Name: an introduction to parasitic wasps of drosophila and the antiparasite immune response
Uploaded: 2012-05-07T12:00:00
Description: Watch this Scientific Journal Video about An Introduction to Parasitic Wasps of Drosophila and the Antiparasite Immune Response at JoVE.com

We are grateful to Prof. Todd Schlenke for Trichopria drosophilae, Prof. Tony Ip for transgenic fly strains, and Prof. Carl Hashimoto for anti-Sp&auml;tzle antibodies. We thank present and past members of the lab for their contributions to this presentation. This work was supported by the following grants: from NIH (S06 GM08168, RISE 41399-009, and G12-RR03060), USDA (NRI/USDA CSREES 2006-03817 and 2009-35302-05277) and PSC-CUNY.

The entire protocol for the experiment is divided into four steps (Fig. 9). (1) Culturing wasps on fly larvae; (2) Setting up infections and preparing animals for dissection; (3) Isolating and fixing host/parasite structures; (4) Analyzing immune tissues.
1. Culturing Wasps on Drosophila Larvae
Maintenance of wasp cultures requires careful planning. Relative to growing flies, it is fairly labor intensive. We maintain our wasp colonies in the ...

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A. <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+a+lamellocyte+transcriptional+enhancer+located+within+the+misshapen+gene+of+Drosophila+melanogaster.">Characterization of a lamellocyte transcriptional enhancer located within the misshapen gene of Drosophila melanogaster.</a> PLoS One. 4, e6429 (2009).</li><li>Morales, J., Chiu, H., Oo, T., Plaza, R., Hoskins, S., Govind, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biogenesis,+structure,+and+immune-suppressive+effects+of+virus-like+particles+of+a+Drosophila+parasitoid,+Leptopilina+victoriae.">Biogenesis, structure, and immune-suppressive effects of virus-like particles of a Drosophila parasitoid, Leptopilina victoriae.</a> J. Insect Physiol. 51, 181-195 (2005).</li><li>Bettencourt, R., Asha, H., Dearolf, C., Ip, Y. 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Interest in parasitic wasps of Drosophila is surging as molecular techniques to decode whole genomes become efficient and cost-effective. However, relative to their exceptionally well-studied hosts, many fascinating aspects of wasp biology remain obscure. These include issues related to host range, immune suppression, superparasitism, and behavior. The focus of this presentation was to demonstrate the effects of infection on the fly's immune tissues. The dissection techniques demonstrated here can be used for th...

<table border="1">
	<tbody>
		<tr>
			<td>Materials </td>
			<td>Type</td>
			<td>Company</td>
			<td>Catalog number</td>
		</tr>
		<tr>
			<td>Materials for insect culture maintenance</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Yeast</td>
			<td>Active dry</td>
			<td>Fisher Scientific</td>
			<td>S802453</td>
		</tr>
		<tr>
			<td>Fly food</td>
			<td>Corn meal, sugar</td>
			<td>&nbsp;</td>
			<td>Standard recipe</td>
		</tr>
		<tr>
			<td>Honey</td>
			<td>Clover</td>
			<td>Dutch Gold</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Vials</td>
			<td>Polypropylene shell vials (narrow)</td>
			<td>Fisher Scientific</td>
			<td>AS514</td>
		</tr>
		<tr>
			<td>Vial closures</td>
			<td>Cotton plug</td>
			<td>Fisher Scientific</td>
			<td>AS212</td>
		</tr>
		<tr>
			<td>Vial closures</td>
			<td>Buzz plug</td>
			<td>Genesee Scientific</td>
			<td>AS273</td>
		</tr>
		<tr>
			<td>Refrigerated incubator</td>
			<td>Precision 815</td>
			<td>Thermo Scientific</td>
			<td>3721</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Materials for sample preparation</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>CO2 tank</td>
			<td>Bone dry grade</td>
			<td>TW Smith</td>
			<td>UN1013</td>
		</tr>
		<tr>
			<td>Spatula</td>
			<td>Micro spatula (14 cm)</td>
			<td>Fisher Scientific</td>
			<td>21-401-15</td>
		</tr>
		<tr>
			<td>Pyrex spot test plates</td>
			<td>9-well dissecting plate 85 mm X 100 mm</td>
			<td>Thomas Scientific</td>
			<td>7812G17</td>
		</tr>
		<tr>
			<td>Pasteur Pipettes</td>
			<td>Soda lime</td>
			<td>J &amp; H Berge</td>
			<td>71-5200-05</td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Style # 5</td>
			<td>Sigma</td>
			<td>T-4662</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>190 proof USP</td>
			<td>Fisher Scientific</td>
			<td>04-355-221</td>
		</tr>
		<tr>
			<td>Formaldehyde</td>
			<td>37% w/w</td>
			<td>Fisher Scientific</td>
			<td>F79-1</td>
		</tr>
		<tr>
			<td>Secondary antibody Cy3 AffiniPure donkey anti-rabbit IgG (H + L)</td>
			<td>1:50 Excitation 546 nm; Emission 565 nm</td>
			<td>Jackson Immuno Research Laboratories, Inc.</td>
			<td>711-165-152</td>
		</tr>
		<tr>
			<td>Antifade (N-propyl gallate)</td>
			<td>4 &mu;g/ml in 50% glycerol in 1X PBS</td>
			<td>MP Biomedicals</td>
			<td>10274790</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>&nbsp;</td>
			<td>Fisher Scientific</td>
			<td>G33-1</td>
		</tr>
		<tr>
			<td>Hoechst 33258</td>
			<td>0.2 &mu;g/ml Excitation 352 nm; Emission 461 nm</td>
			<td>Molecular Probes</td>
			<td>H-1398</td>
		</tr>
		<tr>
			<td>Rhodamine phalloidin</td>
			<td>200 units/ml (6.6 &mu;M) Excitation 540 nm; Emission 565 nm</td>
			<td>Molecular Probes</td>
			<td>R415</td>
		</tr>
		<tr>
			<td>Alexa Fluor 488 phalloidin</td>
			<td>300 units/ml Excitation 495 nm; Emission 518 nm</td>
			<td>Molecular Probes</td>
			<td>A12379</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Disposables </td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Wash bottle</td>
			<td>Fisherbrand</td>
			<td>Fisher Scientific</td>
			<td>03-409-22A</td>
		</tr>
		<tr>
			<td>Kimwipes</td>
			<td>Kimberly Clark</td>
			<td>Fisher Scientific</td>
			<td>06-666A</td>
		</tr>
		<tr>
			<td>Paper Towel</td>
			<td>1 ply C-Fold</td>
			<td>Quill</td>
			<td>901-7CFTB2400</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Microscopy </td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Leica stereomicroscope</td>
			<td>MZFLIII</td>
			<td>Empire Imaging Systems, Inc.</td>
			<td>10446208</td>
		</tr>
		<tr>
			<td>Zeiss Stereomicroscope</td>
			<td>Stemi 1000 or 2000-C</td>
			<td>Carl Zeiss</td>
			<td>000000-1006-126</td>
		</tr>
		<tr>
			<td>Light Source - LED</td>
			<td>Gooseneck illuminator</td>
			<td>Fisher Scientific</td>
			<td>12563501</td>
		</tr>
		<tr>
			<td>Stage</td>
			<td>Transmitted light box with plate</td>
			<td>Carl Zeiss</td>
			<td>455137000</td>
		</tr>
		<tr>
			<td>Zeiss laser scanning confocal microscope</td>
			<td>LSM 510</td>
			<td>Carl Zeiss</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Zeiss compound microscope</td>
			<td>Axioplan 2 upright</td>
			<td>Carl Zeiss</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>
<table border="1">
	<tbody>
		<tr>
			<td>Wasp Strains</td>
			<td>Fly Strains</td>
		</tr>
		<tr>
			<td>Leptopilina victoriae16</td>
			<td>y w</td>
		</tr>
		<tr>
			<td>Leptopilina boulardi 171</td>
			<td>UAS-GFP-Dorsal17</td>
		</tr>
		<tr>
			<td>Leptopilina heterotoma2</td>
			<td>SerpentHemoGal413</td>
		</tr>
		<tr>
			<td>Leptopilina heterotoma 141</td>
			<td>MSNF9-moCherry14</td>
		</tr>
		<tr>
			<td>Trichopria drosophilae </td>
			<td>MSNF-GFP15</td>
		</tr>
		<tr>
			<td>Ganaspis xanthopoda18</td>
			<td>y w Serpent-Gal4 UAS GFP-Dorsal/Basc4</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>y w ; Drosomycin-GFP/CyO y+12</td>
		</tr>
	</tbody>
</table>

an introduction to parasitic wasps of drosophila and the antiparasite immune response

Most known parasitoid wasp species attack the larval or pupal stages of Drosophila. While Trichopria drosophilae infect the pupal stages of the host (Fig. 1A-C), females of the genus Leptopilina (Fig. 1D, 1F, 1G) and Ganaspis (Fig. 1E) attack the larval stages. We use these parasites to study the molecular basis of a biological arms race. Parasitic wasps have tremendous value as biocontrol agents. Most of them carry virulence and other factors that modify host physiology and immunity. Analysis of Drosophila wasps is providing insights into how species-specific interactions shape the genetic structures of natural communities. These studies also serve as a model for understanding the hosts' immune physiology and how coordinated immune reactions are thwarted by this class of parasites.
The larval/pupal cuticle serves as the first line of defense. The wasp ovipositor is a sharp needle-like structure that efficiently delivers eggs into the host hemocoel. Oviposition is followed by a wound healing reaction at the cuticle (Fig. 1C, arrowheads). Some wasps can insert two or more eggs into the same host, although the development of only one egg succeeds. Supernumerary eggs or developing larvae are eliminated by a process that is not yet understood. These wasps are therefore referred to as solitary parasitoids.
Depending on the fly strain and the wasp species, the wasp egg has one of two fates. It is either encapsulated, so that its development is blocked (host emerges; Fig. 2 left); or the wasp egg hatches, develops, molts, and grows into an adult (wasp emerges; Fig. 2 right). L. heterotoma is one of the best-studied species of Drosophila parasitic wasps. It is a "generalist," which means that it can utilize most Drosophila species as hosts1. L. heterotoma and L. victoriae are sister species and they produce virus-like particles that actively interfere with the encapsulation response2. Unlike L. heterotoma, L. boulardi is a specialist parasite and the range of Drosophila species it utilizes is relatively limited1. Strains of L. boulardi also produce virus-like particles3 although they differ significantly in their ability to succeed on D. melanogaster1. Some of these L. boulardi strains are difficult to grow on D. melanogaster1 as the fly host frequently succeeds in encapsulating their eggs. Thus, it is important to have the knowledge of both partners in specific experimental protocols.
In addition to barrier tissues (cuticle, gut and trachea), Drosophila larvae have systemic cellular and humoral immune responses that arise from functions of blood cells and the fat body, respectively. Oviposition by L. boulardi activates both immune arms1,4. Blood cells are found in circulation, in sessile populations under the segmented cuticle, and in the lymph gland. The lymph gland is a small hematopoietic organ on the dorsal side of the larva. Clusters of hematopoietic cells, called lobes, are arranged segmentally in pairs along the dorsal vessel that runs along the anterior-posterior axis of the animal (Fig. 3A). The fat body is a large multifunctional organ (Fig. 3B). It secretes antimicrobial peptides in response to microbial and metazoan infections.
Wasp infection activates immune signaling (Fig. 4)4. At the cellular level, it triggers division and differentiation of blood cells. In self defense, aggregates and capsules develop in the hemocoel of infected animals (Fig. 5)5,6. Activated blood cells migrate toward the wasp egg (or wasp larva) and begin to form a capsule around it (Fig. 5A-F). Some blood cells aggregate to form nodules (Fig. 5G-H). Careful analysis reveals that wasp infection induces the anterior-most lymph gland lobes to disperse at their peripheries (Fig. 6C, D).
We present representative data with Toll signal transduction pathway components Dorsal and Sp&auml;tzle (Figs. 4,5,7), and its target Drosomycin (Fig. 6), to illustrate how specific changes in the lymph gland and hemocoel can be studied after wasp infection. The dissection protocols described here also yield the wasp eggs (or developing stages of wasps) from the host hemolymph (Fig. 8).

Watch this Scientific Journal Video about An Introduction to Parasitic Wasps of Drosophila and the Antiparasite Immune Response at JoVE.com

An Introduction to Parasitic Wasps of Drosophila and the Antiparasite Immune Response

Parasitoid (parasitic) wasps constitute a major class of natural enemies of many insects including Drosophila melanogaster. We will introduce the techniques to propagate these parasites in Drosophila spp. and demonstrate how to analyze their effects on immune tissues of Drosophila larvae.

An Introduction to Parasitic Wasps of Drosophila and the Antiparasite Immune Response

Most known parasitoid wasp species attack the larval or pupal stages of Drosophila. While Trichopria drosophilae infect the pupal stages of the host (Fig. ...

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The rhesus macaque model is currently the best available model for HIV-AIDS with respect to understanding the pathogenesis as well as for the development ...

Quantitative Measurement of the Immune Response and Sleep in Drosophila

A complex interaction between the immune response and host behavior has been described in a wide range of species. Excess sleep, in particular, is known to occur as a response to infection in mammals 1 and has also recently been described in Drosophila melanogaster2. It is generally accepted that sleep is beneficial to the host during an infection and that it is important for the maintenance of a robust immune system3,4. However, experimental evidence that supports this hypothesis is limited4, and the function of excess sleep during an immune response remains unclear. We have used a multidisciplinary approach to address this complex problem, and have conducted studies in the simple genetic model system, the fruitfly Drosophila melanogaster. We use a standard assay for measuring locomotor behavior and sleep in flies, and demonstrate how this assay is used to measure behavior in flies infected with a pathogenic strain of bacteria. This assay is also useful for monitoring the duration of survival in individual flies during an infection. Additional measures of immune function include the ability of flies to clear an infection and the activation of NF&kappa;B, a key transcription factor that is central to the innate immune response in Drosophila. Both survival outcome and bacterial clearance during infection together are indicators of resistance and tolerance to infection. Resistance refers to the ability of flies to clear an infection, while tolerance is defined as the ability of the host to limit damage from an infection and thereby survive despite high levels of pathogen within the system5. Real-time monitoring of NF&kappa;B activity during infection provides insight into a molecular mechanism of survival during infection. The use of Drosophila in these straightforward assays facilitates the genetic and molecular analyses of sleep and the immune response and how these two complex systems are reciprocally influenced.

Quantitative Measurement of the Immune Response and Sleep in Drosophila

To understand a link between the immune response and behavior, we describe a method to measure locomotor behavior in Drosophila during bacterial infection as well as the ability of flies to mount an immune response by monitoring survival, bacterial load, and real-time activity of a key regulator of innate immunity, NF&kappa;B.

A complex interaction between the immune response and  host behavior has been described in a wide range of species. Excess sleep, in  particular, is known ...

Quantification of the Respiratory Burst Response as an Indicator of Innate Immune Health in Zebrafish

The phagocyte respiratory burst is part of the innate immune response to pathogen infection and involves the production of reactive oxygen species (ROS). ROS are toxic and function to kill phagocytized microorganisms. In vivo quantification of phagocyte-derived ROS provides information regarding an organism's ability to mount a robust innate immune response. Here we describe a protocol to quantify and compare ROS in whole zebrafish embryos upon chemical induction of the phagocyte respiratory burst. This method makes use of a non-fluorescent compound that becomes fluorescent upon oxidation by ROS. Individual zebrafish embryos are pipetted into the wells of a microplate and incubated in this fluorogenic substrate with or without a chemical inducer of the respiratory burst. Fluorescence in each well is quantified at desired time points using a microplate reader. Fluorescence readings are adjusted to eliminate background fluorescence and then compared using an unpaired t-test. This method allows for comparison of the respiratory burst potential of zebrafish embryos at different developmental stages and in response to experimental manipulations such as protein knockdown, overexpression, or treatment with pharmacological agents. This method can also be used to monitor the respiratory burst response in whole dissected kidneys or cell preparations from kidneys of adult zebrafish and some other fish species. We believe that the relative simplicity and adaptability of this protocol will complement existing protocols and will be of interest to researchers who seek to better understand the innate immune response.

The innate immune response protects organisms against pathogen infection. A critical component of the innate immune response, the phagocyte respiratory burst, generates reactive oxygen species that kill invading microorganisms. We describe a respiratory burst assay that quantifies reactive oxygen species produced when the innate immune response is chemically induced.

The phagocyte respiratory burst is part of the innate immune response to  pathogen infection and involves the production of reactive oxygen species (ROS). ...

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a prerequisite for pneumococcal infections such as pneumonia and otitis media. In vitro adherence assays can be used to study the attachment of pneumococci to epithelial cell monolayers and to investigate potential interventions, such as the use of probiotics, to inhibit pneumococcal&#160;colonization.&#160;The protocol described here is used to investigate the effects of the probiotic Streptococcus salivarius on the adherence of pneumococci to the human epithelial cell line CCL-23 (sometimes referred to as HEp-2 cells). The assay involves three main steps: 1) preparation of epithelial and bacterial cells, 2) addition of bacteria to epithelial cell monolayers, and 3) detection of adherent pneumococci by viable counts (serial dilution and plating) or quantitative real-time PCR (qPCR). This technique is relatively straightforward and does not require specialized equipment other than a tissue culture setup. The assay can be used to test other probiotic species and/or potential inhibitors of pneumococcal colonization and can be easily modified to address other scientific questions regarding pneumococcal adherence and invasion.

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

In vitro adherence assays can be used to study the attachment of Streptococcus pneumoniae to epithelial cell monolayers and to investigate potential interventions such as the use of probiotics for inhibiting pneumococcal colonization.

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a ...

Using RNA-interference to Investigate the Innate Immune Response in Mouse Macrophages

Macrophages are key phagocytic innate immune cells. When macrophages encounter a pathogen, they produce antimicrobial proteins and compounds to kill the pathogen, produce various cytokines and chemokines to recruit and stimulate other immune cells, and present antigens to stimulate the adaptive immune response. Thus, being able to efficiently manipulate macrophages with techniques such as RNA-interference (RNAi) is critical to our ability to investigate this important innate immune cell. However, macrophages can be technically challenging to transfect and can exhibit inefficient RNAi-induced gene knockdown. In this protocol, we describe methods to efficiently transfect two mouse macrophage cell lines (RAW264.7 and J774A.1) with siRNA using the Amaxa Nucleofector 96-well Shuttle System and describe procedures to maximize the effect of siRNA on gene knockdown. Moreover, the described methods are adapted to work in 96-well format, allowing for medium and high-throughput studies. To demonstrate the utility of this approach, we describe experiments that utilize RNAi to inhibit genes that regulate lipopolysaccharide (LPS)-induced cytokine production.

In this protocol, we describe methods to efficiently transfect murine macrophage cell lines with siRNAs using the Amaxa Nucleofector 96-well Shuttle System, stimulate the macrophages with lipopolysaccharide, and monitor the effects on inflammatory cytokine production.

Macrophages are key phagocytic innate immune cells.  When macrophages encounter a pathogen, they produce antimicrobial proteins and compounds to kill the ...

The Utilization of Oropharyngeal Intratracheal PAMP Administration and Bronchoalveolar Lavage to Evaluate the Host Immune Response in Mice

The host immune response to pathogens is a complex biological process. The majority of in vivo studies classically employed to characterize host-pathogen interactions take advantage of intraperitoneal injections of select bacteria or pathogen associated molecular patterns (PAMPs) in mice. While these techniques have yielded tremendous data associated with infectious disease pathobiology, intraperitoneal injection models are not always appropriate for host-pathogen interaction studies in the lung. Utilizing an acute lung inflammation model in mice, it is possible to conduct a high resolution analysis of the host innate immune response utilizing lipopolysaccharide (LPS). Here, we describe the methods to administer LPS using nonsurgical oropharyngeal intratracheal administration, monitor clinical parameters associated with disease pathogenesis, and utilize bronchoalveolar lavage fluid to evaluate the host immune response. The techniques that are described are widely applicable for studying the host innate immune response to a diverse range of PAMPs and pathogens. Likewise, with minor modifications, these techniques can also be applied in studies evaluating allergic airway inflammation and in pharmacological applications.

The host immune response to pathogen infection is a tightly regulated process. Utilizing a lipopolysaccharide lung exposure model in mice, it is possible to conduct high resolution evaluations of the complex mechanisms associated with disease pathogenesis.

The host immune response to pathogens is a complex biological process. The majority of in vivo studies classically employed to characterize host-pathogen ...

In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection

An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in mice. Recently, myeloid differentiation factor 88 (MyD88) signaling was shown to be important for initial T cell priming and memory T cell development during WNV NS4B-P38G mutant infection. In this study, two flow cytometry-based methods &#8211; an in vitro T cell priming assay and an intracellular cytokine staining (ICS) &#8211; were utilized to assess dendritic cells (DCs) and T cell functions. In the T cell priming assay, cell proliferation was analyzed by flow cytometry following co-culture of DCs from both groups of mice with carboxyfluorescein succinimidyl ester (CFSE) - labeled CD4+ T cells of OTII transgenic mice. This approach provided an accurate determination of the percentage of proliferating CD4+ T cells with significantly improved overall sensitivity than the traditional assays with radioactive reagents. A microcentrifuge tube system was used in both cell culture and cytokine staining procedures of the ICS protocol. Compared to the traditional tissue culture plate-based system, this modified procedure was easier to perform at biosafety level (BL) 3 facilities. Moreover, WNV- infected cells were treated with paraformaldehyde in both assays, which enabled further analysis outside BL3 facilities. Overall, these in vitro immunological assays can be used to efficiently assess cell-mediated immune responses during WNV infection.

In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection

Two flow cytometry-based methods &#8211; an in vitro T cell priming assay and intracellular cytokine staining were utilized to measure antigen presenting capacity of dendritic cells and antigen-specific T cell responses to a West Nile virus mutant infection in mice.

An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in ...

Non-invasive Imaging of the Innate Immune Response in a Zebrafish Larval Model of Streptococcus iniae Infection

The aquatic pathogen, Streptococcus iniae, is responsible for over 100 million dollars in annual losses for the aquaculture industry and is capable of causing systemic disease in both fish and humans. A better understanding of S. iniae disease pathogenesis requires an appropriate model system. The genetic tractability and the optical transparency of the early developmental stages of zebrafish allow for the generation and non-invasive imaging of transgenic lines with fluorescently tagged immune cells. The adaptive immune system is not fully functional until several weeks post fertilization, but zebrafish larvae have a conserved vertebrate innate immune system with both neutrophils and macrophages. Thus, the generation of a larval infection model allows the study of the specific contribution of innate immunity in controlling S. iniae infection.
The site of microinjection will determine whether an infection is systemic or initially localized. Here, we present our protocols for otic vesicle injection of zebrafish aged 2-3 days post fertilization as well as our techniques for fluorescent confocal imaging of infection. A localized infection site allows observation of initial microbe invasion, recruitment of host cells and dissemination of infection. Our findings using the zebrafish larval model of S. iniae infection indicate that zebrafish can be used to examine the differing contributions of host neutrophils and macrophages in localized bacterial infections. In addition, we describe how photolabeling of immune cells can be used to track individual host cell fate during the course of infection.

Non-invasive Imaging of the Innate Immune Response in a Zebrafish Larval Model of Streptococcus iniae Infection

Here, we present a protocol for the generation and imaging of a localized bacterial infection in the zebrafish otic vesicle.

The aquatic pathogen, Streptococcus iniae, is responsible for over 100 million dollars in annual losses for the aquaculture industry and is capable of ...

An In Vitro Model for Measuring Immune Responses to Malaria in the Context of HIV Co-infection

Malaria and HIV co-infection is a growing health priority. However, most research on malaria or HIV currently focuses on each infection individually. Although understanding the disease dynamics for each of these pathogens independently is vital, it is also important that the interactions between these pathogens are investigated and understood. 
We have developed a versatile in vitro model of HIV-malaria co-infection to study host immune responses to malaria in the context of HIV infection. Our model allows the study of secreted factors in cellular supernatants, cell surface and intracellular protein markers, as well as RNA expression levels. The experimental design and methods used limit variability and promote data reliability and reproducibility. 
All pathogens used in this model are natural human pathogens (Plasmodium falciparum and HIV-1), and all infected cells are naturally infected and used fresh. We use human erythrocytes parasitized with P. falciparum and maintained in continuous in vitro culture. We obtain freshly isolated peripheral blood mononuclear cells from chronically HIV-infected volunteers. Every condition used has an appropriate control (P. falciparum parasitized vs. normal erythrocytes), and every HIV-infected donor has an HIV uninfected control, from which cells are harvested on the same day. This model provides a realistic environment to study the interactions between malaria parasites and human immune cells in the context of HIV infection.

An In Vitro Model for Measuring Immune Responses to Malaria in the Context of HIV Co-infection

Human co-infection is difficult to replicate in vitro. However, human malaria parasites can readily be cultured in vitro, as can freshly isolated human peripheral blood mononuclear cells naturally infected with HIV. This provides an excellent model for studying early immune responses to malaria parasites in the context of HIV co-infection.

Malaria and HIV co-infection is a growing health priority. However, most research on malaria or HIV currently focuses on each infection individually. ...

Inoculating Anopheles gambiae Mosquitoes with Beads to Induce and Measure the Melanization Immune Response

The stimulation of immune responses is a common tool in invertebrate studies to examine the efficacy and the mechanisms of immunity. This stimulation is based on the injection of non-pathogenic particles into insects, as the particles will be detected by the immune system and will induce the production of immune effectors. We focus here on the stimulation of the melanization response in the mosquito Anopheles gambiae. The melanization response results in the encapsulation of foreign particles and parasites with a dark layer of melanin. To stimulate this response, mosquitoes are inoculated with beads in the thoracic cavity using microcapillary glass tubes. Then, after 24 hr, the mosquitoes are dissected to retrieve the beads. The degree of melanization of the bead is measured using image analysis software. Beads do not have the pathogenic effects of parasites, or their capacity to evade or suppress the immune response. These injections are a way to measure immune efficacy and the impact of immune stimulations on other life history traits, such as fecundity or longevity. It is not exactly the same as directly studying host-parasite interactions, but it is an interesting tool to study immunity and its evolutionary ecology.

Inoculating Anopheles gambiae Mosquitoes with Beads to Induce and Measure the Melanization Immune Response

Through inoculation with beads, the described technique enables the stimulation of the mosquito melanization response in the hemolymph circulating system. The amount of melanin covering the beads can be measured after dissection as a measure of the immune response.

The stimulation of immune responses is a common tool in invertebrate studies to examine the efficacy and the mechanisms of immunity. This stimulation is ...