Genetic variation in mitochondrial DNA among Enterobius vermicularis in Denmark

Detection of Enterobius vermicularis in archived formalin-fixed paraffin-embedded (FFPE) appendectomy blocks: It's potential to compare genetic variations based on mitochondrial DNA (cox1) gene

Acute appendicitis represents one of the most common causes of emergency abdominal surgery worldwide. Meanwhile, Enterobius vermicularis has been suggested as one of the probable causes of appendicitis. In this study, the morphological characteristics of the remnant pinworms and pathologic changes were explored in old-archived FFPE tissues of appendectomies. Moreover, we provide the first molecular identification, genetic, and haplotype variation of this nematode from the old-archived FFPE tissue section of appendectomy using the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Seventeen FFPE appendectomies with E. vermicularis infection, stored over 12-22 years, were collected from two different geographical areas of Iran. In the histopathological examination, tissue changes were observed in thirteen cases (76.4%) and inflammation in four blocks (23.5%). After DNA extraction, the cox1 gene was amplified in twelve (70.6%) cases using the nested polymerase chain reaction (PCR). Phylogenetic analysis and a median-joining network of 78 available cox1 sequences of E. vermicularis revealed 59 haplotypes. We identified five haplotypes that fell into type B. All Haplotypes are novel except for two haplotypes, Hap32 and Hap37, identical to E. vermicularis sequences from Iran, Greece, and Germany. The ranges of diversity distance and haplotype diversity within the isolates were 0-1.9% and HD:0.643-0.667, subsequently. Overall, the absence of inflammation or even tissue changes in some sections can suggest the possible non-inflammatory role of E. vermicularis in appendicitis. Although FFPE material suffers from PCR inhibition, we could successfully use nested PCR to characterize E. vermicularis in old-archived appendectomy blocks and suggest this method as a complementary diagnosis technique in pathology. While the predominant type was B in the Middle East and Europe, further studies on a larger sample size from different geographical regions could probably confirm the results obtained in the present study.

Molecular and phylogenetic analysis of E. vermicularis in appendectomy specimens from Iran

Human infection with Enterobius vermicularis occurs worldwide, particularly in children. The role of E. vermicularis in appendicitis is neglected. This study was designed to investigate genotypes of E. vermicularis detected from appendectomy specimens in the human population from Iran and clarify the intra-species variation of the parasite. Seventy appendectomies for acute clinical appendicitis isolates from Azerbaijan and North Khorasan of Iran were used in the present study. The genetic information of Tehran and Hamedan regions was also obtained from GenBank for comparison and analysis. The nucleotide sequence of cytochrome c oxidase subunit 1 (cox1) gene was analyzed to perform genetic differentiation, haplotype network analysis, and population structure. Phylogenetic analysis of all the isolates were included in type B haplogroup. The number of haplotypes in all geographical locations of Iran is not much. Network analysis of sequences for regions such as Thailand, Iran, Denmark, and Poland show three classified subtypes B1, B2, and B3 in the B haplogroup. It seems that the haplotypes of E. vermicularis detected from appendectomy are B type, and divided into three subtypes. Further research using another genetic marker is required to elucidate the genetic variation of the parasites in detail.

A PCR-based method for the diagnosis of Enterobius vermicularis in stool samples, specifically designed for clinical application

BACKGROUND

Enterobius vermicularis (E. vermicularis) is a nematode that infects up to 200 million people worldwide, despite effective medications being available. Conventional diagnostic tests are hindered by low sensitivity and poor patient compliance. Furthermore, no biomolecular techniques are available for clinical application. The aim of this study was to develop a procedure specifically designed for clinical application to detect E. vermicularis by means of PCR.

MATERIALS AND METHODS

Two subject groups were taken into account: a group of 27 infected patients and a control group of 27 healthy subjects. A nested-PCR was performed on fecal samples to detect E. vermicularis. Due to the intrinsic difficulties of the fecal matrix, several countermeasures were adopted to ensure the efficient performance of the method: (a) a large amount of feces for the extraction process (20 g instead of 200 mg); (b) a combination of chemical and physical treatments to grind the fecal matrix; (c) an additional purification process for the negative samples after the first nested-PCR; and (d) the selection of a very specific target region for the PCR.

RESULTS

Due to the lack of overlap with other organisms, a sequence of the 5S ribosomal DNA (rDNA) spacer region including the tract SL1 was chosen to design appropriate external and internal primers. The first nested-PCR detected E.vermicularis in 19/27 samples from infected patients. After further purification, 5/8 of the negative samples resulted positive at the second PCR. Conversely, all the samples from healthy controls resulted negative to both PCRs. Sensitivity and specificity of the method were, respectively, 88.9% and 100%.

CONCLUSION

The results prove the high diagnostic accuracy of the proposed method, addressing and overcoming the challenges posed by both conventional tests and PCR-based approaches. Therefore, the method can be proposed for clinical application.

Prevalence and genetic analysis of Enterobius vermicularis in schoolchildren in lower northern Thailand

Enterobius vermicularis, a nematode parasite with a global distribution causes enterobiasis in schoolchildren and is considered a neglected parasite. An understanding of the prevalence and genetic diversity of enterobiasis is crucial for appropriate control measures. Therefore, the objectives of this research were to study the prevalence and genetic diversity of E. vermicularis in schoolchildren from lower northern Thailand, based on cytochrome c oxidase subunit I (COI) and internal transcribed spacer 2 (ITS2) sequences. Using the scotch tape technique, 7.4% (188/2544) of schoolchildren from 21 primary schools were found positive for E. vermicularis eggs, which is a relatively low infection rate. Phylogenetic trees of partial COI sequences (397 bp) revealed similar topologies using maximum likelihood (ML) and neighbor-joining (NJ) methods and identified E. vermicularis type A (105 sequences) and B (1 sequence). Haplotype network analysis of the COI sequences demonstrated a high haplotype diversity (H_d = 0.9028). In contrast, phylogenetic analysts of a 343 bp region of the ITS2 locus (52 sequences) revealed a monophyletic group. More sequence analyses of E. vermicularis from humans and other hosts in Thailand are necessary to better understand the genetic diversity of this parasite.

Genetic variation of Enterobius vermicularis among schoolchildren in Thailand

Enterobiasis, caused by the nematode Enterobius vermicularis, is a common health problem among schoolchildren in Thailand. We provide the first molecular identification of this nematode from Thai schoolchildren and document genetic variation among E. vermicularis eggs using sequence analyses of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene and the nuclear ribosomal DNA second internal transcribed spacer (ITS2). A cross-sectional parasitological survey was conducted in schoolchildren (n = 491) in five regions of Thailand between May 2015 and December 2016. The diagnosis of Enterobius infection was made using the adhesive tape perianal swab technique. Enterobius eggs were recovered from 43 participants (8.75%). DNA was extracted from these eggs and the cox1 gene and partial ITS2 region amplified using the polymerase chain reaction (PCR). Nineteen amplified PCR products of the cox1 gene (441 bp) and 18 of the ITS2 region (623 bp) were subsequently sequenced. All sequences were identified as belonging to E. vermicularis based on database searches. Phylogenetic analysis and a median-joining network of available E. vermicularis cox1 sequences showed 66 haplotypes. We found haploclusters (types A and B) represented among the Thai sequences. Six haplotypes from Thailand fell into type A (of Nakano et al., 2006) (along with sequences from Japan and Korea) and five haplotypes into type B (with sequences from Japan, Iran, Czech Republic, Greece, Denmark and Sudan). The overall haplotype diversity (Hd) was 0.9888. Transmission of worms with type B haplotypes from primates to humans in Asia or from humans in Europe possibly occurs in Thailand.

Hypothesis: Multiple sclerosis is caused by three-hits, strictly in order, in genetically susceptible persons

Multiple Sclerosis is a chronic, progressive and debilitating neurological disease which, despite extensive study for over 100 years, remains of enigmatic aetiology. Drawn from the epidemiological evidence, there exists a consensus that there are environmental (possibly infectious) factors that contribute to disease pathogenesis that have not yet been fully elucidated. Here we propose a three-tiered hypothesis: 1) a clinic-epidemiological model of multiple sclerosis as a rare late complication of two sequential infections (with the temporal sequence of infections being important); 2) a proposal that the first event is helminthic infection with Enterobius Vermicularis, and the second is Epstein Barr Virus infection; and 3) a proposal for a testable biological mechanism, involving T-Cell exhaustion for Epstein-Barr Virus protein LMP2A. We believe that this model satisfies some of the as-yet unexplained features of multiple sclerosis epidemiology, is consistent with the clinical and neuropathological features of the disease and is potentially testable by experiment. This model may be generalizable to other autoimmune diseases.

Lack of genetic structure in pinworm populations from New World primates in forest fragments

Microevolutionary processes in parasites are driven by factors related to parasite biology, host abundance and dispersal, and environmental conditions. Here, we test the prediction that isolation of host populations results in reduced genetic diversity and high differentiation among parasite populations. We conducted a population genetic analysis of two pinworms, Trypanoxyuris minutus and Trypanoxyuris atelis, commonly found parasitizing howler and spider monkeys in tropical rainforests across south-eastern Mexico, whose populations are currently isolated due to anthropogenic habitat loss and fragmentation. Mitochondrial DNA was employed to assess parasite genetic patterns, as well as to analyse their demography and population history. Both pinworm species showed high haplotype diversity but, unexpectedly, lower nucleotide diversity than that reported for other parasites. No genetic differentiation or population structure was detected in either pinworm species despite habitat loss, fragmentation and host isolation. Several scenarios are discussed that could help to explain the genetic panmixia found in both pinworm species, including higher than expected primate inter-fragment dispersal movements, and passive dispersal facilitating gene flow between parasite populations. The results suggest that large population sizes of parasites could be helping them to cope with the isolation and fragmentation of populations, delaying the effects of genetic drift. The present study highlights the complexity of the drivers that intervene in the evolutionary processes of parasites. Detailed genetic studies are needed, both in host and parasite populations, to assess the effects that habitat perturbation and environmental changes could have on the evolutionary dynamics of pinworms and primates.

Parasitic worms and allergies in childhood: insights from population studies 2008-2013

The last few decades have seen a marked increase in the global prevalence of allergic diseases particularly among children. Among the factors attributed to this rise has been reduced exposure to pathogens during childhood leading to insufficient maturation of the regulatory arm of developing immune systems. Over the years, a number of epidemiological studies have observed an inverse relationship between parasitic worm (helminth) infections and allergies. The purpose of this review is to highlight insights from population studies conducted among children published between 2008 and 2013 that explore the complex dynamics between helminth infections and allergies. These insights include the effect of anthelmintic treatment on allergic responses, an elucidation of immune mechanisms and an examination of helminth-induced immunoglobulin E cross-reactivity. A better understanding of the relationship between helminths and allergies is imperative as research directions move toward harnessing the therapeutic potential of helminths and their products in the treatment of allergic disorders.

Sequence variability in four mitochondrial genes among pinworm Aspicularis tetraptera isolates from laboratory mice in four provinces, China

This research aimed at exploring sequence variability in four mitochondrial (mt) genes, namely, cytochrome c oxidase subunit 1 (cox1), cytochrome b (cytb) and NADH dehydrogenase subunits 1 and 5 (nad1 and nad5), among pinworm Aspicularis tetraptera isolates from laboratory mice in four different provinces, China. A part of the cox1 (pcox1), cytb (pcytb), nad1 and nad5 genes (pnad1 and pnad5) were amplified separately from individual pinworms by polymerase chain reaction (PCR) and sequenced to determine sequence variations and examine their phylogenetic relationships. Herein, the intra-specific sequence variations within A. tetraptera were 0-0.5% for pcox1, 0-1.4% for pcytb, 0-1.8% for pnad1 and 0-1.7% for pnad5, respectively. In contrast, the inter-specific sequence differences among members of the Oxyuridae were significantly higher, being 13.7-17.0% for pcox1, 24.5-34.7% for pcytb, 26.6-29.6% for pnad1 and 24.4-25.5% for pnad5, respectively. Three methods, namely, Bayesian inference (BI), maximum likelihood (ML) and maximum parsimony (MP), were used for phylogenetic analyses based on the combined sequences of the four mt gene sequences, and the results indicated that all A. tetraptera samples form monophyletic groups, but samples from the same geographical origin did not always cluster together. This study demonstrated the existence of low-level intra-specific variation in four mtDNA sequences among A. tetraptera isolates from laboratory mice in different geographic regions in China, indicating no obvious geographical distinction among A. tetraptera isolates in China. These findings have important implications for studying systematics, molecular epidemiology and population genetics of A. tetraptera.