding great apes) clustered with B. sulcata with high support, suggesting the existence of a new species within this genus. The cysts of Buxtonella and Neobalantidium are morphologically indistinguishable and the presence of Buxtonella-like ciliates in primates opens the question about possible occurrence of these pathogens in humans.

High-level genetic diversity but no population structure inferred from nuclear and mitochondrial markers of the peritrichous ciliate Carchesium polypinum in the Grand River basin (North America)

Studies that assess intraspecific genetic variation in ciliates are few and quite recent. Consequently, knowledge of the subject and understanding of the processes that underlie it are limited. We sought to assess the degree of intraspecific genetic variation in Carchesium polypinum (Ciliophora: Peritrichia), a cosmopolitan, freshwater ciliate. We isolated colonies of C. polypinum from locations in the Grand River basin in Southwestern Ontario, Canada. We then used the nuclear markers--ITS1, ITS2, and the hypervariable regions of the large subunit rRNA--and an 819-bp fragment of the mitochondrial cytochrome c oxidase I gene (cox-1) to investigate the intraspecific genetic variation of C. polypinum and the degree of resolution of the above-mentioned markers at the population level. We also sought to determine whether the organism demonstrated any population structure that mapped onto the geography of the region. Our study shows that there is a high degree of genetic diversity at the isolate level, revealed by the mitochondrial markers but not the nuclear markers. Furthermore, our results indicate that C. polypinum is likely not a single morphospecies as previously thought.

Current world status of Balantidium coli

Balantidium coli is a cosmopolitan parasitic-opportunistic pathogen that can be found throughout the world. Pigs are its reservoir hosts, and humans become infected through direct or indirect contact with pigs. In rural areas and in some developing countries where pig and human fecal matter contaminates the water supply, there is a greater likelihood that balantidiosis may develop in humans. The infection may be subclinical in humans, as it mostly is in pigs, or may develop as a fulminant infection with bloody and mucus-containing diarrhea; this can lead to perforation of the colon. The disease responds to treatment with tetracycline or metronidazole. Balantidiosis is a disease that need never exist given access to clean water and a public health infrastructure that monitors the water supply and tracks infections. Its spread can be limited by sanitary measures and personal hygiene, but it is a disease that will be around as long as there are pigs. Immunocompromised individuals have developed balantidiosis without any direct contact with pigs, perhaps with rats or contaminated produce as a possible source of infection. For the clinician, balanatidiosis should be included in the differential diagnosis for persistent diarrhea in travelers to or from Southeast Asia, the Western Pacific islands, rural South America, or communities where close contact with domestic swine occurs. Warming of the earth's surface may provide a more favorable environment, even in the now-temperate areas of the world, for survival of trophic and cystic stages of Balantidium, and its prevalence may increase. Effective sanitation and uncontaminated water are the most useful weapons against infection. Fortunately, balantidiosis responds to antimicrobial therapy, and there have been no reports of resistance to the drugs of choice.

Intraspecific genetic variation in Paramecium revealed by mitochondrial cytochrome C oxidase I sequences

Studies of intraspecific genetic diversity of ciliates, such as population genetics and biogeography, are particularly hampered by the lack of suitable DNA markers. For example, sequences of the non-coding ribosomal internal transcribed spacer (ITS) regions are often too conserved for intraspecific analyses. We have therefore identified primers for the mitochondrial cytochrome c oxidase I (COI) gene and applied them for intraspecific investigations in Paramecium caudatum and Paramecium multimicronucleatum. Furthermore, we obtained sequences of the ITS regions from the same strains and carried out comparative sequence analyses of both data sets. The mitochondrial sequences revealed substantially higher variation in both Paramecium species, with intraspecific divergences up to 7% in P. caudatum and 9.5% in P. multimicronucleatum. Moreover, an initial survey of the population structure discovered different mitochondrial haplotypes of P. caudatum in one pond, thereby demonstrating the potential of this genetic marker for population genetic analyses. Our primers successfully amplified the COI gene of other Paramecium. This is the first report of intraspecific variation in free-living protozoans based on mitochondrial sequence data. Our results show that the high variation in mitochondrial DNA makes it a suitable marker for intraspecific and population genetic studies.

Improved strategy for presumptive identification of methanogens using 16S riboprinting

The predicted 16S riboprint patterns of 10 restriction endonucleases for 26 diverse methanogens were compared to actual patterns produced on agarose gels. The observed patterns corroborated the expected riboprints. Our analyses confirmed that the endonuclease HaeIII gave the best results generating 15 different riboprint sets. Six of these 15 riboprints represented more than one strain. Of these, three riboprint sets were further differentiated: Methanomicrobium mobile, Methanolacinia paynteri, and Methanoplanus petrolearius were differentiated from each other by the endonuclease AluI; Methanofollis liminatans, Methanospirillum hungatei, and Methanoculleus bourgensis were differentiated from each other by HpaII; and the combination of FokI and MluNI was used to differentiate Methanobrevibacter sp. ZA-10, and Methanobrevibacter arboriphilicus strains DH-1, AZ, and DC from each other. We could not differentiate the following pairs of strains from each other: Methanosarcina mazeii S-6 and C16, Methanobacterium bryantii MoH and MoH-G, Methanobacterium thermoautotrophicum GC-1 and DeltaH, and Methanobrevibacter arborophillicus DC and A2. This riboprint strategy provided a simple and rapid method to presumptively identify 22 of the 26 diverse strains of methanogens belonging to 13 genera from a range of environments.