Patent Application
20230028364
This invention relates to the field of detection of intestinal parasites from patient, food or environmental samples, preferably from a stool sample. Particularly, the present invention provides a polymerase chain reaction (PCR) based assay method for detection of intestinal parasite infection, particularly the infection of parasite species selected from a group consisting of Hymenolepis nana, Hymenolepis diminuta, Fasciolopsis buski, Encephalitozoon spp. (such as E. intestinalis, E. cuniculi and E. hellem), Enterocytozoon bieneusi, Enterobius vermicularis, Diphyllobothrium latum, Diphyllobothrium nihonkaiense, Schistosoma mansoni, Blastocystis hominis, Ancylostoma duodenale and liver worms, such as Clonorchis sinensis, Opisthorchis spp., and Metorchis spp. The present invention further provides materials such as primers, primer pairs and probes for use in the method of the invention. Preferably, the method of the invention is a multiplex real-time PCR assay for rapid determination of clinically important intestinal parasites.
Intestinal parasite infections are a major health problem worldwide causing morbidity, but also mortality especially of infants in the developing countries. Intestinal parasite infections are also a reported problem for travelers and are commonly caused by contamination of food or water, infected soil and improper hygiene. Intestinal parasite infections may cause mild symptoms, but severe infections with abdominal pain, bloody diarrhoea and vomiting exist. These symptoms negatively impact nutritional status, loss of appetite, weight loss, and intestinal blood loss that can often result in anemia.
At present, there is no uniform standard for the identification of intestinal parasites (Garcia et al., 2018). At present, the diagnosis of many parasites depends on microscopy of a stool sample. It is well known that microscopy takes a long time, has low inspection efficiency, and requires high clinical experience for the examiner. Moreover, intestinal parasites may be present as cysts or eggs that are similar in shape with multiple parasite species and cannot thus be distinguished from each other by ordinary light microscope. The prior art methods thus often lead to misjudgments. Also immunodiagnosis have been used for the parasite detection, but although immunodiagnosis is more efficient than microscopy, it is often limited by sensitivity and specificity.
Although a number of PCR based assays for detecting intestinal parasite species are already disclosed, there is still a need in the field for further PCR assays which are able to provide high specificity and reliability for the detection of specific intestinal parasite species, for instance in multiplex assays. The present inventors have now located DNA sequence regions in parasite genomes that are surprisingly well-suited for specific and sensitive amplification of markers in particular intestinal parasite species.
The sample matrix, which in parasite diagnostics is commonly a stool or food sample, is likely to contain a host of PCR inhibitors. This reduces amplification efficiency of the PCR reaction and thus even more careful optimization is expected from the amplicon design step to verify that all templates and copy numbers are amplified equally but also efficiently enough. Hence, oligonucleotide design enabling high PCR efficiency (optimally as close to 100% as possible) is required. The detection method used may also affect amplification efficiency and/or bias.
The present inventors have now located DNA sequence regions that are well suited for specific and sensitive amplification and quantification of intestinal parasite species. The amplicons have been designed to be so specific that they can be combined into any multiplex sets with each other. Naturally a prerequisite to this is that all the disclosed amplicons have also been designed to amplify in the same reaction and cycling conditions. The aim of the invention is to replace antigen testing and microscoping as a screening test for intestinal parasites, and thus provide process improvements for the laboratory and clinical benefits in improved patient management by providing rapidly a rich set of information. Further, infection control could benefit if clinical microbiology laboratories could readily differentiate between intestinal parasite species.
The number of intestinal parasites is large and a parasite test method should optimally identify as many as possible. Having one PCR reaction per species can be cumbersome, since the number of samples tested is typically large. It would be optimal to detect multiple species within one reaction. In a PCR setting the most obvious alternative is ‘multiplex’ PCR amplification. In multiplex PCR, several oligonucleotide sets, each designed to amplify one species/species group, are included in the same reaction vessel and each oligonucleotide set is used to amplify its respective pathogen DNA during the same PCR reaction. In this invention, we describe a PCR based method for rapid detection of clinically important intestinal parasites, particularly Hymenolepis nana, Hymenolepis diminuta, Fasciolopsis buski, Encephalitozoon spp. (such as E. intestinalis, E. cuniculi and E. hellem), Enterocytozoon bieneusi, Enterobius vermicularis, Diphyllobothrium latum, Diphyllobothrium nihonkaiense, Schistosoma mansoni, Blastocystis hominis, Ancylostoma duodenale and liver worms, such as Clonorchis sinensis, Opisthorchis spp., and Metorchis spp. The present invention discloses primers and probes designed for target sequences conserved in said intestinal parasites. These primers and probes are compatible for use in any multiplex qPCR determining the presence of multiple intestinal parasites.
Multiplex PCR presents a challenge for quantitation of the pathogen DNA (qPCR): the different amplicons compete for the same PCR reaction components (eg. DNA polymerase and MgCl2) and this can compromise the quantitative nature of the reaction between and, especially, quantitative comparisons between samples. It is commonly known in the art that there is bias in the amplification efficiencies between different template amounts or lengths so that e.g. short amplicons are favoured in the expense of longer ones.
At the same time, undesired cross-reactions of multiplex set oligo combinations must be avoided. One must also remember to check mis-priming to any other sequences present in the sample.
Finding suitable primer and probe sequences for the detection of a diverse group of pathogenic microbes can be far from trivial especially when designing multiplex set ups where all amplicons and templates should be amplified with equal efficiency. Many of the species are relatively closely related, making it challenging to locate sequences that are unique for each species. Some genes possess complex repetive closely related elements which is challenging from the amplicon design point of view, especially when designing amplicons for multiplex PCR.
The sample matrix, which in intestinal parasite diagnostics is commonly a stool or food sample, is likely to contain a host of PCR inhibitors. This reduces amplification efficiency of the PCR reaction and thus even more careful optimization is expected from the amplicon design step to verify that all templates and copy numbers are amplified equally but also efficiently enough. Hence, oligonucleotide design enabling high PCR efficiency (optimally as close to 100% as possible) is required. The detection method used may also affect amplification efficiency and/or bias.
In an aspect, the present invention is directed to a method for determining the presence of one or more intestinal parasites in a biological sample comprising the steps of:
i) contacting the sample or nucleic acid isolated therefrom with oligonucleotide primers in an amplification assay to provide a reaction mix for nucleic acid amplification;
ii) performing a nucleic acid amplification reaction with the reaction mix obtained from step i) comprising DNA from the biological sample as a template, so that the target sequences of the intestinal parasite(s) is/are specifically amplified, whenever said sequences are present in the sample; and
iii) detecting the presence of an amplified target sequence in the reaction mix, wherein the presence of the target sequence is indicative of the presence of intestinal parasites in the sample;
wherein said one or more intestinal parasites is/are selected from the group consisting of Hymenolepis nana, Hymenolepis diminuta, Fasciolopsis buski, Encephalitozoon spp. (such as E. intestinalis, E. cuniculi and E. hellem), Enterocytozoon bieneusi, Enterobius vermicularis, Diphyllobothrium latum, Diphyllobothrium nihonkaiense, Schistosoma mansoni, Blastocystis hominis, Ancylostoma duodenale and liver worms, such as Clonorchis sinensis, Opisthorchis spp., and Metorchis spp;
wherein said target sequence(s) is/are selected from the group consisting of the sequences as defined by SEQ ID Nos: 1-16 and 46-47, wherein said oligonucleotide primers comprise a primer pair which binds to one of the target sequences as defined by SEQ ID Nos: 1-16 and 46-47 and allow amplification of at least part of the target sequence in step ii).
The present invention provides a nucleic acid amplification based assay method for detection of intestinal parasites, particularly one or more intestinal parasites selected from the group consisting of Hymenolepis nana, Hymenolepis diminuta, Fasciolopsis buski, Encephalitozoon spp. (such as E. intestinalis, E. cuniculi and E. hellem), Enterocytozoon bieneusi, Enterobius vermicularis, Diphyllobothrium latum, Diphyllobothrium nihonkaiense, Schistosoma mansoni, Blastocystis hominis, Ancylostoma duodenale and liver worms, such as Clonorchis sinensis, Opisthorchis spp., and Metorchis spp. The present invention further provides materials such as primers, primer pairs (i.e. a pair of a forward primer and a reverse primer) and probes for use in the method of the invention. Particularly, the present invention provides a method for determining the presence of intestinal parasites in a biological sample comprising the steps of i) contacting the sample or nucleic acid isolated therefrom with oligonucleotide primers in an amplification assay to provide a reaction mix for nucleic acid amplification;
ii) performing a nucleic acid amplification reaction with the reaction mix obtained from step i) comprising DNA from the biological sample as a template, so that the target sequences of the intestinal parasite(s) is/are specifically amplified, whenever said sequences are present in the sample; and
iii) detecting the presence of an amplified target sequence in the reaction mix, wherein the presence of the target sequence is indicative of the presence of intestinal parasites in the sample;
wherein said target sequence(s) is/are selected from the group consisting of the sequences as defined by SEQ ID Nos: 1-16 and 46-47, wherein said oligonucleotide primers comprise a primer pair which binds to one of the target sequences as defined by SEQ ID Nos: 1-16 and 46-47 and allow amplification of at least part of the target sequence in step ii).
Said biological sample can be a stool sample, a food sample, such as a meat sample, or any environmental sample. The sample may be enriched before step i).
Preferably, said nucleic acid amplification reaction is a polymerase chain reaction (PCR). As well-known in the art, PCR is a method whereby a limited segment of a nucleic acid molecule, i.e. a target sequence, is amplified repetitively to produce a large amount of DNA molecules consisting of only that segment. The procedure depends on repetition of a large number of priming and transcription cycles. In each cycle, two oligonucleotide primers, i.e. a forward primer and a reverse primer, bind to the segment, and define the limits of the segment. A primer-dependent DNA polymerase then transcribes, or replicates, the strands to which the primers have bound. The resulting PCR products are called amplicons. In a particular example, the methods disclosed herein include the step of PCR amplifying a portion of the genome of an intestinal parasite.
“Target sequence” as defined herein is a nucleic acid segment present in the genome of a intestinal parasite whose detection, quantitation, qualitative detection, or a combination thereof, is intended. For example, the target sequence is a specific nucleic acid in intestinal parasite genome, the amplification of which is intended. Purification or isolation of a template molecule, if needed, for initiation of the amplification reaction can be conducted by methods known to those in the art. For example, isolation of the template can be achieved by using a commercially available purification kit or the like.
Preferred target sequences (or amplicons) amplified in target organisms are listed in Table 1. However, a person skilled in the art knows that these target sequences naturally vary in related strains. This minor variation can be taken into account while designing primers suitable to amplify said amplicons in the method of the present invention. Preferably, at least 20, 25, 30, 35, 40, 50, 60, 70, 80, 90 100, or 125 nucleotides long sequence of each of the target sequences selected from the group consisting of SEQ ID NOS:1-16 and 46-47 are amplified in the method.
Hymenolepis cox1
Hymenolepis cox1, v2
Fasciolopsis buski ITS1
Encephalitozoon sp 18S
Encephalitozoon sp 18S v2
Encephalitozoon sp 18S v3
Enterocytozoon bieneusi 18S
Enterobius vermicularis ITS
Diphyllobothrium latum/nihonkaiense cox1
Diphyllobothrium latum/nihonkaiense cox1 v2
Diphyllobothrium latum/nihonkaiense cox1 v3
Schistosoma mansoni cox1
Blastocystis hominis 18S
Blastocystis hominis 18S v2
C.sinensis/Opisthorchis sp./Metorchis sp. 18S
Ancylostoma duodenale ITS gB 1
Ancylostoma duodenale ITS gB 2
Primer pairs, which are preferably used in the present method to amplify the target sequences are listed in Table 2.
The method of the invention is characterized in that the presence of the amplified target sequence, i.e. the product, of each of primer pairs in the PCR reaction in step iv) indicates the presence of intestinal parasites in the sample in the following way:
Preferably, each primer of said primer pairs is less than 25, 30, 35, 40, 45, 50 or 55 nucleotides long, and more preferably, less than 50 nucleotides long. Each of the present primers can also be defined as comprising or consisting of at least 10, 15, 16, 17 or 18 contiguous nucleotides present in at least one primer sequence selected from the group consisting of SEQ ID NOS:17-45 and 48-51. Each of the present primers can further be defined as having at least 80%, 85%, or 90% sequence identity to at least one primer sequence selected from the group consisting of SEQ ID NOS:17-45 and 48-51.
One specific embodiment of the invention is to perform said method as a real-time polymerase chain reaction and in that case nucleic acid probes comprising or consisting of the following sequences are specifically used with each of primer pairs A) to T) in the following manner:
The melting temperature, Tm, of some of the probes (such as probes for primer pairs G), H), K) and L)) is preferably increased at least 5 degrees ° C. by addition of modified nucleotides. The amount of modified nucleotides in one probe is 1, 2, 3 or preferably 4. The underlined nucleotides in the above list are modified nucleotides each increasing the Tm of the probe. The modified nucleotide can be a LNA nucleotide (Exiqon A/S), minor groove binder (MGB™), SuperBase, or Peptide Nucleic Acid (PNA) or any other modification increasing the Tm of the probe.
Preferably, the above probes comprise the sequences as defined and are less than 25, 30, 35, 40, 45, 50 or 55 nucleotides long, and more preferably, less than 50 nucleotides long. Each of the present probes can also be defined as comprising or consisting of at least 10 or 15, 16, 17 or 18 contiguous nucleotides present in one probe sequence selected from the group consisting of SEQ ID NOS:52-67 or complements thereof.
A probe preferably includes a detectable label, such as a fluorophore. Examples of the fluorophores are fluorescein and derivatives thereof such as 6-carboxyfluorescein (FAM) and fluorescein isothiocyanate (FITC). The detectable label may produce a signal in the presence of a target amplicon, or result in a decreased signal in the presence of a target amplicon, depending on the particular construction of the probe.
The method of the invention is based on multiplex PCR technique simultaneously analyzing nucleic acids of many templates from a sample, i.e. a multiplex PCR reaction comprises a set of primer pairs capable of simultaneous amplification of various target sequences.
In a further embodiment, the invention provides nucleotide probes comprising or consisting of any of the probe sequences as defined above.
The present invention is preferably directed to a method for determining the presence of intestinal parasites in a sample, wherein the presence of at least one of the pathogens Hymenolepis nana, Hymenolepis diminuta, Fasciolopsis buski, Encephalitozoon spp. (such as E. intestinalis, E. cuniculi and E. hellem), Enterocytozoon bieneusi, Enterobius vermicularis, Diphyllobothrium latum, Diphyllobothrium nihonkaiense, Schistosoma mansoni, Blastocystis hominis, Ancylostoma duodenale and liver worms, such as Clonorchis sinensis, Opisthorchis spp., and Metorchis spp., is detected. In preferred embodiments, the presence of any combination of the above listed intestinal parasites is detected. Accordingly, each combination of 2, 3, 4, 5, 6, 7, 8 or more of said intestinal parasites is a preferred embodiment for the present invention.
In a preferred embodiment, at least the presence of Hymenolepis nana and Hymenolepis diminuta are detected in the method, wherein the target sequences are at least as defined by SEQ ID NOS: 1 and 2. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS: 17, 18, and 19.
In a preferred embodiment, at least the presence of Fasciolopsis buski is detected in the method, wherein the target sequence is at least as defined by SEQ ID NO: 3. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS: 20 and 21.
In a preferred embodiment, at least the presence of Encephalitozoon spp. (such as E. intestinalis, E. cuniculi and E. hellem) are detected in the method, wherein the target sequences are at least as defined by SEQ ID NOS:4-6. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS:22-27.
In a preferred embodiment, at least the presence of Enterocytozoon bieneusi is detected in the method, wherein the target sequence is at least as defined by SEQ ID NO:7. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS: 28 and 29.
In a preferred embodiment, at least the presence of Enterobius vermicularis is detected in the method, wherein the target sequence is at least as defined by SEQ ID NO:8. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS: 30 and 31.
In a preferred embodiment, at least the presence of Diphyllobothrium latum and Diphyllobothrium nihonkaiense are detected in the method, wherein the target sequences are at least as defined by SEQ ID NOS:9-12. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS:32-37.
In a preferred embodiment, at least the presence of Schistosoma mansoni is detected in the method, wherein the target sequence is at least as defined by SEQ ID NO:13. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS:38 and 39.
In a preferred embodiment, at least the presence of Blastocystis hominis is detected in the method, wherein the target sequences are at least as defined by SEQ ID NOS:14 and 15. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS: 40-43.
In a preferred embodiment, at least the presence of liver worms, such as Clonorchis sinensis, Opisthorchis spp., and Metorchis spp. are detected in the method, wherein the target sequence is at least as defined by SEQ ID NO:16. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS: 44 and 45.
In a preferred embodiment, the presence of at least Hymenolepis nana, Hymenolepis diminuta and liver worms Clonorchis sinensis, Opisthorchis spp., and Metorchis spp are detected in the method, wherein the target sequences are at least as defined by SEQ ID NOS:1, 2 and 16. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS:17, 18, 19, 44 and 45.
In another preferred embodiment, the presence of at least Enterocytozoon bieneusi, Enterobius vermicularis, and Schistosoma mansoni are detected in the method, wherein the target sequences are at least as defined by SEQ ID NOS:7, 8 and 13. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS:28, 29, 30, 31, 38 and 39.
In a preferred embodiment, at least the presence of Ancylostoma duodenalis is detected in the method, wherein the target sequences are at least as defined by SEQ ID NOS:46 and 47. More preferably, a primer pair set allowing amplification of at least part of said target sequences comprise or consist of at least 15 consecutive nucleotides of the sequences as defined in SEQ ID NOS: 48-51.
The present invention is further directed to the use of nucleotide primers, primer pairs or probes as defined above for determining the presence of intestinal parasites in a sample.
The present invention also provides kits for the detection of the presence of intestinal parasites in a sample. Such a kit comprises primer pairs selected from the group consisting of primer pairs as defined above. The kit may further comprise a probe selected from the probes as defined above. The use of the primer pairs and probes are described above and in the Example below. Preferably, said kit comprises means for a real-time polymerase chain reaction, such as labelled probes, polymerase enzymes, buffers and nucleotides.
Unless explained otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described below. The materials, methods, and examples are illustrative only and not intended to be limiting.
This example describes results from a proof-of-concept study of the detection of Hymenolepis nana, Hymenolepis diminuta, Fasciolopsis buski, Encephalitozoon spp. (such as E. intestinalis, E. cuniculi and E. hellem), Enterocytozoon bieneusi, Enterobius vermicularis, Diphyllobothrium latum, Diphyllobothrium nihonkaiense, Schistosoma mansoni, Blastocystis hominis and liver worms, such as Clonorchis sinensis, Opisthorchis spp., and Metorchis spp. in a proprietary multiplex qPCR assay. Sample material for this designed assay is a spiked stool sample.
Materials and Methods
qPCR Reagents:
Mobidiag's qPCR Mastermix (MM)
Assay mixture consisting of parasite target specific primers as defined in Table 2 and probes as defined above.
Devices:
BIO-RAD CFX96
PCR Setup
In reaction:
PCR Protocol:
Two-step qPCR with detection by labelled probes.
Samples:
Spiked samples, representing the pathogens listed above, in a stool background. Samples have been collected from commercially available biobanks (such as ATCC) or from Mobidiag sample storage facilities and the analyses are performed in a series of ten-fold sample dilutions.
Results
All targets were detected in all sample concentrations in a high multiplexing condition (
This example describes results from a study of potential false positive results in the intestinal parasites qPCR assay due to a cross-reaction. Sample material for this designed assay is preferably stool sample. Therefore, pathogens other than parasites (bacteria and viruses) associated with gastrointestinal infections, and which are not covered by assay panel, can cause potential cross-reaction. Also, other eukaryotic microbes may cross-react.
Materials and Methods
qPCR Reagents:
Mobidiag's qPCR Mastermix (MM)
Assay mixture consisting of parasite target specific primers as defined in Table 2 and probes as defined above.
Devices:
BIO-RAD CFX96
PCR Setup
In reaction:
10 μl2×MM
5 μl 4×Primer mix
2 μl sample/H2O
20 μl
PCR Protocol
A two-step qPCR with detection by labelled probes:
Samples:
In total, 61 living or attenuated microbes or extracted DNA samples from different micro-organisms (Table 3). Strains have been mainly collected from commercially available biobanks (ATCC, DSMZ, Microbiologics Qnostics and Vircell). All samples are analysed at high (>108 CFU/mL) concentrations.
Acanthamoeba castellanii
Neospora caninum
Perkinsus marinus
Prototheca wickerhamii
Tetrahymena thermophila
Aspergillus fumigatus
Debaryomyces hansenii
Eremothecium gossypii
Malassezia globosa
Malassezia pachydermatis
Penicillium rubens
Saprolegnia diclina
Trichoderma reesei
Trichophyton interdigitale
Geotrichum candidum
Iodamoeba butschlii
Endolimax nana
Entamoeba coli
Entamoeba dispar
Plasmodium falciparum
Plasmodium malariae
Aspergillus fumigatus
Candida albicans
Candida glabrata
Candida krusei
Fusarium solani
Saccharomyces cervisiae
Aeromonas hydrophila
Escherichia coli, non toxigenic
Escherichia coli, EAEC
Escherichia coli, EIEC
Escherichia coli, EPEC
Escherichia coli, ETEC
Bacillus cereus
Bacteroides fragilis
Campylobacter coli
Campylobacter jejuni
Clostridium difficile
Clostridium perfringens
Clostridium sordellii
Enterobacter cloacae
Enterococcus faecalis
Enterococcus faecium
Helicobacter pylori
Klebsiella pneumoniae
Lactobacillus acidophilus
Proteus vulgaris
Pseudomonas aeruginosa
Salmonella enterica subsp. enterica, Typhimurium
Shigella sonnei
Serratia marcescens
Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus bovis
Vibrio parhaemolyticus
Yersinia enterocolitica subsp. enterocolitica
Yersinia pseudotuberculosis
Results
The cross-reactivity test showed no false positives (see Table 3 above).
For the experiment, two set of samples were used: a set of (n=8) known Encephalitozoon spp. positive samples from clinical origin (one per patient) and a set of (n=104) stool samples negative for Encephalitozoon spp. (see Table 4). Positive samples were prepared by spiking the known strains into negative stool background in clinically relevant concentrations. In total, 120 Novodiag cartridges (Mobidiag, Finland) were run.
Sample Quantitation
The known Encephalitozoon samples from commercially available biobank (ATCC) were quantified in CFX96 qPCR instrument against known standard DNA sample of the same target diluted in a 10-fold fashion. The standard series ranged from 200 to 200 000 c/μL. The final “clinical” samples were prepared by spiking the primary Encephalitozoon spp. samples into eSwab-stool-suspension in clinically relevant concentration (ranging from 100 to 80 000 cells/mL).
Sample Analysis
Each sample (positive and negative) were pre-treated and run in the Novodiag instrument.
E. intestinalis {sample 1)
E. intestinalis (sample 2)
E. intestinalis (sample 3)
E. cuniculi (sample 4)
E. cuniculi (sample 5)
E. cuniculi (sample 6)
E. hellem (sample 7)
E. hellem (sample 8)
Oligonucleotides
Encephalitozoon Assay mix comprised the following oligonucleotides:
Encephalitozoon_sp_18S_F3.1 (SEQ ID NO:22)
Encephalitozoon_sp_18S_F3.2 (SEQ ID NO:24)
Encephalitozoon_sp_18S_F3.3 (SEQ ID NO:26)
Encephalitozoon_sp_18S_P2.1 as
Encephalitozoon_sp_18S_P2.2 as
Encephalitozoon_sp_18S_R2.1 (SEQ ID NO:23)
Encephalitozoon_sp_18S_R2.2 (SEQ ID NO:25)
Encephalitozoon_sp_18S_R2.3 (SEQ ID NO:27)
Results
The results of positive samples with cell count approximation are presented in Table 5 below:
E. intestinalis ATCC 50651
E. intestinalis ATCC 50507
E. cuniculi ATCC 50503
E. hellem ATCC 50504
E. hellem ATCC 50451
E. intestinalis ATCC 50506
E. cuniculi ATCC 50789
E. cuniculi ATCC 50612
1Conversion factor 11 comes from the number of copies of 18S genes found in Encephalitozoon spp. nuclei. Biderre C, Peyretaillade E, Duffieux F, Peyret P, Méténier G, Vivarès C. The rDNA Unit of Encephalitozoon cuniculi (Microsporidia): Complete 23S Sequence and Copy Number. J Eukaryot Microbiol. Nov-Dec 1997; 44(6): 76S.
2 Graczyk TK, Johansson MA, Tamang L, Visvesvara GS, Moura LS, DaSilva AJ, Girouard AS, Matos O. Retrospective Species Identification of Microsporidian Spores in Diarrheic Fecal Samples from Human Immunodeficiency Virus/AIDS Patients by Multiplexed Fluorescence In Situ Hybridization. J Clin Microbiol. 2007 Apr; 45(4): 1255-60.
3 Kahler AM, Thurston-Enriquez JA. Human pathogenic microsporidia detection in agricultural samples: method development and assessment. Parasitol Res. 2007 Feb; 100(3): 529-38.
The final results are summarized below in Table 6:
Encephalitozoon spp.
E. cuniculi
E. hellem
E. intestinalis
Overall sensitivity and specificity of the assay for detection of Encephalitozoon spp. with spiked and Encephalitozoon spp. negative stool samples was 100% (95% CI 63.1-100%) and 100% (95% CI 96.5-100%), respectively.
Overall positive predictive value (PPV) and negative predictive value (NPV) was 100% (95% CI 63.1-100%) and 100% (95% CI 96.5-100%), respectively.
This experiment was conducted with Ancylostoma duodenale primers as described in SEQ ID NOS:48-51 and the results were compared to the reference O&P microscopic method.
The final results are:
Ancylostoma
duodenale
Overall sensitivity and specificity of the NVD SP assay for detection of Ancylostoma duodenale from unpreserved stool samples was 100% (95% CI 29.2-100%) and 100% (95% CT 96.1-100%), respectively.
Overall PPV and NPV was 100% (95% CI 29.2-100%) and 100% (95% CI 96.1-100%), respectively.
One invalid run was observed from the sample set (1/96) yielding 1% invalidity rate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20195975 | Nov 2019 | FI | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FI2020/050766 | 11/16/2020 | WO |
