Commensal Protozoa Research Articles

Feeding Mechanisms of Pathogenic Protozoa with a Focus on Endocytosis and the Digestive Vacuole

Endocytosis is a quintessential feature of eukaryotes, and the emergence of endocytosis played a major role in the origin and evolution of eukaryotes. During the early evolution of eukaryotes, phagocytosis and the digestion of prey (i.e., bacteria) combined with the endocytosis of macromolecules opened a new source of nutrients beyond osmotrophy. Pathogenic and commensal protozoa have retained endocytosis as a major mechanism of nutrient acquisition even though, in theory, nutrients could be obtained from the host through osmotrophy. Nearly all pathogenic protozoa exhibit endocytosis and have lysosomal-like compartments that function as digestive vacuoles, and endocytosis appears to play a major role in the acquisition of nutrients. Cryptosporidium is a possible exception that may not exhibit endocytosis. Phagotrophy, however, is only observed in parasites of the intestinal lumen and appears to have been lost in blood and tissue parasites. Overall, the basic features of endocytosis and lysosomes are similar to other eukaryotes. Nonetheless, adaptation to the host has generated some novel features that are specific to certain protozoan lineages.

Widespread, human-associated redondoviruses infect the commensal protozoan Entamoeba gingivalis

Redondoviruses are circular Rep-encoding single-stranded DNA (CRESS) viruses of high prevalence in healthy humans. Redondovirus abundance is increased in oro-respiratory samples from individuals with periodontitis, acute illness, and severe COVID-19. We investigated potential host cells supporting redondovirus replication in oro-respiratory samples and uncovered the oral amoeba Entamoeba gingivalis as a likely host. Redondoviruses are closely related to viruses of Entamoeba and contain reduced GC nucleotide content, consistent with Entamoeba hosts. Redondovirus and E.gingivalis co-occur in metagenomic data from oral disease and healthy human cohorts. When grown in xenic cultures with feeder bacteria, E.gingivalis was robustly positive for redondovirus RNA and DNA. A DNA proximity-ligation assay (Hi-C) on xenic culture cells showed enriched cross-linking of redondovirus and Entamoeba DNA, supporting E.gingivalis as the redondovirus host. While bacteria are established hosts for bacteriophages within the human virome, this work shows that eukaryotic commensals also contribute an abundant human-associated virus.

Commensal Intestinal Protozoa-Underestimated Members of the Gut Microbial Community.

The human gastrointestinal microbiota contains a diverse consortium of microbes, including bacteria, protozoa, viruses, and fungi. Through millennia of co-evolution, the host-microbiota interactions have shaped the immune system to both tolerate and maintain the symbiotic relationship with commensal microbiota, while exerting protective responses against invading pathogens. Microbiome research is dominated by studies describing the impact of prokaryotic bacteria on gut immunity with a limited understanding of their relationship with other integral microbiota constituents. However, converging evidence shows that eukaryotic organisms, such as commensal protozoa, can play an important role in modulating intestinal immune responses as well as influencing the overall health of the host. The presence of several protozoa species has recently been shown to be a common occurrence in healthy populations worldwide, suggesting that many of these are commensals rather than invading pathogens. This review aims to discuss the most recent, conflicting findings regarding the role of intestinal protozoa in gut homeostasis, interactions between intestinal protozoa and the bacterial microbiota, as well as potential immunological consequences of protozoa colonization.

A Murine Commensal Protozoan Influences Host Glucose Homeostasis by Facilitating Free Choline Generation

ABSTRACTRecent progress indicates that the gut microbiota plays important role in regulating the host’s glucose homeostasis. However, the mechanisms remain unclear. Here, we reported that one integral member of the murine gut microbiota, the protozoan Tritrichomonas musculis could drive the host’s glucose metabolic imbalance. Using metabolomics analysis and in vivo assays, we found that mechanistically this protozoan influences the host glucose metabolism by facilitating the production of a significant amount of free choline. Free choline could be converted sequentially by choline-utilizing bacteria and then the host to a final product trimethylamine N-oxide, which promoted hepatic gluconeogenesis. Together, our data reveal a previously underappreciated gut eukaryotic microorganism by working together with other members of microbiota to influence the host’s metabolism. Our study underscores the importance and prevalence of metabolic interactions between the gut microbiota and the host in modulating the host’s metabolic health.IMPORTANCE Blood glucose levels are important for human health and can be influenced by gut microbes. However, its mechanism of action was previously unknown. In this study, researchers identify a unique member of the gut microbes in mice that can influence glucose metabolism by promoting the host’s ability to synthesis glucose by using nonglucose materials. This is because of its ability to generate the essential nutrient choline, and choline, aided by other gut bacteria and the host, is converted to trimethylamine N-oxide, which promotes glucose production. These studies show how gut microbes promote metabolic dysfunction and suggest novel approaches for treating patients with blood glucose abnormality.

Prevalence of intestinal parasites in a cohort of HIVinfected patients from Antioquia, Colombia.

Introduction: HIV infection is still a public health problem worldwide and co-infections with other infectious agents including intestinal parasites are of particular concern, mainly in developing countries like Colombia.Objective: To conduct a cross-sectional study in patients attending an HIV care program in Antioquia given that there have been few intestinal parasites prevalence studies among the HIV population in the country.Material and methods: We evaluated stool samples from 192 patients by direct wet mount and concentration, modified Ziehl Neelsen staining, and agar plate culture. Univariate and correlation analyses were done to explore the association between socio-demographic and clinical characteristics and parasitological data.Results: The overall prevalence of intestinal parasites in HIV-positive subjects was 29.2% (56/192; 95% CI: 22.8% - 35.6%). Entamoeba histolytica/dispar/moshkosvkii with 13.0% (25/192; 95% CI: 8.2% - 17.8%) and Blastocystis with 12.0% (23/192; 95% CI: 7.4% -16.6%) were the most frequent. Opportunistic parasites like Cryptosporidium spp. and Cystoisospora belli were less prevalent, each one with 0.5% of positive samples (1/192; 95% CI: 0.1% - 1.5%). Commensal protozoa were also detected with a prevalence of 18.8% (36/192; 95% CI: 13.3% - 24.3%). Most of the individuals in the study had a controlled viral load and an LTCD4 count greater than 200 cel/µL. A small percentage (9.3%) had diarrhea. Bivariate analysis and multivariate logistic regression showed that only age and having pets had a significant association with intestinal parasites in this cohort.Conclusions: Our results confirmed that the evaluated population is at high risk of intestinal parasite infection, which highlights the need for routine screening of gastrointestinal parasites to provide prompt treatment and reduce possible complications.

Periodic deworming programme in Brazil

To evaluate the periodic deworming programme (PDP) against soil-transmitted helminth infection and estimate the cost-benefit of this action in a Northeastern Brazilian State. An observational descriptive study was peformed by two branches: an epidemiological analysis of parasitological stool tests positivity in the 7 health micro-regions of Sergipe State, from January to June 2019, and a cost-benefitial analysis through comparison between estimated costs of PDP and conventional diagnose and treatment method from 2014 to 2018. From the 1110 parasitological stool tests evaluated, 317 were positive: 20 (1.8 %) for helminths and 307 (26.7%) for protozoan parasites. Among positive tests, 61 (19.2%) were in PDP age target group (5-14 years). An annual average of 255,283 Albendazole tablets (400mg, single dose) were distributed with an annual average coverage rate of 84.2%. To support the programme, approximately R$ 281,859.25 (US$ 89,775.67) were transferred per year to the state of Sergipe. PDP estimated cost-effectiveness was R$ 1.10 (US$ 0.34) per event prevented and generated a cost-minimization of approximately R$ 335.617,60 (US$124,568.00) when compared to the conventional diagnose and treat method. The positive rates of soil-transmitted helminth infection in parasitological tests in Sergipe were low and the recommendation for PDP seems to be currently inadequate. Most positive tests were for commensal protozoa species. PDP estimated cost is lower than conventional diagnose and treatment method. Protozoa infections prevention policies should be evaluated as they are the major parasitic infection in our community after PDP.

Commensal Bacteria Impact a Protozoan's Integration into the Murine Gut Microbiota in a Dietary Nutrient-Dependent Manner.

Our current understanding of the host-microbiota interaction in the gut is dominated by studies focused primarily on prokaryotic bacterial communities. However, there is an underappreciated symbiotic eukaryotic protistic community that is an integral part of mammalian microbiota. How commensal protozoan bacteria might interact to form a stable microbial community remains poorly understood. Here, we describe a murine protistic commensal, phylogenetically assigned as Tritrichomonas musculis, whose colonization in the gut resulted in a reduction of gut bacterial abundance and diversity in wild-type C57BL/6 mice. Meanwhile, dietary nutrient and commensal bacteria also influenced the protozoan's intestinal colonization and stability. While mice fed a normal chow diet had abundant T. musculis organisms, switching to a Western-type high-fat diet led to the diminishment of the protozoan from the gut. Supplementation of inulin as a dietary fiber to the high-fat diet partially restored the protozoan's colonization. In addition, a cocktail of broad-spectrum antibiotics rendered permissive engraftment of T. musculis even under a high-fat, low-fiber diet. Furthermore, oral administration of Bifidobacterium spp. together with dietary supplementation of inulin in the high-fat diet impacted the protozoan's intestinal engraftment in a bifidobacterial species-dependent manner. Overall, our study described an example of dietary-nutrient-dependent murine commensal protozoan-bacterium cross talk as an important modulator of the host intestinal microbiome.IMPORTANCE Like commensal bacteria, commensal protozoa are an integral part of the vertebrate intestinal microbiome. How protozoa integrate into a commensal bacterium-enriched ecosystem remains poorly studied. Here, using the murine commensal Tritrichomonas musculis as a proof of concept, we studied potential factors involved in shaping the intestinal protozoal-bacterial community. Understanding the rules by which microbes form a multispecies community is crucial to prevent or correct microbial community dysfunctions in order to promote the host's health or to treat diseases.

Balantidium coli in Pigs of Distinct Animal Husbandry Categories and Different Hygienic-Sanitary Standards in the Central Region of Rio Grande do Sul State, Brazil

Background: Balantidium coli is a commensal protozoan that infects several animals, but it has pigs as its natural reservoir. In the presence of predisposing factors, B. coli can become pathogenic for swine, causing enteric lesions. Infections determined by this protozoan may be a risk to public health, due to dysentery in animal keepers and veterinarians. This study aimed to determine the occurrence of infection by B. coli in pigs of distinct husbandry categories, as well as unlike physiological state, kept in farms with different hygienic-sanitary standards, located in the central region of Rio Grande do Sul State in Brazil.Materials, Methods & Results: Stool samples were collected from 12 different farms with different hygienic-sanitary standards being four farms of finisher pigs (G1; n = 287), four farms with pregnant females (G2; n = 60) and four farms with lactation sows (G3; n = 40), and all samples were submitted to coproparasitological analyses to verify the presence of cysts or trophozoites of B. coli. The infection levels were considered mild (1-100 cyst/trophozoite), moderate (101300 cyst/trophozoite) and high (>300 cysts/trophozoite). In addition, information about hygienic-sanitary conditions of each farm was collected. The occurrence of B. coli infection in all swine stool samples analyzed was 60.9% (236/387); however, in G1, G2 and G3 was 54.7% (157/287), 91.7% (55/60) and 65% (26/40) respectively. There was significant difference in the occurrence of G1 (P < 0.05) except between farms B and C (67.9% and 56.6% respectively). There was also a significant difference (P < 0.05) between the occurrence of B. coli found in G2 and G3. The infection levels were considered predominantly mild in G1; and mild to moderate in G2 and G3.Discussion: In this research it was confirmed the presence of B. coli in swine farms located in the central region of Rio Grande do Sul State in Brazil. This area is known as being an important producer of pigs in Brazil. The results obtained in this study, demonstrated that swine farms with better hygienic and sanitary standards, had mild infections by B. coli. However, the presence of intestinal parasites, especially protozoa, can occur even in properties with good management practices. However, protozoa infections can cause important production losses, especially when associated with other pathogens or nutritional problems. The occurrence of B. coli observed in pregnant (G2) and lactating (G3) females was significant, and the infection level was mild to moderate. These conditions suggest that pregnancy, childbirth and lactation are critical stages for females, mainly due to physiological stress, resulting in a change in the hormonal levels and immune status of the animals. Thus, these factors cause declines in the immune response of pigs making them susceptible to infections and the increase of cyst excretion of B. coli in feces. The abundance of protozoan cysts in feces contaminates the environment and increases the risk of infections in humans. In addition, it was demonstrated the occurrence of B. coli in an important site of swine production in RS, Brazil. B. coli is related to the physiological state of the animals and the hygienic and sanitary management in different categories of swine. In conclusion, this study highlights the epidemiological importance of swine as natural reservoir of Balantidium coli and the risk potential of infection to animals and humans. Additionally, sanitary program in farming pigs must be improved in order to guarantee healthy and food-safe product for consumers.

A Commensal Protozoan Strikes a Balance in the Gut.

Gut commensals profoundly affect host immunity and intestinal homeostasis, but the impact of commensal eukaryotic protozoans is poorly understood. In a recent Cell paper, Chudnovskiy etal. (2016) identify a commensal protozoan, Tritrichomonas musculis, that can enhance anti-bacterial defenses, but at the cost of increasing intestinal inflammation.

PREVALÊNCIA DE PARASITOSES INTESTINAIS DE ACORDO COM O GÊNERO EM UM HOSPITAL UNIVERSITÁRIO NO SUL DO BRASIL

Introdução: As parasitoses intestinais apresentam elevada morbimortalidade, especialmente em áreas endêmicas. O Brasil é um país de extrema heterogeneidade econômica e pouco se sabe sobre a prevalência de parasitoses intestinais na região Sul. O objetivo desse estudo é relatar a prevalência de parasitoses intestinais em exames de fezes, e avaliar se há diferenças em relação ao gênero. Métodos: Estudo de coorte histórico, analítico transversal, que avaliou exames parasitológicos de fezes (PPFs) realizados em laboratório de Hospital Universitário. Resultados: Foram incluídos 3.126 resultados de PPFs, onde 44,4% pertenciam a homens e 10,1% eram positivos. Protozoários comensais foram os mais frequentes (7,7%) e E. nana foi o mais prevalente (3,7%). Entre os patogênicos, o mais frequente foi G. lamblia (1,3%), seguido de S. stercoralis (0,7%). De uma forma geral, os homens apresentaram maior proporção de exames positivos (13,0% vs. 7,8%; P < 0,001), tanto para parasitos comensais (7,2% vs. 5,1%; P = 0,016), quanto para patogênicos (4,5% vs. 1,8%; P < 0,001); tanto para protozoários (10,7% vs. 6,4%; P < 0,001) quanto para nematodos (1,4% vs. 0,6%; P = 0,036). Igualmente, os homens apresentaram uma maior proporção de resultados positivos para E. nana (5,2% vs. 2,6%; P < 0,001), E. coli (3,5% vs. 1,6%; P < 0,001), G. lamblia (2,2% vs. 0,6%; P < 0,001) e S. stercoralis (1,1% vs. 0,3%; P = 0,013) quando comparados às mulheres. Conclusões: Parasitos foram encontrados em 10% dos exames, sendo os comensais mais prevalentes. Os homens exibiram maior proporção de enteroparasitoses que as mulheres.

Could be the swine responsible of transmission to the humans of Dientamoeba fragilis infection?

Dientamoeba fragilis, atypical protozoon because “flagellate without flagella” but amoeba-like, of whom we know only the trophozoitic stage (an so its brittleness outside intestinal tract), is a frequent responsible of intestinal human infections, worldwide, and some authors relate that D. fragilis is the most frequent protozoon and parasite that can infects humans. Actually we don’t know a sure potential “reservoir” in animals who are strictly in contact with humans, and it is difficult to understand its epidemiological chain, otherwise the transmissions to humans and from humans to humans. For all these reasons we performed another study on subjects of swine breedings, and among people who work in these breedings, that are in direct contact or not with pigs. Using standardized methodologies, we analyzed 224 faecal specimens of swine and 15 human specimens.We use for identification of D. fragilis the Giemsa stain.These were the results: D. fragilis was observed in 50.9% of pigs and 20% among humans (30% in workers strictly in contact with breedings and pigs, 0% in familiars or other without a closed contact with swines). Other commensal protozoa were observed with variable associations, but in this article we want to analyze the possible transmission from this pigs to humans (and for us this protozoon is undoubtedly a “reservoir” of D. fragilis for humans), and underline two aspects: for the research of this protozoon, standard procedures area mandatory, with a permanent stain, as Giemsa stain, is necessary, and in all humans with various intestinal infections or troubles, particularly “irritable bowel syndrome” (or similar ones), the specimens must be analyzed for D. fragilis. At least we think that in the near future molecular studies are important for confirming this our observations, and for verifying eventual and probable differences inside genotypes of this very suggestive protozoon, that until now present not rarely phenotypic diversities.

Diagnosis of Giardia infections by PCR-based methods in children of an endemic area

The present study was designed to estimate the prevalence of Giardia infection in preschool- and school-aged children living in an endemic area. Fecal samples from 573 children were processed by zinc sulfate centrifugal flotation, centrifugal sedimentation (using a commercial device for fecal concentration - TF-Test kit®) and polymerase chain reaction (PCR)-based methods. Of the stool samples assessed, 277 (48.3%) were positive for intestinal parasites and/or commensal protozoa. Centrifugal flotation presented the highest diagnostic sensitivity for Giardia infections. The kappa index revealed that both coproparasitological techniques closely agreed on the Giardia diagnosis (86%) versus satisfactory (72%) and poor (35%) concordances for commensal protozoan and helminth infections, respectively. Concerning Giardia molecular diagnosis, from the 71 microscopy-positive samples, specific amplification of gdh and tpi fragments was noted in 68 (95.7%) and 64 (90%) samples, respectively. Amplification of gdh and tpi genes was observed, respectively, in 95.7% and 90% of microscopy-positive Giardia samples. For 144 microscopy-negative samples, gdh and tpi gene amplification products were obtained from 8.3% and 35.9% samples, respectively. The agreement between these genes was about 40%. The centrifuge-flotation based method was the most suitable means of Giardia diagnosis assessed in the present study by combining accuracy and low cost.

PCR Detection and Molecular Characterization of Pentatrichomonas hominis from Feces of Dogs with Diarrhea in the Republic of Korea

Pentatrichomonas hominis is considered a commensal protozoan in the large intestine of a number of mammalian hosts, such as cats, dogs, and non-human primates. The resulting infections, which can induce diarrhea, have been attributed to opportunistic overgrowth of P. hominis. This study was performed to confirm the P. hominis infection and its molecular characterization from the feces of puppies with diarrhea. Fecal samples were obtained from 14 German shepherd puppies with diarrhea over 1 week (7 females and 7 males, 2-9 months of age) residing on a dog farm in August 2007. Species-specific PCR assay identified P. hominis 18S rRNA genes in 3 of the 14 puppies (1 female and 2 males; 1 aged 2 months and 2 aged 9 months). This phylogenetic analysis established that P. hominis belonged to the 1st clade, which is comprised of Bos taurus and Felines.

Identification of Pentatrichomonas hominis in feline fecal samples by polymerase chain reaction assay

Pentatrichomonas hominis is considered to be a commensal protozoan of the vertebrate digestive tract. On the basis of light microscopic examination of feces, some investigators presumptively identified P. hominis as a causative agent of feline diarrhea. However, molecular identification of P. hominis infection in the cat has not been reported. Another trichomonad, Tritrichomonas foetus, is recognized as an intestinal pathogen in cats and often presumptively diagnosed on the basis of the presence of trichomonads in diarrheic feces. It is of importance to determine if cats are natural hosts for P. hominis, as the presence of this organism could result in inaccurate assumption of T. foetus infection. In this study, we used a species-specific PCR assay to identify P. hominis 18S rRNA genes in fecal samples collected from a convenience population of cats in which a high prevalence of T. foetus infection had been previously identified (cat show) or suspected (submitted for T. foetus diagnostic testing). The prevalence of T. foetus infection in these samples was 31% and 28.6%, respectively. P. hominis infection was identified by PCR of DNA extracted from feces of five cats (1.9% and 2.1% of fecal samples, respectively). All cats in which P. hominis was identified were also infected with T. foetus. PCR identification of P. hominis infection in the cat should facilitate future studies to determine the pathogenicity of this species and enable differentiation of P. hominis from other known or as-yet unidentified species of trichomonads that may infect cats.

Possible evolutionary futures for mankind

1. 1. With the development of techniques of gene transfer, human genetic defects such as sickle cell anaemia, phenylketonurea, cystic fibrosis, haemophilia, Huntington's chorea, etc. will be eliminated. Ninety nine percent of humans in the year 2500 will be much the same as at present, but healthier. 2. 2. Studies of Comparative Biochemistry and Physiology show that many strategies have been developed in the Animal Kingdom that could be advantageous in furthering human survival. Some of these strategies are discussed in the present article. 3. 3. Commensal algae that will live in the epidermis of domestic animals (pigs, goats, cattle) will be developed enabling these animals to live in dry environments with minimal demands for food and water. Once successful in domestic animals, the algae could be adapted to live in some humans, i.e. the “Green Man”. 4. 4. Commensal protozoa and bacteria that digest cellulose and lignin will be developed so that they can live in the human gut and convert the material to sugars, volatile fatty acids and amino acids that can be absorbed and metabolized by Man, thus making many inexpensive vegetable food resources available. 5. 5. Mammalian embryos will be able to develop through to full term in vitro in a cleidoic egg; and the in vitro fertilized egg will not have to depend on finding a surrogate mother. 6. 6. Some people will have an altered pattern of sexual activity. Many patterns will be available; one suggested here is of protogynous hermaphroditism, i.e. the individuals would be female for the first 30 years of life and male for the remaining years. 7. 7. Most groups of animals have representatives that have returned to living in the oceans. It is suggested that some humans will adapt or develop so as to live the whole of their lives in the ocean. 8. 8. Technological developments will produce a hybrid man. Instead of just having glasses, hearing aids, artificial hip joints and cardiac pace makers, new electronic implants will be developed to improve physical functions and to enable increased sensory awareness and continuous access to information technology.

Use of Commensal Protozoa as Biological Indicators of Water Quality and Pollution

Use of Commensal Protozoa as Biological Indicators of Water Quality and Pollution

A Descriptive Study of an Oligochaete Worm of the Family Encliytraeidae; with all Appendix on certain Commensal Protozoa

A Descriptive Study of an Oligochaete Worm of the Family Encliytraeidae; with all Appendix on certain Commensal Protozoa