Molecular, morphological and histopathological evidence of Spirometra mansoni in wild and domestic animals from Costa Rica

Spirometra mansoni is a diphyllobothroid cestode and one of the causing agents of sparganosis, a zoonotic foodborne and waterborne infection in humans. This parasite has an indirect life cycle with domestic and wild canids or felids as definitive hosts. The last report of S. mansoni in Costa Rica was done in 2004 by morphological assessment of worms, whereas molecular evidence of this species was obtained recently in the Americas. Herein, we present seven cases of spirometrosis in four dogs, three cats and a coyote from different regions of Costa Rica occurring in a time span of a year. Dog cases presented vomiting, hyporexia, lethargy and diarrhea, whereas cats were mostly asymptomatic. Moreover, the coyote was found with Spirometra sp. proglottids incidentally. Cytochrome oxidase subunit 1 (cox1) sequences of eggs or proglottids derived from all cases were analyzed with a Bayesian Inference phylogenetic tree and a haplotype network. These analyses showed the clustering of S. mansoni from Costa Rica with other sequences derived from Asia and America. Moreover, cox1 sequences clustered in two separate haplotypes, suggesting the high genetic diversity of the species. The present cases represent the first molecular evidence of the parasite in Central America; thus, extending its known range in the American continent.

Aberrant sparganosis in cat caused by Spirometra mansoni (Cestoda: Diphyllobothriidae): a case report

BACKGROUND

Sparganosis is a rare zoonotic disease caused by plerocercoid larvae of the genera Spirometra or Sparganum (Cestoda: Diphyllobothriidae). The larvae of Spirometra generally do not undergo asexual reproduction, whereas those of Sparganum can induce proliferative lesions in infected tissues. This paper presents an unusual case of proliferative sparganosis due to infection with Spirometra mansoni in a cat, normally considered a definitive host of the species.

CASE PRESENTATION

A 9-year-old male domestic cat was presented with a mass on the right side of the face that underwent progressive enlargement for 1 month. The morphological and histopathological examinations revealed multiple asexual proliferative cestode larvae in the lesions, suggestive of proliferative sparganosis. Next-generation sequencing analysis of formalin-fixed and paraffin-embedded specimens of surgically excised tissue indicated that the worm was Spirometra mansoni.

CONCLUSION

Although S. mansoni a common tapeworm species found in the small intestine of domestic cats and dogs in Japan, proliferative sparganosis is extremely rare. This is the first confirmed case of proliferative sparganosis due to infection with S. mansoni in cat.

Molecular identification of Spirometra infections in companion animals and wildlife in Japan

Spirometra infections in companion animals and wildlife in Japan have been diagnosed based on the morphology of the adult worms and eggs, and the etiological agent has been mainly ascribed to Spirometra erinaceieuropaei. However, recent studies have revealed that two other species, Spirometra mansoni and Spirometra asiana, coexist in Japan. Spirometra asiana is a new species recently discovered in Japan. Although morphological discrimination between these two species is difficult, molecular identification is useful. Therefore, to understand which species commonly parasitizes companion animals and wildlife in Japan, a preliminary study was performed based on mitochondrial DNA analysis. Eleven adult worms examined were identified as S. mansoni, suggesting that S. mansoni infects companion animals and wildlife commonly than S. asiana in Japan.

Cestodiasis in 2 Puerto Rican crested anoles

Two adult male Puerto Rican crested anoles (Anolis cristatellus cristatellus) housed in a research facility were presented with debilitation and were euthanized. On autopsy, anole 1 had a large cystic white structure in the left pelvic limb, which protruded through the ruptured epidermis, and a large, poorly demarcated swelling in the right caudal abdomen. Anole 2 had masses in the mid-dorsum, caudal dorsum, left pelvic limb, and tail. These masses contained variably sized cestode larvae, which ruptured into the coelomic cavity. Evaluation of the larvae revealed a thickened and wrinkled anterior end, with a cleft-like invagination, consistent with either a plerocercoid sparganum or a tetrathyridium. Histologically, several cestode larvae were contained in the body wall of both anoles. These were up to 650 μm in diameter, with a thin tegument and a spongy parenchyma. The spongy parenchyma contained numerous, up to 30 μm diameter, sharply demarcated, basophilic-to-black structures (calcareous corpuscles). There was pneumonia and hepatitis in anole 2, suggestive of potential secondary infection subsequent to immunosuppression. Molecular amplification of the cytochrome C oxidase subunit 1 revealed 100% homology for the COX1 gene of the diphyllobothriid tapeworm Spirometra erinaceieuropaei, also known as Spirometra mansoni.

Molecular Characterization of Spirometra erinaceieuropaei from Jungle Cat (Felis chaus) in North of Iran

PURPOSE

The aim of this study is to conduct a molecular characterization of Spirometra tapeworm from jungle cat (Felis chaus) in Guilan Province, north of Iran using DNA sequence analysis of the mitochondrial cytochrome c oxidase subunit 1 (Cox1) and 12S rDNA sequences.

METHODS

Morphological features of the adult tapeworm of Spirometra were evaluated using specific staining and light microscopy. The molecular characterization was performed using partial Cox1 and 12S rDNA regions. Genetic diversity was calculated and phylogenetic trees of the obtained sequences were constructed.

RESULTS

Morphological features were compatible with previous description of adult Spirometra erinaceieuropaei. The Cox1 sequence of the specimen showed 100% similarity with S. erinaceieuropaei sequences in GenBank from Korea, China and Iran. Also, the 12S rDNA sequence revealed 99.7% similarity with S. erinaceieuropaei isolates from China and Japan. Intra-species variation within isolates of S. erinaceieuropaei was 0-1.4% and 0-4.6% for Cox1 and 12S rDNA genes, respectively.

CONCLUSION

This is the first report of molecular characterization of S. erinaceieuropaei in jungle cat, F. chaus in Iran. Jungle cat probably plays a major role as reservoir host in maintaining of this parasite in this area with favorable climate condition. Needs for further assessment on the role of appropriate hosts, especially intermediate/paratenic hosts as well as the potential risk of human infectivity with sparganosis is emphasized.

Description of Spirometra asiana sp. nov. (Cestoda: Diphyllobothriidae) found in wild boars and hound dogs in Japan

According to the latest taxonomy of Spirometra species, six species (lineages) have been tentatively classified as valid. These species are Spirometra erinaceieuropaei, S. folium, S. mansoni, undescribed Spirometra sp. 1, and S. decipiens complex 1 and 2. Among these species, the undescribed species was first discovered as plerocercoid larvae in wild boars in Japan and further studies have confirmed that this species is a new taxon belonging to the genus Spirometra. Here, we describe Spirometra asiana sp. nov., which is difficult to distinguish morphologically from known Spirometra species. However, it is genetically easily distinct from other Spirometra species, thus facilitating identification. We also emphasize that S. mansoni and S. asiana, but not S. erinaceieuropaei, are etiological agents that cause human sparganosis and/or spirometrosis in Asia.

Molecular identification of sparganum of Spirometra mansoni isolated from the abdominal cavity of a domestic cat in Vietnam

Cats normally play a role of the definitive host in which the plerocercoid (sparganum), the second larval form of Spirometra spp., develops into an adult in the intestines. However, some cases of cats with visceral or subcutaneous sparganosis were sporadically reported worldwide. We herein documented the discovery of a sparganum in abdominal cavity of a domestic cat during a surgery of dystocia. The larva was molecularly identified as Spirometra mansoni, belonging to Type I, that was recently misidentified to be S. erinaceieuropaei in several Asian countries. This is the first report for sparganum of S. mansoni in the cat. The future study is necessary to provide further insights into the species of Spirometra causing sparganosis and spirometrosis in humans and other animals.

Presence of Spirometra mansoni, Causative Agent of Sparganosis, in South America

We report molecular identification of an adult Spirometra mansoni tapeworm retrieved from a crab-eating fox (Cerdocyon thous) in Colombia, confirming presence of this parasite in South America. This tapeworm is the causative agent of human sparganosis, commonly reported from Southeast Asia, and represents the second congeneric species with known zoonotic potential in the Americas.

Transcriptome profiling of plerocercoid and adult developmental stages of the neglected medical tapeworm Spirometra erinaceieuropaei

The plerocercoid larvae of the tapeworm Spirometra erinaceieuropaei can parasitize humans and animals and cause serious parasitic zoonosis. However, our knowledge of the developmental process of S. erinaceieuropaei is still inadequate. To better characterize differential and specific genes and pathways associated with parasite development, a comparative transcriptomic analysis of the plerocercoid stage and the adult stage was performed using RNA-seq and de novo analysis. Approximately 13,659 differentially expressed genes (DEGs) were identified in plerocercoids versus adults, of which 6455 DEGs were upregulated and 7204 were downregulated. DEGs involved in parasite immunoevasion were more active in plerocercoid larvae than in adults, while DEGs associated with metabolic activity were upregulated in adults. Gene Ontology (GO) and Kyoto Encyclopedia of Genes (KEGG) analyses revealed that most DEGs involved in protein phosphorylation/dephosphorylation and the Wnt signalling pathway were much more active in plerocercoid larvae. The molecular functions of upregulated unigenes in adults were mainly enriched for metabolic activities. qPCR validated that the expression levels of 10 selected DEGs were consistent with those in RNA-seq, confirming the accuracy of the RNA-seq results. Our results contributed to increasing the knowledge on the S. erinaceieuropaei gene repertoire and expression profile and also provide valuable resources for functional studies on the molecular mechanisms of S. erinaceieuropaei.

The first records of Spirometra erinaceieuropaei (Cestoda: Diphyllobothriidae), a causative agent of human sparganosis, in Latvian wildlife

Diphyllobothriid tapeworms of the genus Spirometra are causative agents of sparganosis, food-borne zoonotic parasitic disease. They have been recorded in broad spectrum of hosts, including humans, in all continents except Antarctica. Spirometra tapeworms have been intensively studied in several Asian countries; however, they have been rather neglected in Europe. The aim of this study was to provide a pilot screening of Spirometra spp. in Latvia, where data on sparganosis are not available. Tapeworms morphologically identified as diphyllobothriid species were isolated from grey wolves Canis lupus and Eurasian lynxes Lynx lynx from Latvia during the hunting periods 2013-2019. The parasites were subjected to molecular genotyping using sequences of the partial large (LSU rDNA; 615 bp) and small (SSU rDNA; 720 bp) subunits of the nuclear ribosomal RNA gene and complete (1566 bp) cytochrome c oxidase subunit I gene of the mitochondrial DNA (cox1 mtDNA). Analyses of both ribosomal subunits of 13 tapeworms revealed no intraspecific variation within the respective rDNA subunits. On the other hand, sequence analysis of mitochondrial cox1 revealed intraspecific polymorphism displayed by 12 cox1 haplotypes. Comparison of the current data with sequences of the corresponding DNA regions deposited in the GenBank revealed 99.3-99.5% (LSU rDNA), 99.2% (SSU rDNA) and 99.6-100% (cox1 mtDNA) identity of studied tapeworms with Spirometra erinaceieuropaei, which provided the first confirmation of this diphyllobothriid tapeworm in Latvia. Since S. erinaceieuropaei is probably prevalent in Latvian wildlife and may also occur in other potential host species, further studies are needed in order to acquire complex data on its geographic distribution and transmission in the natural environment of Latvia, as well as on the spectrum of its intermediate, paratenic, and definitive hosts.

Spirometra species from Asia: Genetic diversity and taxonomic challenges

Despite considerable controversy concerning the taxonomy of species within the genus Spirometra, human sparganosis and spirometrosis mainly in Asia and Europe has long been confidently ascribed to Spirometra erinaceieuropaei. Recently, the mitochondrial genomes of purported "S. erinaceieuropaei", "Spirometra decipiens" and "Spirometra ranarum" from Asia have been determined. However, it has been pointed out that the morphological criteria used for identifying these species are unsuitable and thus these identifications are questionable. In the present study, therefore, Spirometra samples from Asia were re-examined based on mitochondrial cytochrome c oxidase subunit 1 gene sequences and the identification of these species was discussed. Haplotype network and phylogenetic analyses revealed that: i) two distinct Spirometra species, Type I and Type II, are present in Asia and neither of which is close to likely European "S. erinaceieuropaei"; ii) Type I is genetically diverse and widely distributed, however Type II is known so far from Japan and Korea; iii) "S. decipiens" and "S. ranarum" reported from Asia are conspecific with Type I; iv) Type I is probably conspecific with Spirometra mansoni, and Type II may represent an undescribed species.

Global genetic diversity of Spirometra tapeworms

Spirometra larvae are etiological agents of human sparganosis. However, the systematics of spirometrid cestodes has long been controversial. In order to determine the current knowledge on the evolution and genetic structure of Spirometra, an exhaustive population diversity analysis of spirometrid cestodes using the mitochondrial gene: cytochrome c oxidase subunit 1 (cox1) was performed. All publicly available cox1 sequences available in the GenBank and 127 new sequencing genes from China were used as the dataset. The haplotype identify, network, genetic differentiation and phylogenetic analysis were conducted successively. A total of 488 sequences from 20 host species, representing four spirometrid tapeworms (S. decipiens, S. ranarum, S. erinaceieuropaei and Sparganum proliferum) and several unclassified American and African isolates from 113 geographical locations in 17 countries, identified 45 haplotypes. The genetic analysis revealed that there are four clades of spirometrid cestodes: Clade 1 (Brazil + USA) and Clade 2 (Argentina + Venezuela) included isolates from America, Clade 3 contained African isolates and one Korean sample, and the remainders from Asia and Australia belonged to Clade 4; unclassified Spirometra from America and Africa should be considered the separate species within the genus; and the taxonomy of two Korea isolates (S. erinaceieuropaei KJ599680 and S. decipiens KJ599679) was still ambiguous and needs to be further identified. In addition, the demographical analyses supported population expansion for the total spirometrid population. In summary, four lineages were found in the spirometrid tapeworm, and further investigation with deeper sampling is needed to elucidate the population structure.

Molecular Identification of Spirometra erinaceieuropaei Tapeworm in Cases of Human Sparganosis, Hong Kong

Human sparganosis is a foodborne zoonosis endemic in Asia. We report a series of 9 histologically confirmed human sparganosis cases in Hong Kong, China. All parasites were retrospectively identified as Spirometra erinaceieuropaei. Skin and soft tissue swelling was the most common symptom, followed by central nervous system lesions.

Case report: the first case of human infection by adult of SPIROMETRA ERINACEIEUROPAEI in VIETNAM

BACKGROUND

Tapeworms of the genus Spirometra include species whose larval stages can infect humans, causing a disease called sparganosis. Cases of human infection with adult worms are very rare and have been reported in Korea and China. Here we report the first case of human infection with an adult of Spirometra erinaceieuropaei in Vietnam.

CASE PRESENTATION

A 23-year-old male was admitted to 103 Military Hospital, Hanoi, Vietnam with fever, weight loss and epigastric discomfort. Preliminary diagnosis based on discovery of parasite eggs in his faeces incorrectly determined a fluke as the agent of the infection and praziquantel was prescribed. Two days later he passed out proglottids in his stool. The tapeworm was identified as Spirometra erinaceieuropaei using morphological and molecular tools.

CONCLUSION

This is the first case of human infection with adult worm of Spirometra erinaceieuropaei in Vietnam.

The phylogenetic diversity of Spirometra erinaceieuropaei isolates from southwest China revealed by multi genes

The larval plerocercoid of Spirometra erinaceieuropaei can parasitize humans, causing a serious food borne parasitic zoonosis known as sparganosis. Sparganosis have increased in China in recent years. In this study, the prevalence of sparganum infection in wild frogs in 9 geographical areas in southwest China was firstly investigated. Of 276 caught frogs, 55 frogs were found to be infected with sparganum. Then, the population genetic structure of these sparganum isolates was explored based on four molecular markers (cytb, cox1, rrnS and 28S rDNA D1). Highly genetic diversity and the genetic differentiation among sparganum isolates from different sites were revealed in the DNA polymorphism analyses. Both the phylogenetic inference and the analysis of the median-joining network supported two clades in the southwest S. erinaceieuropaei population. However, none demographic population expansion of the southwest S. erinaceieuropaei population was observed in the neutrality test, mismatch distribution analysis and Bayesian skyline plot analysis. Finally, the phylogenetic diversity of S. erinaceieuropaei from eastern, central, southern and southwest China was analyzed, the result suggested that Chinese S. erinaceieuropaei population should be divided into two groups (Group I and Group II), and they started to divergence in the middle Pliocene.

Genetic structure analysis of Spirometra erinaceieuropaei isolates from central and southern China

Background

Sparganosis caused by invasion of the plerocercoid larvae (spargana) of Spirometra erinaceieuropaei have increased in recent years in China. However, the population genetic structure regarding this parasite is still unclear. In this study, we used the sequences of two mitochondrial genes cytochrome b (cytb) and cytochrome c oxidase subunit I (cox1) to analyze genetic variation and phylogeographic structure of the S. erinaceieuropaei populations.

Methodology/Principal Findings

A total of 88 S. erinaceieuropaei isolates were collected from naturally infected frogs in 14 geographical locations of China. The complete cytb and cox1 genes of each sample was amplified and sequenced. Total 61 haplotypes were found in these 88 concatenated sequences. Each sampled population and the total population have high haplotype diversity (Hd), accompanied by very low nucleotide diversity (Pi). Phylogenetic analyses of haplotypes revealed two distinct clades (HeN+HuN+GZ-AS clade and GX+HN+GZ-GY clade) corresponding two sub-networks yielded by the median-joining network. Pairwise F_ST values supported great genetic differentiation between S. erinaceieuropaei populations. Both negative Fu’s F_S value of neutrality tests and unimodal curve of mismatch distribution analyses supported demographic population expansion in the HeN+HuN+GZ-AS clade. The BEAST analysis showed that the divergence time between the two clades took place in the early Pleistocene (1.16 Myr), and by Bayesian skyline plot (BSP) an expansion occurred after about 0.3 Myr ago.

Conclusions

S. erinaceieuropaei from central and southern China has significant phylogeographic structure, and climatic oscillations during glacial periods in the Quaternary may affect the demography and diversification of this species.

Survey and genetic variation of Spirometra erinaceieuropaei sparganum in frogs and snakes from Guangxi of southern China

The prevalence of sparganum infection in wild frogs (Rana rugulosa and R. temporaria) and snakes (Enhydris chinensis) was investigated in Guangxi Zhuang Autonomous Region of Southern China from June 2013 to August 2013. The results showed that 30.37% (65/214) of the caught wild frogs and 50% (3/6) of examined snakes were found to be infected with plerocercoids (spargana) of the genus Spirometra. To investigate the genetic variation of the collected spargana, three mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 and 3 (cox1 and cox3), NADH dehydrogenase subunits 4 (nad4) were amplified, sequenced, and analyzed. The sequences of cox1, cox3 and pnad4 are 444, 387 and 585 bp in length, respectively. The base composition of cox1, cox3 and pnad4 were generally AT rich with a mean of 62.7%, 67.2% and 64.9%, respectively. Phylogenetic analyses using Bayesian inference (BI) and maximum parsimony (MP) indicated that all the Spirometra sparganum isolates in Guangxi represented S. erinaceieuropaei.

MOLECULAR EVIDENCE OF SPIROMETRA ERINACEIEUROPAEI INFECTION IN SNAKES PTYAS KORROS FROM LAO PDR AND THAILAND AND FROGS HOPLOBATRACHUS RUGULOSUS FROM MYANMAR

Sparganosis is a parasitic disease in humans and animals caused by plerocercoid larvae (spargana) of the genus Spirometra. Spirometra erinaceieuropaei is the major causative agent of the disease in Asian countries. However, molecular evidence of the causative parasite species in animals remains lacking. A total of 19 spargana specimens were obtained from frogs, Hoplobatrachus rugulosus, collected from Myanmar and snakes, Ptyas korros, from Lao PDR and Thailand. A partial sequence of mitochondrial cytochrome c oxidase subunit1 gene (cox1) was amplified, sequenced, and the phylogenetic relationship was constructed using maximum likelihood method. Results revealed that the level of nucleotide variations in the partial cox1 sequence (429 bp) among the spargana ranged 0-3.5%, with 15 variable sites. Phylogenetic analysis indicated that all spargana specimens were S. erinaceieuropaei. This is the first report of S. erinaceieuropaei in P. korros from Lao PDR and Thailand and H. rugulosus from Myanmar. The results emphasize the need for prevention and control of sparganosis in these regions.

The genome of the sparganosis tapeworm Spirometra erinaceieuropaei isolated from the biopsy of a migrating brain lesion

BACKGROUND

Sparganosis is an infection with a larval Diphyllobothriidea tapeworm. From a rare cerebral case presented at a clinic in the UK, DNA was recovered from a biopsy sample and used to determine the causative species as Spirometra erinaceieuropaei through sequencing of the cox1 gene. From the same DNA, we have produced a draft genome, the first of its kind for this species, and used it to perform a comparative genomics analysis and to investigate known and potential tapeworm drug targets in this tapeworm.

RESULTS

The 1.26 Gb draft genome of S. erinaceieuropaei is currently the largest reported for any flatworm. Through investigation of β-tubulin genes, we predict that S. erinaceieuropaei larvae are insensitive to the tapeworm drug albendazole. We find that many putative tapeworm drug targets are also present in S. erinaceieuropaei, allowing possible cross application of new drugs. In comparison to other sequenced tapeworm species we observe expansion of protease classes, and of Kuntiz-type protease inhibitors. Expanded gene families in this tapeworm also include those that are involved in processes that add post-translational diversity to the protein landscape, intracellular transport, transcriptional regulation and detoxification.

CONCLUSIONS

The S. erinaceieuropaei genome begins to give us insight into an order of tapeworms previously uncharacterized at the genome-wide level. From a single clinical case we have begun to sketch a picture of the characteristics of these organisms. Finally, our work represents a significant technological achievement as we present a draft genome sequence of a rare tapeworm, and from a small amount of starting material.

Bioinformatic analysis for structure and function of TCTP from Spirometra mansoni

OBJECTIVE

To predict structure and function of translationally controlled tumor protein (TCTP) from Spirometra mansoni by bioinformatics technology, and to provide a theoretical basis for further study.

METHODS

Open reading frame (ORF) of EST sequence from Spirometra mansoni was obtained by ORF finder and was translated into amino acid residue by DNAclub. The structure domain was analyzed by Blast. By the method of online analysis tools: Protparam, InterProScan, protscale, SignalP-3.0, PSORT II, BepiPred, TMHMM, VectorNTI Suite 9 packages and Phyre2, the structure and function of the protein were predicted and analyzed.

RESULTS

The results showed that the EST sequence was Sm TCTP with 173 amino acid residues, theoretical molecular weight was 19 872.0 Da. The protein has the closest evolutionary status with Clonorchis sinensis, Schistosoma mansoni, and Schistosoma japonicum. Then it had no signal peptide site and transmembrane domain. Secondary structure of TCTP contained two α -helices and eight β -strands.

CONCLUSIONS

Sm TCTP was a variety of biological functions of protein that may be used as a vaccine candidate molecule and drug target.

[Construction and identification of a full-length cDNA library from Spirometra erinaceieuropaei]

The full-length pBluescript II SK cDNA library of adult Spirometra erinaceieuropaei was constructed by using the SMART method. Data showed that 95.5% of the library was recombinant and the titer of the library was 1.06 x 10(6). The average insert size of the library was about 1.4 kb. Forty-eight randomly selected clones were sequenced. A set of 36 effective expressed sequence tags (ESTs) with the average size of 674 bp was obtained after excluding clones shorter than 450 bp. The unigenes occupied 58.3% of the 36 ESTs. The rate of full-length cDNAs were 57.7% (15/26). The high-quality of full-length cDNA library could be used for large scale EST sequencing.

[Screening of stage-specific expression genes of Spirometra erinacei-europaei plerocercoid by mRNA differential display technique]

OBJECTIVE

To screen stage-specific expression genes of plerocercoid of Spirometra erinacei-europaei.

METHODS

RNA was extracted by the acid guanidinium thiocyanate-phenol-chloroform from plerocercoid and adult worm of Spirometra erinacei-europaei. Contaminated DNA in the RNA was digested by RNase-free DNase. cDNA was synthesized by using T12MA, T12MC, T12MG and T12MT primers, and PCR was then done using the same T12MN and one random primers. The PCR products were fractionated on 8% denatured polyacrylamide gel, differential bands of plerocercoid found in the gel were cut out, amplified by PCR and sequenced after the gel was dried out and autoradiographed. Northern hybridization was conducted to identify the stage-specific expression genes.

RESULTS

Eleven differential bands were selected from the gel and classified into 3 kinds of gene fragments by hybridization after they were amplified by PCR. The fragments 1 and 2 were confirmed to express specifically in plerocercoid by Northern hybridization, but the fragment 3 was expressed in both plerocercoid and adult worm. When the 3 gene fragments were homologically analyzed in GenBank, the sequence which was homologous with the fragments 1 and 2 was not found, but the fragment 3 had high homology with many kinds of 28S rRNA.

CONCLUSION

The gene expression of plerocercoid was different from that of adult worm probably because they live in different hosts. Two kinds of different gene fragments in plerocercoid were identified by mRNA differential display technique.

Intraspecific variation of Spirometra erinaceieuropaei and phylogenetic relationship between Spirometra and Diphyllobothrium inferred from mitochondrial CO1 gene sequences

Spirometra erinaceieuropaei is a diphyllobothriid cestode whose adult stage occurs mainly in cat-like carnivores, but occasionally in canids and humans. Although it is generally accepted that the distribution of S. erinaceieuropaei is cosmopolitan, it is controversial as to whether all of S. erinaceieuropaei reported are the same species. This study determined partial sequences of the CO1 gene from several isolates in Asian countries and compared them to sequence data from the GenBank/EMBL/DDBJ nucleotide sequence database. Then intraspecific variation of S. erinaceieuropaei and its phylogenetic relationship with Diphyllobothrium were evaluated. The level of nucleotide variation in the CO1 gene sequences within S. erinaceieuropaei was less than 2.6%. Although it was a little larger than that within each species of Diphyllobothrium (0.1-1.0%), it was much smaller than the interspecific variation within the genus Diphyllobothrium (6.2-14%). These facts indicate that all isolates of S. erinaceieuropaei used in this study, which were collected from Asia, Australia and New Zealand, belong to the same species. Based on CO1 gene sequences, genus Spirometra is clearly separate from the genus Diphyllobothrium. It seems that the genus Spirometra is not a synonym of the genus Diphyllobothrium. The phylogenetic relationship between S. erinaceieuropaei and Sparganum proliferum inferred from the CO1 gene clearly confirm the previous opinion that S. proliferum is a distinct species from S. erinaceieuropaei.

Cloning of the novel putative apoptosis-related gene of Spirometra erinacei (Order Pseudophyllidae)

We postulated that apolysis was processed in accordance with apoptotic changes occurring in a cestode, Spirometra erinacei (Pseudophyllidea). We cloned the novel putative apoptosis-associated gene from S. erinacei via screening of a S. erinacei cDNA library with a ced-3 gene (activator of apoptosis) probe from Caenorhabditis elegans. We identified a 261-bp cDNA sequence, which encodes for an 86-amino acid protein. The cloned gene expression was observed in the neck and gravid proglottids via Northern blotting, using cloned cDNA inserts as probes, but the clone was not expressed in any of other tissues. We suggest that this gene may be involved in the apolysis of S. erinacei during normal tissue development and differentiation in cestode parasites.

Spirometra erinacei / S. erinaceieuropaei in a feral cat in Manawatu with chronic intermittent diarrhoea

CASE HISTORY

A feral cat captured in the Manawatu region of New Zealand was treated for worms and fleas, and kept confined in a metabolic cage. It showed good appetite and weight gain but had intermittent watery, yellow diarrhoea.

CLINICAL FINDINGS

Clinical examination under sedation was unremarkable and routine blood tests showed no significant abnormalities. The cat was negative for feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV). Different canned cat foods did not alter the course of the diarrhoea, and the cat was euthanised 6 months after capture. At necropsy, two sections of adult Spirometra tapeworms were found in the jejunum and typical Spirometra eggs were found in colonic contents. Molecular identification of the parasite was undertaken, using the cytochrome-c oxidase subunit-1 gene (cox1) sequence.

DIAGNOSIS

Chronic intermittent diarrhoea associated with Spirometra erinacei / S. erinaceieuropaei infection.

CLINICAL RELEVANCE

Spirometra has not been reported in New Zealand before but has been associated with gastrointestinal disease in cats in other parts of the world. It requires species targeted treatment to be eliminated effectively, and is zoonotic. Diagnosis could be difficult for clinicians who are not familiar with the parasite and its life cycle.

Excretory/secretory products from plerocercoids of Spirometra erinaceieuropaei suppress interleukin-1beta gene expression in murine macrophages

The present study shows that ES products from plerocercoids of Spirometra erinaceieuropaei suppressed interleukin-1beta mRNA expression in lipopolysaccharide-stimulated RAW 264.7 macrophages in the absence or presence of a cyclic AMP analogue, dibutyryl cyclic AMP. Investigation using the inhibitors of mitogen-activated protein kinase (MAPK) pathways revealed that extracellular signal-regulated protein kinase 1/2 and p38 mitogen-activated protein kinase pathways are crucial for full induction of interleukin-1beta mRNA expression. ES products additionally suppressed interleukin-1beta mRNA expression in the cells treated with p38 mitogen-activated protein kinase inhibitor (SB203580) or extracellular signal-regulated protein kinase 1/2 inhibitor (PD98059). Western blot analysis showed that dibutyryl cyclic AMP enhanced lipopolysaccharide-induced phosphorylation of extracellular signal-regulated protein kinase 1/2, p38 mitogen-activated protein kinase and cyclic AMP responsive element binding protein (CREB) and, in turn, we demonstrated that ES products reduced the lipopolysaccharide and dibutyryl cyclic AMP-induced phosphorylation of extracellular signal-regulated protein kinase 1/2 and p38 mitogen-activated protein kinase, but not cyclic AMP responsive element binding protein. These data demonstrate that ES products from the plerocercoids of S. erinaceieuropaei may evade induction of interleukin-1beta mRNA by inhibiting extracellular signal-regulated protein kinase 1/2 and p38 mitogen-activated protein kinase pathways in lipopolysaccharide and/or dibutyryl cyclic AMP-stimulated macrophages.

Stage-specific expression genes of the Spirometra erinaceieuropaei plerocercoid screened by mRNA differential display technique

BACKGROUND

The stage-specific expression of genes is one of the most characteristics of parasites. It has been found that a lot of genes of Spriometra erinaceieuropaei are specifically expressed in pleroceroid in large amount, but not expressed when the plerocercoid development into adult worm. The study is to screen other stage-specific ecpression genes of plerocercoid of Spirtmetra erinceieuropaei.

METHODS

RNA was separately extracted by acid guanidinium thiocyanate-phenol-chloroform from plerocercoids and adult worms of Spirometra erinaceieuropaei, DNA contaminated in the RNA was digested by RNase-free DNase. After the RNA was reverse transcripted to cDNA using T12MA, T12MC, T12MG and T12MT anchor-primers, PCR was done using the same T12MN and one random primer with alpha 35S-dATP in the system. The PCR products were fractionated on an 8% denatured polyacrylamide gel. Differential bands of the plerocercoid found in the gel were cut out, amplified by PCR and sequenced. Northern hybridization was used to identify the stage-specific expression genes.

RESULTS

Eleven differential bands were selected from the gel and classified into 3 kinds of gene fragments by hybridization, after they were amplified by PCR. Fragments 1 (238 bp) and 2 (383 bp), were confirmed by Northern hybridization, as being expressed in the plerocercoid. However, fragment 3 (433 bp), was expressed in both the plerocercoid and the adult worm. Data from the 3 gene fragments underwent homological analysis in GenBank. The sequence which was homologous with fragments 1 and 2 was not found, but fragment 3 had high homology with many kinds of 28S rRNA.

CONCLUSIONS

The gene expressions of plerocercoids are different from adult worms because they live in different hosts. Two types of different gene fragments from the plerocercoid were found by mRNA differential display technique.

Single-strand conformation polymorphism-based analysis reveals genetic variation within Spirometra erinacei (Cestoda: Pseudophyllidea) from Australia

This study examined genetic variability within Spirometra erinacei (Cestoda: Pseudophyllidea) from different host species and geographical origins in Australia using a polymerase chain reaction (PCR)-based mutation detection approach, followed by DNA sequencing. Part of the cytochrome c oxidase subunit 1 gene (p cox 1) was amplified by PCR, scanned for sequence variation by single-strand conformation polymorphism (SSCP), and representative samples from different host species were selected for DNA sequencing. While no variation in SSCP profiles was detected among S. erinacei samples from dog, fox, cat, tiger snake and python, they differed in profile from 5 specimens from the green tree frog (Litoria caerulea). This was supported by sequence data which demonstrated that p cox 1 sequences of samples from the latter host species differed at 8 of 393 (2%) nucleotide positions from those from the non-amphibian host. Using a nucleotide difference in the p cox 1 sequence, a PCR-linked restriction fragment length polymorphism (RFLP) could be employed to unequivocally delineate between samples from non-amphibian and amphibian hosts. These findings demonstrate the existence of at least two genotypes within S. erinacei, which may have important implications for studying the epidemiology, ecology and systematics of this cestode.

Phylogenetic identification of Sparganum proliferum as a pseudophyllidean cestode by the sequence analyses on mitochondrial COI and nuclear sdhB genes

Sparganum proliferum is a larval cestode for which the adult stage is unknown. It is characterized by the continuous branching and budding when parasitized to humans, and causes fatal human sparganosis. However, the biological features of S. proliferum, including its taxonomic status, still remain obscure. Our previous investigation suggested that S. proliferum might be phylogenetically distinct from Spirometra erinaceieuropaei, by the analysis on mitochondrial NADH dehydrogenase subunit 3 (ND3) gene. However, mitochondrial DNA sequence in Platyhelminth is known to have heteroplasmy within a species. Therefore, in the present study, we have investigated the complete nucleotide sequences of mitochondrial cytochrome c oxidase subunit I (COI) gene and the partial nucleotide sequences of nuclear coded succinate dehydrogenase iron-sulfur protein subunit gene (sdhB). The results clearly demonstrated that S. proliferum is a distinct species from S. erinaceieuropaei, and that S. proliferum belongs to the order Pseudophyllidea.

[Molecular cloning of a cDNA encoding an antigenic polypeptide containing repeat units of Spirometra erinaceieuropaei plerocercoid]

AIM

To study the gene structure encoding some antigenic polypeptides of plerocercoid of Spirometra erinaceieuropaei (SEP).

METHODS

A cDNA library constructed from SEP was immunoscreened using mouse anti-SEP polyclonal antibody. The gene structure was analyzed by computer after the insert of positive clone was subcloned and the nucleotide sequences of the insert were determined. The length of mRNA hybridized with cDNA was detected by Northern blotting.

RESULTS

A cDNA clone of 1,084 bp encoding an antigenic polypeptide was isolated. The clone contained one open reading frame composed of 828 bp encoding 276 amino acids. The open reading frame contained tandem repeating unit of 123 bp which appeared 5 times in this clone. The 41 amino acids deduced from 123 bp repeating unit consisted of 53.7% of hydrophobic amino acid residues. In Northern blot assay of poly (A)+RNA, a strong band of about 1.1 kb and a weak band of about 1.7 kb were found in the plerocercoids but no band was found in the adult worms.

CONCLUSION

The repeating element derived from the plerocercoids may be associated with the migration of the plerocercoids in the host tissue. The polypeptides with repeating element may act as evasive antigens of the parasite to escape from the destruction of host immune reactions.

Genetic comparison between Spirometra erinacei and S. mansonoides using PCR-RFLP analysis

The only observed morphological difference between Spirometra erinacei and S. mansonoides is the uterine shape of the mature proglottid. Two species of worms are thought to be evolutionarily closely related. Biomolecular comparison of the two worms by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was conducted to observe the genetic distance. The 28s rDNA, mitochondrial cytochrome c oxidase subunit I (mCOI), and ribosomal internal transcribed spacer 1 (ITS1) fragments were obtained from the worms by PCR. The PCR products were cleaved by 5 four-base pair restriction enzyme combinations (Msp I, Hae III, Alu I, Cfo I, Rsa I), electrophoresed and analyzed with PAUP 3.1.1. The fragment patterns of 28S rDNA and ITS1 demonstrated that two worms were in identical systematic tree with bootstrap number 94 and 100, respectively. As for mCOI, bootstrap number was 74 in a different tree. Above results are indicative of recent common ancestry between S. erinacei and S. mansonoides.

The nucleotide sequence and predicted secondary structure of small subunit (18S) ribosomal RNA from Spirometra erinaceieuropaei

The nucleotide (nt) sequence of a small subunit (18S) ribosomal RNA gene from the plerocercoid of Spirometra erinaceieuropaei (SEP) was determined. The gene with 2182 bp in length is larger than that of most eukaryotes. Extra nt sequences occur in regions known to be variable (V4 and V7). The predicted secondary structure of the nt positions 679-933 (V4) revealed different helices from that of other eukaryotes. The region between nt positions 1540 and 1749 (V7) was different from that of other eukaryotes, but the secondary structure prediction by computer analysis demonstrated that this part of 18S rRNA sequence from S. erinaceieuropaei may form a single extended helix. Nt that were aligned with those of nine other parasites were used to estimate phylogenetic relationships. The data presented here clearly indicate that S. erinaceieuropaei is closely related to Echinococcus granulosus.

Molecular cloning and expression of the gene encoding a cysteine proteinase of Spirometra erinacei

A cDNA library constructed from plerocercoid of Spirometra erinacei (SEP) was immunoscreened using rabbit anti-plerocercoid proteinase polyclonal antibody. A 1.0-kb cDNA clone encoding a cysteine proteinase composed of 336 amino acids was isolated. The amino acid sequence predicted from the cDNA showed significant homology with human and mouse cathepsin L. N-terminal amino acid sequence of the native cysteine proteinase extracted from SEP was the same as that of mature proteinase predicted from the cloned gene. The gene encoding the proteinase was characterized by Southern and Northern blot analysis using the cDNA as a probe. The proteinase with a molecular mass of 34 kDa was demonstrated in in vitro translation products using anti-proteinase polyclonal antibody. A fusion protein derived from the cDNA synthesized by Escherichia coli (TB1) using the expression vector, pMAL-c2 was identified as an immunodominant antigen by epitope-selection method and had no cross-reactivity with other parasite-infected sera. A genomic DNA library derived from SEP was screened by the colony hybridization technique using the cDNA probe. A gene with 4.5 kb encoding the proteinase was obtained, which comprised three exons and two introns.

Molecular characterization of the Spirometra mansonoides genome: renaturation kinetics, methylation, and hybridization to human cDNA probes

High molecular weight DNA from pleroceroid larvae of the tapeworm Spirometra mansonoides was purified from isolated nuclei by conventional techniques. The DNA so isolated has a melting temperature (Tm) of 87 degrees C and a guanine plus cytosine (G/C) content of 44%. 5-Methyl cytosine could not be detected in plerocercoid DNA by HPLC analysis of DNA hydrolysates, by radiolabeling 5'-termini of MspI digests with polynucleotide kinase, or by comparing restriction patterns generated by MspI and HpaII. Renaturation kinetics demonstrated that the genome of S. mansonoides contains repetitive as well as single copy sequences and has a genome size estimated at approx. 1.6 X 10(9) bp. Hybridization was carried out between plerocercoid DNA and cDNAs for human beta-actin, alpha-tubulin and growth hormone (hGH). Rationale for this analysis was based on known homologies among actin and tubulin genes in numerous species and on apparent similarities between hGH and a plerocercoid growth factor that may be reflected in similar DNA sequence. Scanning densitometry of dot blots demonstrated that the hGH probe annealed to the same extent at low stringency (1 M NaCl, 55 degrees C) to DNA from plerocercoids, rat liver and chicken erythrocytes; but this interaction was less than to DNA from human lymphocytes, calf thymus and mouse skin. Similar results were obtained when restriction endonuclease digests of these DNAs were analyzed by Southern transfer. Little or no hybridization of the growth hormone probe to plerocercoid DNA was evident at higher stringency (1 M NaCl, 65 degrees C). In contrast, human tubulin and actin probes showed extensive hybridization to pleroceroid restriction fragments under the high stringency conditions.