Comparative study of three xenic media culture for cultivation of Balantidium coli strains

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.

Comparative Genomic and Transcriptomic Profiling Revealed the Molecular Basis of Starch Promoting the Growth and Proliferation of Balantioides coli

Carbohydrates are the main source of nutrition for B. coli, supplying energy for cell growth and development. The research aimed at investigating the mechanism of starch on the growth and replication of B. coli. Single-cell separation was used to isolate single trophozoites of B. coli under a stereomicroscope, transcriptomic profiling was conducted based on the SMART-seq2 single-cell RNA-seq method. Comparative genomic analysis was performed on B. coli and eight other ciliates to obtain specific and expanded gene families of B. coli. GO and KEGG enrichment analysis were used to analyze the key genes of B. coli under the action of starch in the present study. The results of single-cell RNA-seq depicts starch affected the growth and replication of B. coli in two ways: (1) the cell cycle was positively promoted by the activation of the cAMP/PKA signaling pathway via glycolysis; (2) the cell autophagy was suppressed through the PI3K/AKT/mTOR pathway. Genes involved in endocytosis, carbohydrate utilization, and the cAMP/PKA signaling pathway were highly enriched in both specific and expanded gene families of B. coli. Starch can be ingested and hydrolyzed into glucose, in turn affecting various biological processes of B. coli. The molecular mechanism of the effect of starch on the growth and proliferation of B. coli by promoting cell cycle and inhibiting the autophagy of trophozoites has been elucidated in our study.

Phylogenetics and Pathogenicity of Balantioides coli Isolates in Vietnamese Weaned Pigs

PURPOSE

This study aimed to investigate the diversity of Balantioides coli (B. coli) based on the 18S rDNA of isolates collected from weaned pigs with diarrhea and then select a B. coli isolate to determine its pathogenicity in weaned pigs through experimental infection.

METHODS

The genetic analysis of field-isolated B. coli strains was based on sequencing of the partial 18S rDNA genetic fragment and the pathogenicity of an isolate of B. coli (DN2018-2-DTD) was identified through an experimental infection.

RESULTS

The fourteen B. coli isolates shared 98.47-100% nucleotide similarity and were divided into two clades in a phylogenetic tree. In an infection experiment, a slight increase in the body temperature was identified in two infected groups as compared to that in the control group (P < 0.05) from days post-infection (dpi) 12-18 and from dpi 20-27. In the group infected with 3000 CPG/TPG, 2/9 pigs started to develop diarrhea on day two. In the group infected with 500 CPG/TPG, 8/9 pigs had diarrhea on dpi 3. Trophozoites/cysts of B. coli were firstly detected in feces on dpi 3 in a group of pigs infected with a dose of 3000 CPG/TPG, and CPG/TPG reached its peak at dpi 5 in both groups of infected pigs (35,450 and 13,250 CPG/TPG). There was a significant difference in the bodyweight of the control group (noninfected) as compared to that of the groups of infected pigs on dpi 7 (P < 0.05), 14 (P < 0.001) and 28 (P < 0.01). Lesions were solely recorded in infected pigs, including white ulcerative nodules with necrosis scattered in the mucosa of the colon and cecum on dpi 7, 14, and 28.

CONCLUSION

This is the first study to investigate the pathogenicity of B. coli in Vietnamese pigs to demonstrate that B. coli could induce necrotic ulcerative enteritis and diarrhea in weaned pigs.

Cyst detection and viability assessment of Balantioides coli in environmental samples: Current status and future needs

The ciliate Balantioides coli is a human enteric parasite that can cause life-threatening infections. It is a food- and waterborne parasite, with cysts being the infective stage. Despite its importance as a potential pathogen, few reports have investigated its presence in environmental samples, and some issues need attention including i) The accuracy of B. coli identification. In most cases, the protozoa is identified only by its morphological traits, which can be identical to those from other parasitic ciliates of animals. Genetic analysis of cysts recovered from environmental samples is necessary for species confirmation. In addition, genetic methods used with faecal samples need to be adequately validated with environmental matrices. ii) The methodology for searching this parasite in environmental samples. The protocols include an initial phase to isolate the cysts from the matrix followed by a second phase in which concentration procedures are usually applied. The methods may be valid but are not standardised and differences between studies could affect the results obtained. iii) The areas that needs further research. The development of genetic identification methods and standardised analytical protocols in environmental samples are required, as well as the assessment of viability and infectivity of B. coli cysts. The development of axenic culture systems will boost research on this parasite.

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Balantioides coli is mainly considered a foodborne parasite for humans.

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Detection methods in environmental samples are not standardised.

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Correct identification should be made by genetic analysis.

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Methods for B. coli cyst viability and infectivity assessment are to be developed.

Modified DMEM xenic culture medium for propagation, isolation and maintenance of Balantioides coli

Balantioides coli is a known ciliated zoonotic protozoan that mainly causes diarrhea in humans and pigs. An efficient and reliable culture system for this parasite remains unavailable until now. In this study, a modified Dulbecco's modified eagle medium (DMEM) with pH 7.0-7.5, containing 5 mg/mL starch and 20% new calf serum, was optimized for propagation of B. coli at 28°C-32°C. At the growth-peaking stage, the average trophozoite density was up to 12,970 trophozoites per milliliter. A reproducible protocol for isolation and maintenance of this parasite was also developed based on the modified DMEM culture medium. Moreover, cloning results of B. colipopulations showed that 250 trophozoites in 3 mL modified DMEM medium were the minimal number of trophozoites that propagated to the growth-peaking stage, and finally obtained the individual population. However, less than 250 trophozoites failed to continuously grow in the modified DMEM culture medium under the optimal conditions for growth of B. coli. These data showed that the modified DMEM culture medium is an ideal and efficient medium for propagation and maintenance of B. coli in vitro and will help studies on its biology, genome, transcriptome, proteome, and drug screening.

Liver infusion tryptose (LIT): the best choice for growth, viability, and infectivity of Leishmania infantum parasites

Leishmania spp. parasites have a complex biological cycle presenting basically two different morphological stages, the amastigote and promastigote forms. In vitro cultivation allows a more complete study of the biological aspects of these parasites, indicating better conditions for infection, immunoassay tests, drug evaluations, and vaccines. Thus, we evaluated the three most used culture media for Leishmania spp., Grace’s insect cell culture medium (Grace’s), liver infusion tryptose (LIT), and Schneider’s insect medium (Schneider’s), without supplementation or supplemented with fetal calf serum (FCS) and bovine serum albumin (Albumin) to evaluate the growth, viability, and infectivity of the L. infantum promastigotes. It was observed that promastigote forms have a better growth in LIT and Schneider’s with or without FCS when compared to that in Grace’s. The supplementation with albumin promoted greater viability of the parasites independent of the medium. For in vitro infection of J774.A1 macrophages using light microscopy and flow cytometry analyses, FCS-supplemented LIT and Grace’s promoted higher percentage of infected macrophages and parasite load compared with Schneider’s media. Taken together, our results demonstrated that the supplementation of LIT culture medium with FCS is the most suitable strategy to cultivate Leishmania infantum parasites enabling the maintenance of growth and infective parasites for research uses.

Research and extension action for parasitic control in pig breeding families located in Tanguá, Rio de Janeiro

ABSTRACT: This study aimed to analyze the parasites infesting pigs and their producers on family farms in Tanguá, RJ, Brazil, and to conduct extension activities between 2018 and 2019. Fecal samples were collected from 132 pigs, as well as, skin scrapings from the ears of 125 animals. In addition, 36 stool specimens from farmers and their families were analyzed. The collected material was processed by direct examination, sedimentation and flotation techniques. Gastrointestinal parasites were detected in 88.6% of the pigs, especially coccidia (71.8%), Balantioides coli (55%), strongyles (40.2%) and Strongyloides ransomi (31.6%) which showed statistically significance (p<0.05). Ectoparasites were identified in 16% of the pigs, mostly Sarcoptes scabiei var. suis (76.2%). Parasites were detected in 19.4% of the humans, including, Entamoeba coli (19.4%), Ascaris lumbricoides (8.3%) and Trichuris trichiura (5.5%). The frequency of B. coli and S. scabiei var. suis (p<0.05) were statistically significant, when analyzing the age group of the animals, having been more detected in the older years, fatterners phase. The pig farmers participated in these activities extension, which included lecture and “field day”, aimed at imparting information about parasites and their prophylaxis. The situation in Tanguá pig farms reinforces the need to carry out programs that provide technical support to these farmers, whose livelihood depends on pig farming.

Gene expression concerning fatty acid and amino acid metabolism in Chlorella vulgaris cultured with antibiotics

The green alga Chlorella vulgaris has potential as a source of clean bioenergy with abundant metabolites and a high oil content, and antibiotics are often applied to remove bacteria from culture to obtain axenic algal strains. In this work, ceftazidime and gentamicin sulphate (GS) were added separately and in combination in the aseptic processing of C. vulgaris, and gene expression and metabolites were evaluated. The results showed that ceftazidime and GS effectively inhibited the proliferation of Cyanobacteria and Bacteroidetes, respectively. Overall, the effects of antibiotics on C. vulgaris differed: GS increased the algal concentration, whereas ceftazidime alone and in combination with GS treatment decreased the specific algal growth rate. Based on comparative transcription analysis, 5917 and 5899 differentially expressed genes (DEGs) were respectively upregulated and downregulated by ceftazidime, 963 and 3921 DEGs by GS, and 4532 and 1675 DEGs by the ceftazidime and GS combination. Pathway enrichment analysis showed that the downregulated DEGs in the ceftazidime groups were enriched in the fatty acid biosynthesis pathway but that the upregulated DEGs in the GS group were enriched in the fatty acid degradation pathway. Some pathways related to amino acid metabolism were markably influenced by antibiotic treatment. The results further indicated that antibiotics affected the intracellular concentration of fatty acids and amino acids in C. vulgaris. This study provides a new viewpoint regarding the response of C. vulgaris to antibiotics in the process of obtaining axenic algal strains. KEY POINTS: • Ceftazidime and gentamicin sulphate influenced bacterial proliferation. • Downregulated differentially expressed genes mapped to the fatty acid biosynthesis pathway. • Antibiotics affected intracellular concentrations of fatty acids and amino acids.