Name: detection of enterohemorrhagic escherichia coli colonization in murine host by non-invasive in vivo bioluminescence system
Uploaded: 2018-04-09T12:30:00
Description: Watch this Scientific Journal Video about Detection of Enterohemorrhagic Escherichia Coli Colonization in Murine Host by Non-invasive In Vivo Bioluminescence System at JoVE.com

We acknowledge Chi-Chung Chen from the Department of Medical Research, Chi Mei Medical Center (Tainan, Taiwan) for the help in mouse infection, and the support from the laboratory animal center of National Cheng Kung University. This work is supported by the Minister of Science and Technology (MOST) grants (MOST 104-2321-B-006-019, 105-2321-B-006 -011, and106-2321-B-006 -005) to CC.

Caution: EHEC O157:H7 is a biosafety level 2 (BSL-2) pathogen according to the Centers for Disease Control and Prevention (CDC) biosafety instruction (https://www.cdc.gov/). Therefore, all experimental procedures involving EHEC must be performed in a BSL-2 facility. Wear lab coats and gloves while performing the experiment. Work in a certified biosafety cabinet (BSC). Disinfect the experimental bench before and after the experimental procedure with 70% ethanol. All instruments or equipment that contact (or potentially co...

<ol>
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It has been reported that EHEC transformed with luciferase plasmid has been utilized to examine its localization in hosts or gene expression in vivo8,11,12. The murine model demonstrated here has also been reported to detect the EHEC colonized timing and localization in murine host8. Nevertheless, we provide the detail protocol of how to administer EHEC inoculation to mice intragastrically and ho...

EHEC O157:H7 is a pathogen that causes diarrhea1, HS2, HUS3, and even acute renal failure4 through contaminated water or food. EHEC is a pathogenic enterobacterium and colonizes to the gastrointestinal tract of humans1. When EHEC first adhere to host intestinal epithelium, they inject the colonization factors into host cells through the type III secretion system (T3SS) that functions as a molecular syringe inducing an attaching and effacing (A/E) lesion subsequently to enforce adhesion (colonization)5. These genes involved in A/E lesion formation are encoded by the locus of enterocyte effacement (LEE) pathogenicity island5.
Bioluminescence is a light-producing chemical reaction, in which luciferase catalyzes its substrate luciferin to generate visible light6. This enzymatic process often requires the presence of oxygen or adenosine triphosphate (ATP)6. Bioluminescence imaging (BLI) allows researchers the visualization and quantization of host-pathogen interactions in live animals7. BLI can characterize the bacterial infection cycle in live animals by following the bioluminescent bacteria as they migrate to and invade different tissues7; this reveals a dynamic progression of infection. Moreover, the bacterial load in animals is related to the bioluminescent signal8; thus, it is a convenient indicator to estimate the pathological conditions of experimental animals in a simple and direct way.
The plasmid used here contained the luciferase operon, luxCDABE, which is from the bacterium Photorhabdus luminescens that encodes its own luciferase substrate7,9. By transforming this luciferase-expressing plasmid into bacteria, the colonization and infection processes can be monitored by observing these bioluminescent bacteria in live animals. Overall, BLI and bioluminescence-labeled bacteria allow researchers to monitor the bacterial numbers and location, bacterial viability with antibiotics/therapy treatment, and bacterial gene expression in infection/colonization6,7. Numerous pathogenic bacteria have been reported that express the luxCDABE operon to examine their infection cycle and/or gene expression in infection. These bacteria, including uropathogenic E. coli10, EHEC8,11,12,13, enteropathogenic E. coli (EPEC)8, Citrobacter rodentium14,15, Salmonella typhimurium16, Listeria monocytogenes17, Yersinia enterocolitica18,19, and Vibrio cholerae20, have been documented.
Several experimental models have been developed to facilitate the study of EHEC colonization in vitro and in vivo21,22,23. However, there is a lack of suitable animal models to study the EHEC colonization in vivo, and thus a resulting paucity of details. To facilitate the study of the EHEC colonization mechanism in vivo, it is valuable to build animal models to observe and quantify EHEC colonization in live animals in a non-invasive method.
This manuscript describes a mouse-EHEC colonization model that uses a bioluminescent expressing system to monitor EHEC colonization over time in living hosts. Mice are intragastrically inoculated with bioluminescence-labeled EHEC and the bioluminescent signal is detected in mice with a non-invasive in vivo imaging system13. Mice infected with bioluminescence-labeled EHEC showed significant bioluminescent signals in their intestine after 2 days post infection, which suggested that those bacteria colonized in the host intestine after 2 days post infection. Ex vivo image data showed that this colonization is specifically in the cecum and colon of mice. By using this mouse-EHEC model, the bioluminescent EHEC colonization can be detected in the living host by an in vivo imaging system, to study the detailed mechanisms of enteric bacteria colonization, which may promote further understanding in EHEC-induced physiological and pathological changes.

<table border="0" cellpadding="0" cellspacing="0" width="721">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Shaker incubator</td>
			<td style="width:175px;">YIH DER</td>
			<td style="width:143px;">LM-570R</td>
			<td style="width:167px;">bacteria incubation&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Orbital shaking incubator</td>
			<td style="width:175px;">FIRSTEK</td>
			<td style="width:143px;">S300</td>
			<td>bacteria incubation&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">pBSL180</td>
			<td style="width:175px;"></td>
			<td style="width:143px;"></td>
			<td>source of nptII gene</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">pAKlux2</td>
			<td style="width:175px;"></td>
			<td style="width:143px;"></td>
			<td>source of luxCDABE operon</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">T&#38;A Cloning Kit</td>
			<td>Yeastern Biotech</td>
			<td style="width:143px;">FYC001-20P</td>
			<td>use for TA cloning&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nsi I</td>
			<td style="width:175px;">NEB</td>
			<td>R0127S</td>
			<td>use for plasmid cloning&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sca I</td>
			<td style="width:175px;">NEB</td>
			<td>R0122S</td>
			<td>use for plasmid cloning&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Spe I-HF</td>
			<td style="width:175px;">NEB</td>
			<td>R0133S</td>
			<td>use for plasmid cloning&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sma I&#160;</td>
			<td style="width:175px;">NEB</td>
			<td>R0141S</td>
			<td>use for plasmid cloning&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">T4 ligase</td>
			<td style="width:175px;">NEB</td>
			<td style="width:143px;">M0202S</td>
			<td>use for plasmid cloning&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Ex Taq</td>
			<td style="width:175px;">TaKaRa</td>
			<td>RR001A</td>
			<td>use for PCR amplification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">10X Ex Taq Buffer</td>
			<td style="width:175px;">TaKaRa</td>
			<td>RR001A</td>
			<td>use for PCR amplification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">dNTP Mixture&#160;</td>
			<td style="width:175px;">TaKaRa</td>
			<td>RR001A</td>
			<td>use for PCR amplification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">PCR machine</td>
			<td style="width:175px;">applied Biosystem&#160;</td>
			<td style="width:143px;">2720 thermal cycler&#160;</td>
			<td>&#160;for PCR amplification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Glycerol</td>
			<td style="width:175px;">SIGMA</td>
			<td style="width:143px;">G5516-1L</td>
			<td>use for bacteria stocking solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">NaCl</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:143px;">31434-5KG-R</td>
			<td>chemical for making LB medium, 10 g/L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Tryptone</td>
			<td style="width:175px;">CONDA pronadisa</td>
			<td style="width:143px;">Cat 1612.00</td>
			<td>chemical for making LB medium, 10 g/L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Yeast Extract powder</td>
			<td style="width:175px;">Affymetrix</td>
			<td style="width:143px;">23547-1 KG</td>
			<td>chemical for making LB medium, 5 g/L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Agar</td>
			<td style="width:175px;">CONDA pronadisa</td>
			<td style="width:143px;">Cat 1802.00</td>
			<td>chemical for making LB agar</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">kanamycin&#160;</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:143px;">K4000-5G</td>
			<td>antibiotics, use for seleciton</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">streptomycin&#160;</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:143px;">S6501-100G</td>
			<td>antibiotics, eliminate the microbiota in mice</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">EDL933 competent cell</td>
			<td style="width:175px;">Homemade</td>
			<td style="width:143px;"></td>
			<td>method is on supplemental document&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Electroporator</td>
			<td style="width:175px;">MicroPulser</td>
			<td style="width:143px;"></td>
			<td>for electroporation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Electroporation Cuvettes</td>
			<td style="width:175px;">Gene Pulser/MicroPulser</td>
			<td style="width:143px;">1652086</td>
			<td>for electroporation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">High-speed centrifuge</td>
			<td style="width:175px;">Beckman Coulter</td>
			<td style="width:143px;">Avanti, J-26S XP</td>
			<td>use for centrifuging bacteria&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Fixed-Angle Rotor</td>
			<td style="width:175px;">Beckman Coulter</td>
			<td style="width:143px;">JA25.5</td>
			<td>use for centrifuging bacteria&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Fixed-Angle Rotor</td>
			<td style="width:175px;">Beckman Coulter</td>
			<td style="width:143px;">JLA10.5</td>
			<td>use for centrifuging bacteria&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">centrifuge bottles</td>
			<td>Beckman Coulter</td>
			<td>REF357003</td>
			<td>use for centrifuging bacteria&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">centrifuge bottles</td>
			<td style="width:175px;">Thermo Fisher scientific</td>
			<td style="width:143px;">3141-0500</td>
			<td>use for centrifuging bacteria&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">eppendorf biophotometer plus&#160;</td>
			<td>eppendorf</td>
			<td>AG 22331 hamburg</td>
			<td>for measuring the OD600 value of bacteria</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">C57BL/6 mice&#160;</td>
			<td colspan="2">Laboratory Animal Center of NCKU</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">lab coat, gloves</td>
			<td style="width:175px;"></td>
			<td style="width:143px;"></td>
			<td>for personnel protection&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">isoflurane&#160;</td>
			<td>Panion &#38; BF Biotech Inc.</td>
			<td style="width:143px;">G-8669</td>
			<td>for mice anesthesia, pharmaceutical grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1ml syringe&#160;</td>
			<td style="width:175px;"></td>
			<td style="width:143px;"></td>
			<td>use for oral gavage of mice</td>
		</tr>
		<tr height="21">
			<td colspan="2" height="21" style="height:21px;">Reusable 22 G ball-tipped feeding needle</td>
			<td style="width:143px;">&#966;0.9 mm X L 50 mm</td>
			<td>use for oral gavage of mice</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">surgical&#160; scissors&#160;</td>
			<td></td>
			<td style="width:143px;"></td>
			<td>use for mice experiment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Xenogen IVIS 200 imaging system</td>
			<td>Perkin Elmer</td>
			<td>IVIS spectrum</td>
			<td>use for bioluminescent image capture&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Living Image Software</td>
			<td>Perkin Elmer</td>
			<td style="width:143px;">version 4.1</td>
			<td>use for quantifying the image data</td>
		</tr>
	</tbody>
</table>

detection of enterohemorrhagic escherichia coli colonization in murine host by non-invasive in vivo bioluminescence system

Enterohemorrhagic E. coli (EHEC) O157:H7, which is a foodborne pathogen that causesdiarrhea, hemorrhagic colitis (HS), and hemolytic uremic syndrome (HUS), colonize to the intestinal tract of humans. To study the detailed mechanism of EHEC colonization in vivo, it is essential to have animal models to monitor and quantify EHEC colonization. We demonstrate here a mouse-EHEC colonization model by transforming the bioluminescent expressing plasmid to EHEC to monitor and quantify EHEC colonization in living hosts. Animals inoculated with bioluminescence-labeled EHEC show intense bioluminescent signals in mice by detection with a non-invasive in vivo imaging system. After 1 and 2 days post infection, bioluminescent signals could still be detected in infected animals, which suggests that EHEC colonize in hosts for at least 2 days. We also demonstrate that these bioluminescent EHEC locate to mouse intestine, specifically in the cecum and colon, from ex vivo images. This mouse-EHEC colonization model may serve as a tool to advance the current knowledge of the EHEC colonization mechanism.

We administered bioluminescence-labeled EHEC (~ 109 bacterial cells) to 6-week old female C57BL/6 mice by oral gavage. After oral inoculation of EHEC to mice within 1 h, the animals were examined for bioluminescent signal by the in vivo imaging system as shown in Figure 7. The results showed a strong bioluminescent signal in gavage mice with bioluminescence-labeled EHEC. We examined the signals on 2 days post infection. As shown in <strong...

Watch this Scientific Journal Video about Detection of Enterohemorrhagic Escherichia Coli Colonization in Murine Host by Non-invasive In Vivo Bioluminescence System at JoVE.com

Detection of Enterohemorrhagic Escherichia Coli Colonization in Murine Host by Non-invasive In Vivo Bioluminescence System

A detailed protocol of a mouse model for enterohemorrhagic E. coli (EHEC) colonization by using bioluminescence-labeled bacteria is presented. The detection of these bioluminescent bacteria by a non-invasive in vivo imaging system in live animals can advance our current understanding of EHEC colonization.

Detection of Enterohemorrhagic Escherichia Coli Colonization in Murine Host by Non-invasive In Vivo Bioluminescence System

Enterohemorrhagic E. coli (EHEC) O157:H7, which is a foodborne pathogen that causesdiarrhea, hemorrhagic colitis (HS), and hemolytic uremic syndrome ...

The overall goal of this experiment is to detect enterohemorrhagic E.coli colonization in mice using a non-invasive in vivo imaging system. This method can help answer key questions in the enterohemorrhagic E.coli pathogenicity field such as colonization. The main advantage of this technique is that EHEC colonization can be detected in living animal without sacrificing animal.To begin, streak a negative 80 degree Celsius stock of E.coli O157:H7 EDL933 bacteria harboring a luciferase plasmid onto an LB agar plate with 50 micrograms per milliliter of kanamycin. Grow the bacteria for 16 to 18 hours at 37 degree Celsius. Pick a single colony from the overnight plate and inoculate three milliliters of LB medium with 50 micrograms per milliliter of kanamycin.Then, incubate the culture at 37 degree Celsius and 220 rpm for 16 to 18 hours. The following day, prepare a two milliliters of a one to 100 dilution of the overnight culture and inoculate it into 200 milliliters of LB with kanamycin. Incubate the culture at 37 degree Celsius and 200 rpm for 2.5 to three hours or until the optical density at 600 nanometers reaches between 0.9 and one.Next, centrifuge the re-cultured bacteria at 8000 times gravity and four degree Celsius for 30 minutes. Discard the supernatant without disturbing the pellet and wash the bacteria with 100 milliliters of 0.9%sterile normal saline by gentle agitation. Following the wash, centrifuge the bacterial culture again and gently discard the supernatant.Then, use 0.9%sterile normal saline to concentrate the pellet 100-fold. After treating mice with streptomycin water for 24 hours according to the text protocol, fill a syringe with 100 microliters of EHEC bacteria. Gently lift the animal and place it on the top of the cage with care.Then, carefully grasp the mouse by the tail so that the animal grips onto the top of the cage and attempts to get away. Gently restrain the mouse by use the thumb and forefinger to grasp the loose skin of the neck and back of the animal to prevent the head from moving. Then, hold the mouse in a vertical position and ensure the head of the mouse is immobilized in this position.Insert the gavage needle into the animal's mouth following the roof of the mouth and move down into the esophagus toward the stomach. When the inserted needle is half or two-thirds of the way in the mouse, inject the 100 microliters of EHEC bacteria which contains approximately 10 to the ninth CFU's of cells. After visualizing the bioluminescent cells according to the text protocol, open the Acquisition Control Panel of the software.Select luminescent, photograph, and overlay. Set the exposure time to auto. Then set binning to medium.Set the F/stop at one for luminescence and eight for photograph. F/stop controls the amount of light received by the CCD detector. Once the mice samples are ready for imaging, click acquire for image acquisition.Open the image data that was acquired then open the tool palette panel. Select ROI tools such as the circle to define the bioluminescent area on the images. Next, using the pencil icon, click measure ROI's to measure the surface bioluminescence intensity.The ROI measurement panel and the quantification values will appear. Then, on the left corner of the ROI measurements panel, use configure measurement to select the values/information needed. Otherwise, click Export to export this data table and save it as a csv file.Finally use the values of the total flux p/s column as the bioluminescence intensity quantification in the csv file. As demonstrated in this image, a strong bioluminescence signal was seen in mice exposed to oral gavage with bioluminescence labeled EHEC inoculation. In this figure, mice inoculated with bioluminescence labeled wild-type EHEC EDL933 showed intense bioluminescent signals even at two days post-infection suggesting that EHEC colonized hosts within two days.However, mice infected with a mutant E.coli with defects in lipopolysaccharides exhibit no bioluminescence suggesting that a reduced number or no bacteria colonized these mice. To localize the bioluminescence-labeled bacteria, the intestines of sacrificed animals were imaged ex vivo. The organs from mice infected with bioluminescence-labeled EHEC showed a significant bioluminescence signal in the cecum and colon indicating colonization in these organs.In contrast, mice infected with an LPS mutant showed decreased bioluminescence in the intestinal tissue which is consistent with the in vivo image. After watching this video, you should have a good understanding of how to conduct the experiment using the IV system to monitor EHEC colonization in mice.

detection-enterohemorrhagic-escherichia-coli-colonization-murine-host

Research

JoVE Journal

Immunology and Infection

Non-invasive Imaging of Leukocyte Homing and Migration in vivo

Two-photon (2P) microscopy is a high resolution imaging technique that has been broadly adapted by biologists. The value of 2P microscopy is that it provides rich spatiotemporal information regarding cell behaviors within intact tissues and in live mice. Leukocyte recruitment plays a significant role in host defense against infection and when unchecked, can contribute to inflammatory and autoimmune diseases. Studying leukocyte recruitment in vivo is technically challenging since cells are moving rapidly within vessels located deep within light scattering tissues. To date, most intravital imaging studies require surgical preparation to expose the blood vessels and tissues. To avoid the tissue damage and inflammation induced by surgery itself, here, we describe a non-invasive single-cell imaging approach that can be used to study leukocyte trafficking in the mouse footpad and phalanges. We discuss the technical aspects of our 2P imaging preparation and walk the reader through a typical experiment from initial set up to execution and data collection.

Non-invasive Imaging of Leukocyte Homing and Migration in vivo

Here, we describe a non-invasive two-photon (2P) microscopy approach to study leukocyte homing in the mouse footpad. We discuss the technical aspects of our tissue imaging preparation and walk the reader through a typical experiment from initial set up to execution and data collection.

Two-photon (2P) microscopy is a high resolution imaging technique that has been broadly adapted by biologists.  The value of 2P microscopy is that it ...

Non-invasive Imaging of Disseminated Candidiasis in Zebrafish Larvae

Disseminated candidiasis caused by the pathogen Candida albicans is a clinically important problem in hospitalized individuals and is associated with a 30 to 40% attributable mortality6. Systemic candidiasis is normally controlled by innate immunity, and individuals with genetic defects in innate immune cell components such as phagocyte NADPH oxidase are more susceptible to candidemia7-9. Very little is known about the dynamics of C. albicans interaction with innate immune cells in vivo. Extensive in vitro studies have established that outside of the host C. albicans germinates inside of macrophages, and is quickly destroyed by neutrophils10-14. In vitro studies, though useful, cannot recapitulate the complex in vivo environment, which includes time-dependent dynamics of cytokine levels, extracellular matrix attachments, and intercellular contacts10, 15-18. To probe the contribution of these factors in host-pathogen interaction, it is critical to find a model organism to visualize these aspects of infection non-invasively in a live intact host. 
The zebrafish larva offers a unique and versatile vertebrate host for the study of infection. For the first 30 days of development zebrafish larvae have only innate immune defenses2, 19-21, simplifying the study of diseases such as disseminated candidiasis that are highly dependent on innate immunity. The small size and transparency of zebrafish larvae enable imaging of infection dynamics at the cellular level for both host and pathogen. Transgenic larvae with fluorescing innate immune cells can be used to identify specific cells types involved in infection22-24. Modified anti-sense oligonucleotides (Morpholinos) can be used to knock down various immune components such as phagocyte NADPH oxidase and study the changes in response to fungal infection5. In addition to the ethical and practical advantages of using a small lower vertebrate, the zebrafish larvae offers the unique possibility to image the pitched battle between pathogen and host both intravitally and in color. 
The zebrafish has been used to model infection for a number of human pathogenic bacteria, and has been instrumental in major advances in our understanding of mycobacterial infection3, 25. However, only recently have much larger pathogens such as fungi been used to infect larva5, 23, 26, and to date there has not been a detailed visual description of the infection methodology. Here we present our techniques for hindbrain ventricle microinjection of prim25 zebrafish, including our modifications to previous protocols. Our findings using the larval zebrafish model for fungal infection diverge from in vitro studies and reinforce the need to examine the host-pathogen interaction in the complex environment of the host rather than the simplified system of the Petri dish5.

The rapid development, small size and transparency of zebrafish are tremendous advantages for the study of innate immune control of infection1-4. Here we demonstrate techniques for infecting zebrafish larvae using the fungal pathogen Candida albicans by microinjection, methodology recently used to implicate phagocyte NADPH oxidase activity in control of fungal dimorphism5.

Disseminated candidiasis caused by the pathogen Candida albicans is a clinically important problem in hospitalized individuals and is associated with a 30 ...

Non-Invasive Model of Neuropathogenic Escherichia coli Infection in the Neonatal Rat

Investigation of the interactions between animal host and bacterial pathogen is only meaningful if the infection model employed replicates the principal features of the natural infection. This protocol describes procedures for the establishment and evaluation of systemic infection due to neuropathogenic Escherichia coli K1 in the neonatal rat. Colonization of the gastrointestinal tract leads to dissemination of the pathogen along the gut-lymph-blood-brain course of infection and the model displays strong age dependency. A strain of E. coli O18:K1 with enhanced virulence for the neonatal rat produces exceptionally high rates of colonization, translocation to the blood compartment and invasion of the meninges following transit through the choroid plexus. As in the human host, penetration of the central nervous system is accompanied by local inflammation and an invariably lethal outcome. The model is of proven utility for studies of the mechanism of pathogenesis, for evaluation of therapeutic interventions and for assessment of bacterial virulence.

Non-Invasive Model of Neuropathogenic Escherichia coli Infection in the Neonatal Rat

Here, a procedure is described for the establishment of systemic infection in the neonatal rat with cultures of Escherichia coli K1. This non-invasive procedure permits colonization of the gastrointestinal tract, translocation of the pathogen to the systemic circulation, and invasion of the central nervous system at the choroid plexus.

Investigation of the interactions between animal host and bacterial pathogen is only meaningful if the infection model employed replicates the principal ...

One-step Negative Chromatographic Purification of Helicobacter pylori Neutrophil-activating Protein Overexpressed in Escherichia coli in Batch Mode

Helicobacter pylori neutrophil-activating protein (HP-NAP) is a major virulence factor of Helicobacter pylori (H. pylori). It plays a critical role in H. pylori-induced gastric inflammation by activating several innate leukocytes including neutrophils, monocytes, and mast cells. The immunogenic and immunomodulatory properties of HP-NAP make it a potential diagnostic and vaccine candidate for H. pylori and a new drug candidate for cancer therapy. In order to obtain substantial quantities of purified HP-NAP used for its clinical applications, an efficient method to purify this protein with high yield and purity needs to be established.
In this protocol, we have described a method for one-step negative chromatographic purification of recombinant HP-NAP overexpressed in Escherichia coli (E. coli) by using diethylaminoethyl (DEAE) ion-exchange resins (e.g., Sephadex) in batch mode. Recombinant HP-NAP constitutes nearly 70% of the total protein in E. coli and is almost fully recovered in the soluble fraction upon cell lysis at pH 9.0. Under the optimal condition at pH 8.0, the majority of HP-NAP is recovered in the unbound fraction while the endogenous proteins from E. coli are efficiently removed by the resin.
This purification method using negative mode batch chromatography with DEAE ion-exchange resins yields functional HP-NAP from E. coli in its native form with high yield and purity. The purified HP-NAP could be further utilized for the prevention, treatment, and prognosis of H. pylori-associated diseases as well as cancer therapy.

One-step Negative Chromatographic Purification of Helicobacter pylori Neutrophil-activating Protein Overexpressed in Escherichia coli in Batch Mode

A high yield method for one-step negative purification of recombinant Helicobacter pylori neutrophil-activating protein (HP-NAP) overexpressed in Escherichia coli by using diethylaminoethyl resins in batch mode is described. HP-NAP purified by this method is beneficial for the development of vaccines, drugs, or diagnostics for H. pylori-associated diseases.

Helicobacter pylori neutrophil-activating protein (HP-NAP) is a major virulence factor of Helicobacter pylori (H. pylori). It plays a critical role in H. ...

A Murine Model of Group B Streptococcus Vaginal Colonization

Streptococcus agalactiae (group B Streptococcus, GBS), is a Gram-positive, asymptomatic colonizer of the human gastrointestinal tract and vaginal tract of 10 - 30% of adults. In immune-compromised individuals, including neonates, pregnant women, and the elderly, GBS may switch to an invasive pathogen causing sepsis, arthritis, pneumonia, and meningitis. Because GBS is a leading bacterial pathogen of neonates, current prophylaxis is comprised of late gestation screening for GBS vaginal colonization and subsequent peripartum antibiotic treatment of GBS-positive mothers. Heavy GBS vaginal burden is a risk factor for both neonatal disease and colonization. Unfortunately, little is known about the host and bacterial factors that promote or permit GBS vaginal colonization. This protocol describes a technique for establishing persistent GBS vaginal colonization using a single &#946;-estradiol pre-treatment and daily sampling to determine bacterial load. It further details methods to administer additional therapies or reagents of interest and to collect vaginal lavage fluid and reproductive tract tissues. This mouse model will further the understanding of the GBS-host interaction within the vaginal environment, which will lead to potential therapeutic targets to control maternal vaginal colonization during pregnancy and to prevent transmission to the vulnerable newborn. It will also be of interest to increase our understanding of general bacterial-host interactions in the female vaginal tract.

A Murine Model of Group B Streptococcus Vaginal Colonization

The purpose of this protocol is to imitate human group B Streptococcus (GBS) vaginal colonization in a murine model. This method may be used to investigate host immune responses and bacterial factors contributing to GBS vaginal persistence, as well as to test therapeutic strategies.

Streptococcus agalactiae (group B Streptococcus, GBS), is a Gram-positive, asymptomatic colonizer of the human gastrointestinal tract and vaginal tract of ...

Non-invasive In Vivo Fluorescence Optical Imaging of Inflammatory MMP Activity Using an Activatable Fluorescent Imaging Agent

This paper describes a non-invasive method for imaging matrix metalloproteinases (MMP)-activity by an activatable fluorescent probe, via in vivo fluorescence optical imaging (OI), in two different mouse models of inflammation: a rheumatoid arthritis (RA) and a contact hypersensitivity reaction (CHR) model. Light with a wavelength in the near infrared (NIR) window (650 - 950 nm) allows a deeper tissue penetration and minimal signal absorption compared to wavelengths below 650 nm. The major advantages using fluorescence OI is that it is cheap, fast and easy to implement in different animal models.
Activatable fluorescent probes are optically silent in their inactivated states, but become highly fluorescent when activated by a protease. Activated MMPs lead to tissue destruction and play an important role for disease progression in delayed-type hypersensitivity reactions (DTHRs) such as RA and CHR. Furthermore, MMPs are the key proteases for cartilage and bone degradation and are induced by macrophages, fibroblasts and chondrocytes in response to pro-inflammatory cytokines. Here we use a probe that is activated by the key MMPs like MMP-2, -3, -9 and -13 and describe an imaging protocol for near infrared fluorescence OI of MMP activity in RA and control mice 6 days after disease induction as well as in mice with acute (1x challenge) and chronic (5x challenge) CHR on the right ear compared to healthy ears.

Non-invasive In Vivo Fluorescence Optical Imaging of Inflammatory MMP Activity Using an Activatable Fluorescent Imaging Agent

This paper explains the application of fluorescent imaging using an activatable optical imaging probe to visualize the in vivo activity of key matrix metalloproteinases in two different experimental models of inflammation.

This paper describes a non-invasive method for imaging matrix metalloproteinases (MMP)-activity by an activatable fluorescent probe, via in vivo ...

Overexpression and Purification of Human Cis-prenyltransferase in Escherichia coli

Prenyltransferases (PT) are a group of enzymes that catalyze chain elongation of allylic diphosphate using isopentenyl diphosphate (IPP) via multiple condensation reactions. DHDDS (dehydrodolichyl diphosphate synthase) is a eukaryotic long-chain cis-PT (forming cis double bonds from the condensation reaction) that catalyzes chain elongation of farnesyl diphosphate (FPP, an allylic diphosphate) via multiple condensations with isopentenyl diphosphate (IPP). DHDDS is of biomedical importance, as a non-conservative mutation (K42E) in the enzyme results in retinitis pigmentosa, ultimately leading to blindness. Therefore, the present protocol was developed in order to acquire large quantities of purified DHDDS, suitable for mechanistic studies. Here, the usage of protein fusion, optimized culture conditions and codon-optimization were used to allow the overexpression and purification of functionally active human DHDDS in E. coli. The described protocol is simple, cost-effective and time sparing. The homology of cis-PT among different species suggests that this protocol may be applied for other eukaryotic cis-PT as well, such as those involved in natural rubber synthesis.

Overexpression and Purification of Human Cis-prenyltransferase in Escherichia coli

A simple protocol for overexpression and purification of codon-optimized, human cis-prenyltransferase, under non-denaturing conditions, from Escherichia coli, is described, along with an enzymatic activity assay. This protocol can be generalized for production of other cis- prenyltransferase proteins in quantity and quality suitable for mechanistic studies.

Prenyltransferases (PT) are a group of enzymes that catalyze chain elongation of allylic diphosphate using isopentenyl diphosphate (IPP) via multiple ...

A Facile Protocol to Generate Site-Specifically Acetylated Proteins in Escherichia Coli

Post-translational modifications that occur at specific positions of proteins have been shown to play important roles in a variety of cellular processes. Among them, reversible lysine acetylation is one of the most widely distributed in all domains of life. Although numerous mass spectrometry-based acetylome studies have been performed, further characterization of these putative acetylation targets has been limited. One possible reason is that it is difficult to generate purely acetylated proteins at desired positions by most classic biochemical approaches. To overcome this challenge, the genetic code expansion technique has been applied to use the pair of an engineered pyrrolysyl-tRNA synthetase variant, and its cognate tRNA from Methanosarcinaceae species, to direct the cotranslational incorporation of acetyllysine at the specific site in the protein of interest. After first application in the study of histone acetylation, this approach has facilitated acetylation studies on a variety of proteins. In this work, we demonstrated a facile protocol to produce site-specifically acetylated proteins by using the model bacterium Escherichia coli as the host. Malate dehydrogenase was used as a demonstration example in this work.

A Facile Protocol to Generate Site-Specifically Acetylated Proteins in Escherichia Coli

Genetic code expansion serves as a powerful tool to study a wide range of biological processes, including protein acetylation. Here we demonstrate a facile protocol to exploit this technique for generating homogeneously acetylated proteins at specific sites in Escherichia coli cells.

Post-translational modifications that occur at specific positions of proteins have been shown to play important roles in a variety of cellular processes. ...

Recurrent Escherichia coli Urinary Tract Infection Triggered by Gardnerella vaginalis Bladder Exposure in Mice

Recurrent urinary tract infections (rUTI) caused by uropathogenic Escherichia coli (UPEC) are common and costly. Previous articles describing models of UTI in male and female mice have illustrated the procedures for bacterial inoculation and enumeration in urine and tissues. During an initial bladder infection in C57BL/6 mice, UPEC establish latent reservoirs inside bladder epithelial cells that persist following clearance of UPEC bacteriuria. This model builds on these studies to examine rUTI caused by the emergence of UPEC from within latent bladder reservoirs. The urogenital bacterium Gardnerella vaginalis is used as the trigger of rUTI in this model because it is frequently present in the urogenital tracts of women, especially in the context of vaginal dysbiosis that has been associated with UTI. In addition, a method for in situ bladder fixation followed by scanning electron microscopy (SEM) analysis of bladder tissue is also described, with potential application to other studies involving the bladder.

Recurrent Escherichia coli Urinary Tract Infection Triggered by Gardnerella vaginalis Bladder Exposure in Mice

A mouse model of uropathogenic E. coli (UPEC) transurethral inoculation to establish latent intracellular bladder reservoirs and subsequent bladder exposure to G. vaginalis to induce recurrent UPEC UTI is demonstrated. Also demonstrated are the enumeration of bacteria, urine cytology, and in situ bladder fixation and processing for scanning electron microscopy.

Recurrent urinary tract infections (rUTI) caused by uropathogenic Escherichia coli (UPEC) are common and costly. Previous articles describing models of ...

Real-Time Quantification of Reactive Oxygen Species in Neutrophils Infected with Meningitic Escherichia Coli

Escherichia coli (E. coli) is the most common Gram-negative bacteria causing neonatal meningitis. The occurrence of bacteremia and bacterial penetration through the blood-brain barrier are indispensable steps for the development of E. coli meningitis. Reactive oxygen species (ROS) represent the major bactericidal mechanisms of neutrophils to destroy the invaded pathogens. In this protocol, the time-dependent intracellular ROS production in neutrophils infected with meningitic E. coli was quantified using fluorescent ROS probes detected by a real-time fluorescence microplate reader. This method may also be applied to the assessment of ROS production in mammalian cells during pathogen-host interactions.

Real-Time Quantification of Reactive Oxygen Species in Neutrophils Infected with Meningitic Escherichia Coli

Escherichia coli is the leading cause of neonatal Gram-negative bacterial meningitis. During the bacterial infection, reactive oxygen species produced by neutrophils play a major bactericidal role. Here we introduce a method to detect the reactive oxygen species in neutrophils in response to meningitis E. coli.

Escherichia coli (E. coli) is the most common Gram-negative bacteria causing neonatal meningitis. The occurrence of bacteremia and bacterial penetration ...