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Blastocystis Isolates from Patients with Irritable Bowel Syndrome and from Asymptomatic Carriers Exhibit Similar Parasitological Loads, but Significantly Different Generation Times and Genetic Variability across Multiple Subtypes.

Vargas-Sanchez GB, Romero-Valdovinos M, Ramirez-Guerrero C, Vargas-Hernandez I, Ramirez-Miranda ME, Martinez-Ocaña J, Valadez A, Ximenez C, Lopez-Escamilla E, Hernandez-Campos ME, Villalobos G, Martinez-Hernandez F, Maravilla P - PLoS ONE (2015)

Bottom Line: Interestingly, the group of cases showed scarce mean nucleotide diversity (π) as compared to the control group (0.011±0.016 and 0.118±0.177, respectively), whilst high gene flow and small genetic differentiation indexes between different ST were found.Besides, Tajima's D test showed negative values for ST1-ST3.Interestingly, slow growth of isolates recovered from cases in comparison to those of controls was observed (p<0.05).

View Article: PubMed Central - PubMed

Affiliation: Escuela Superior de Medicina, Instituto Politecnico Nacional, Plan de San Luis y Diaz Mirón s/n, Casco de Santo Tomas, 11340, Mexico City, DF, Mexico.

ABSTRACT
Blastocystis spp is a common intestinal parasite of humans and animals that has been associated to the etiology of irritable bowel syndrome (IBS); however, some studies have not found this association. Furthermore, many biological features of Blastocystis are little known. The objective of present study was to assess the generation times of Blastocystis cultures, from IBS patients and from asymptomatic carriers. A total of 100 isolates were obtained from 50 IBS patients and from 50 asymptomatic carriers. Up to 50 mg of feces from each participant were cultured in Barret's and in Pavlova's media during 48 h. Initial and final parasitological load were measured by microscopy and by quantitative PCR. Amplicons were purified, sequenced and submitted to GenBank; sequences were analysed for genetic diversity and a Bayesian inference allowed identifying genetic subtypes (ST). Generation times for Blastocystis isolates in both media, based on microscopic measures and molecular assays, were calculated. The clinical symptoms of IBS patients and distribution of Blastocystis ST 1, 2 and 3 in both groups was comparable to previous reports. Interestingly, the group of cases showed scarce mean nucleotide diversity (π) as compared to the control group (0.011±0.016 and 0.118±0.177, respectively), whilst high gene flow and small genetic differentiation indexes between different ST were found. Besides, Tajima's D test showed negative values for ST1-ST3. No statistical differences regarding parasitological load between cases and controls in both media, as searched by microscopy and by qPCR, were detected except that parasites grew faster in Barret's than in Pavlova's medium. Interestingly, slow growth of isolates recovered from cases in comparison to those of controls was observed (p<0.05). We propose that generation times of Blastocystis might be easily affected by intestinal environmental changes due to IBS probably because virulent strains with slow growth may be selected, reducing their genetic variability.

No MeSH data available.


Related in: MedlinePlus

Generation time (Tg) values of Blastocystis isolates between case and control groups.Average and standard deviation of Tg in Barret’s and Pavlova media, based on microscopic measures and qPCR assays.
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pone.0124006.g003: Generation time (Tg) values of Blastocystis isolates between case and control groups.Average and standard deviation of Tg in Barret’s and Pavlova media, based on microscopic measures and qPCR assays.

Mentions: During the counting of parasites in the cultured samples, the predominant stage was the vacuolar form in both media; after 48h of culture in both groups, few amoeboid and granular forms were observed, with a light increase of the granular form in Pavlova’s medium. No differences were found regarding the parasitological load between cases and controls in both media by microscopy and by qPCR, perhaps due to a high variance within data (Fig 2); however, some statistical differences between media and among groups were found, such as parasites showed faster growth in Barret’s medium than in Pavlova’s medium (p<0.001, t-test related samples). Interestingly, slow growth for isolates recovered from cases in comparison with controls was observed (p<0.05 by microscopy and p = 0.001 by qPCR; Fig 3).


Blastocystis Isolates from Patients with Irritable Bowel Syndrome and from Asymptomatic Carriers Exhibit Similar Parasitological Loads, but Significantly Different Generation Times and Genetic Variability across Multiple Subtypes.

Vargas-Sanchez GB, Romero-Valdovinos M, Ramirez-Guerrero C, Vargas-Hernandez I, Ramirez-Miranda ME, Martinez-Ocaña J, Valadez A, Ximenez C, Lopez-Escamilla E, Hernandez-Campos ME, Villalobos G, Martinez-Hernandez F, Maravilla P - PLoS ONE (2015)

Generation time (Tg) values of Blastocystis isolates between case and control groups.Average and standard deviation of Tg in Barret’s and Pavlova media, based on microscopic measures and qPCR assays.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414267&req=5

pone.0124006.g003: Generation time (Tg) values of Blastocystis isolates between case and control groups.Average and standard deviation of Tg in Barret’s and Pavlova media, based on microscopic measures and qPCR assays.
Mentions: During the counting of parasites in the cultured samples, the predominant stage was the vacuolar form in both media; after 48h of culture in both groups, few amoeboid and granular forms were observed, with a light increase of the granular form in Pavlova’s medium. No differences were found regarding the parasitological load between cases and controls in both media by microscopy and by qPCR, perhaps due to a high variance within data (Fig 2); however, some statistical differences between media and among groups were found, such as parasites showed faster growth in Barret’s medium than in Pavlova’s medium (p<0.001, t-test related samples). Interestingly, slow growth for isolates recovered from cases in comparison with controls was observed (p<0.05 by microscopy and p = 0.001 by qPCR; Fig 3).

Bottom Line: Interestingly, the group of cases showed scarce mean nucleotide diversity (π) as compared to the control group (0.011±0.016 and 0.118±0.177, respectively), whilst high gene flow and small genetic differentiation indexes between different ST were found.Besides, Tajima's D test showed negative values for ST1-ST3.Interestingly, slow growth of isolates recovered from cases in comparison to those of controls was observed (p<0.05).

View Article: PubMed Central - PubMed

Affiliation: Escuela Superior de Medicina, Instituto Politecnico Nacional, Plan de San Luis y Diaz Mirón s/n, Casco de Santo Tomas, 11340, Mexico City, DF, Mexico.

ABSTRACT
Blastocystis spp is a common intestinal parasite of humans and animals that has been associated to the etiology of irritable bowel syndrome (IBS); however, some studies have not found this association. Furthermore, many biological features of Blastocystis are little known. The objective of present study was to assess the generation times of Blastocystis cultures, from IBS patients and from asymptomatic carriers. A total of 100 isolates were obtained from 50 IBS patients and from 50 asymptomatic carriers. Up to 50 mg of feces from each participant were cultured in Barret's and in Pavlova's media during 48 h. Initial and final parasitological load were measured by microscopy and by quantitative PCR. Amplicons were purified, sequenced and submitted to GenBank; sequences were analysed for genetic diversity and a Bayesian inference allowed identifying genetic subtypes (ST). Generation times for Blastocystis isolates in both media, based on microscopic measures and molecular assays, were calculated. The clinical symptoms of IBS patients and distribution of Blastocystis ST 1, 2 and 3 in both groups was comparable to previous reports. Interestingly, the group of cases showed scarce mean nucleotide diversity (π) as compared to the control group (0.011±0.016 and 0.118±0.177, respectively), whilst high gene flow and small genetic differentiation indexes between different ST were found. Besides, Tajima's D test showed negative values for ST1-ST3. No statistical differences regarding parasitological load between cases and controls in both media, as searched by microscopy and by qPCR, were detected except that parasites grew faster in Barret's than in Pavlova's medium. Interestingly, slow growth of isolates recovered from cases in comparison to those of controls was observed (p<0.05). We propose that generation times of Blastocystis might be easily affected by intestinal environmental changes due to IBS probably because virulent strains with slow growth may be selected, reducing their genetic variability.

No MeSH data available.


Related in: MedlinePlus