Application of Nested-qPCR-High Resolution Melting (HRM) Technology on Strongyloides stercoralis Isolates from Iran.

PURPOSE: Strongyloides stercoralis is a parasite with special characteristics presenting it as a unique nematode. Iran is an endemic area for S. stercoralis. In this study, nested-qPCR-high resolution melting (HRM) technology was applied on some human isolates of S. stercoralis from this country by focusing on evolutionary genetics analysis. METHODS: Twelve human isolates of S. stercoralis were collected from four endemic provinces of Iran. Genomic DNA was extracted from a single filariform larva for every isolate. Using specific primers targeting partial regions in cox1 gene, nested-qPCR-HRM was performed and melting-curve profiles were analyzed alongside the evaluation of genetic proximity and phylogenetic analysis using MEGA7 and DnaSP5 software. RESULTS: The melting temperature (Tm) values of the isolates were 77.9 °C-78.3 °C. All isolates from Guilan, Mazandaran, and Khouzestan Provinces shared Tm values of 78.2 °C to 78.3 °C, while the isolates from Hormozgan Province showed Tm values of 77.9 °C, 78.0 °C, and 78.1 °C. The phylogenetic tree illustrated that the sequences of the current study included nine haplotypes. Tajima's D index analyses showed that cox1 gene in S. stercoralis isolates was negative (Tajima's D = - 0.27). CONCLUSION: The isolates were divided into five temperature groups. Although HRM assay compared to PCR sequencing identified more limited genetic changes, it revealed that the mean of Tm of the isolates from Hormozgan Province was lower than those of other provinces and represented specific haplotypes for this geographical region on the phylogenetic tree.

Molecular Characterization of Mesocestoides litteratus (Cestoda: Cyclophyllidea: Mesocestoididae) Tetrathyridium Isolated from Two Species of Rodents from Iran.

PURPOSE: Mesocestoides spp. are Cyclophyllidean tapeworms with zoonotic importance. The current study aimed to investigate the molecular characteristics of Mesocestoides larvae (tetrathyridium) isolated from the abdominal cavity of persion jird, Meriones persicus, and from the liver of grey hamster, Cricetulus migratorius, in Ardabil Province, northwest Iran. METHODS: Genomic DNA of the isolates of Mesocestoides tetrathyridium were extracted, and mitochondrial gene of cytochrome-c oxidase subunit1 (cox1) was amplified. Sequencing of PCR products were performed and phylogenic analysis was run using MEGA 6.0 software. RESULTS: Both isolates were identified as Mesocestoides litteratus, showing high identity with M. litteratus sequences available in GenBank. Also, they had 100% homology to each other. Intra-species variation within isolates of M. litteratus were 0-2.4%. The phylogenetic reconstruction based on the partial sequence of the cox1 gene showed that our sequences of M. litteratus were clustered with M. litteratus isolates from Slovakia, Netherlands, Germany and Italy. CONCLUSION: This is the first molecular description of M. litteratus from M. persicus and C. migratorius. Phylogenetic analysis illustrated that M. litteratus isolates of the current study had very high identities with the isolates of this species from other countries.

Evaluation of a novel Echinococcus granulosus recombinant fusion B-EpC1 antigen for the diagnosis of human cystic echinococcosis using indirect ELISA in comparison with a commercial diagnostic ELISA kit.

Cystic echinococcosis (CE) is a zoonotic parasitic disease caused by the metacestode of Echinococcus granulosus sensu lato (s.l.). A large proportion of the patients are asymptomatic at the early and late stages of the disease. CE diagnosis is mainly based on imaging techniques. Laboratory diagnosis including antibody-antigen (recombinant or fusion recombinant) can be used for the diagnosis and follow up of CE and alveolar echinococcosis (AE), but need optimization and standardization. This study aimed to evaluate the efficacy of a recombinant B-EpC1 (rB-EpC1) fusion antigen comprising B1, B2, B4, and EpC1 antigens of E. granulosus using indirect ELISA in comparison with a commercial ELISA kit for the serodiagnosis of CE. The recombinant protein was expressed in the expression host, E. coli BL21, and purified. This recombinant antigen was then evaluated by indirect ELISA and compared to the commercial CE diagnostic kit (Vircell, Spain). The study samples included 124 human sera consisting of 62 sera of patients with CE, and 62 sera of individuals without clinical evidences of CE and specific anti-CE antibodies in routine indirect ELISA. The diagnostic sensitivity and specificity of the indirect rB-EpC1-ELISA test for detection of specific anti-hydatid cyst antibodies in human CE were 95.2% and 96.8%, respectively. Also, the diagnostic sensitivity and specificity of the commercial ELISA test were 96.8% in this study. Initial evaluation of the recombinant fusion antigen (B-EpC1) was promising for the detection of CE by ELISA in clinical settings. Standardization and evaluation of recombinant fusion protein require further studies.

Gastrointestinal Helminthic Parasites of Stray Cats (Felis catus) in Northwest Iran.

BACKGROUND: Stray cats are considered an important source of various human and animal diseases, particularly diseases of parasitic helminths. We aimed to investigate the distribution of zoonotic species of gastrointestinal helminths in stray cats in Meshkin-Shahr district in Ardabil Province in the northwest of Iran. METHODS: The gastrointestinal tract of 104 stray cats from villages of Meshkin-Shahr district were provided during 2014-2015. Each gastrointestinal tract was cut into distinct sections, including esophagus, stomach, small intestine, and large intestine, and each section was examined separately for detection of helminths. Helminths were collected and then identified at the species level after clearing and staining. RESULTS: Overall, 88 out of 104 cats (84.6%) were found to be infected with at least one gastrointestinal helminth. The rate of infection for each species was as follows: Toxocara mystax (syn. cati) (49%), Taenia taeniaeformis (44.2%), Joyexiella pasqualei (32.7%), Dipylidium caninum (23.1%), Rictularia cahirensis (4.8%), and Physaloptera praeputialis (4.8%). Among these parasites, only Ph. praeputialis was collected from the stomach, all other helminths were collected from the small intestine. CONCLUSION: The results demonstrate a high infection rate of stray cats with zoonotic helminths. The presence of zoonotic species in stray cats, particularly T. mystax, has public health importance.

In vitro effects of tropisetron and granisetron against Echinococcus granulosus (s.s.) protoscoleces by involvement of calcineurin and calmodulin.

BACKGROUND: Cystic echinococcosis (CE) is a disease caused by the larval stage of Echinococcus granulosus sensu lato  (s.l.). The treatment of CE mainly relies on the use of benzimidazoles, which can commonly cause adverse side effects. Therefore, more efficient treatment options are needed. Drug repurposing is a useful approach for advancing drug development. We have evaluated the in vitro protoscolicidal effects of tropisetron and granisetron in E. granulosus sensu stricto (s.s.) and assessed the expression of the calcineurin (CaN) and calmodulin (CaM) genes, both of which have been linked to cellular signaling activities and thus are potentially promising targets for the development of drugs. METHODS: Protoscoleces (PSC) of E. granulosus (s.s.) (genotype G1) obtained from sheep hepatic hydatid cysts were exposed to tropisetron and granisetron at concentrations of 50, 150 and 250 µM for various periods of time up to 10 days. Cyclosporine A (CsA) and albendazole sulfoxide were used for comparison. Changes in the morphology of PSC were investigated by light microscopy and scanning electron microscopy. Gene expression was assessed using real-time PCR at the mRNA level for E. granulosus calcineurin subunit A (Eg-CaN-A), calcineurin subunit B (Eg-CaN-B) and calmodulin (Eg-CaM) after a 24-h exposure at 50 and 250 µM, respectively. RESULTS: At 150 and 250 µM, tropisetron had the highest protoscolicidal effect, whereas CsA was most effective at 50 µM. Granisetron, however, was less effective than tropisetron at all three concentrations. Examination of morphological alterations revealed that the rate at which PSC were killed increased with increasing rate of PSC evagination, as observed in PSC exposed to tropisetron. Gene expression analysis revealed that tropisetron at 50 µM significantly upregulated Eg-CaN-B and Eg-CaM expression while at 250 µM it significantly downregulated both Eg-CaN-B and Eg-CaM expressions; in comparison, granisetron decreased the expression of all three genes at both concentrations. CONCLUSIONS: Tropisetron exhibited a higher efficacy than granisetron against E. granulosus (s.s.) PSC, which is probably due to the different mechanisms of action of the two drugs. The concentration-dependent effect of tropisetron on calcineurin gene expression might reflect its dual functions, which should stimulate future research into its mechanism of action and evaluation of its potential therapeutical effect in the treatment of CE.

Seroprevalence of Toxocara Infection in Association with Different Risk Factors among Children of 4-12 Years Old Referred to Some Medical Centers in Aras Free Zone, Northwest Iran.

BACKGROUND: Toxocariosis is a parasitic disease caused by the larval stage of Toxocara species from dog and cat. It has a worldwide distribution with higher prevalence in children. This study aimed to determine seroprevalence of Toxocara infection and its association with some risk factors among children of Aras Free Zone (Jolfa City) in Northwest of Iran. METHODS: Sera were collected from 514 children aged 4-12 yr old attending to some medical centers in the study area from May 2018 to Feb 2019. Anti-Toxocara IgG antibodies assay was performed using commercial ELISA kit (Nova Tec, Germany). The seropositivity rate was determined and its association with different demographic criteria and risk factors were statistically analyzed. RESULTS: The overall seroprevalence was 2.3% (12/514). Risk factors of children's age group and contact with either pet animals (dog and cat) and/or soil were significantly associated with seropositivity. However, there was not any relationship between Toxocara infection and gender of children, place of residency (urban or rural) and their mothers' education level. CONCLUSION: Both girls and boys are at risk of Toxocara infection in the study area. Younger age of childhood and contact with sources of infection were important associated factors. More probably, additional criteria are involved in the initiation of infection.

A Systematic Review and Meta-analysis of Toxocariasis in Iran: Is it Time to Take it Seriously?

BACKGROUND: Toxocariasis is one of the neglected zoonosis with considerable public health importance around the world. The current study aimed to elucidate the overall prevalence of Toxocara infection in human and definitive hosts and also the contamination of soil and raw vegetables with the ova of these parasites, in Iran, using systematic review and meta-analysis. METHODS: Six English and Persian databases were explored from 2000 to 2017 using the terms toxocariasis, Toxocara spp., visceral larva migrans, Iran, epidemiology, and prevalence. This meta-analysis conducted using STATA, and for all statistical tests, a p value less than 0.05 was considered significant. The random-effects model was used to the report of the pooled prevalence with a 95% confidence interval (CI). RESULTS: The pooled prevalence of toxocariasis in human was calculated as 11% (95% CI 8-13%). In terms of definitive hosts, the pooled prevalence of Toxocara infection in dogs and cats were calculated as 17% (95% CI 14-20%) and 37% (95% CI 26-48%), respectively. Also, the pooled prevalence of Toxocara spp. eggs in the soil and raw vegetable samples were calculated as 18% (95% CI 13-23%) and 2% (95% CI 1-3%), respectively. CONCLUSIONS: The results of current study demonstrate that toxocariasis should be taken more seriously by health authorities. Implementing an appropriate control program is necessary to reduce the incidence of this disease in Iran.

Design and Construction of a Fusion Peptide Containing B1, B2, B4, and EPC1 Epitopes for Diagnosis of Human Cystic Echinococcosis.

BACKGROUND: Cystic echinococcosis (CE), larval stage of Echinococcus granulosus, immunodiagnostics is still a challenge due to asymptomatic nature of CE during the early phase of infection and imperfection of diagnostic antigens. In silico design and assessments of hydatid cyst antigens provide preeminent information for novel and favorable diagnostic methods. METHODS: This study was performed at the Tehran University of Medical Sciences, Tehran, Iran in 2018. The sequences of B2, EPC1, B1 and B4 antigens were collected and analyzed for sequence conservancy by protein BLAST search and CLUSTALW multiple sequence alignment. The secondary and 3D structures were predicted using ab initio and threading methods. The antigens were analyzed for their B cell epitopic content using linear and conformational B cell epitope prediction tools. The final diagnostic antigen was designed by fusing the selected epitopic determinants form each antigen. RESULTS: Given the conservancy results and B cell epitope predictions, the whole B2 antigen along with amino acids spanning 1-50, 1-30, and 30-81 regions of EPC1, B1 and B4 antigens were selected to design the final antigen. High surface accessibility (75%), protein stability, low free energy and high number of amino acids involved in B cell epitopes were desirable properties for the final antigen to interact with antibodies against CE. CONCLUSION: In silico design of such antigens is useful for better diagnosis of CE, decrease the cost and the time required for antigen design, while avoiding the ethical aspects of in vivo studies.

Molecular characterization of human isolates of Strongyloides stercoralis and Rhabditis spp. based on mitochondrial cytochrome c oxidase subunit 1 (cox1).

BACKGROUND: Due to the similarity of Strongyloides stercoralis with free-living nematodes of Rhabditis species they might be miss-diagnosed with each other in microscopical examination of stool samples. The aim of this study was molecular characterization and differentiation of human derived isolates of S. stercoralis and Rhabditis species based on the mitochondrial gene of cytochrome c oxidase subunit 1 (cox1) amplification. METHODS: Using parasitological methods, ten isolates of S. stercoralis and three isolates of Rhabditis spp. were obtained from fresh stool samples of patients and the genomic DNA of the samples were extracted. PCR amplification of cox1 gene was carried out for all the isolates and the products were sequenced. RESULTS: The phylogenetic analysis illustrated that S. stercoralis and Rhabditis spp. isolates were placed in two distinguishable separate clades. Inter-species genetic variation between isolates of S. stercoralis and Rhabditis spp. were ranged from 13.5 to 14.5%. CONCLUSIONS: Cox1 gene was a suitable marker for discrimination of S. stercoralis from Rhabditis spp. retrieved from human in the current study. The availability of gene sequence information will be helpful in the future development and validation of discriminatory PCR-based assays of these nematodes.

Critical diagnosis of complicated strongyloidosis with nested-PCR and High Resolution Melting analysis (HRM)

Diagnosis of strongyloidosis is sometimes problematic and requires novel techniques. Here, critical diagnosis of a complicated case of strongyloidosis using molecular methods is reported. A young woman referred to the Diagnostic Laboratory of Strongyloidiasis in School of Public Health, Tehran University of Medical Sciences. She had taken albendazole before referring to the laboratory. She had cerebral edema, behavior disorders, hypereosinophilia and titer of IgE >2000 IU/mL. The patient had history of intestinal and skin disorders and steroid therapy. For detection of Strongyloides stercoralis infection, parasitological techniques and novel methods of nested-PCR and HRM analysis were applied on stool samples upon admission and during the following up. On the samples provided upon first admission, parasitology showed negative results, while both molecular methods revealed infection with S. stercoralis. After specific treatment, during the following up, the patient general health was much improved and the results of all parasitological and molecular tests were negative for strongyloidosis. Application of novel sensitive diagnostic methods for detection of S. stercoralis is necessary, especially once parasitological techniques have lack of sensitivity.

First molecular report of Hydatigera krepkogorski (Schulz and Landa, 1934) in abdominal cavity of gerbil (Rhombomys opimus) in Iran.

A polycephalic larva of Taeniidae family isolated from abdominal cavity of a great gerbil (Rhombomys opimus) from Golestan province, northern Iran, was subjected to molecular analysis. Genomic DNA from the larva was obtained using a DNA extraction tissue kit. Polymerase chain reaction was performed for amplification of the partial 12S rRNA, cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase 1 (nad1) mitochondrial genes. BLAST analysis of DNA sequencing indicated 99.00% homology in 12S rRNA and cox1 genes and 98.00% homology in nad1 gene with Hydatigera krepkogorski (accession No. AB731762). The sequences of current isolate were deposited in GenBank by accession Nos. MF281971, MF281972 and MF281973 for 12 SrRNA, cox1 and nad1 genes, respectively. This study was the first report of molecular characterization of H. krepkogorski from Iran. Isolation and characterization of the adult stage from definitive host will help to better clarify incomplete life cycle and morphology data of this species in the world.

BALB/c Mice Immunity to Hydatidosis Induced by In-vitro Reared Echinococcus granulosus Adult Worm Antigens.

BACKGROUND: Echinococcosis is a zoonotic parasitic disease caused by the larval stage of Echinococcus granulosus. Several native and recombinant antigens, derived from different stages of E. granulosus life cycle, have been used for vaccine trials. In vitro reared adult worms are good candidates for vaccination as they do not produce fertile egg/s and do not have any risk of contamination for researchers. OBJECTIVE: To evaluate different antigens derived from in vitro reared E. granulosus adult worms for the immunization of BALB/c mice against secondary hydatidosis. METHODS: Viable protoscoleces (PCSs) of sheep hydatid cyst were cultivated in S.10E.H media. Excretory secretory (E/S) and crude antigens were prepared from reared adult worms. A total of fifty BALB/c mice, each 8-weeks-old, were divided into 5 groups of 10 mice. Three groups were subcutaneously immunized with crude, E/S and immunodominant antigens on days 1 and 28. The fourth group received only PBS and the fifth group had no injection. Three weeks following the second immunization, all groups were challenged, intraperitoneal, with viable PSCs. After the autopsy of the mice and opening their abdominal wall, cysts were counted and measured followed by histopathological observations. RESULTS: The highest protective immunity (98.7%) against hydatidosis was induced by crude antigen, followed by E/S and immunodominant antigens. CONCLUSION: Antigens (crude antigens in particular) derived from in vitro reared E. granulosus adult worms, and their different protein components are suitable candidates for the vaccination of intermediate hosts against hydatidosis.

Human intestinal sarcocystosis in Iran: there but not seen.

Human sarcocystosis is a rare infection caused by the genus Sarcocystis who human serve as definitive (intestinal form of infection) host or intermediate (extraintestinal form) host for some various Sarcocystis species. The detection of Sarcocystis oocysts/sporocysts in the feces usually incidentally and is achieved by microscopic examination of the fresh or preserved specimens. To rule out any parasitological etiology among 23,875 (aged 2 months to 95 years) apparently immunocompetent Iranian individuals (from October of 2010 to June of 2016) with abdominal discomforts referred to several teaching hospitals and local clinical laboratories in Fars Province, Iran, their fecal samples were examined using light microscopy. Most pathogenic parasite-positive and doubtful samples were sent to the Intestinal Protozoology Laboratories of Fasa and Shiraz Universities of Medical Sciences to further examination to detect probable co-infection with other underdiagnose parasitoses. In addition to the common protozoal and helminthic infections, during the course of examining stool specimens using direct smear mixed with saline or iodine mounts and by formalin-ethyl acetate techniques, four cases of intestinal Sarcocystis infection as only or concurrently infected with other parasites were found. The present paper presents cases of human intestinal Sarcocystis infection in Iran. Since Sarcocystis are small in size and usually rare in stool, they often go unnoticed. It should be noted that stool smears must be examined with great care to avoid misinterpretation of Sarcocystis infections in microscopic examinations. To the best of our knowledge, co-infection of intestinal sarcocystosis and other principal parasitoses in stool investigations has not been reported earlier.

Production of Toxocara cati TES-120 Recombinant Antigen and Comparison with its T. canis Homolog for Serodiagnosis of Toxocariasis.

Toxocariasis is a cosmopolitan zoonotic disease caused by the infective larvae of Toxocara canis and T. cati. Diagnosis in humans is usually based on clinical symptoms and serology. Immunoglobulin G (IgG)-enzyme-linked immunosorbent assay kits using T. canis excretory-secretory (TES) larval antigens are commonly used for serodiagnosis. Differences in the antigens of the two Toxocara species may influence the diagnostic sensitivity of the test. In this study, T. cati recombinant TES-120 (rTES-120) was cloned, expressed, and compared with its T. canis homolog in an IgG4-western blot. The diagnostic sensitivity and specificity of T. cati rTES-120 were 70% (33/47) and 100% (39/39), respectively. T. canis rTES-120 showed 57.4% sensitivity and 94.4% specificity. When the results of assays using rTES-120 of both species were considered, the diagnostic sensitivity was 76%. This study shows that using antigens from both Toxocara species may improve the serodiagnosis of toxocariasis.

Development of a Double Glass Mounting Method Using Formaldehyde Alcohol Azocarmine Lactophenol (FAAL) and its Evaluation for Permanent Mounting of Small Nematodes.

BACKGROUND: Permanent slide preparation of nematodes especially small ones is time consuming, difficult and they become scarious margins. Regarding this problem, a modified double glass mounting method was developed and compared with classic method. METHODS: A total of 209 nematode samples from human and animal origin were fixed and stained with Formaldehyde Alcohol Azocarmine Lactophenol (FAAL) followed by double glass mounting and classic dehydration method using Canada balsam as their mounting media. The slides were evaluated in different dates and times, more than four years. Different photos were made with different magnification during the evaluation time. RESULTS: The double glass mounting method was stable during this time and comparable with classic method. There were no changes in morphologic structures of nematodes using double glass mounting method with well-defined and clear differentiation between different organs of nematodes in this method. CONCLUSION: Using this method is cost effective and fast for mounting of small nematodes comparing to classic method.

First molecular identification of Sarcocystis miescheriana (Protozoa, Apicomplexa) from wild boar (Sus scrofa) in Iran.

Sarcocystis isolate obtained from the thigh muscle of a wild boar (Sus scrofa), captured from Gilan Province, northern Iran, was subjected to molecular analysis. Genomic DNA was obtained using a DNA extraction tissue kit and Polymerase chain reaction (PCR) for amplification of the 18S ribosomal DNA region yielded an 842 bp DNA band on agarose gel. Analysis of DNA sequencing by BLAST confirmed the isolate as Sarcocystis miescheriana and the sequence was deposited in GenBank by Accession No. GU395554. This is the first molecular identification of an isolate of S. miescheriana in Iran.

Severe diarrhea due to Isospora belli in a patient with thymoma.

Opportunistic isosporidial infection of the gastrointestinal tract is frequently encountered in patients with acquired immunodeficiency syndrome (AIDS) and is considered to be an AIDS-defining illness. Chronic severe watery diarrhea due to Isospora belli has also been reported in other immunodeficiency states. This report describes severe chronic debilitating diarrhea due to isosporiasis in a patient with mediastinal thymoma, a common tumor of the anterior mediastinum, originating from the epithelial cells of the thymus. Numerous oocysts of I. belli were detected in direct smear preparation of the diarrheic stool sample of the patient, who had an 8-month history of recurrent diarrhea. Duodenal and colonic mucosal biopsies revealed slight degrees of atrophic changes associated with infiltration of the lamina propria by an appreciable number of eosinophiles and the presence of unizoit tissue cysts of I. belli in the surface epithelium of the duodenal mucosa. The patient was first treated with trimethoprim-sulfamethoxazole and subsequently underwent complete thymectomy. Later, due to recurrence of the diarrhea, he was treated with ciprofloxacin.

A case of fatal strongyloidiasis in a patient with chronic lymphocytic leukemia and molecular characterization of the isolate.

Strongyloides stercoralis is a human intestinal parasite which may lead to complicated strongyloidiasis in immunocompromised. Here, a case of complicated strongyloidiasis in a patient with chronic lymphocytic leukemia is reported. Presence of numerous S. stercoralis larvae in feces and sputum confirmed the diagnosis of hyperinfection syndrome in this patient. Following recovery of filariform larvae from agar plate culture of the stool, the isolate was characterized for the ITS1 region of ribosomal DNA gene by nested-PCR and sequencing. Albendazole therapy did not have cure effects; and just at the beginning of taking ivermectin, the patient died. The most important clue to prevent such fatal consequences is early diagnosis and proper treatment.