Name: disclosing hemolymph collection and inoculation of metarhizium blastospores into rhipicephalus microplus ticks towards invertebrate pathology studies
Uploaded: 2019-06-01T15:00:00
Description: Watch this Scientific Journal Video about Disclosing Hemolymph Collection and Inoculation of Metarhizium Blastospores into Rhipicephalus Microplus Ticks Towards Invertebrate Pathology Studies at JoVE.

This study was financed in part by the Coordenac&#227;o de Aperfei&#231;oamento de Pessoal de N&#237;vel Superior (CAPES) from Brazil, finance code 001. CAPES provided Ph.D. scholarship for A.F. Marciano. We thank National Council for Scientific and Technological Development (CNPq) of Brazil for providing Ph.D. scholarship for J. Fiorotti. This research was also supported by grants of Carlos Chagas Filho Foundation for Research of the State of Rio de Janeiro (FAPERJ) and CNPq. V.R.E.P. Bittencourt is a CNPq researcher.

Ticks used in the present study were obtained from an artificial colony, mantained at Federal Rural University of Rio de Janeiro, which methods have been approved by the Committee on Ethics for the Use of Vertebrate Animals (CEUA-IV/UFRRJ #037/2014).
1. Tick engorged females
<ol>
	<li>After tick gathering, wash engorged females using tap water and immerse them in 0.5% (v/v) sodium hypochlorite solution for 3 min in a 500 mL glass beaker recipient, for cuticle hygiene (Fi...

<ol>
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C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+serpins+involved+in+cellular+immune+response+of+Rhipicephalus+microplus+challenged+with+fungi.">Detection of serpins involved in cellular immune response of Rhipicephalus microplus challenged with fungi.</a> Biocontrol Science and Technology. 24 (3), 351-360 (2014).</li><li>De Paulo, J. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rhipicephalus+microplus+infected+by+Metarhizium:+unveiling+hemocyte+quantification,+GFP-fungi+virulence,+and+ovary+infection.">Rhipicephalus microplus infected by Metarhizium: unveiling hemocyte quantification, GFP-fungi virulence, and ovary infection.</a> Parasitology Research. 117, 1847-1856 (2018).</li><li>Marmaras, V. J., Lampropoulou, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulators+and+signalling+in+insect+haemocyte+immunity.">Regulators and signalling in insect haemocyte immunity.</a> Cell Signal. 21, 186-195 (2009).</li><li>Hinzmann, M. F., Lopes-Lima, M., Gon&#231;alves, J., Machado, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antiaggregant+and+toxic+properties+of+different+solutions+on+hemocytes+of+three+freshwater+bivalves.">Antiaggregant and toxic properties of different solutions on hemocytes of three freshwater bivalves.</a> Toxicological &amp; Environmental Chemistry. 95, 790-805 (2013).</li><li>Nation, J. 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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=.">.</a> Biology of ticks. , (2014).</li><li>Tan, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+hemocytes+proliferation+in+larval+silkworm+Bombyx+mori.">Characterization of hemocytes proliferation in larval silkworm Bombyx mori.</a> Journal of Insect Physiology. 59 (6), 595-603 (2013).</li><li>Bowden, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+humoral+immune+systems+of+the+American+lobster+(Homarus+americanus)+and+the+European+lobster+(Homarus+gammarus).">The humoral immune systems of the American lobster (Homarus americanus) and the European lobster (Homarus gammarus).</a> Fish Research. 186, 367-371 (2017).</li><li>Sonenshine, D. E., Hynes, W. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+characterization+and+related+aspects+of+the+innate+immune+response+in+ticks.">Molecular characterization and related aspects of the innate immune response in ticks.</a> Frontiers in Bioscience. 13, 7046-7063 (2008).</li><li>Tsakas, S., Marmaras, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insect+immunity+and+its+signaling:+an+overview.">Insect immunity and its signaling: an overview.</a> Invertebrate Survival Journal. 7, 228-238 (2010).</li><li>Burgdorfer, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemolymph+Test.+A+technique+for+detection+of+Rickettsiae+in+ticks.">Hemolymph Test. A technique for detection of Rickettsiae in ticks.</a> American Journal of Tropical Medicine and Hygiene. 19, 1010-1014 (1970).</li><li>Dunham-Ems, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Live+imaging+reveals+a+biphasic+mode+of+dissemination+of+Borrelia+burgdorferi+within+ticks.">Live imaging reveals a biphasic mode of dissemination of Borrelia burgdorferi within ticks.</a> Journal of Clinical Investigation. 119, 3652-3665 (2009).</li><li>Patton, T. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Saliva,+salivary+gland,+and+hemolymph+collection+from+Ixodes+scapularis+ticks.">Saliva, salivary gland, and hemolymph collection from Ixodes scapularis ticks.</a> Journal of Visualized Experiments. 60, e3894 (2012).</li></ol>

Inoculation of pathogens is useful when the study aims to investigate the in vivo action of microorganisms in experimental arthropod models because it assures that the pathogen is inside the host. The technique can also be applied to inoculate molecules such as RNA interference (RNAi). Inoculation between the scutum and capitulum is considered easier to perform but frequently damages Gen&#233;&#39;s organ, impairing the eggs viability12,13. Gen&#233;&#39;s organ ...

The cattle tick, Rhipicephalus microplus, is an hematophagus ectoparasite with an enormous negative impact on livestock in tropical areas. This tick is the vector of pathogenic agents such as Babesia bovis, Babesia bigemina, and Anaplasma marginale that, combined with the direct hemofeeding damage, can reduce milk and meat production, cause anemia and ultimately death. Losses caused by this ectoparasite were estimated in 3.24 billion dollars annually in Brazil1. Sustainable methods are demanded and the use of entomopathogenic agents is considered a promising alternative to reduce the use of chemical&#160;acaricides2,3,4.
Entomopathogenic fungi, such as Metarhizium spp., are natural enemies of arthropods including ticks, and some isolates can be used as biocontrollers. These pathogens actively infect the host through the cuticle and colonize their body2,5,6. As the infection develops, cellular and humoral responses are mediated by the tick immune system. Analysis of the tick hemolymph is reported as a useful tool to evaluate the immune responses after the challenging with pathogens7,8.
Arthropods&#39; immune response is divided into humoral and cellular responses. The humoral response involves hemagglutination processes and production of antimicrobial proteins/peptides, whereas the cellular immune response is performed through the hemocytes. These cells are present in the hemolymph from all arthropods and are reported to develop an expressive role in studies involving innate immune response9, as it is directly related to the phagocytosis and encapsulation processes. Accordingly, studies about hemocytes can help to investigate death pathway and understand processes such as autophagy, apoptosis, and necrosis. In some invertebrates as bivalves, the hemocytes&#39; collection faces limitations like cell disruption, low hemolymph volume obtained, and low concentration of recovered cells10. Very frequently, depending on the methodology applied, reduced concentration of cells is obtained, impacting directly on cells quantification and analysis.
The number of hemocytes circulating in the hemolymph is variable among different arthropods and it can change in the same species due to different physiological stages such as sex, age, and the arthropod&#39;s developmental stage11. Hemocytes can also be found adhered to some organs and be released into circulation just after the infection process11. Nevertheless, most studies reported use insects, while ticks remain less explored regarding their physiology and pathology. Despite pathogen inoculation and hemolymph collection in ticks are less used techniques, establishing standard methods helps the development of more accurate studies.
The aim of the present study was to compare the most used methods for hemolymph collection and inoculation of pathogens into R. microplus ticks, evaluating the efficacy in the hemolymph acquisition and hemocytes concentration.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Alkaline Hypochlorite solution</td>
			<td style="width:116px;">Sigma-Aldrich</td>
			<td style="width:158px;">A1727</td>
			<td style="width:172px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">D-(+)-Glucose</td>
			<td style="width:116px;">Sigma-Aldrich</td>
			<td style="width:158px;">G8270-1KG</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">EDTA</td>
			<td style="width:116px;">Synth</td>
			<td style="width:158px;">2706</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Fetal Bovine Serum</td>
			<td style="width:116px;">Gibco</td>
			<td style="width:158px;">16000036</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Flexible rubber</td>
			<td style="width:116px;">BD</td>
			<td style="width:158px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Giemsa stain</td>
			<td style="width:116px;">Sigma-Aldrich</td>
			<td style="width:158px;">48900-500ML-F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Glass capillary</td>
			<td style="width:116px;">CTechGlass</td>
			<td style="width:158px;">CT95-02</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Insulin syringe (needle)</td>
			<td style="width:116px;">BD</td>
			<td style="width:158px;">SKU:&#160;324910</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">KH2PO4</td>
			<td style="width:116px;">Vetec</td>
			<td style="width:158px;">60REAVET014512</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Leibovitz&#39;s L-15 culture medium&#160;</td>
			<td style="width:116px;">Gibco</td>
			<td style="width:158px;">11415-064</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Methanol</td>
			<td style="width:116px;">Sigma-Aldrich</td>
			<td style="width:158px;">34860-1L-R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Microscope slides</td>
			<td style="width:116px;">Kasvi</td>
			<td style="width:158px;">K5-7105</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Microtubes</td>
			<td style="width:116px;">BRAND</td>
			<td style="width:158px;">Z336769-1PAK</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Na2HPO4</td>
			<td style="width:116px;">Vetec</td>
			<td style="width:158px;">60REAVET014593</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">NaCl</td>
			<td style="width:116px;">Sigma-Aldrich</td>
			<td style="width:158px;">S7653-1KG</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Neubauer chamber&#160;</td>
			<td style="width:116px;">Kasvi</td>
			<td style="width:158px;">K5-0111</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Penicillin</td>
			<td style="width:116px;">Gibco</td>
			<td style="width:158px;">15140163</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Protease inhibitor cocktail</td>
			<td style="width:116px;">Sigma-Aldrich</td>
			<td style="width:158px;">P2714</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Tween 80</td>
			<td style="width:116px;">Vetec</td>
			<td style="width:158px;">60REAVET003662</td>
			<td></td>
		</tr>
	</tbody>
</table>

disclosing hemolymph collection and inoculation of metarhizium blastospores into rhipicephalus microplus ticks towards invertebrate pathology studies

Ticks are obligate hematophagous ectoparasites and Rhipicephalus microplus has great importance in veterinary medicine because it causes anemia, weight loss, depreciation of the animals&#39; leather and also can act as a vector of several pathogens. Due to the exorbitant costs to control these parasites, damage to the environment caused by the inappropriate use of chemical acaricides, and the increased resistance against traditional parasiticides, alternative control of ticks, by the use of entomopathogenic fungi, for example, has been considered an interesting approach. Nevertheless, few studies have demonstrated how the tick&#39;s immune system acts to fight these entomopathogens. Therefore, this protocol demonstrates two methods used for entomopathogen inoculation into engorged females and two techniques used for hemolymph collection and hemocytes harvesting. Inoculation of pathogens at the leg insertion in the tick female&#39;s body allows evaluation of females biologic parameters unlike the inoculation between the scutum and capitulum, which frequently damages Gen&#233;&#39;s organ. Dorsal hemolymph collection yielded a higher volume recovery than collection through the legs. Some limitations of tick hemolymph collection and processing include i) high rates of hemocytes&#39; disruption, ii) hemolymph contamination with disrupted midgut, and iii) low hemolymph volume recovery. When hemolymph is collected through the leg cutting, the hemolymph takes time to accumulate at the leg opening, favoring the clotting process. In addition, fewer hemocytes are obtained in the collection through the leg compared to the dorsal collection, even though the first method is considered easier to be performed. Understanding the immune response in ticks mediated by entomopathogenic agents helps to unveil their pathogenesis and develop new targets for tick control. The inoculation processes described here require very low technological resources and can be used not only to expose ticks to pathogenic microorganisms. Similarly, the collection of tick hemolymph may represent the first step for many physiological studies.

This article approaches inoculation and hemolymph collection methods applied to ticks. After the inoculation between the leg thigh and the tick female&#39;s body, some fluid (hemolymph) can be secreted during the process; however, it is important to note that when the inoculation is finished, no liquid or tissues were present in the needle tip or at the inoculation site, ensuring that the fungal suspension was completely inoculated. When the inoculation process was correctly performed, th...

Watch this Scientific Journal Video about Disclosing Hemolymph Collection and Inoculation of Metarhizium Blastospores into Rhipicephalus Microplus Ticks Towards Invertebrate Pathology Studies at JoVE.

Disclosing Hemolymph Collection and Inoculation of Metarhizium Blastospores into Rhipicephalus Microplus Ticks Towards Invertebrate Pathology Studies

Analysis of tick hemolymph represents an important source of information on how some pathogens cause disease and how ticks immunologically respond to this infection. The present study demonstrates how to inoculate fungal propagules and collect hemolymph from Rhipicephalus microplus engorged females.

Disclosing Hemolymph Collection and Inoculation of Metarhizium Blastospores into Rhipicephalus Microplus Ticks Towards Invertebrate Pathology Studies

Ticks are obligate hematophagous ectoparasites and Rhipicephalus microplus has great importance in veterinary medicine because it causes anemia, weight ...

Ticks are hematophagous ectoparasites, Rhipicephalus microplus, popularly known as the cattle tick has enormous negative economical impact on livestock in tropical areas. In addition, increasing concerns about degradated environmental conditions and public health worries caused by inappropriate use of chemical acaricides and increasing resistance of tick populations to traditional parasites, are stimulating research on alternative control methods, such as the use of entomopathogenic fungi. These entomopathogens actively infect arthropod hosts, through their cuticle and colonize their body.The arthropod may have different responses to the fungal infection. Arthropod immune system is divided into humoral and cellular responses. The humoral response involves hemagglutination process and production of antimicrobial molecules, whereas hemocytes mediate the cellular immune response.Most studies on arthropod immune response are reported using insects while tick responses remain less explored. Also, pathogen inoculation and tick hemolymph collection are poorly widespread techniques necessary to the better understand of the arthropod's immune response. Accordingly, this video address techniques\used to film the inoculation, hemolymph collection and processing.Since tick hemocytes harvesting face some limitations, such as cells disruption, low hemolymph value obtaining, and low concentration of recovered cells. Directly infecting on cells configuration and analysis. After tick gathering, wash engorged females.Use tap water and immerse them in 0.5%sodium hypochlorite solution for three minutes in a 500 milliliters glass beaker recipient. For cuticle hygiene, divide females in homogeneous groups with 20 females each. Three replicates of each group were performed.Metarhizium robertsii blastospores were used in the inoculation process. Add on a liquid of five microliters metarhizium blastospores suspension to the surface of a plastic paraffin film. To speed the inoculation process, multiple bubbles can be added to the plastic paraffin film surface, each bubble corresponding to five microliters.Use an one-millimeter ultra-fine insulin syringe and a 0.3 millimeters needle to put a suspension and inoculate it into the tick. Remember to take all the air out of the syringe before using it. Inoculate 5 microliters of fungus suspension into the tick female between the scutum and capitulum.A small volume of hemolymph may be present on the framing after the needle incision. Be careful to do not inoculate air. Inoculate females with fungus suspension between the leg thigh and the female's body using a one-milliliter ultra-fine insulin syringe coupled to a 0.3 millimeter needle.When the metarhizium blastospores inoculation is performed between the leg thigh and the tick female's body, a small volume of hemolymph can be present on the thigh after the needle insertion. Be careful to do not inoculate air. Use the rubber part of a winged infusion set a 0.3 miliimeters capillary tube and a filter tip to perform the hemolymph collection.Disrupt the female dorsal cuticle using a 0.3 millimeters needle. After disruption apply gentle pressure on the anterial part of the tick body. Observe an almost transparent liquid pooling out of the disruption site.Collect the hemolymph by sucking the liquid through the filter tip coupled to a rubber part of a winged infusion set and a 0.3 millimeters capillary tube. Do not press the tick's body hardly during it's immobilization because this may disrupt the midgut and contaminate the hemolymph. Wait until gentle pressure can expel the fluid without contamination.Immobilize the tick. Cut a piece of a front leg. One or more legs can be cut as well as the same leg can be cut more than one time.Apply gentle pressure on the tick's posterior body part. Observe a transparent liquid bubble show up on the cut side and collect it with the capillary tube. Do not press the tick's body hardly, during it's mobilization because this may disrupt the midgut and contaminate the hemolymph.Wait until gentle pressure can expel the fluid without contamination. After hemolymph collection, deposit it in 1.5 mililiters microtube previously filled with 30 microlitres protease cocktail and 82 microlitres saline buffer. Keep the microtubes on ice throughout the hemolymph collection.Centrifuge samples and the soft pellet of hemocytes will be formed after hemolymph centrifugation. For hemolymph quantification, quantify the hemolymph volume obtained by counting the total volume inside the microtube and discounting the volume of protease cocktail and saline buffer. Carefully remove the supernatant cell-free hemolymph, and gently re-suspend the cells.Quantify the hemocytes by placing 10 microlitres of re-suspended hemocytes in the Neubauer chamber. For cells re-suspension a culture media was used. Cut the tick's front leg, apply gentle pressure on the tick's posterior body part, observe a transparent liquid bubble show up on the cut site.Apply the hemolymph drops directly on clean microscope slides. After that use appropriate methods to stain the cells. Inoculation between the leg thigh and tick female body can also damage tick internal organs such as midgut and the malpighian tubules.When the tick midgut is disrupted by the needle at the dorsal hemolymph collection the fluid obtained is red, not transparent. This indicates an incorrect hemolymph collection. In this case, hemolymph shall be discarded as it is contaminated.Hemolymph contamination can also be observed when the tick is naturally infected with high loads of pathogens, or in the final steps after death process caused by inoculated pathogens. The hemolymph volume obtained after the dorsal collection is higher than the volume obtained at the collection through the leg. Despite easiness of contamination is higher in the first collection method.The hemocytes concentration was also significantly higher at the dorsal collection. When correct hemocytes collection is performed a good smear can be obtained and it's possible to distinguish different hemocytes after staining. This video provided information on methods to perform inoculation of pathogen, specifically entomopathogenic fungi, into ticks and collect their hemolymph.The techniques here presented require very low technological resources in our classical steps for studies about tick physiology, tick pathology, and tick's immune response. The correct harvesting of the arthropod cells, and cell-free hemolymph is crucial to afford reliable information for subsequent studies. For that reason, it is also important to be aware of the most common mistakes observed in the execution of these techniques.Additionally, the proposals of this study shall determine the more appropriate site for hemolymph collection through deforming or cutting the legs, considering the difference in the volume obtained and the probability of contamination.

disclosing-hemolymph-collection-inoculation-metarhizium-blastospores

Research

JoVE Journal

Immunology and Infection

RNA Interference in Ticks

Ticks are obligate hematophagous ectoparasites of wild and domestic animals and humans, and are considered to be second worldwide to mosquitoes as vectors of human diseases1 and the most important vectors affecting cattle industry worldwide2. Ticks are classified in the subclass Acari, order Parasitiformes, suborder Ixodida and are distributed worldwide from Arctic to tropical regions3. Despite efforts to control tick infestations, these ectoparasites remain a serious problem for human and animal health4,5.
RNA interference (RNAi)6 is a nucleic acid-based reverse genetic approach that involves disruption of gene expression in order to determine gene function or its effect on a metabolic pathway. Small interfering RNAs (siRNAs) are the effector molecules of the RNAi pathway that is initiated by double-stranded RNA (dsRNA) and results in a potent sequence-specific degradation of cytoplasmic mRNAs containing the same sequence as the dsRNA trigger7-9. Post-transcriptional gene silencing mechanisms initiated by dsRNA have been discovered in all eukaryotes studied thus far, and RNAi has been rapidly developed in a variety of organisms as a tool for functional genomics studies and other applications10.
RNAi has become the most widely used gene-silencing technique in ticks and other organisms where alternative approaches for genetic manipulation are not available or are unreliable5,11. The genetic characterization of ticks has been limited until the recent application of RNAi12,13. In the short time that RNAi has been available, it has proved to be a valuable tool for studying tick gene function, the characterization of the tick-pathogen interface and the screening and characterization of tick protective antigens14. Herein, a method for RNAi through injection of dsRNA into unfed ticks is described. It is likely that the knowledge gained from this experimental approach will contribute markedly to the understanding of basic biological systems and the development of vaccines to control tick infestations and prevent transmission of tick-borne pathogens15-19.

A method for RNA interference (RNAi) by injection of dsRNA into unfed ticks is described. RNAi is the most widely used gene-silencing technique in ticks where the use of other methods of genetic manipulation has been limited.

Ticks are obligate hematophagous ectoparasites of wild and domestic animals and humans, and are considered to be second worldwide to mosquitoes as vectors ...

A Calcium Bioluminescence Assay for Functional Analysis of Mosquito (Aedes aegypti) and Tick (Rhipicephalus microplus) G Protein-coupled Receptors

Arthropod hormone receptors are potential targets for novel pesticides as they regulate many essential physiological and behavioral processes. The majority of them belong to the superfamily of G protein-coupled receptors (GPCRs). We have focused on characterizing arthropod kinin receptors from the tick and mosquito. Arthropod kinins are multifunctional neuropeptides with myotropic, diuretic, and neurotransmitter function. Here, a method for systematic analyses of structure-activity relationships of insect kinins on two heterologous kinin receptor-expressing systems is described. We provide important information relevant to the development of biostable kinin analogs with the potential to disrupt the diuretic, myotropic, and/or digestive processes in ticks and mosquitoes.
The kinin receptors from the southern cattle tick, Boophilus microplus (Canestrini), and the mosquito Aedes aegypti (Linnaeus), were stably expressed in the mammalian cell line CHO-K1. Functional analyses of these receptors were completed using a calcium bioluminescence plate assay that measures intracellular bioluminescence to determine cytoplasmic calcium levels upon peptide application to these recombinant cells. This method takes advantage of the aequorin protein, a photoprotein isolated from luminescent jellyfish. We transiently transfected the aequorin plasmid (mtAEQ/pcDNA1) in cell lines that stably expressed the kinin receptors. These cells were then treated with the cofactor coelenterazine, which complexes with intracellular aequorin. This bond breaks in the presence of calcium, emitting luminescence levels indicative of the calcium concentration. As the kinin receptor signals through the release of intracellular calcium, the intensity of the signal is related to the potency of the peptide.
This protocol is a synthesis of several previously described protocols with modifications; it presents step-by-step instructions for the stable expression of GPCRs in a mammalian cell line through functional plate assays (Staubly et al., 2002 and Stables et al., 1997). Using this methodology, we were able to establish stable cell lines expressing the mosquito and the tick kinin receptors, compare the potency of three mosquito kinins, identify critical amino acid positions for the ligand-receptor interaction, and perform semi-throughput screening of a peptide library. Because insect kinins are susceptible to fast enzymatic degradation by endogenous peptidases, they are severely limited in use as tools for pest control or endocrinological studies. Therefore, we also tested kinin analogs containing amino isobutyric acid (Aib) to enhance their potency and biostability. This peptidase-resistant analog represents an important lead in the development of biostable insect kinin analogs and may aid in the development of neuropeptide-based arthropod control strategies.

A Calcium Bioluminescence Assay for Functional Analysis of Mosquito Aedes aegypti and Tick Rhipicephalus microplus G Protein-coupled Receptors

This protocol provides instructions for clonal-cell line selection and a calcium bioluminescence assay to analyze the structure-activity relationships of synthesized arthropod neuropeptides on their cognate GPCRs. This assay can be used for receptor deorphanization and structure-activity relationship studies for synthetic analog design and peptide/drug-lead discovery.

Arthropod hormone receptors are potential targets for novel pesticides as they regulate many essential physiological and behavioral processes.  The ...

Protocols for Vaginal Inoculation and Sample Collection in the Experimental Mouse Model of Candida vaginitis

Vulvovaginal candidiasis (VVC), caused by Candida species, is a fungal infection of the lower female genital tract that affects approximately 75% of otherwise healthy women during their reproductive years18,32-34. Predisposing factors include antibiotic usage, uncontrolled diabetes and disturbance in reproductive hormone levels due to pregnancy, oral contraceptives or hormone replacement therapies33,34. Recurrent VVC (RVVC), defined as three or more episodes per year, affects a separate 5 to 8% of women with no predisposing factors33.
An experimental mouse model of VVC has been established and used to study the pathogenesis and mucosal host response to Candida3,4,11,16,17,19,21,25,37. This model has also been employed to test potential antifungal therapies in vivo13,24. The model requires that the animals be maintained in a state of pseudoestrus for optimal Candida colonization/infection6,14,23. Under such conditions, inoculated animals will have detectable vaginal fungal burden for weeks to months. Past studies show an extremely high parallel between the animal model and human infection relative to immunological and physiological properties3,16,21. Differences, however, include a lack of Candida as normal vaginal flora and a neutral vaginal pH in the mice.
Here, we demonstrate a series of key methods in the mouse vaginitis model that include vaginal inoculation, rapid collection of vaginal specimens, assessment of vaginal fungal burden, and tissue preparations for cellular extraction/isolation. This is followed by representative results for constituents of vaginal lavage fluid, fungal burden, and draining lymph node leukocyte yields. With the use of anesthetics, lavage samples can be collected at multiple time points on the same mice for longitudinal evaluation of infection/colonization. Furthermore, this model requires no immunosuppressive agents to initiate infection, allowing immunological studies under defined host conditions. Finally, the model and each technique introduced here could potentially give rise to use of the methodologies to examine other infectious diseases of the lower female genital tract (bacterial, parasitic, viral) and respective local or systemic host defenses.

Protocols for Vaginal Inoculation and Sample Collection in the Experimental Mouse Model of Candida vaginitis

Key techniques to be used in the evaluation of Candida vaginitis in an experimental animal model are described. The methods will allow rapid collection of vaginal specimens and lymphocytes from draining lumbar lymph nodes. These techniques could give rise to mouse models of other diseases in the female lower genital tract.

Vulvovaginal candidiasis (VVC), caused by Candida species, is a fungal infection of the lower female genital tract that affects approximately 75% of ...

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne relapsing fever (Borrelia spp.), Rocky Mountain Spotted fever (Rickettsia rickettsii), ehrlichiosis (Ehrlichia chaffeensis and E. equi), anaplasmosis (Anaplasma phagocytophilum), encephalitis (tick-borne encephalitis virus), babesiosis (Babesia spp.), Colorado tick fever (Coltivirus), and tularemia (Francisella tularensis) 1-8. To be properly transmitted into the host these infectious agents differentially regulate gene expression, interact with tick proteins, and migrate through the tick 3,9-13. For example, the Lyme disease agent, Borrelia burgdorferi, adapts through differential gene expression to the feast and famine stages of the tick's enzootic cycle 14,15. Furthermore, as an Ixodes tick consumes a bloodmeal Borrelia replicate and migrate from the midgut into the hemocoel, where they travel to the salivary glands and are transmitted into the host with the expelled saliva 9,16-19.
As a tick feeds the host typically responds with a strong hemostatic and innate immune response 11,13,20-22. Despite these host responses, I. scapularis can feed for several days because tick saliva contains proteins that are immunomodulatory, lytic agents, anticoagulants, and fibrinolysins to aid the tick feeding 3,11,20,21,23. The immunomodulatory activities possessed by tick saliva or salivary gland extract (SGE) facilitate transmission, proliferation, and dissemination of numerous tick-borne pathogens 3,20,24-27. To further understand how tick-borne infectious agents cause disease it is essential to dissect actively feeding ticks and collect tick saliva. This video protocol demonstrates dissection techniques for the collection of hemolymph and the removal of salivary glands from actively feeding I. scapularis nymphs after 48 and 72 hours post mouse placement. We also demonstrate saliva collection from an adult female I. scapularis tick.

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

The collection of infected tick hemolymph, salivary glands, and saliva is important to study how tick-borne pathogens cause disease. In this protocol we demonstrate how to collect hemolymph and salivary glands from feeding Ixodes scapularis nymphs. We also demonstrate saliva collection from female I. scapularis adults.

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne ...

Directed Differentiation of Induced Pluripotent Stem Cells towards T Lymphocytes

Adoptive cell transfer (ACT) of antigen-specific CD8+ cytotoxic T lymphocytes (CTLs) is a promising treatment for a variety of malignancies 1. CTLs can recognize malignant cells by interacting tumor antigens with the T cell receptors (TCR), and release cytotoxins as well as cytokines to kill malignant cells. It is known that less-differentiated and central-memory-like (termed highly reactive) CTLs are the optimal population for ACT-based immunotherapy, because these CTLs have a high proliferative potential, are less prone to apoptosis than more differentiated cells and have a higher ability to respond to homeostatic cytokines 2-7. However, due to difficulties in obtaining a high number of such CTLs from patients, there is an urgent need to find a new approach to generate highly reactive Ag-specific CTLs for successful ACT-based therapies.
TCR transduction of the self-renewable stem cells for immune reconstitution has a therapeutic potential for the treatment of diseases 8-10. However, the approach to obtain embryonic stem cells (ESCs) from patients is not feasible. Although the use of hematopoietic stem cells (HSCs) for therapeutic purposes has been widely applied in clinic 11-13, HSCs have reduced differentiation and proliferative capacities, and HSCs are difficult to expand in in vitro cell culture 14-16. Recent iPS cell technology and the development of an in vitro system for gene delivery are capable of generating iPS cells from patients without any surgical approach. In addition, like ESCs, iPS cells possess indefinite proliferative capacity in vitro, and have been shown to differentiate into hematopoietic cells. Thus, iPS cells have greater potential to be used in ACT-based immunotherapy compared to ESCs or HSCs.
Here, we present methods for the generation of T lymphocytes from iPS cells in vitro, and in vivo programming of antigen-specific CTLs from iPS cells for promoting cancer immune surveillance. Stimulation in vitro with a Notch ligand drives T cell differentiation from iPS cells, and TCR gene transduction results in iPS cells differentiating into antigen-specific T cells in vivo, which prevents tumor growth. Thus, we demonstrate antigen-specific T cell differentiation from iPS cells. Our studies provide a potentially more efficient approach for generating antigen-specific CTLs for ACT-based therapies and facilitate the development of therapeutic strategies for diseases.

Generation of T lymphocytes from induced pluripotent stem (iPS) cells gives an alternative approach of using embryonic stem cells for T cell-based immunotherapy. The method shows that by utilizing either in vitro or in vivo induction system, iPS cells are able to differentiate into both conventional and antigen-specific T lymphocytes.

Adoptive cell transfer (ACT) of antigen-specific CD8+  cytotoxic T lymphocytes (CTLs) is a promising treatment for a variety of  malignancies 1. CTLs can  ...

Feeding of Ticks on Animals for Transmission and Xenodiagnosis in Lyme Disease Research

Transmission of the etiologic agent of Lyme disease, Borrelia burgdorferi, occurs by the attachment and blood feeding of Ixodes species ticks on mammalian hosts. In nature, this zoonotic bacterial pathogen may use a variety of reservoir hosts, but the white-footed mouse (Peromyscus leucopus) is the primary reservoir for larval and nymphal ticks in North America. Humans are incidental hosts most frequently infected with B. burgdorferi by the bite of ticks in the nymphal stage. B. burgdorferi adapts to its hosts throughout the enzootic cycle, so the ability to explore the functions of these spirochetes and their effects on mammalian hosts requires the use of tick feeding. In addition, the technique of xenodiagnosis (using the natural vector for detection and recovery of an infectious agent) has been useful in studies of cryptic infection. In order to obtain nymphal ticks that harbor B. burgdorferi, ticks are fed live spirochetes in culture through capillary tubes. Two animal models, mice and nonhuman primates, are most commonly used for Lyme disease studies involving tick feeding. We demonstrate the methods by which these ticks can be fed upon, and recovered from animals for either infection or xenodiagnosis.

Lyme disease is the most commonly-reported vector-borne disease in North America. The causative agent, Borrelia burgdorferi is a spirochete bacterium transmitted by Ixodid ticks. Transmission and detection of infection in animal models is optimized by the use of tick feeding, which we describe here.

Transmission of the etiologic agent of Lyme disease, Borrelia burgdorferi, occurs by the  attachment and blood feeding of Ixodes species ticks on ...

The Ex Vivo Colon Organ Culture and Its Use in Antimicrobial Host Defense Studies

The intestine displays an architecture of repetitive crypt structures consisting of different types of epithelial cells, lamina propia containing immune cells, and stroma. All of these heterogeneous cells contribute to intestinal homeostasis and participate in antimicrobial host defense. Therefore, identifying a surrogate model for studying immune response and antimicrobial activity of the intestine in an in vitro setting is extremely challenging. In vitro studies using immortalized intestinal epithelial cell lines or even primary crypt organoid culture do not represent the exact physiology of normal intestine and its microenvironment. Here, we discuss a method of culturing mouse colon tissue in a culture dish and how this ex vivo organ culture system can be implemented in studies related to antimicrobial host defense responses. In representative experiments, we showed that colons in organ culture express antimicrobial peptides in response to exogenous IL-1&#946; and IL-18. Further, the antimicrobial effector molecules produced by the colon tissues in the organ culture efficiently kill Escherichia coli in vitro. This approach, therefore, can be utilized to dissect the role of pathogen- and danger-associated molecular patterns and their cellular receptors in regulating intestinal innate immune responses and antimicrobial host defense responses.

The Ex Vivo Colon Organ Culture and Its Use in Antimicrobial Host Defense Studies

The ex vivo organ culture allows investigation of biological processes in the context of the intact tissue architecture. Here, we introduce a method of ex vivo culture of the mouse colon, which can be used to study innate immunity and antimicrobial host defense in the intestine.

The intestine displays an architecture of repetitive crypt structures consisting of different types of epithelial cells, lamina propia containing immune ...

Isolation and Characterization of Neutrophil-derived Microparticles for Functional Studies

Polymorphonuclear neutrophil-derived microparticles (PMN)-MPs) are lipid bilayer, spherical microvesicles with sizes ranging from 50&#8211;1,000 nm in diameter. MPs are a newly evolving, important part of cell-to-cell communication and signaling machinery. Because of their size and the nature of their release, until recently MP existence was overlooked. However, with improved technology and analytical methods their function in health and disease is now emerging. The protocols presented here are aimed at isolating and characterizing PMN-MPs by flow cytometry and immunoblotting. Moreover, several implementation examples are given. These protocols for MP isolation are fast, low-cost, and do not require the use of expensive kits. Furthermore, they allow for the labeling of MPs following isolation, as well as pre-labeling of source cells prior to MP release, using a membrane-specific fluorescent dye for visualization and analysis by flow cytometry. These methods, however, have several limitations including purity of PMNs and MPs and the need for sophisticated analytical instrumentation. A high-end flow cytometer is needed to reliably analyze MPs and minimize false positive reads due to noise or auto-fluorescence. The described protocols can be used to isolate and define MP biogenesis, and characterize their markers and variation in composition under different stimulating conditions. Size heterogeneity can be exploited to investigate whether the content of membrane particles versus exosomes is different, and whether they fulfill different roles in tissue homeostasis. Finally, following isolation and characterization of MPs, their function in cellular responses and various disease models (including, PMN-associated inflammatory disorders, such as Inflammatory Bowel Diseases or Acute Lung Injury) can be explored.

New protocols are described here to isolate and characterize microparticles derived from human and mouse neutrophils. These protocols utilize ultracentrifugation, flow cytometry, and immunoblotting techniques to analyze microparticle content, and they can be used to study the role of microparticles derived from various cell types in cellular function.

Polymorphonuclear neutrophil-derived microparticles (PMN)-MPs) are lipid bilayer, spherical microvesicles with sizes ranging from 50&#8211;1,000 nm in ...

Collection and Processing of Lymph Nodes from Large Animals for RNA Analysis: Preparing for Lymph Node Transcriptomic Studies of Large Animal Species

Large animals (both livestock and wildlife) serve as important reservoirs of zoonotic pathogens, including Brucella, Mycobacterium bovis, Salmonella, and E. coli, and are useful for the study of pathogenesis and/or spread of the bacteria in natural hosts. With the key function of lymph nodes in the host immune response, lymph node tissues serve as a potential source of RNA for downstream transcriptomic analyses, in order to assess the temporal changes in gene expression in cells over the course of an infection. This article presents an overview of the process of lymph node collection, tissue sampling, and downstream RNA processing in livestock, using cattle (Bos taurus) as a model, with additional examples provided from the American bison (Bison bison). The protocol includes information about the location, identification, and removal of lymph nodes from multiple key sites in the body. Additionally, a biopsy sampling methodology is presented that allows for a consistency of sampling across multiple animals. Several considerations for sample preservation are discussed, including the generation of RNA suitable for downstream methodologies like RNA-sequencing and RT-PCR. Due to the long delays inherent in large animal vs. mouse time course studies, representative results from bison and bovine lymph node tissues are presented to describe the time course of the degradation in this tissue type, in the context of a review of previous methodological work on RNA degradation in other tissues. Overall, this protocol will be useful to both veterinary researchers beginning transcriptome projects on large animal samples and to molecular biologists interested in learning techniques for in vivo tissue sampling and in vitro processing.

This protocol provides an overview of procedures for the isolation of RNA for the transcriptomic profiling of lymph node tissues from large animals, including steps in the identification and excision of lymph nodes from livestock and wildlife, sampling approaches to provide consistency across multiple animals, and considerations plus representative results for the post-collection preservation and processing for RNA analysis.

Large animals (both livestock and wildlife) serve as important reservoirs of zoonotic pathogens, including Brucella, Mycobacterium bovis, Salmonella, and ...

Use of the Invertebrate Galleria mellonella as an Infection Model to Study the Mycobacterium tuberculosis Complex

Tuberculosis is the leading global cause of infectious disease mortality and roughly a quarter of the world&#8217;s population is believed to be infected with Mycobacterium tuberculosis. Despite decades of research, many of the mechanisms behind the success of M. tuberculosis as a pathogenic organism remain to be investigated, and the development of safer, more effective antimycobacterial drugs are urgently needed to tackle the rise and spread of drug resistant tuberculosis. However, the progression of tuberculosis research is bottlenecked by traditional mammalian infection models that are expensive, time consuming, and ethically challenging. Previously we established the larvae of the insect Galleria mellonella (greater wax moth) as a novel, reproducible, low cost, high-throughput and ethically acceptable infection model for members of the M. tuberculosis complex. Here we describe the maintenance, preparation, and infection of G. mellonella with bioluminescent Mycobacterium bovis BCG lux. Using this infection model, mycobacterial dose dependent virulence can be observed, and a rapid readout of in vivo mycobacterial burden using bioluminescence measurements is easily achievable and reproducible. Although limitations exist, such as the lack of a fully annotated genome for transcriptomic analysis, ontological analysis against genetically similar insects can be carried out. As a low cost, rapid, and ethically acceptable model for tuberculosis, G. mellonella can be used as a pre-screen to determine drug efficacy and toxicity, and to determine comparative mycobacterial virulence prior to the use of conventional mammalian models. The use of the G. mellonella-mycobacteria model will lead to a reduction in the substantial number of animals currently used in tuberculosis research.

Use of the Invertebrate Galleria mellonella as an Infection Model to Study the Mycobacterium tuberculosis Complex

Galleria mellonella was recently established as a reproducible, cheap, and ethically acceptable infection model for the Mycobacterium tuberculosis complex. Here we describe and demonstrate the steps taken to establish successful infection of G. mellonella with bioluminescent Mycobacterium bovis BCG lux.

Tuberculosis is the leading global cause of infectious disease mortality and roughly a quarter of the world&#8217;s population is believed to be infected ...