Name: 3-d imaging and analysis of neurons infected in vivo with toxoplasma gondii
Uploaded: 2014-12-09T15:00:00
Description: Watch this Scientific Journal Video about 3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii at JoVE.com

We thank the entire Koshy lab for helpful discussions. We thank Patty Jansma and the University of Arizona Neuroscience Department for advice and help with imaging. We also thank the Porreca lab for the use of their Vibratome. This research was supported by the US National Institutes of Health (NIH NS065116, A.A.K.).

NOTE: Mice were bred and maintained in a temperature and humidity controlled room with 12 hr reversed light/dark cycles with food and water available&#160;ad libitum at the University of Arizona. Experiments were conducted under guidelines and approval of the Institutional Animal Care and Use Committee of the University of Arizona. All efforts were made to minimize suffering. The Cre-reporter mice are on a C57BL/6 background11 and are commercially available.
1. Mouse Infectio...

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Given that cellular changes in infected host cells have been linked to disease outcomes in infections with other intracellular organisms such as HIV, Rabies, and Chlamydia18,19, we developed a technique that would allow us to study the intimate interactions that occur between the CNS host cell and Toxoplasma. The method described here accomplishes this goal by enabling efficient imaging of chronically infected neurons. Prior to the development of this method, such imaging was time consuming, costly, o...

A correction was made to <a href="http://www.jove.com/video/52237">"3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii"</a>. The ordering of the authors was inverted. The order has been updated from:
 Anita A. Koshy, Carla M. Cabral
to:
Carla M. Cabral, Anita A. Koshy

A correction was made to <a href="http://www.jove.com/video/52237">"3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii"</a>.

Erratum: 3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii

The overall goal of this method is to obtain high resolution, three-dimensional images of individual neurons that are infected by the obligate intracellular parasite Toxoplasma gondii.
Toxoplasma is often considered one of the most successful parasites because of its large intermediate host range, which includes humans and rodents. In both humans and rodents, after acute infection through ingestion of contaminated food or water, Toxoplasma is able to cause a persistent infection of the CNS by converting from its fast replicating form (the tachyzoite) to its slow-replicating and encysting form (the bradyzoite). In immunocompetent individuals, this latent CNS infection is thought to be relatively asymptomatic, but in immunocompromised individuals such as AIDS patients or transplant recipients, recrudescence of the parasite can lead to fatal toxoplasmic encephalitis1,2. In addition, recent studies have shown that latent infection with Toxoplasma can lead to behavioral changes in rodents3,4, though the mechanism remains unknown.
Surprisingly, despite these data highlighting the importance of the CNS-Toxoplasma interaction, relatively little is known about this relationship, especially at the cellular and molecular level. The ability to study even simple aspects of the brain-parasite interaction has been hampered in part by technologic limitations. For example, the majority of the work showing that neurons are the cells in which cysts persist has been done with electron microscopy (EM)5,6. Though EM gives high resolution, it is time consuming, labor intensive, and expensive. Immunofluorescence (IF) assays have recently been used in conjunction with confocal microscopy to confirm the work done by EM7. IF assays are technically easy to perform and relatively inexpensive, but using these techniques to understand the spatial relationship between the cyst and the infected neuron requires serial reconstruction, which is time consuming, technically difficult, and may lead to loss of valuable information. Thus, we have developed a method that can be used with the mouse model of CNS toxoplasmosis and allows us to image the entirety of infected neurons without EM or immunohistochemistry (IHC). By developing such a technique, we can begin to explore the cellular relationship between the infected cell and the cyst in a relatively quick and inexpensive manner.
The method we developed combines newer techniques for optically clearing and imaging thick brain sections by confocal microscopy8 with a system which marks in vivo cells that have been injected with parasite proteins9,10. In this system, we infect Cre-reporter mice that express a green fluorescent protein (GFP) only after Cre-mediated recombination11 with Toxoplasma strains that express a red fluorescent protein (RFP) and inject Cre recombinase into host cells9. This combination allows us to harvest the infected mouse brain after CNS infection is established, cut thick brain sections, and rapidly identify pertinent areas to image by finding the RFP+ cysts. It is important to note that as host cell expression of GFP depends solely on the injection of Cre by parasites, and not on infection, a number of the GFP+ cells do not contain parasites10. As the goal of this protocol is to be able to image whole infected neurons, the focus is only on GFP+ neurons that also contain an RFP+ cyst, but the protocol can also be used to image the GFP+/RFP- neurons.
Once the infected brain is harvested and sectioned, the sections are rendered transparent by glycerol clearing. Appropriate regions of sections are then imaged with confocal microscopy, allowing unprecedented visualization of infected host cells and the encysted parasites in their entirety. Here we provide a complete protocol for identifying, optically clearing, and imaging infected neurons.

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			<td height="21" style="height:21px;width:469px;">Name of Reagent/ Equipment</td>
			<td style="width:265px;">Company</td>
			<td style="width:135px;">Catalog Number</td>
			<td style="width:1008px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vibratome Series 1000 Sectioning System</td>
			<td>Technical Products International, Inc.</td>
			<td></td>
			<td>Other vibratomes are compatible</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glycerol</td>
			<td>Fisher Scientific</td>
			<td>BP229-1</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;">Tween-20</td>
			<td>Fisher Scientific</td>
			<td>BP337-500</td>
			<td></td>
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			<td height="21" style="height:21px;">Premium Slides</td>
			<td>Fisher Scientific</td>
			<td>12-544-2</td>
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			<td height="21" style="height:21px;">#1.5 Coverslips</td>
			<td>VWR</td>
			<td>48393 251</td>
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			<td height="21" style="height:21px;">Diamond Scriber</td>
			<td>VWR</td>
			<td>52865-005</td>
			<td></td>
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			<td height="21" style="height:21px;">Zeiss LSM 510 Meta confocal microscope</td>
			<td>Zeiss</td>
			<td>LSM 510</td>
			<td></td>
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			<td height="21" style="height:21px;">Ketaject&#174; Ketamine HCl Inj., USP 100mg/ml</td>
			<td>Western Medical Supply, Inc.</td>
			<td>4165</td>
			<td></td>
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			<td height="21" style="height:21px;">AnaSed&#174; Injection Xylazine 20mg/ml</td>
			<td>Lloyd Inc.</td>
			<td></td>
			<td></td>
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			<td height="21" style="height:21px;">ZsGreen Mice</td>
			<td>Jackson Laboratories</td>
			<td>7906</td>
			<td>B6.Cg-Gt(ROSA)26Sortm6(CAG-ZsGreen1)Hze/J</td>
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			<td height="21" style="height:21px;">Surgical equipment</td>
			<td></td>
			<td></td>
			<td>Thumb forceps; Fine scissors-angled to side, sharp-sharp; Sharp-sharp scissors; Kelly hemostats; Mayo scissors; Micro spatula.</td>
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			<td height="21" style="height:21px;">Human Foreskin Fibroblasts (HFF) cells</td>
			<td></td>
			<td></td>
			<td>These are primary cells from human foreskins.&#160; We make these in-house but they may be purchased from outside vendors.</td>
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			<td height="21" style="height:21px;">Dulbecco&#39;s High Glucose Modified Eagles Medium (DMEM)</td>
			<td>HyClone</td>
			<td>SH30081.01</td>
			<td></td>
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			<td height="21" style="height:21px;width:469px;">Penicillin Streptomycin Solution, 100X</td>
			<td>Corning</td>
			<td>30-002-Cl</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:469px;">200mM L-alanyl-L-glutamine</td>
			<td>Corning</td>
			<td>25-015-Cl</td>
			<td></td>
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		<tr height="25">
			<td height="25" style="height:25px;width:469px;">25cm2 Canted neck flask</td>
			<td>Fisher Scientific</td>
			<td>1012639</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate-Buffered Saline, 1X Without Calcium and Magnesium</td>
			<td>VWR</td>
			<td>45000-446</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate-Buffered Saline, 10X, USP Sterile Ultra Pure Grade</td>
			<td>amresco</td>
			<td>K813-500ml</td>
			<td></td>
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			<td height="21" style="height:21px;width:469px;">Fetal Bovine Serum</td>
			<td style="width:265px;">Gibco</td>
			<td style="width:135px;">26140-079</td>
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			<td height="21" style="height:21px;width:469px;">Bright-Line Hemocytometer</td>
			<td style="width:265px;">Sigma-aldrich</td>
			<td>Z359629-1EA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse Brain Slicer Matrix</td>
			<td>Zivic Instruments</td>
			<td>BSMAS005-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:469px;">Sodium Chloride</td>
			<td>Fisher Scientific</td>
			<td style="width:135px;">BP358-1</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:469px;">Heparin sodium salt from porcine intestinal mucosa</td>
			<td style="width:265px;">Sigma-aldrich</td>
			<td style="width:135px;">H3393-100KU</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:469px;">Paraformaldehyde</td>
			<td style="width:265px;">Fisher Scientific</td>
			<td style="width:135px;">O4042-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:469px;">20ml Disposable Scintillation Vials</td>
			<td style="width:265px;">Fisher Scientific</td>
			<td style="width:135px;">FS74500-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alcohol, Ethyl, 95%, 190 Proof</td>
			<td style="width:265px;">In-house</td>
			<td>17212945</td>
			<td>This product is purchased from an in-house stockroom.&#160; Other companies are compatible.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:469px;">Imaris Software</td>
			<td style="width:265px;">Bitplane</td>
			<td style="width:135px;"></td>
			<td></td>
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			<td height="21" style="height:21px;width:469px;">Clear nail polish</td>
			<td style="width:265px;"></td>
			<td style="width:135px;"></td>
			<td>Other brands are compatible</td>
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			<td height="21" style="height:21px;width:469px;">10ml Syringe with Luer-Lok</td>
			<td style="width:265px;">VWR</td>
			<td>BD309604</td>
			<td>Other syringes are compatible</td>
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			<td height="21" style="height:21px;width:469px;">Three-way Stopcock</td>
			<td style="width:265px;"></td>
			<td style="width:135px;"></td>
			<td>Any brand is compatible</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:469px;">Hypodermic needle</td>
			<td style="width:265px;"></td>
			<td style="width:135px;"></td>
			<td>Any brand is compatible - used to pin down mouse.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:469px;">Cell Scraper</td>
			<td style="width:265px;"></td>
			<td style="width:135px;"></td>
			<td>Any brand is compatible</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">25G x 12&#34; Tubing, Safety Blood Collection Set, with Luer Adapter</td>
			<td style="width:265px;">Greiner Bio-One</td>
			<td style="width:135px;">450099</td>
			<td>Other brands are compatible</td>
		</tr>
	</tbody>
</table>

3-d imaging and analysis of neurons infected in vivo with toxoplasma gondii

Toxoplasma gondii is an obligate, intracellular parasite with a broad host range, including humans and rodents. In both humans and rodents, Toxoplasma establishes a lifelong persistent infection in the brain. While this brain infection is asymptomatic in most immunocompetent people, in the developing fetus or immunocompromised individuals such as acquired immune deficiency syndrome (AIDS) patients, this predilection for and persistence in the brain can lead to devastating neurologic disease. Thus, it is clear that the brain-Toxoplasma interaction is critical to the symptomatic disease produced by Toxoplasma, yet we have little understanding of the cellular or molecular interaction between cells of the central nervous system (CNS) and the parasite. In the mouse model of CNS toxoplasmosis it has been known for over 30 years that neurons are the cells in which the parasite persists, but little information is available about which part of the neuron is generally infected (soma, dendrite, axon) and if this cellular relationship changes between strains. In part, this lack is secondary to the difficulty of imaging and visualizing whole infected neurons from an animal. Such images would typically require serial sectioning and stitching of tissue imaged by electron microscopy or confocal microscopy after immunostaining. By combining several techniques, the method described here enables the use of thick sections (160 &#181;m) to identify and image whole cells that contain cysts, allowing three-dimensional visualization and analysis of individual, chronically infected neurons without the need for immunostaining, electron microscopy, or serial sectioning and stitching. Using this technique, we can begin to understand the cellular relationship between the parasite and the infected neuron.

Figure 7 includes representative images of two cyst-containing GFP+ neurons from two different 160 &#181;m thick sections as well as a representative measurement of the distance from cyst-to-cell-body for Figure 7B. Figures 7 A and B illustrate that this new protocol allows for visualization of the infected neuron in its entirety. Figure 7C shows that with this imaging technique, it is now possible to quantify the distance bet...

Watch this Scientific Journal Video about 3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii at JoVE.com

3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii

Using this protocol, we were able to image 160 &#181;m thick brain sections from mice infected with the parasite Toxoplasma gondii, which enables visualization and analysis of the spatial relationship between the encysting parasite and the infected neuron.

3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii

Toxoplasma gondii is an obligate, intracellular parasite with a broad host range, including humans and rodents. In both humans and rodents, Toxoplasma ...

Research

JoVE Journal

Neuroscience

Scalable Fluidic Injector Arrays for Viral Targeting of Intact 3-D Brain Circuits

Our understanding of neural circuits--how they mediate the computations that subserve sensation, thought, emotion, and action, and how they are corrupted ...

Optical Imaging of Neurons in the Crab Stomatogastric Ganglion with Voltage-sensitive Dyes

Voltage-sensitive dye imaging of neurons is a key methodology for the understanding of how neuronal networks are organised and how the simultaneous ...

Retrograde Fluorescent Labeling Allows for Targeted Extracellular Single-unit Recording from Identified Neurons In vivo

Retrograde Fluorescent Labeling Allows for Targeted Extracellular Single-unit Recording from Identified Neurons In vivo

The overall goal of this method is to record single-unit responses from an identified population of neurons. In vivo electrophysiological recordings from ...

Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains ...

In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

The brain's ability to change in response to experience is essential for healthy brain function, and abnormalities in this process contribute to a variety ...

Modification of a Colliculo-thalamocortical Mouse Brain Slice, Incorporating 3-D printing of Chamber Components and Multi-scale Optical Imaging

The ability of the brain to process sensory information relies on both ascending and descending sets of projections. Until recently, the only way to study ...

In Vivo Multimodal Imaging and Analysis of Mouse Laser-Induced Choroidal Neovascularization Model

In Vivo Multimodal Imaging and Analysis of Mouse Laser-Induced Choroidal Neovascularization Model

Laser-induced choroidal neovascularization (CNV) is a well-established model to mimic the wet form of age-related macular degeneration (AMD). In this ...

In Vivo Two-photon Imaging of Cortical Neurons in Neonatal Mice

In Vivo Two-photon Imaging of Cortical Neurons in Neonatal Mice

Two-photon imaging is a powerful tool for the in vivo analysis of neuronal circuits in the mammalian brain. However, a limited number of in vivo imaging ...

Generation of 3-D Collagen-based Hydrogels to Analyze Axonal Growth and Behavior During Nervous System Development

This protocol uses natural type I collagen to generate three-dimensional (3-D) hydrogel for monitoring and analyzing the axonal growth. The protocol is ...