This project was funded by Case Western Reserve University startup funds provided to E. Jolly. Infected snails were provided by the Schistosome Resource Center, NIH-NIAID (NIAID Contract No. HHSN272201000009I). We also thank Chris King and Ronald Blanton for support in securing infected schistosome snails and for helpful discussions.

Safety measures:
Schistosome cercariae can directly penetrate the skin without the needs of a cut or pores, and cause the chronic disease schistosomiasis. S. mansoni is a biosafety level 2 organism, therefore proper personal protective equipment and proper safety measures must be followed when working with infective cercaria. Most of the equipment necessary to grow and transform schistosomes is standard, with a few key exceptions noted in the table at the end of the protocol. All cercarial work should be done in an isolated room. Schistosomules should be cultured in a sterile, approved biosafety hood. Two layers of nitrile or latex gloves should be worn, as should a lab coat, a waterproof pair of shoes, pants with no holes or tears, and waterproof sleeve protectors for your wrists and arms. In case of an accidental spill, immediately spray contaminated area with 70% ethanol or 10% bleach, rubbing vigorously if on your person. This will be sufficient to disable the parasite, but all possible infections should be reported and taken seriously. Although schistosomules are not innately infective, institutional guidelines vary, and should be consulted to determine whether BSL2 precautions are required during noninfectious life stages. Disinfect all surfaces that come into contact with any potentially infectious substance after the experiment is performed and discard waste in an approved biohazard container.
NOTE: Cover snail host bins 1 to 2 days prior to shedding and protect from light
1.	Harvesting cercariae from the snail host
<ol>
<li>Fill a clean, 500mL beaker free of detergents halfway full with distilled water equilibrated to room temperature. If working with host snails infected with miracidia on different dates, use a separate beaker for each infection date (This is particularly important if the snails will be reused for future experiments). The size of the beaker can also be smaller depending on the experience of the user.</li>
<li>Collect infected snail hosts you wish to shed and carefully deposit them in the beaker using a standard aquarium fish net and general purpose forceps as needed.</li>
<li>Place beaker on an emergency spill tray approximately 8 to 12 inches beneath an incandescent light source. Let stand for 1-2 hours under the light. Cercariae exit the snail host when exposed to bright light.</li>
<li>Carefully filter out snails from the cercariae mixture. Take extra safety precautions, as mixture is highly infectious. Remember, cercariae can directly penetrate human skin!</li>
<li>Replace mixture under light source for about 15 minutes, allowing any particulate waste matter to settle.</li>
<li>Transfer cercariae into a clean Erlenmeyer flask using a pipet, avoiding the debris at the bottom of the beaker. Place the flask at approximately a 45° angle on ice in the dark for 45 - 60 minutes, allowing cercariae to settle into one corner.</li>
<li>Use a 50 mL pipet to remove 75 to 90% of the supernatant and deposit it in beaker containing 10% bleach or 70% ethanol, taking care not to let water drops containing cercariae drip from the pipet.</li>
<li>Swirl the Erlenmeyer flask containing cercariae gently to resuspend the cercariae in solution. Use a pipet to transfer the sample to sterile 50 ml conical tubes. Place tubes again on ice for 20 minutes in the dark. Cercariae will settle towards the bottom of the tube in the dark. </li>
</ol>
2.	Manual transformation of cercariae to schistosomules
Before you begin: Make RPMI 1640 complete (RPMI, 5% Fetal Bovine Serum, 1X Pen/Strep) and warm to 37°C. (It is crucial that the fetal bovine serum used has been inactivated by incubation a 56°C for 1 hour as schistosomes can be sensitive to complement). 
<ol>
<li>In a biohazard hood, remove supernatant down to 5 to 10 ml of solution in each 50 ml conical using a pipettor or vacuum device. </li>
<li>Attach a 22 gauge double-ended, luer lok emulsifying needle to an appropriately sized syringe. </li>
<li>Slowly draw mixture into the syringe. Collect cercariae from all 50 ml tubes in a syringe. Be attentive of dripping.</li>
<li>Carefully turn syringe over such that the unattached needle end is up. Attach another syringe to this side of the emulsifying needle.</li>
<li>Pass the mixture through the needle a total of 40 times (20 times back and forth) to transform the cercariae. </li>
<li>Position the syringes vertically such that the mixture is contained in the bottom syringe and the top syringe is empty. Remove top syringe and disinfect in 70% Ethanol. </li>
<li>Deposit mixture drop by drop into a clean high walled 100mm x 50mm pyrex dish or crystallizing dish. Disinfect needle and syringe in 70% Ethanol. </li>
<li>Add 37°C RPMI 1640 complete media such that the bottom of the Petri dish is completely covered, as if pouring a Luria broth plate.</li>
<li>Swirl gently to collect schistosomules in the center of the Petri dish. Avoid splashing. 
Note: It may be useful to turn off the hood light for this step to more adequately visualize the schistosomules in the center.</li>
<li>Immediately deposit concentrated schistosomules into a fresh 12-well cell culture plate well using a sterile dropper. </li>
<li>Repeat 2.9 and 2.10 until schistosomules are no longer present in the center of the dish (approximately 10 times). Deposit each subsequent collection in a fresh well.</li>
<li>Fill each well up halfway (˜1.5 mL ) with prewarmed RPMI complete media. </li>
<li>Visualize on an inverted microscope to verify presence of schistosomules and absence of cercariae. </li>
<li>Grow the schistosomules in a CO2 incubator set to 37°C and 5% CO2.</li>
</ol>
3.	Representative Results: 
Pending transfer of transformed schistosomules into culture media, visualization under an inverted bright-field microscope (See equipment table for an example) should yield an image similar to Figure 1, in which only transformed schistosomules are present in the well. Potential contaminants could include intact cercariae, severed cercarial tails, or other debris. If no inverted microscope is available, a standard microscope or even a dissection scope will be sufficient to visualize the schistosomules. Note that this procedure does not always transform 100% of cercariae. 
<img src="/files/ftp_upload/3191/3191fig1.jpg" alt="Schistosomulum under a microscope with arrow; parasitology study, biological imaging analysis." data-altupdatedat="1747911167000" data-alt="Figure 1"> Figure 1: Transformed Schistosomulum
<img src="/files/ftp_upload/3191/3191fig2.jpg" alt="Microscopic image of cercaria and tails, highlighting parasitic morphology for biological study." data-altupdatedat="1747911167000" data-alt="Figure 2"> Figure 2: Cercariae and Severed Tails

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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schistosomiasis.">Schistosomiasis.</a> N Engl J Med. 346, 1212-1220 (2002).</li><li>Steinmann, P., Keiser, J., Bos, R., Tanner, M., Utzinger, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schistosomiasis+and+water+resources+development:+systematic+review,+meta-analysis,+and+estimates+of+people+at+risk.">Schistosomiasis and water resources development: systematic review, meta-analysis, and estimates of people at risk.</a> Lancet Infect Dis. 6, 411-425 (2006).</li><li>Savioli, L., Albonico, M., Engels, D., Montresor, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+in+the+prevention+and+control+of+schistosomiasis+and+soil-transmitted+helminthiasis.">Progress in the prevention and control of schistosomiasis and soil-transmitted helminthiasis.</a> Parasitol Int. 53, 103-113 (2004).</li><li>King, C. H., Dickman, K., Tisch, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reassessment+of+the+cost+of+chronic+helmintic+infection:+a+meta-analysis+of+disability-related+outcomes+in+endemic+schistosomiasis.">Reassessment of the cost of chronic helmintic infection: a meta-analysis of disability-related outcomes in endemic schistosomiasis.</a> Lancet. 365, 1561-159 (2005).</li><li>Haas, W., Grabe, K., Geis, C., Pach, T., Stoll, K., Fuchs, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recognition+and+invasion+of+human+skin+by+Schistosoma+mansoni+cercariae:+the+key-role+of+L-arginine.+Parasitology.">Recognition and invasion of human skin by Schistosoma mansoni cercariae: the key-role of L-arginine. Parasitology.</a> 124, 153-167 (2002).</li><li>Grabe, K., Haas, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Navigation+within+host+tissues:+cercariae+orientate+towards+dark+after+penetration.">Navigation within host tissues: cercariae orientate towards dark after penetration.</a> Parasitol Res. 93, 111-113 (2004).</li><li>Shiff, C. J., Cmelik, S. H., Ley, H. E., Kriel, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+human+skin+lipids+on+the+cercarial+penetration+responses+of+Schistosoma+haematobium+and+Schistosoma+mansoni.">The influence of human skin lipids on the cercarial penetration responses of Schistosoma haematobium and Schistosoma mansoni.</a> J Parasitol. 58, 476-480 (1972).</li><li>Saladin, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schistosoma+mansoni:+cercarial+responses+to+irradiance+changes.">Schistosoma mansoni: cercarial responses to irradiance changes.</a> J Parasitol. 68, 120-124 (1982).</li><li>Chai, M., McManus, D. P., McInnes, R., Moertel, L., Tran, M., Loukas, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptome+profiling+of+lung+schistosomula,+in+vitro+cultured+schistosomula+and+adult+Schistosoma+japonicum.">Transcriptome profiling of lung schistosomula, in vitro cultured schistosomula and adult Schistosoma japonicum.</a> Cell Mol Life Sci. 63, 919-929 (2006).</li><li>Gobert, G. N., Tran, M. H., Moertel, L., Mulvenna, J., Jones, M. K., McManus, D. 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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+Schistosoma+mansoni+daughter+sporocysts+from+mother+sporocysts+maintained+in+synxenic+culture+with+Biomphalaria+glabrata+embryonic+(Bge)+cells.">Production of Schistosoma mansoni daughter sporocysts from mother sporocysts maintained in synxenic culture with Biomphalaria glabrata embryonic (Bge) cells.</a> J Parasitol. 81, 714-722 (1995).</li><li>Colley, D. G., Wikel, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schistosoma+mansoni:+simplified+method+for+the+production+of+schistosomules.">Schistosoma mansoni: simplified method for the production of schistosomules.</a> Exp Parasitol. 35, 44-51 (1974).</li><li>Lazdins, J. K., Stein, M. J., David, J. 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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schistosoma+mansoni:+ultrastructure+of+early+transformation+of+skin-+and+shear-pressure-derived+schistosomules.">Schistosoma mansoni: ultrastructure of early transformation of skin- and shear-pressure-derived schistosomules.</a> Exp Parasitol. 51, 341-365 (1981).</li><li>Lewis, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schistosomiasis.">Schistosomiasis.</a> Curr Protoc Immunol. Chapter 19, 1-1 (2001).</li></ol>

No conflicts of interest declared.

Several potential problems could arise during the transformation procedure; however, this protocol is designed to avoid most of these problems. One potential hazard is the clogging of the emulsifying needle, which usually arises due to debris left over from the harvesting in step 1.3. Be sure to allow all particulate matter to settle in step 1.5 and to transfer the cercariae carefully in step 1.6 to avoid this problem. Also, as described before, working inside a biological safety cabinet, use of personal protective equipment (even face shields) and avoidance of excessive pressure on the syringes is advisable. 
Detached cercarial tails can be visualized in the media, which is indicative of poor separation during step 2.9. The tails exhibit a spasm-like motion and have a distinct shape (see Figure 2), and thusly are easily distinguishable from the schistosomules. The tails can be removed by washing the schistosomules in excess of RPMI complete allowing the schistosomules to settle. The tails will remain floating and can be vacuumed off.
If intact cercariae are present in the media, the transformation in step 2.5 was not executed properly. An image of an intact cercaria is depicted in Figure 3b for reference. If this problem occurs, insure that the emulsifying needle being used is of the proper size. Also, the number of times the cercarial mixture is passed through the needle can be increased, although 40 times is typically much more than enough to approach 100% shearing of the cercarial tails. 
Transformation of cercaria into schistosomules was first described in 1974 by Colley and Wikel (13). Since then, preparation of schistosomules has been done using either the shearing strategy with a needle and syringe as described in this protocol, or using a vortexing approach and separated with gradients of percoll (14, 15) or swirling as demonstrated in this paper. These two techniques for preparing schistosomules are beautifully described by Fred Lewis (16) and more information for further culturing of schistosomules for long-term growth can be found at the NIAID Schistosome Resource Center (<a href="http://www.schisto-resource.org/">www.schisto-resource.org</a>).

<table><tbody><tr><td>22g x 2-7/8&quot; Emulsifying needle</td><td>Fisher Scientific</td><td>14-825-17G</td><td></td></tr><tr><td>RPMI 1640 Medium 1X (500ml)</td><td>Invitrogen</td><td>11835030</td><td></td></tr><tr><td>Fetal Bovine Serum (FBS) heat inactivated</td><td>Invitrogen</td><td>10082139</td><td></td></tr><tr><td>Penicillin/Streptomycin (100X)</td><td>Invitrogen</td><td>15070063</td><td></td></tr><tr><td>Crystallizing Dish (100mm)</td><td>Fisher Scientific</td><td>08-741D</td><td></td></tr><tr><td>General Purpose Tweezers</td><td>Fisher Scientific</td><td>10-316C</td><td></td></tr><tr><td>Petco Aquarium net for brine shrimp</td><td>Petco</td><td>SKU:1190954</td><td></td></tr></tbody></table>

cercarial transformation and in vitro cultivation of schistosoma mansoni schistosomules

Schistosome parasites are the causative agents of schistosomiasis, a chronically debilitating disease that affects over 200 million people globally and ranks second to malaria among parasitic diseases in terms of public health and socio-economic impact (1-4). Schistosome parasites are trematode worms with a complex life cycle interchanging between a parasitic life in molluscan and mammalian hosts with intervening free-swimming stages. Briefly, free-swimming cercariae infect a mammalian host by penetrating the skin with the aid of secreted proteases, during which time the cercariae lose their tails, transforming into schistosomules. The schistosomules must now evade the host immune system, develop a gut for digestion of red blood cells, and migrate though the lungs and portal circulation en route to their final destination in the hepatic portal system and eventually the mesenteric veins (for S. mansoni) where male and female worms pair and mate, producing hundreds of eggs daily. Some of the eggs are excreted from the body into fresh water, where the eggs hatch into free-swimming miracidia (5-10). The miracidia infect specific snail species and transform into mother and daughter sporocysts, which in turn, produce infective cercariae, completing the life cycle. Unfortunately, the entire schistosome life cycle cannot be cultured in vitro, but infective cercariae can be transformed into schistosomules, and the schistosomules can be cultured for weeks for the analysis of schistosome development in vitro or microarray analysis. In this protocol, we provide a visual description of cercarial transformation and in vitro culturing of schistosomules. We shed infectious cercariae from the snail host Biomphalaria glabrata and manually transform them into schistosomules by detaching their tails using an emulsifying double-ended needle. The in vitro cercarial transformation and schistosomules culture techniques described avoid the use of a mammalian host, which simplifies visualization of schistosomes and facilitates the collection of the parasite for experimental analysis. in vitro transformation and culturing techniques of schistosomes have been done for years (11, 12), but no visual protocols have been developed that are available to the entire community.

Watch this Scientific Journal Video about Cercarial Transformation and in vitro Cultivation of Schistosoma mansoni Schistosomules at JoVE.com

Cercarial Transformation and in vitro Cultivation of Schistosoma mansoni Schistosomules

We describe an in vitro method for culturing schistosomula of the flatworm parasite Schistosoma mansoni, via the harvesting and transformation of infective cercariae from the fresh water snail intermediate host Biomphalaria glabrata.

Cercarial Transformation and in vitro Cultivation of Schistosoma mansoni Schistosomules

Schistosome parasites are the causative agents of schistosomiasis, a chronically debilitating disease that affects over 200 million people globally and ...

cercarial-transformation-vitro-cultivation-schistosoma-mansoni

Research

JoVE Journal

Immunology and Infection

18.1K Views.  Case Western Reserve University. Beschrijven we een In vitro Methode voor het kweken van schistosomula van de platworm parasiet Schistosoma mansoni, Via het oogsten en de transformatie van infectieuze cercariae van het zoete water slak tussengastheer Biomphalaria glabrata.

Video: Cercarial Transformation and in vitro Cultivation of Schistosoma mansoni Schistosomules

Using Eggs from Schistosoma mansoni as an In vivo Model of Helminth-induced Lung Inflammation

Schistosoma parasites are blood flukes that infect an estimated 200 million people worldwide 1. In chronic infection with Schistosoma, the severe pathology, including liver fibrosis and splenomegaly, is caused by the immune response to the parasite eggs rather than the parasite itself 2. Parasite eggs induce a Th2 response characterized by the production of IL-4, IL-5 and IL-13, the alternative activation of macrophages and the recruitment of eosinophils. Here, we describe injection of Schistosoma mansoni eggs as a model to examine parasite-specific Th2 cytokine responses in the lung and draining lymph nodes, the formation of pulmonary granulomas surrounding the egg, and airway inflammation. 
Following intraperitoneal sensitization and intravenous challenge, S. mansoni eggs are transported to the lung via the pulmonary arteries where they are trapped within the lung parenchyma by granulomas composed of lymphocytes, eosinophils and alternatively activated macrophages 3-6. Associated with granuloma formation, inflammation in the broncho-alveolar spaces, expansion of the draining lymph nodes and CD4 T cell activation can be observed. Here we detail the protocol for isolating Schistosoma mansoni eggs from infected livers (modified from 7), sensitizing and challenging mice, and recovering the organs (broncho-alveolar lavage (BAL), lung and draining lymph nodes) for analysis. We also include representative histologic and immunologic data and suggestions for additional immunologic analysis. 
Overall, this method provides an in vivo model to investigate helminth-induced immunologic responses in the lung, which is broadly applicable to the study of Th2 inflammatory diseases including helminth infection, fibrotic diseases, allergic inflammation and asthma. Advantages of this model for the study of type 2 inflammation in the lung include the reproducibility of a potent Th2 inflammatory response in the lung and draining lymph nodes, the ease of assessment of inflammation by histologic examination of the granulomas surrounding the egg, and the potential for long-term storage of the parasite eggs.

Using Eggs from Schistosoma mansoni as an In vivo Model of Helminth-induced Lung Inflammation

Schistosoma mansoni eggs are potent stimulators of the T helper type 2 (Th2) immune response, characteristic of parasite infection, asthma and allergic inflammation. This protocol utilizes S. mansoni egg injection to generate a CD4 Th2 cytokine-induced inflammatory response in the lung, characterized by lung granuloma formation around the egg, eosinophilia and macrophage alternative activation.

Schistosoma parasites are blood flukes that infect an estimated 200 million people worldwide 1. In chronic infection with Schistosoma, the severe ...

Mass Isolation and In Vitro Cultivation of Intramolluscan Stages of the Human Blood Fluke Schistosoma Mansoni

Human blood flukes, Schistosoma spp., have a complex life cycle that involves asexual and sexual developmental phases within a snail intermediate and mammalian final host, respectively. The ability to isolate and sustain the different life cycle stages under in vitro culture conditions has greatly facilitated investigations of the cellular, biochemical and molecular mechanisms regulating parasite growth, development and host interactions. Transmission of schistosomiasis requires asexual reproduction and development of multiple larval stages within the snail host; from the infective miracidium, through primary and secondary sporocysts, to the final cercarial stage that is infective to humans. In this paper we present a step-by-step protocol for mass hatching and isolation of Schistosoma mansoni miracidia from eggs obtained from livers of infected mice, and their subsequent introduction into in vitro culture. It is anticipated that the detailed protocol will encourage new researchers to engage in and broaden this important field of schistosome research.

Mass Isolation and In Vitro Cultivation of Intramolluscan Stages of the Human Blood Fluke Schistosoma Mansoni

This article describes a protocol for the large-scale axenic isolation and collection of free-swimming miracidia of the human blood fluke Schistosoma mansoni and their subsequent processing for introduction into in vitro culture.

Human blood flukes, Schistosoma spp., have a complex life cycle that involves asexual and sexual developmental phases within a snail intermediate and ...

Developmental Biology

Transient Transduction of the Strobilated Forms of Echinococcus granulosus

Cystic echinococcosis or hydatid disease is one of the most important zoonotic parasitic diseases caused by Echinococcus granulosus, a small tapeworm harbored in the intestine of canines. There is an urgent need for applied genetic research to understand the mechanisms of pathogenesis and disease control and prevention. However, the lack of an effective gene evaluation system impedes direct interpretation of the functional genetics of cestode parasites, including the Echinococcus species. The present study demonstrates the potential of lentiviral gene transient transduction in the metacestode and strobilated forms of E. granulosus. Protoscoleces (PSCs) were isolated from hydatid cysts and transferred to specific biphasic culture media to develop into strobilated worms. The worms were transfected with harvested third-generation lentivirus, along with HEK293T cells as a transduction process control. A pronounced fluorescence was detected in the strobilated worms over 24 h and 48 h, indicating transient lentiviral transduction in E. granulosus. This work presents the first attempt at lentivirus-based transient transduction in tapeworms and demonstrates the promising outcomes with potential implications in experimental studies on flatworm biology.

Transient Transduction of the Strobilated Forms of Echinococcus granulosus

We describe a rapid transient transduction technique in different developmental stages of Echinococcus granulosus using third-generation lentiviral vectors.

Cystic echinococcosis or hydatid disease is one of the most important zoonotic parasitic diseases caused by Echinococcus granulosus, a small tapeworm ...

Genetics

Use of Shigella flexneri to Study Autophagy-Cytoskeleton Interactions

Shigella flexneri is an intracellular pathogen that can escape from phagosomes to reach the cytosol, and polymerize the host actin cytoskeleton to promote its motility and dissemination. New work has shown that proteins involved in actin-based motility are also linked to autophagy, an intracellular degradation process crucial for cell autonomous immunity. Strikingly, host cells may prevent actin-based motility of S. flexneri by compartmentalizing bacteria inside &#8216;septin cages&#8217; and targeting them to autophagy. These observations indicate that a more complete understanding of septins, a family of filamentous GTP-binding proteins, will provide new insights into the process of autophagy. This report describes protocols to monitor autophagy-cytoskeleton interactions caused by S. flexneri in vitro using tissue culture cells and in vivo using zebrafish larvae. These protocols enable investigation of intracellular mechanisms that control bacterial dissemination at the molecular, cellular, and whole organism level.

Use of Shigella flexneri to Study Autophagy-Cytoskeleton Interactions

To counteract pathogen dissemination, host cells reorganize their cytoskeleton to compartmentalize bacteria and induce autophagy. Using Shigella infection of tissue culture cells, host and pathogen determinants underlying this process are identified and characterized. Using zebrafish models of Shigella infection, the role of discovered molecules and mechanisms are investigated in vivo.

Shigella flexneri is an intracellular pathogen that can escape from phagosomes to reach the cytosol, and polymerize the host actin cytoskeleton to promote ...

Isolation and Characterization of Extracellular Vesicles from Adult Schistosoma japonicum

Extracellular vesicles (EVs) are membranous vesicles released by a variety of cells into the extracellular microenvironment. EVs represent a population of heterogeneous vesicles, whose size range between 40 and 1,000 nm. Accumulated evidence indicated that EVs play important regulatory roles in pathogen-host interactions. A deep understanding of schistosome EVs should provide insights into the mechanisms underlying schistosome-host interactions, enabling development of novel strategies against schistosomiasis. Here, we aim to further study EVs functions in schistosomes by presenting a protocol for the isolation and characterization of EVs from adult Schistosoma japonicum (S. japonicum). EVs were isolated from in vitro culture medium using centrifugation combined with a commercial exosome isolation kit. The isolated S. japonicum EVs (SjEVs) typically possess a diameter of 100 - 400 nm, and are characterized by transmission electronic microscopy and western blotting. The usage of PKH67 dye-labeled SjEVs has demonstrated that SjEVs are internalized by the recipient cells. Overall, our protocol provides an alternative method for isolating EVs from adult schistosomes; the isolated SjEVs may be suitable for functional analysis.

Isolation and Characterization of Extracellular Vesicles from Adult Schistosoma japonicum

Here, we present a protocol to describe extracellular vesicles (EVs) isolation in in vitro cultured medium from adult Schistosoma japonicum.

Extracellular vesicles (EVs) are membranous vesicles released by a variety of cells into the extracellular microenvironment. EVs represent a population of ...

Generating Transgenics and Knockouts in Strongyloides Species by Microinjection

The genus Strongyloides consists of multiple species of skin-penetrating nematodes with different host ranges, including Strongyloides stercoralis and Strongyloides ratti. S.&#160;stercoralis is a human-parasitic, skin-penetrating nematode that infects approximately 610 million people, while the rat parasite S.&#160;ratti is closely related to S.&#160;stercoralis and is often used as a laboratory model for S.&#160;stercoralis. Both S.&#160;stercoralis and S.&#160;ratti are easily amenable to the generation of transgenics and knockouts through the exogenous nucleic acid delivery technique of intragonadal microinjection, and as such, have emerged as model systems for other parasitic helminths that are not yet amenable to this technique.
Parasitic Strongyloides adults inhabit the small intestine of their host and release progeny into the environment via the feces. Once in the environment, the larvae develop into free-living adults, which live in feces and produce progeny that must find and invade a new host. This environmental generation is unique to the Strongyloides species and similar enough in morphology to the model free-living nematode Caenorhabditis elegans that techniques developed for C. elegans can be adapted for use with these parasitic nematodes, including intragonadal microinjection. Using intragonadal microinjection, a wide variety of transgenes can be introduced into Strongyloides. CRISPR/Cas9 components can also be microinjected to create mutant Strongyloides larvae. Here, the technique of intragonadal microinjection into Strongyloides, including the preparation of free-living adults, the injection procedure, and the selection of transgenic progeny, is described. Images of transgenic Strongyloides larvae created using CRISPR/Cas9 mutagenesis are included. The aim of this paper is to enable other researchers to use microinjection to create transgenic and mutant Strongyloides.

Generating Transgenics and Knockouts in Strongyloides Species by Microinjection

The functional genomic toolkit for the parasitic nematodes Strongyloides stercoralis and Strongyloides ratti includes transgenesis, CRISPR/Cas9-mediated mutagenesis, and RNAi. This protocol will demonstrate how to use intragonadal microinjection to introduce transgenes and CRISPR components into S.&#160;stercoralis and S.&#160;ratti.

The genus Strongyloides consists of multiple species of skin-penetrating nematodes with different host ranges, including Strongyloides stercoralis and ...

Generating Genetically Modified Plasmodium berghei Sporozoites

Malaria is a deadly disease caused by the parasite Plasmodium and is transmitted through the bite of female Anopheles mosquitoes. The sporozoite stage of Plasmodium deposited by mosquitoes in the skin of vertebrate hosts undergoes a phase of mandatory development in the liver before initiating clinical malaria. We know little about the biology of Plasmodium development in the liver; access to the sporozoite stage and the ability to genetically modify such sporozoites are critical tools for studying the nature of Plasmodium infection and the resulting immune response in the liver. Here, we present a comprehensive protocol for the generation of transgenic Plasmodium berghei sporozoites. We genetically modify blood-stage P. berghei and use this form to infect Anopheles mosquitoes when they take a blood meal. After the transgenic parasites undergo development in the mosquitoes, we isolate the sporozoite stage of the parasite from the mosquito salivary glands for in vivo and in vitro experimentation. We demonstrate the validity of the protocol by generating sporozoites of a novel strain of P. berghei expressing the green fluorescent protein (GFP) subunit 11 (GFP11), and show how it could be used to investigate the biology of liver-stage malaria.

Generating Genetically Modified Plasmodium berghei Sporozoites

Malaria is transmitted through inoculation of the sporozoite stage of Plasmodium by infected mosquitoes. Transgenic Plasmodium has allowed us to understand the biology of malaria better and has contributed directly to malaria vaccine development efforts. Here, we describe a streamlined methodology to generate transgenic Plasmodium berghei sporozoites.

Malaria is a deadly disease caused by the parasite Plasmodium and is transmitted through the bite of female Anopheles mosquitoes. The sporozoite stage of ...

Nucleofection and In Vivo Propagation of Chicken Eimeria Parasites

Transfection is a technical process through which genetic material, such as DNA and double-stranded RNA, are delivered into cells to modify the gene of interest. Currently, transgenic technology is becoming an indispensable tool for the study of Eimeria, the causative agents of coccidiosis in poultry and livestock. This protocol provides a detailed description of stable transfection in eimerian parasites: purification and nucleofection of sporozoites or second-generation merozoites, and in vivo propagation of transfected parasites. Using this protocol, we achieved transfection in several species of Eimeria. Taken together, nucleofection is a useful tool to facilitate genetic manipulation in eimerian parasites.

Nucleofection and In Vivo Propagation of Chicken Eimeria Parasites

Here, we provided a method to achieve stable transfection of chicken Eimeria parasites by nucleofecting sporozoites or second-generation merozoites. Genetically modified eimerian parasites expressing heterologous antigenic genes could be used as vaccine delivery vehicles.

Transfection is a technical process through which genetic material, such as DNA and double-stranded RNA, are delivered into cells to modify the gene of ...

Biology

Plasmodium falciparum Gametocyte Culture and Mosquito Infection Through Artificial Membrane Feeding

Malaria remains one of the most important public health problems, causing significant morbidity and mortality. Malaria is a mosquito borne disease transmitted through an infectious bite from the female Anopheles mosquito. Malaria control will eventually rely on a multitude of approaches, which includes ways to block transmission to, through and from mosquitoes. To study mosquito stages of malaria parasites in the laboratory, we have optimized a protocol to culture highly infectious Plasmodium falciparum gametocytes, a parasite stage required for transmission from the human host to the mosquito vector. P. falciparum gametocytes mature through five morphologically distinct steps, which takes approximately 1-2 weeks. Gametocyte culture described in this protocol is completed in 15 days and are infectious to mosquitoes from days 15-18. These protocols were developed to maintain a continuous cycle of infection competent gametocytes and to maintain uninterrupted supply of mosquito stages of the parasite. Here, we describe the methodology of gametocyte culture and how to infect mosquitoes with these parasites using glass membrane feeders.

Plasmodium falciparum Gametocyte Culture and Mosquito Infection Through Artificial Membrane Feeding

Detailed investigations on mosquito stages of malaria parasites are critical to design effective transmission blocking strategies. This protocol demonstrates how to effectively culture infectious gametocytes and then feed these gametocytes to mosquitoes to generate mosquito stages of P. falciparum.

Malaria remains one of the most important public health problems, causing significant morbidity and mortality. Malaria is a mosquito borne disease ...

Identifying Kinases Rewiring in Malaria Parasite: A Chemical Genetics Approach

Understanding the Development of Compensatory Pathways in a Mutant Malaria Parasite Harbouring Hypomorphic Allele of Plant-Like Kinases

One of the mechanisms for subverting the effect of drugs by&#160;the malaria parasite is through rewiring of its transcriptome. The effect is more pronounced for target genes belonging to the multigene family. Plasmodium falciparum protein kinases belonging to the CDPK family are essential for blood stage development. As such, CDPKs are considered good targets for the development of anti-malarial compounds. The chemical genetics approach has been historically used to elucidate the function of protein kinases in higher eukaryotes. It requires the substitution of gatekeeper residue for another amino acid with a different side chain through genetic manipulation. Amino acid substitution at the gatekeeper position modulates the activity of a protein kinase and changes its susceptibility to a specific class of compounds known as bumped kinase inhibitors (BKIs) that help in the functional identification of the target gene. Here, we have exploited the chemical genetics approach to understand compensatory mechanisms evolved by a mutant parasite harboring a hypomorphic allele of cdpk1. Overall, our approach helps in identifying compensatory pathways that may be simultaneously targeted to prevent the development of drug resistance against individual kinases.

Author Spotlight: Identifying Compensatory Pathways in Malaria Parasites Containing Hypomorphic Allele of Essential Protein Kinases

Chemical genetics involves the substitution of a gatekeeper residue with an amino acid containing a different side chain at the target locus. Here, we have generated a mutant parasite containing a hypomorphic allele of cdpk1 and identified compensatory pathways adopted by the parasite in the mutant background.

Cercarial Transformation and in vitro Cultivation of Schistosoma mansoni Schistosomules

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