Echinococcus spp. and genotypes infecting humans in Tibet Autonomous Region of China: a molecular investigation with near-complete/complete mitochondrial sequences.

BACKGROUND: Molecular markers are essential to identify Echinococcus species and genotypes in areas with multiple Echinococcus species to understand their epidemiology and pathology. Tibet Autonomous Region (TAR) is one of the areas worst hit by echinococcosis. However, molecular epidemiology is still missing among echinococcosis patients in TAR. This research explored the Echinococcus species and genotypes infecting humans in TAR and the population diversity and the possible origin of G1 in TAR. METHODS: Cyst samples were collected in one echinococcosis-designated hospital in TAR. Echinococcus species and genotypes were identified through a maximum-likelihood approach with near-complete/complete mtDNA using IQ-TREE. Phylogenetic networks were built with PopART, and the phylogeographical diffusion pattern was identified using a Bayesian discrete phylogeographic method. RESULTS: Using phylogenetic trees made with near-complete/complete mtDNA obtained from 92 cysts from TAR patients, the Echinococcus species and genotypes infecting humans in TAR were identified as Echinococcus granulosus (s.s.) G1 (81, 88.04%), accounting for the majority, followed by G6 of the E. canadensis cluster (6, 6.52%), E. granulosus (s.s.) G3 (3, 3.26%), and E. multilocularis (2, 2.17%). An expansion trend and a possible recent bottleneck event were confirmed among the G1 samples in TAR. Adding the other near-complete mtDNA of G1 samples globally from the literature, we identified the possible phylogeographic origin of the G1 samples in TAR as Turkey. CONCLUSIONS: Using near-complete/complete mtDNA sequences of Echinococcus spp. obtained from echinococcosis patients, a variety of Echinococcus species and genotypes infecting humans throughout TAR were identified. As far as we know, this is the first comprehensive molecular investigation of Echinococcus species and genotypes infecting humans throughout TAR. We identified, for the first time to our knowledge, the possible origin of the G1 in TAR. We also enriched the long mtDNA database of Echinococcus spp. and added two complete E. multilocularis mtDNA sequences from human patients. These findings will improve our knowledge of echinococcosis, help to refine the targeted echinococcosis control measures, and serve as a valuable baseline for monitoring the Echinococcus species and genotypes mutations and trends of the Echinococcus spp. population in TAR.

Characterizing dynamic changes of plasma cell-free Echinococcus granulosus DNA before and after cystic echinococcosis treatment initiation.

Over one million people are living with cystic echinococcosis (CE) and alveolar echinococcosis (AE). For CE, long-term albendazole treatment is often needed, which requires regular follow-up. Follow-up is mainly through imaging which is insensitive to subtle changes and subjective to experience. We investigated the changes of Echinococcus granulosus (Eg) cell-free DNA (cfDNA) in plasma of CE patients before and after albendazole treatment to evaluate its potential as an objective marker for treatment follow-up. Plasma samples of nine CE patients were collected before and after treatment. We identified Eg cfDNA from every sample through high-throughput sequencing. Eg cfDNA concentration and fragment length increased significantly after the treatment period. Ultrasound examination before and after the treatment initiation reflected the drug effects to a certain extent, as the cyst size of four patients reduced. Our findings indicated that Eg cfDNA from plasma could be a potential marker in the monitoring of CE treatment.

Comprehensive characterization of plasma cell-free Echinococcus spp. DNA in echinococcosis patients using ultra-high-throughput sequencing.

BACKGROUND: Echinococcosis is a life-threatening parasitic disease caused by Echinococcus spp. tapeworms with over one million people affected globally at any time. The Echinococcus spp. tapeworms in the human body release DNA to the circulatory system, which can be a biomarker for echinococcosis. Cell-free DNA (cfDNA) is widely used in medical research and has been applied in various clinical settings. As for echinococcosis, several PCR-based tests had been trialed to detect cell-free Echinococcus spp. DNA in plasma or serum, but the sensitivity was about 20% to 25%. Low sensitivity of PCR-based methods might be related to our limited understanding of the features of cell-free Echinococcus spp. DNA in plasma, including its concentration, fragment pattern and release source. In this study, we applied ultra-high-throughput sequencing to comprehensively investigate the characteristics of cell-free Echinococcus spp. DNA in plasma of echinococcosis patients. METHODOLOGY/PRINCIPAL FINDINGS: We collected plasma samples from 23 echinococcosis patients. Total plasma cfDNA was extracted and sequenced with a high-throughput sequencing platform. An average of 282 million read pairs were obtained for each plasma sample. Sequencing data were analyzed with bioinformatics workflow combined with Echinococcus spp. sequence database. After identification of cell-free Echinococcus spp. reads, we found that the cell-free Echinococcus spp. reads accounted for 1.8e-5 to 4.0e-9 of the total clean reads. Comparing fragment length distribution of cfDNA between Echinococcus spp. and humans showed that cell-free Echinococcus spp. DNA of cystic echinococcosis (CE) had a broad length range, while that of alveolar echinococcosis (AE) had an obvious peak at about 135 bp. We found that most of the cell-free Echinococcus spp. DNA reads were from the nuclear genome with an even distribution, which might indicate a random release pattern of cell-free Echinococcus spp. DNA. CONCLUSIONS/SIGNIFICANCE: With ultra-high-throughput sequencing technology, we analyzed the concentration, fragment length, release source, and other characteristics of cell-free Echinococcus spp. DNA in the plasma of echinococcosis patients. A better understanding of the characteristics of cell-free Echinococcus spp. DNA in plasma may facilitate their future application as a biomarker for diagnosis.

Association of prenatal organochlorine pesticide-dichlorodiphenyltrichloroethane exposure with fetal genome-wide DNA methylation.

AIMS: To investigate whether intrauterine organochlorine pesticide (OCP)-dichlorodiphenyltrichloroethane (DDT) exposure could lead to epigenetic alterations by DNA methylation with possible important lifetime health consequences for offspring. MAIN METHODS: We used Illumina Infinium HumanMethylation 450 K BeadChip to explore the pattern of genome-wide DNA methylation containing >485,000 gene sites in cord blood of 24 subjects in a 12 mother-newborn pairs birth cohort. Based on the genome-wide DNA methylation data, we chose one potential gene, BRCA1, to verify the results in another group comprising 126 subjects. KEY FINDINGS: We identified 1,131 significantly different CpG sites which included 690 hypermethylation sites and 441 hypomethylation sites in the DNA methylation level between case and control group. The identified sites were located in 598 unique genes. In subsequent validation studies, we found that the DNA methylation level of the identified CpGs of BRCA1 increased with increased exposure to dichlorodiphenyltrichloroethane (DDT) and the level of gene expression in the identified CpGs of BRCA1 decreased with increased exposure to dichlorodiphenyltrichloroethane (DDT). SIGNIFICANCE: The results indicated that epigenetic processes played a possible role in the development of fetuses affected by maternal OCP-DDT exposure. Early prenatal exposure to DDT may affect fetal BRCA1 gene methylation, and increased exposure leads to a higher DNA methylation level and lower gene expression level.

Hymenobacter rubripertinctus sp. nov., isolated from Antarctic tundra soil.

A red-pigmented, Gram-reaction-negative, aerobic, non-motile and rod-shaped bacterium, designated NY03-3-30T, was isolated from a soil sample collected from Inexpressible Island, Northern Victoria Land of the Antarctic Ross Orogen, and subjected to a polyphasic taxonomic study. Growth occurred at 4-28 °C (optimum 20 °C) and at pH 6.0-9.0 (optimum pH 7.0). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NY03-3-30T belonged to the genus Hymenobacter in the family Cytophagaceae. 16S rRNA gene sequence similarities between strain NY03-3-30T and the type strains of Hymenobacter species with validly published names ranged from 92.7 to 96.2 %. Strain NY03-3-30T contained summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0, C16 : 0, C16 : 1ω5c, anteiso-C15 : 0 and summed feature 4 (iso-C17 : 1-I and/or anteiso-C17 : 1-B) as major cellular fatty acids, MK-7 as the respiratory quinone and phosphatidylethanolamine as the main polar lipid. The DNA G+C content of strain NY03-3-30T was 59.4 mol%. On the basis of phylogenetic, physiological and chemotaxonomic data, strain NY03-3-30T is considered to represent a novel species of genus Hymenobacter, for which the name Hymenobacter rubripertinctus sp. nov. is proposed. The type strain is NY03-3-30T (=CCTCC AB 2017095T=KCTC 62163T).

Deinococcus taklimakanensis sp. nov., isolated from desert soil.

A gamma- and UV radiation-tolerant, Gram-negative, short-rod-shaped bacterial strain, designated X-121T, was isolated from soil samples collected from the Taklimakan desert in Xinjiang, China. Strain X-121T showed the highest 16S rRNA gene sequence similarity with Deinococcus depolymerans TDMA-24T (94.7 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain X-121T is a member of a novel species belonging to the clade formed by members of the genus Deinococcus in the family Deinococcaceae. The DNA G+C content of strain X-121T was 63.6 mol%. The chemotaxonomic charateristics of strain X-121T were typical of members of the genus Deinococcus, with MK-8 being the predominant respiratory quinone, summed feature 3 (16 : 1ω7c,16 : 1ω6c), 16 : 0 and 17 : 1ω8c as major cellular fatty acid, several unidentified phosphoglycolipids and glycolipids as the dominant polar lipids, galactose as the predominant cell-wall sugar and the presence of peptidoglycan with l-ornithine. Strain X-121T is therefore identified as representing a novel species, for which the name Deinococcus taklimakanensis sp. nov. is proposed, with the type strain X-121T(=CCTCC AB 207228T=KCTC 33842T).

Sphingomonas antarctica sp. nov., isolated from Antarctic tundra soil.

Strain 200T, isolated from a soil sample taken from Antarctic tundra soil around Zhongshan Station, was found to be a Gram-stain-negative, yellow-pigmented, catalase-positive, oxidase-negative, non-motile, non-spore-forming, rod-shaped and aerobic bacterium. Strain 200T grew optimally at pH 7.0 and in the absence of NaCl on R2A. Its optimum growth temperature was 20 °C. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 200T belonged to the genus Sphingomonas. Strain 200T showed the highest sequence similarities to Sphingomonas kyeonggiense THG-DT81T (95.1 %) and Sphingomonas molluscorum KMM 3882T (95.1 %). Chemotaxonomic analysis showed that strain 200T had characteristics typical of members of the genus Sphingomonas. Ubiquinone 10 was the predominant respiratory quinone and sym-homospermidine was the polyamine. The major polar lipids were sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylcholine. The G+C content of the genomic DNA was determined to be 60.9 mol%. Strain 200T contained C16 : 0 (31.6 %), summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c, 22.7 %), summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c, 11.2 %), C18 : 0 (7.8 %) and C14 : 0 2OH (6.7 %) as the major cellular fatty acids. On the basis of phylogenetic analysis, and physiological and biochemical characterization, strain 200T should be classified as representing a novel species of the genus Sphingomonas, for which the name Sphingomonasantarctica sp. nov. is proposed. The type strain is 200T (=CCTCC AB 2016064T=KCTC 52488T).

Flavitalea antarctica sp. nov., isolated from Fildes Peninsula, Antarctica.

A bright-yellow, Gram-stain-negative, rod-shaped, gliding and aerobic bacterium, designated strain AQ6-291T, was isolated from the Fildes Peninsula, Antarctica, and its taxonomic position was investigated by genotypic, phenotypic and chemotaxonomic analyses. Growth occurred at 4-28 °C (optimum 20 °C) and at pH 5.0-8.0 (optimum pH 7.0). Strain AQ6-291T contained iso-C15 : 1 G, iso-C15 : 0, C16 : 1ω5c, iso-C17 : 0 3-OH and summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c) as the major cellular fatty acids. The main polar lipids were phosphatidylethanolamine, unknown aminophospholipids, unknown phospholipids, five unknown aminolipids and two unknown polar lipids. MK-7 was the major respiratory quinone. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain AQ6-291T belonged to the genus Flavitalea. The DNA G+C content was 48.1 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain AQ6-291T is considered to represent a novel species of the genus Flavitalea, for which the name Flavitalea antarctica sp. nov. is proposed. The type strain is AQ6-291T (=CCTCC AB 2016109T=KCTC 52491T).

Terrimonas crocea sp. nov., isolated from the till of a high Arctic glacier.

A yellow-pigmented bacterial strain, designated M1-33108T, was isolated from the till of high Arctic glacier Midtre Lovénbreen near Ny-Ålesund, in the West Svalbard Archipelago, Norway. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain M1-33108T belonged to the genus Terrimonas and its closest neighbour was Terrimonas arctica R9-86T with 96.12 % 16S rRNA gene sequence similarity. Cells of strain M1-33108T were Gram-reaction-negative, aerobic, non-spore-forming, rod-shaped bacteria that lacked motility. Cells contained iso-C15 : 1 G, iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 0 and summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c) as its major cellular fatty acids and menaquinone-7 as the sole respiratory quinone. The polar lipid profile of strain M1-33108T consisted of phosphatidylethanolamine, two unknown aminophospholipids, eight unknown aminolipids, an unknown glycolipid and three unknown polar lipids. The DNA G+C content was 45.0 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain M1-33108T is considered to represent a novel species in the genus Terrimonas, for which the name Terrimonas crocea sp. nov. is proposed. The type strain is M1-33108T (=CCTCC AB 2016103T=KCTC 52448T).