This study was supported by the Defense Threat Reduction Agency (DTRA) under contract HDTRA1-14-C-0116, and the Center for Excellence in Infection Genomics (DOD #W911NF-11-1-0136).

This work was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. Animal protocols involving rodents were approved by the University of Texas at San Antonio Institutional Animal Care and Use Committee (IACUC) under protocol MU009(RA).
1. Prepare Catheter, Trachea Indicator, and F. tularensis Inoculum
<ol>
	<li>Prepare Catheter (20 G x 2 in)
	<ol>
		<li>Cut the 20 G x 2 in needle and grind the tip of the needle to a blunt and smooth finish with a rotary tool. 
		NOTE: The length of the blunted needle should allow the metal tip to rescind approximately 3 mm into the catheter sleeve when fully seated onto the blunted needle. The blunted needle gives the catheter structural rigidity to allow placement of the catheter in the trachea, and the absence of the blunted needle tip protruding from the catheter sleeve prevents injury to the trachea.</li>
		<li>Clean the blunted needles and catheters using 70% ethanol and sterilize under UV light for 15 min.</li>
	</ol>
	</li>
	<li>Prepare Trachea Indicator
	<ol>
		<li>Trim a 1,000 &#181;L pipette tip to allow the tip to sit into a catheter opening and form an air-tight seal.</li>
		<li>Remove a filter from a 200 &#181;L aerosol barrier pipette tip and place inside the previously trimmed 1,000 &#181;L pipette tip.</li>
		<li>Ensure the filter can move freely inside the 1,000 &#181;L pipette tip when the tip is pointed tip-down.</li>
	</ol>
	</li>
	<li>F. tularensis Inoculum
	<ol>
		<li>Grow F. tularensis strain overnight on appropriate agar plate at 37 &#176;C. Scrape approximately 100 &#181;L of the bacterial lawn from the agar plate with a sterile inoculating loop and use to inoculate a 500 mL Erlenmeyer flask containing 250 mL of appropriate liquid growth medium (for Fn: tryptic soy broth (TSB) supplemented with 0.1% L-Cysteine hydrochloride monohydrate) and incubate shaking overnight at 37 &#176;C. 
		NOTE: F. novicida used in the video was grown on a tryptic soy agar (TSA) plate supplemented with 0.1% L-Cysteine hydrochloride monohydrate.</li>
		<li>Centrifuge the overnight grown liquid culture at 4,221 x g at room temperature for 10 min and remove the supernatant without disrupting the bacteria pellet. 
		CAUTION: Please follow institution&#39;s biosafety recommendations to discard supernatant.</li>
		<li>Gently re-suspend the bacterial pellet with 25 mL of appropriate liquid medium (Fn: TSB supplemented with 0.1% L-Cysteine hydrochloride monohydrate) containing 10% glycerol, using a 25 mL pipette.</li>
		<li>Using a 1 mL pipette, aliquot the resuspended bacterial culture into 500 &#181;L aliquots in vials, freeze in a dry ice/ethanol bath, and store at -80 &#176;C.</li>
		<li>To determine the titer of the frozen culture vials, remove two frozen vials stored at -80 &#176;C, thaw on ice, and perform serial dilutions in Phosphate-buffered Saline (PBS) followed by plating on appropriate growth medium (Fn: TSA containing 0.1% L-Cysteine hydrochloride). Plates are incubated 24 - 48 h at 37 &#176;C, and colony forming units (CFU) are enumerated to calculate the number of bacterial cells within the frozen culture vials (average of two vials).</li>
		<li>Prepare the bacterial inoculum by thawing a frozen vial on ice, and then dilute the culture with PBS to the final concentration of 107 CFU/100 &#181;L. The inoculum should be at a concentration that will yield the desired CFU in 100 &#181;L (the final concentration of glycerol within the inoculum cannot be more than 3%, to prevent asphyxiation of the rat). Frozen culture vials stored at -80 &#176;C can be used for up to six months after preparation.</li>
	</ol>
	</li>
</ol>
2. Rat Anesthesia
<ol>
	<li>Connect the anesthesia chamber to the properly operating isoflurane vaporizer of an anesthesia machine.</li>
	<li>Connect the gas scavenging tube on the anesthesia chamber to the gas scavenging system.</li>
	<li>Open the oxygen flow on the anesthesia machine to 4 L/min.</li>
	<li>Set the isoflurane vaporizer to 5%.</li>
	<li>Place the rat in the anesthesia chamber. 
	NOTE: We typically utilize rats between 8 - 10 weeks old (130 - 180 g); younger rats are difficult to inoculate via this technique due to the small size of the mouth cavity.</li>
	<li>When the induction of anesthesia has taken place, maintain the rat at 5% isoflurane, 2 L/min oxygen to effect. This takes about 3 - 10 min.</li>
	<li>Determine the depth of anesthesia by the quality and rate of respiration and heartbeat, and reaction to reflex stimulation as in the toe pinch test. Ideal depth of anesthesia is indicated by 1 - 1.5 s count between each breath.</li>
</ol>
3. Intratracheal Inoculation
<ol>
	<li>Remove the rat from the anesthesia chamber and place the rat dorsally on the rodent intubation stand. Attach the front teeth of rat to the holder to keep rat in place. 
	NOTE: If the rat starts to awaken during the procedure, the catheter can be removed and the rat returned to the anesthesia chamber to reach a deeper plane of anesthesia.</li>
	<li>Use dominant hand to move the tongue to same side as support hand with broad point dressing thumb forceps.</li>
	<li>Use support hand and secure the tongue with the laryngoscope against the rat&#39;s lower jaw and visualize the trachea and esophagus of the animal. The trachea will open and close as the rat breathes.</li>
	<li>Insert the catheter containing a 20-gauge blunted-needle, prepared in step 1.1, into the trachea. There may be slight resistance, and insertion into trachea may be &#34;bumpy&#34; due to the catheter rubbing the tracheal cartilages. Due to moisture or shallow respiration, the trachea can be covered by the epiglottis which prevents visualization of the trachea. Gently touching the edge of the epiglottis cartilage will cause the cartilage flap to open and uncover the trachea.</li>
	<li>Remove the blunted-needle from the catheter while ensuring the catheter remains in the trachea.</li>
	<li>Allow a few seconds to pass for rat to be able to breathe around catheter inserted into trachea.</li>
	<li>Firmly seat the trachea indicator onto the catheter opening. Movement of the aerosol barrier will indicate the catheter is inserted correctly into the trachea.</li>
	<li>Ensure that the rat is laying on the intubation stand such that the chest of the animal is facing perpendicular to the plane of the intubation stand.</li>
	<li>Remove the trachea indicator and deliver 100 &#181;L (107 CFU) of the inoculum containing F. tularensis using a 200 &#181;L pipette tip, firmly seating the tip against the catheter opening.</li>
	<li>Attach a 1 mL slip tip tuberculin syringe filled with air and deliver 300 &#181;L of air to ensure inoculum reaches the lungs of the rat.</li>
	<li>Remove the catheter from the trachea and remove the rat from the surgical platform.</li>
	<li>Allow the rat to awaken and return to the cage. Make sure that the breathing has returned to normal.</li>
	<li>Determine the CFU in the F. tularensis inoculum as described in step 1.3.5 to confirm the CFU delivered in the trachea.</li>
	<li>Repeat steps 3.1 - 3.9 on unvaccinated (na&#239;ve) animals with 100 &#181;L PBS in place of the inoculum.</li>
</ol>

<ol>
	<li>Ellis, J., Oyston, P. C. F., Green, M., Titball, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tularemia.">Tularemia.</a> Clin Microbiol Rev. 15 (4), 631-646 (2002).</li><li>Lyons, C. R., Wu, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+Francisella+tularensis+infection.">Animal models of Francisella tularensis infection.</a> Ann N Y Acad Sci. 1105, (2007).</li><li>Hutt, J. A., Lovchik, J. A., Dekonenko, A., Hahn, A. C., Wu, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Natural+History+of+Pneumonic+Tularemia+in+Female+Fischer+344+Rats+after+Inhalational+Exposure+to+Aerosolized+Francisella+tularensis+subspecies+tularensis+Strain+Schu+S4.">The Natural History of Pneumonic Tularemia in Female Fischer 344 Rats after Inhalational Exposure to Aerosolized Francisella tularensis subspecies tularensis Strain Schu S4.</a> Am J Pathol. 187 (2), 252-267 (2017).</li><li>Ray, H. 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=The+Fischer+344+rat+reflects+human+susceptibility+to+Francisella+pulmonary+challenge+and+provides+a+new+platform+for+virulence+and+protection+studies.">The Fischer 344 rat reflects human susceptibility to Francisella pulmonary challenge and provides a new platform for virulence and protection studies.</a> PloS one. 5, e9952 (2010).</li><li>Jemski, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Respiratory+tularemia:+comparison+of+selected+routes+of+vaccination+in+Fischer+344+rats.">Respiratory tularemia: comparison of selected routes of vaccination in Fischer 344 rats.</a> Infect Immun. 34 (3), 766-772 (1981).</li><li>Wu, T. H., 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=Vaccination+of+Fischer+344+rats+against+pulmonary+infections+by+Francisella+tularensis+type+A+strains.">Vaccination of Fischer 344 rats against pulmonary infections by Francisella tularensis type A strains.</a> Vaccine. 27 (34), 4684-4693 (2009).</li><li>Mara-Koosham, G., Hutt, J. A., Lyons, C. R., Wu, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibodies+contribute+to+effective+vaccination+against+respiratory+infection+by+type+A+Francisella+tularensis+strains.">Antibodies contribute to effective vaccination against respiratory infection by type A Francisella tularensis strains.</a> Infect Immun. 79 (4), 1770-1778 (2011).</li><li>Oyston, P. C., Sjostedt, A., Titball, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tularaemia:+bioterrorism+defence+renews+interest+in+Francisella+tularensis.">Tularaemia: bioterrorism defence renews interest in Francisella tularensis.</a> Nat Rev Microbiol. 2 (12), 967-978 (2004).</li><li>Kingry, L. C., Petersen, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+review+of+Francisella+tularensis+and+Francisella+novicida.">Comparative review of Francisella tularensis and Francisella novicida.</a> Front Cell Infect Microbiol. 4, 35 (2014).</li><li>Rohmer, L., 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=Comparison+of+Francisella+tularensis+genomes+reveals+evolutionary+events+associated+with+the+emergence+of+human+pathogenic+strains.">Comparison of Francisella tularensis genomes reveals evolutionary events associated with the emergence of human pathogenic strains.</a> Genome Biol. 8 (6), R102 (2007).</li><li>Chu, P., 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+attenuated+Francisella+novicida+vaccine+protects+against+Francisella+tularensis+pulmonary+challenge+in+rats+and+non-human+primates.">Live attenuated Francisella novicida vaccine protects against Francisella tularensis pulmonary challenge in rats and non-human primates.</a> PLoS Pathog. 10 (10), e1004439 (2014).</li><li>Signarovitz, A. L., 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=Mucosal+Immunization+with+Live+Attenuated+Francisella+novicida+U112&#916;iglB+Protects+against+Pulmonary+F.+tularensis+SCHU+S4+in+the+Fischer+344+Rat+Model.">Mucosal Immunization with Live Attenuated Francisella novicida U112&#916;iglB Protects against Pulmonary F. tularensis SCHU S4 in the Fischer 344 Rat Model.</a> PloS one. 7 (10), e47639 (2012).</li><li>Cunningham, A. L., 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=Enhancement+of+vaccine+efficacy+by+expression+of+a+TLR5+ligand+in+the+defined+live+attenuated+Francisella+tularensis+subsp.+novicida+strain+U112DiglB::fljB.">Enhancement of vaccine efficacy by expression of a TLR5 ligand in the defined live attenuated Francisella tularensis subsp. novicida strain U112DiglB::fljB.</a> Vaccine. 32 (40), 5234-5240 (2014).</li></ol>

The authors have nothing to disclose

The Fischer 344 rat is becoming an important model for tularemia vaccine development3. Exposure to F. tularensis through the pulmonary route is critical for demonstrating efficacy against weaponized forms of F. tularensis, because these are delivered as aerosols. Intratracheal inoculation of the rat facilitates exposure of the rat lungs to F. tularensis without the need for large, expensive, and complicated aerosol generating equipment. All experiments utilizing select a...

F. tularensis (Ft) causes the human disease, tularemia. When the bacteria are acquired through the pulmonary route, this leads to pneumonic tularemia, which has high morbidity and mortality1. F. tularensis is considered a biothreat agent due to the danger associated with aerosolized forms, and there is currently no vaccine approved for human use in the U.S. An intensive effort is currently underway to develop vaccines and therapeutic measures against pneumonic tularemia, to protect the human population against the illicit use of this bacterial biothreat.
Much of the tularemia research has focused on the mouse model, due to the extreme sensitivity of mice to F. tularensis infection, and the prevalence of reagents. However, mice have proven to be a difficult model for vaccine development, due to the difficulty of demonstrating vaccine efficacy in this model2. Recently, the Fischer 344 rat has been developed as a model for tularemia vaccine development3. The sensitivity of the Fischer 344 rat to various F. tularensis subspecies mimics human sensitivity4, and rats can be protected against F. tularensis pulmonary challenge by vaccination with a live vaccine strain known to protect humans5,6,7. Because the Fischer 344 rat models some features of F. tularensis infection of humans, it may be an extremely useful model for the development of a vaccine that protects against pulmonary F. tularensis exposure.
An effective vaccine needs to protect humans against pulmonary exposure to F. tularensis. The most likely pulmonary exposure from weaponized F. tularensis would be aerosolized bacteria inhaled into the lungs8. However, aerosol generation of F. tularensis is both dangerous and cumbersome, and requires specialized equipment and containment. An alternate route of pulmonary exposure in the rat that is perhaps more adaptable for multiple laboratories lacking specialized equipment is via intratracheal inoculation6. This technique utilizes a laryngoscope for the correct placement of a catheter within the trachea of an anesthetized rat. Placement within the trachea, rather than the esophagus, is verified by a simple device that visualizes airflow from the lungs. F. tularensis is subsequently delivered into the lungs through the catheter by administration with a syringe, followed by the introduction of air into the catheter to ensure pulmonary delivery of the bacteria. In contrast, Jemski5 previously reported that F. tularensis inoculated into Fischer 344 rats via the intranasal route could not be cultured from the lungs until 3 days post-inoculation, indicating that intranasal inoculation in rats does not result in direct delivery of bacteria into the lungs.
Select agent forms of F. tularensis (F. tularensis subsp. tularensis, F. tularensis subsp. holarctica) require Biosafety Level 3 (BSL3) containment procedures, which would prevent videography. However, F. novicida (Fn) is exempt from select agent status due to its avirulence in healthy humans, and can be utilized safely under Biosafety Level 2 (BSL2) conditions9,10. Moreover, Fn serves as the basis for live attenuated vaccines that can protect against F. tularensis pulmonary exposure when delivered via intratracheal inoculation11,12,13. The technique presented here allows for the study of infections that occur through the pulmonary route utilizing rats as a model for humans. This technique can be performed without the need for specialized aerosol-generating equipment. Fn was used for the techniques filmed here.

<table width="1062">
	<tbody>
		<tr height="40">
			<td height="40" style="width:376px;height:40px;">GreenLine fiber optic blade size 0</td>
			<td style="width:175px;">Carefusion</td>
			<td style="width:344px;">5-5231-00</td>
			<td style="width:167px;">Macintosh American profile</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">GreenLight system laryngoscope handle</td>
			<td>Carefusion</td>
			<td>4559GSP</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Exel International Safelet I.V. Catheter</td>
			<td>EXEL INTERNATIONAL</td>
			<td>26743</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Slip Tip Sterile Syringes 1ml</td>
			<td>BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Broad Point Dressing Thumb Forceps</td>
			<td>Thermo Scientific</td>
			<td>76-302</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">200ul barrier tip</td>
			<td>GeneseeScientific</td>
			<td>24-142</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">1000ul pipette tip</td>
			<td>Olympus Plastics</td>
			<td>24-173</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Dremel 3000-2/28 Rotary tool kit</td>
			<td>Dremel</td>
			<td>3000228</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Rodent Intubation Stand</td>
			<td>Braintree Scientific</td>
			<td>RIS 200</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Isoflurane</td>
			<td style="width:175px;">Butler Schein</td>
			<td>NDC 11695-6776-2</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Rodent anesthesia machine</td>
			<td>Surgivet</td>
			<td>VTC302 Classic T3</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Rodent Anesthesia chamber</td>
			<td>Braintree Scientific</td>
			<td>AB 1</td>
			<td></td>
		</tr>
	</tbody>
</table>

intratracheal inoculation of fischer 344 rats with francisella tularensis

Pulmonary infection with the bacterium Francisella tularensis can lead to the serious and potentially fatal disease, tularemia, in humans. Due to the current lack of an approved tularemia vaccine for humans, research is focused on vaccine development utilizing appropriate animal models. The Fischer 344 rat has emerged as a model that reflects human susceptibility to F. tularensis infection, and thus is an attractive model for tularemia vaccine development. Intratracheal inoculation of the Fischer 344 rat with F. tularensis mimics pulmonary exposure in humans. The successful delivery into the rat trachea is critical for pulmonary delivery. A laryngoscope with illumination is used to properly intubate the tracheae of anesthetized rats; the correct placement within the trachea is determined by a simple device to detect breathing. Following intubation, the F. tularensis culture is delivered in a measured dose via syringe. This technique standardizes pulmonary delivery of F. tularensis within the rat trachea to evaluate vaccine efficacy.

The humoral response to intratracheal inoculation of F. tularensis in the rat can be determined by enzyme-linked immunosorbent assay (ELISA) against UV-inactivated bacteria, as described previously11. Total Immunoglobulin G (IgG) response of Fischer 344 rats to inactivated whole cell bacteria was assessed post-intratracheal inoculation with an attenuated strain of Fn (107 CFU inoculum) at day 14 and day 28 (Figure 1...

Watch this Scientific Journal Video about Intratracheal Inoculation of Fischer 344 Rats with Francisella tularensis at JoVE.com

Intratracheal Inoculation of Fischer 344 Rats with Francisella tularensis

This protocol describes intratracheal inoculations of Fischer 344 rats with Francisella tularensis. This procedure mimics pulmonary exposure of humans to this potential biothreat agent and can be used to test vaccine and therapeutic efficacy against pulmonary tularemia.

Intratracheal Inoculation of Fischer 344 Rats with Francisella tularensis

Pulmonary infection with the bacterium Francisella tularensis can lead to the serious and potentially fatal disease, tularemia, in humans. Due to the ...

intratracheal-inoculation-fischer-344-rats-with-francisella

Research

JoVE Journal

Immunology and Infection

7.1K Views.  University of Texas San Antonio. This protocol describes intratracheal inoculations of Fischer 344 rats with Francisella tularensis. This procedure mimics pulmonary exposure of humans to this potential biothreat agent and can be used to test vaccine and therapeutic efficacy against pulmonary tularemia.

Video: Intratracheal Inoculation of Fischer 344 Rats with Francisella tularensis

Orthotopic Hind-Limb Transplantation in Rats

Composite tissue allotransplantation (CTA) now represents a valid therapeutic option after the loss of a hand, forearm or digits and has become a novel therapeutic entity in reconstructive surgery. However, long term high-dose multi-drug immunosuppressive therapy is required to ensure graft survival, bearing the risk of serious side effects which halters broader application. Further progression in this field may depend on better understanding of basic immunology and ischemia reperfusion injury in composite tissue grafts.
To date, orthotopic hind limb transplantation in rats has been the preferred rodent model for reconstructive transplantation (RT), however, it is an extremely demanding procedure that requires extraordinary microsurgical skills for reattachment of vasculature, bones, muscles and nerves.
We have introduced the vascular cuff anastomosis technique to this model, providing a rapid and reliable approach to rat hind limb transplantation. This technique simplifies and shortens the surgical procedure and enables surgeons with basic microsurgical experience to successfully perform the operation with high survival and low complication rates. The technique seems to be well suited for immunological as well as ischemia reperfusion injury (IRI) studies.

Here we describe the orthotopic rat hind-limb transplantation procedure, which seems to be the gold standard in vivo model for composite tissue allotransplantation research.

Composite tissue allotransplantation (CTA) now represents a valid therapeutic option after the loss of a hand, forearm or digits and has become a novel ...

Non-surgical Intratracheal Instillation of Mice with Analysis of Lungs and Lung Draining Lymph Nodes by Flow Cytometry

Phagocytic cells such as alveolar macrophages and lung dendritic cells (LDCs) continuously sample antigens from the alveolar spaces in the 
lungs. LDCs, in particular, are known to migrate to the lung draining lymph nodes (LDLNs) where they present inhaled antigens to T cells initiating an 
appropriate immune response to a variety of immunogens1,2. To model interactions between the lungs and airborne antigens in mice, antigens can be 
administered intranasally1,3,4, intratracheally5 or as aerosols6. Delivery by each route involves distinct technical skills and limitations that need to be 
considered before designing an experiment. For example, intranasal and aerosolized exposure delivers antigens to both the lungs and the upper respiratory 
tract. Hence antigens can access the nasal associated lymphoid tissue (NALT)7, potentially complicating interpretation of the results. In addition, swallowing, 
sneezing and the breathing rate of the mouse may also lead to inconsistencies in the doses delivered. Although the involvement of the upper respiratory tract may 
be preferred for some studies, it can complicate experiments focusing on events specifically initiated in the lungs. In this setting, the intratracheal (i.t) 
route is preferable as it delivers test materials directly into the lungs and bypasses the NALT. Many i.t injection protocols involve either blind intubation of the 
trachea through the oral cavity or surgical exposure of the trachea to access the lungs. Herein, we describe a simple, consistent, non-surgical method for i.t 
instillation. The opening of the trachea is visualized using a laryngoscope and a bent gavage needle is then inserted directly into the trachea to deliver the 
innoculum. We also describe procedures for harvesting and processing of LDLNs and lungs for analysis of antigen trafficking by flow cytometry.

We illustrate non-surgical delivery of test materials into the lungs of anesthetized mice via the trachea. This method permits lung exposure to bacterial and viral pathogens, cytokines, antibodies, beads, chemicals, or dyes. We further describe harvesting and processing of lungs and lung draining lymph nodes (LDLNs) for flow cytometry.

Phagocytic cells such as alveolar macrophages and lung dendritic cells (LDCs) continuously sample antigens from the alveolar spaces in the 
lungs. LDCs, ...

Diagnosis of Ecto- and Endoparasites in Laboratory Rats and Mice

Internal and external parasites remain a significant concern in laboratory rodent facilities, and many research facilities harbor some parasitized animals. Before embarking on an examination of animals for parasites, two things should be considered. One: what use will be made of the information collected, and two: which test is the most appropriate. Knowing that animals are parasitized may be something that the facility accepts, but there is often a need to treat animals and then to determine the efficacy of treatment. Parasites may be detected in animals through various techniques, including samples taken from live or euthanized animals. Historically, the tests with the greatest diagnostic sensitivity required euthanasia of the animal, although PCR has allowed high-sensitivity testing for several types of parasite. This article demonstrates procedures for the detection of endo- and ectoparasites in mice and rats. The same procedures are applicable to other rodents, although the species of parasites found will differ.

This article describes various procedures for screening rats and mice to detect endo- or ectoparasitism. Several diagnostic assays will be demonstrated, both those suitable for use on live animals and those used after euthanasia of the animal. Photographs to aid in identification of rat and mouse parasites will be included.

Internal and external parasites remain a significant concern in laboratory rodent facilities, and many research facilities harbor some parasitized ...

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 ...

Procedures for Identifying Infectious Prions After Passage Through the Digestive System of an Avian Species

Infectious prion (PrPRes) material is likely the cause of fatal, neurodegenerative transmissible spongiform encephalopathy (TSE) diseases1. Transmission of TSE diseases, such as chronic wasting disease (CWD), is presumed to be from animal to animal2,3 as well as from environmental sources4-6. Scavengers and carnivores have potential to translocate PrPRes material through consumption and excretion of CWD-contaminated carrion. Recent work has documented passage of PrPRes material through the digestive system of American crows (Corvus brachyrhynchos), a common North American scavenger7.
We describe procedures used to document passage of PrPRes material through American crows. Crows were gavaged with RML-strain mouse-adapted scrapie and their feces were collected 4 hr post gavage. Crow feces were then pooled and injected intraperitoneally into C57BL/6 mice. Mice were monitored daily until they expressed clinical signs of mouse scrapie and were thereafter euthanized. Asymptomatic mice were monitored until 365 days post inoculation. Western blot analysis was conducted to confirm disease status. Results revealed that prions remain infectious after traveling through the digestive system of crows and are present in the feces, causing disease in test mice.

Scavengers have potential to translocate infectious transmissible spongiform encephalopathy prions in their feces to disease-free areas. We detail methods used to determine if mouse-adapted scrapie prions remain infectious after passage though the digestive tract of American crows (Corvus brachyrhynchos), a common consumer of dead animals.

Infectious prion (PrPRes) material is likely the cause of fatal, neurodegenerative transmissible spongiform encephalopathy (TSE) diseases1. Transmission ...

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 ...

Complete Thymectomy in Adult Rats with Non-invasive Endotracheal Intubation

Thymectomy in neonatal rodents is an established and reliable procedure for immunological studies. However, in adult rats, complications of hemorrhage and pneumothorax from pleural disruption can result in a significant mortality rate. This protocol is a simple method of rat thymectomy that utilizes a mini-sternotomy and endotracheal intubation. Intubation is accomplished with a non-invasive and easily reproducible method and allows for positive pressure ventilation to prevent pneumothorax and a controlled airway that allows sufficient time for careful thymus dissection to minimize pleural disruption. A 1.5 cm sternal incision decreases contact with mediastinal vessels and pleura, while still providing full visualization of the thymus. Following exposure of the mediastinum, the thymus is removed by blunt dissection under magnification. The pleural space is then sealed by suture closure of the pre-tracheal muscles followed by the application of surgical glue. The thorax is then closed by suture closure of the sternum, followed by suture closure of the skin. All thymectomies were complete as evidenced by immunohistochemical (IHC) staining of mediastinal tissue, and absence of na&#239;ve T-cells by flow cytometry, and the procedure had a 96% survival rate. This method is suitable when complete thymectomy with minimal complications is desired for further immunological studies in athymic adult rats.

Rodent thymectomy is a valuable technique in immunological research. Here, a protocol for complete thymectomy in adult rats using a mini-sternotomy along with non-invasive intubation and positive pressure ventilation to minimize perioperative morbidity and mortality is described.

Thymectomy in neonatal rodents is an established and reliable procedure for immunological studies. However, in adult rats, complications of hemorrhage and ...

Analysis of Lymphocyte Extravasation Using an In Vitro Model of the Human Blood-brain Barrier

Lymphocyte extravasation into the central nervous system (CNS) is critical for immune surveillance. Disease-related alterations of lymphocyte extravasation might result in pathophysiological changes in the CNS. Thus, investigation of lymphocyte migration into the CNS is important to understand inflammatory CNS diseases and to develop new therapy approaches. Here we present an in vitro model of the human blood-brain barrier to study lymphocyte extravasation. Human brain microvascular endothelial cells (HBMEC) are confluently grown on a porous polyethylene terephthalate transwell insert to mimic the endothelium of the blood-brain barrier. Barrier function is validated by zonula occludens immunohistochemistry, transendothelial electrical resistance (TEER) measurements as well as analysis of evans blue permeation. This model allows investigation of the diapedesis of rare lymphocyte subsets such as CD56brightCD16dim/- NK cells. Furthermore, the effects of other cells, cytokines and chemokines, disease-related alterations, and distinct treatment regimens on the migratory capacity of lymphocytes can be studied. Finally, the impact of inflammatory stimuli as well as different treatment regimens on the endothelial barrier can be analyzed.

Analysis of Lymphocyte Extravasation Using an In Vitro Model of the Human Blood-brain Barrier

Here, we describe a human blood-brain barrier model enabling to investigate lymphocyte transmigration into the central nervous system in vitro.

Lymphocyte extravasation into the central nervous system (CNS) is critical for immune surveillance. Disease-related alterations of lymphocyte ...

Analysis of Shear Flow-induced Migration of Murine Marginal Zone B Cells In Vitro

Marginal zone B cells (MZBs) are a population of B cells that reside in the mouse splenic marginal zones that envelop follicles. To reach the follicles, MZBs must migrate up the shear force of blood flow. We present here a method for analyzing this flow-induced MZB migration in vitro. First, MZBs are isolated from the mouse spleen. Second, MZBs are settled on integrin ligands in flow chamber slides, exposed to shear flow, and imaged under a microscope while migrating. Third, images of the migrating MZBs are processed using the MTrack2 automatic cell tracking plugin for ImageJ, and the resulting cell tracks are quantified using the Ibidi chemotaxis tool. The migration data reveal how fast the cells move, how often they change direction, whether the shear flow vector affects their migration direction, and which integrin ligands are involved. Although we use MZBs, the method can easily be adapted for analyzing migration of any leukocyte that responds to the force of shear flow.

Marginal zone B cells (MZBs) respond to the force of shear flow by re-orienting their migration path up the flow. This protocol shows how to record and analyze the migration using a fluidics unit, pump, microscope imaging system, and free software.

Marginal zone B cells (MZBs) are a population of B cells that reside in the mouse splenic marginal zones that envelop follicles. To reach the follicles, ...

Application of Consistent Massage-Like Perturbations on Mouse Calves and Monitoring the Resulting Intramuscular Pressure Changes

Massage is generally recognized to be beneficial for relieving pain and inflammation. Although previous studies have reported anti-inflammatory effects of massage on skeletal muscles, the molecular mechanisms behind are poorly understood. We have recently developed a simple device to apply local cyclical compression (LCC), which can generate intramuscular pressure waves with varying amplitudes. Using this device, we have demonstrated that LCC modulates inflammatory responses of macrophages in situ and alleviates immobilization-induced muscle atrophy. Here, we describe protocols for the optimization and application of LCC as a massage-like intervention against immobilization-induced inflammation and atrophy of skeletal muscles of mouse hindlimbs. The protocol that we have developed can be useful for investigating the mechanism underlying beneficial effects of physical exercise and massage. Our experimental system provides a prototype of the analytical approach to elucidate the mechanical regulation of muscle homeostasis, although further development needs to be made for more comprehensive studies.

Here we describe the protocols for applying defined mechanical loads to mouse calves and for monitoring the concomitant intramuscular pressure changes. The experimental systems that we have developed can be useful for investigating the mechanism behind the beneficial effects of physical exercise and massage.

Massage is generally recognized to be beneficial for relieving pain and inflammation. Although previous studies have reported anti-inflammatory effects of ...