We thank John Kelly and Martin Taylor (London School of Hygiene &#38; Tropical Medicine) for providing T. b. brucei GVR35-VSL-2 and Dr. Andrea Zelmer (LSHTM) for advice on in vivo imaging. This work was supported by the Bill and Melinda Gates Foundation Global Health Program (grant number OPPGH5337).

Ethics 
All work was carried out under the approval of the UK Home Office Animals (Scientific Procedures) Act 1986 and the London School of Hygiene &#38; Tropical Medicine Animal Welfare and Ethics Review Board. ARRIVE guideline are followed in this report.
1. In Vivo Passage of Bioluminescent Trypanosoma brucei brucei 
<ol>
	<li>Remove a cryopreserved stock (termed stabilate) of T. b. brucei strain GVR35-VSL-2 (available from Professor John Kelly at...

<ol>
	<li>Brun, R., Blum, J., Chappuis, F., Burri, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+African+trypanosomiasis.">Human African trypanosomiasis.</a> Lancet. 375 (9709), 148-159 (2010).</li><li>Rodgers, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trypanosomiasis+and+the+brain.">Trypanosomiasis and the brain.</a> Parasitology. 137 (14), 1995-2006 (2010).</li><li>Barrett, M. P., Boykin, D. W., Brun, R., Tidwell, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+African+trypanosomiasis:+pharmacological+re-engagement+with+a+neglected+disease.">Human African trypanosomiasis: pharmacological re-engagement with a neglected disease.</a> Br. J. Pharmacol. 152 (8), 1155-1171 (2007).</li><li>Barrett, M. P., Vincent, I. M., Burchmore, R. J. S., Kazibwe, A. J. N., Matovu, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drug+resistance+in+human+African+trypanosomiasis.">Drug resistance in human African trypanosomiasis.</a> Future Microbiol. 6 (9), 1037-1047 (2011).</li><li>Jennings, F. W., Whitelaw, D. D., Urquhart, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+relationship+between+duration+of+infection+with+Trypanosoma+brucei+in+mice+and+the+efficacy+of+chemotherapy.">The relationship between duration of infection with Trypanosoma brucei in mice and the efficacy of chemotherapy.</a> Parasitology. 75 (2), 143-153 (1977).</li><li>Andreu, N., Zelmer, A., Wiles, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+biophotonic+imaging+for+studies+of+infectious+disease.">Noninvasive biophotonic imaging for studies of infectious disease.</a> FEMS Microbiol. Rev. 35 (2), 360-394 (2011).</li><li>Sadikot, R. T., Blackwell, T. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioluminescence+imaging.">Bioluminescence imaging.</a> Proc. Am. Thorac. Soc. 2 (6), 537-540 (2005).</li><li>Burrell-Saward, H., Rodgers, J., Bradley, B., Croft, S. L., Ward, 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=A+sensitive+and+reproducible+in+vivo+imaging+mouse+model+for+evaluation+of+drugs+against+late-stage+human+African+trypanosomiasis.">A sensitive and reproducible in vivo imaging mouse model for evaluation of drugs against late-stage human African trypanosomiasis.</a> J. Antimicrob. Chemother. 70 (2), 510-517 (2015).</li><li>McLatchie, A. 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=Highly+sensitive+in+vivo+imaging+of+Trypanosoma+brucei+expressing+'red-shifted'+luciferase.">Highly sensitive in vivo imaging of Trypanosoma brucei expressing 'red-shifted' luciferase.</a> PLoS Negl. Trop. Dis. 7 (11), e2571 (2013).</li><li>Jennings, F. W., 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=Human+African+trypanosomiasis:+potential+therapeutic+benefits+of+an+alternative+suramin+and+melarsoprol+regimen.">Human African trypanosomiasis: potential therapeutic benefits of an alternative suramin and melarsoprol regimen.</a> Parasitol. Int. 51 (4), 381-388 (2002).</li><li>Wiles, S., Robertson, B. D., Frankel, G., Kerton, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioluminescent+monitoring+of+in+vivo+colonization+and+clearance+dynamics+by+light-emitting+bacteria.">Bioluminescent monitoring of in vivo colonization and clearance dynamics by light-emitting bacteria.</a> Methods Mol. Biol. 574, 137-153 (2009).</li><li>Rodgers, J., Bradley, B., Kennedy, P. G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combination+chemotherapy+with+a+substance+P+receptor+antagonist+(aprepitant)+and+melarsoprol+in+a+mouse+model+of+human+African+trypanosomiasis.">Combination chemotherapy with a substance P receptor antagonist (aprepitant) and melarsoprol in a mouse model of human African trypanosomiasis.</a> Parasitol. Int. 56 (4), 321-324 (2007).</li><li>Kamerkar, S., Davis, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxoplasma+on+the+brain:+understanding+host-pathogen+interactions+in+chronic+CNS+infection.">Toxoplasma on the brain: understanding host-pathogen interactions in chronic CNS infection.</a> J. Parasitol. Res. 2012, 589295 (2012).</li><li>Franke-Fayard, B., 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=Murine+malaria+parasite+sequestration:+CD36+is+the+major+receptor,+but+cerebral+pathology+is+unlinked+to+sequestration.">Murine malaria parasite sequestration: CD36 is the major receptor, but cerebral pathology is unlinked to sequestration.</a> Proc. Natl. Acad. Sci. U.S.A. 102 (32), 11468-11473 (2005).</li><li>Hitziger, N., Dellacasa, I., Albiger, B., Barragan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissemination+of+Toxoplasma+gondii+to+immunoprivileged+organs+and+role+of+Toll/interleukin-1+receptor+signalling+for+host+resistance+assessed+by+in+vivo+bioluminescence+imaging.">Dissemination of Toxoplasma gondii to immunoprivileged organs and role of Toll/interleukin-1 receptor signalling for host resistance assessed by in vivo bioluminescence imaging.</a> Cell. Microbiol. 7 (6), 837-848 (2005).</li><li>Lewis, M. D., 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=Bioluminescence+imaging+of+chronic+Trypanosoma+cruzi+infections+reveals+tissue-specific+parasite+dynamics+and+heart+disease+in+the+absence+of+locally+persistent+infection.">Bioluminescence imaging of chronic Trypanosoma cruzi infections reveals tissue-specific parasite dynamics and heart disease in the absence of locally persistent infection.</a> Cell. Microbiol. 16 (9), 1285-1300 (2014).</li></ol>

The development of a bioluminescent T. b. brucei GVR35 strain allows the visualization of a trypanosome infection from the early to the late stage. Previous infection models were unable to detect the late stage, when parasites are in the brain, in real time from blood film microscopy, and required the culling and removal of brains from the infected mice to determine parasite burden12. The bioluminescence reduces inter-mouse variability as a single mouse can be tracked throughout the entirety of the in...

Human African trypanosomiasis (HAT), or sleeping sickness, is caused by the vector-borne protozoan parasites of the Trypanosoma brucei spp1. Estimated numbers of current cases is fewer than 7 thousand every year with almost 70 million people exposed to the risk of the parasite infection within the African continent. The disease, which is most often lethal if left untreated, comprises an early hemolymphatic stage where parasites are present in the blood, progressing to the late stage when parasites invade the central nervous system (CNS) and are no longer susceptible to treatment by early stage trypanosomal drugs2. The current drug therapies for late-stage HAT have both complex, prolonged, treatment regimens and severe adverse effects as well as reported resistance, therefore research into new drug therapies is imperative3,4. 
The study of late-stage human African trypanosomiasis (HAT) within traditional mouse models is lengthy and complex, with the removal of brain tissue being required to monitor parasitic burden5. The animal infective strain T. b. brucei is used as the study model of trypanosomiasis with the late stage appearing 21 days post infection (dpi). To monitor the wild type nonbioluminescent parasite infection in the mouse model, peripheral blood films or quantitative PCR are the only methods to determine parasite burden. For parasite burden in the brain, the mouse needs to be culled, brain excised and qPCR carried out on tissues, making it impossible to track parasites through multiple time points in the late stage infection. This results in the inability to follow real-time infections within the central nervous system (CNS). 
In vivo bioluminescence imaging (BLI) can provide highly sensitive, non-invasive detection of parasite dissemination and disease progression in a mouse model that can be followed in a single animal for the entirety of the experiment6. BLI is based on the emission of light in the visible spectrum produced by a luciferase-catalyzed reaction. The emitted photons are then detected by a charge coupled device (CCD) camera7. For this purpose, the pathogen is genetically modified to express a luciferase protein and the substrate, luciferin, is introduced at time points of interest by injection. The main advantage of this method is the ability to carry out longitudinal studies, in which the same animal can be imaged several times with minimal adverse effects. The acquired bioluminescence signal can be quantified, thus indicating the pathogen burden.
The optimization and validation of a red-shifted bioluminescent T. b. brucei has enabled the investigation of the late stage infection through non-invasive procedures, detecting parasites earlier than blood film microscopy and greatly reducing the time, cost and numbers of animals needed to study CNS infection and drug screening in late-stage trypanosomiasis8,9. In this protocol we demonstrate infection of mice with bioluminescent trypanosomes and how to then visualize the parasites in vivo for quantification of disease progression and CNS penetration.

<table border="0" cellpadding="0" cellspacing="0" width="860">
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">PBS</td>
			<td style="width:189px;">Sigma, UK</td>
			<td style="width:155px;">P4417</td>
			<td style="width:283px;">tablets pH 7.4</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Glucose</td>
			<td style="width:189px;">Sigma, UK</td>
			<td style="width:155px;">G8270</td>
			<td style="width:283px;">99.5% (molecular) grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Ammonium chloride</td>
			<td style="width:189px;">Sigma, UK</td>
			<td style="width:155px;">A9434</td>
			<td style="width:283px;">99.5% (molecular) grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Heparin (lithium salt)</td>
			<td style="width:189px;">Sigma, UK</td>
			<td style="width:155px;">H0878</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:233px;">Hi-FCS</td>
			<td style="width:189px;">Gibco, Life Technologies, UK</td>
			<td style="width:155px;">10500-064</td>
			<td style="width:283px;">500 ml</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">DPBS</td>
			<td style="width:189px;">Sigma, UK</td>
			<td style="width:155px;">D4031</td>
			<td style="width:283px;">Sterile filtered</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Mr. Frosty</td>
			<td style="width:189px;">Nalgene, UK</td>
			<td style="width:155px;"></td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Giemsa</td>
			<td style="width:189px;">Sigma, UK</td>
			<td style="width:155px;">G5637</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="44" rowspan="2" style="height:44px;width:233px;">D-Luciferin</td>
			<td style="width:189px;">Perkin Elmer, UK</td>
			<td style="width:155px;"></td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:189px;">Sigma, UK</td>
			<td style="width:155px;">115144-35-9</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Diminazene aceturate</td>
			<td style="width:189px;">Sigma, UK</td>
			<td style="width:155px;">D7770</td>
			<td style="width:283px;">Analytical grade</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:233px;">IVIS Lumina II</td>
			<td style="width:189px;">Perkin Elmer, UK</td>
			<td style="width:155px;"></td>
			<td style="width:283px;">other bioimagers available e.g. from Bruker, Kodak</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:233px;">Living Image v. 4.2</td>
			<td style="width:189px;">Perkin Elmer, UK</td>
			<td style="width:155px;"></td>
			<td style="width:283px;">proprietary software for Perkin Elmer IVIS instruments; other instruments may have their own</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">1 ml syringe</td>
			<td style="width:189px;">Fisher Scientific, UK</td>
			<td>10142104</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">20 ml syringe</td>
			<td style="width:189px;">Fisher Scientific, UK</td>
			<td>10743785</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">25G Needles</td>
			<td style="width:189px;">Greiner Bio-one</td>
			<td>N2516</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">21G Needles</td>
			<td style="width:189px;">Greiner Bio-one</td>
			<td>N2138</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Twin-frosted microscope slide</td>
			<td style="width:189px;">VWR, UK</td>
			<td>631-0117</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">1.5 ml microcentrifuge tube</td>
			<td style="width:189px;">StarLab, UK</td>
			<td>I1415-1000</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">7 ml Bijou tube</td>
			<td style="width:189px;">StarLab, UK</td>
			<td>E1412-0710</td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:233px;">Mouse restrainer</td>
			<td style="width:189px;">Sigma, UK</td>
			<td>Z756903</td>
			<td style="width:283px;">our restrainer was made in-house, this is a similar model</td>
		</tr>
	</tbody>
</table>

bioluminescence imaging to detect late stage infection of african trypanosomiasis

Human African trypanosomiasis (HAT) is a multi-stage disease that manifests in two stages; an early blood stage and a late stage when the parasite invades the central nervous system (CNS). In vivo study of the late stage has been limited as traditional methodologies require the removal of the brain to determine the presence of the parasites.
Bioluminescence imaging is a non-invasive, highly sensitive form of optical imaging that enables the visualization of a luciferase-transfected pathogen in real-time. By using a transfected trypanosome strain that has the ability to produce late stage disease in mice we are able to study the kinetics of a CNS infection in a single animal throughout the course of infection, as well as observe the movement and dissemination of a systemic infection.
Here we describe a robust protocol to study CNS infections using a bioluminescence model of African trypanosomiasis, providing real time non-invasive observations which can be further analyzed with optional downstream approaches.

This protocol demonstrates how to follow disease progression following infection of mice with T. b. brucei, a model for human African trypanosomiasis. Figure 1 shows the timeline of the experimental protocol, demonstrating the timetable for treatment and imaging steps. Figure 2 demonstrates a typical field of view in a fixed Giemsa-stained blood smear used to quantitate peripheral parasitemia, with trypanosomes and red blood cells present. Develo...

Watch this Scientific Journal Video about Bioluminescence Imaging to Detect Late Stage Infection of African Trypanosomiasis at JoVE.com

Bioluminescence Imaging to Detect Late Stage Infection of African Trypanosomiasis

This manuscript describes the use of a bioluminescent strain of African trypanosomes to enable the tracking of late stage infection and demonstrates how in vivo live imaging can be used to visualize infections within the central nervous system in real-time.

Human African trypanosomiasis (HAT) is a multi-stage disease that manifests in two stages; an early blood stage and a late stage when the parasite invades ...

The overall goal of this protocol is to use in vivo live imaging to track a real-time trypanosome infection, visualizing the early blood to the late brain infection stages in the mouse, mimicking the clinical sleeping sickness progression. This method can help answer key questions in the trypanosome biology field, identifying potential new therapeutic treatments and evaluating the efficacy against the infection. The main advantage of this technique is that the drug evaluation can be established in 90 days, as opposed to the 180 days required for the previous role type model.This protocol can provide insight into human African trypanosomiasis but is also applicable to other models of infectious diseases such as tuberculosis or Chagas disease. Begin by placing 21 to 25 gram CD1 female mice into a heating box to dilate the tail veins. Then, place the warmed mice individually into a plastic restraining device and use a 25 gauge needle to inject 0.2 milliliters of diluted innoculum of the trypanosome brucei GVR35VSL2 intravenously into the tail vein, placing pressure at the injection site immediately after to stem the bleeding.To monitor the infection through blood-film microscopy, spot five micro-liters of blood onto a glass slide. Use a second glass slide to gently smear the drop across the first slide, producing a thin film. Allow the slides to air dry and then fix the blood in 100%methanol followed by 10 minutes in Giemsa.At the end of the incubation rinse the slides with distilled water and allow them to air dry. Then, count the number of trypanosomes in 10 fields of view under a 100x subjective. To track the infection by bio luminescent imaging warm an aliquot of D-luciferin to room temperature.Then, use a 25 gauge needle to intraperitoneally inject 150 milligrams per kilogram of the warmed luciferin per animal. Next, initialize the machine using the imager software according to the manufacturer's instructions. Then, when the camera and heated plate have reached the appropriate temperatures, place large black separators between the anesthetized animals to minimize the bleed-through of any bright bio luminescent signal.Image the mice using a series of exposure times with medium binning, one F-stop and an open filter and a field of view E of 12.5 times 12.5 centimeters. To ensure a thorough imaging of the mice, rotate the animals to obtain ventral, dorsal, and lateral views. On day 21 image and blood-film the mice as demonstrated.Then, dose the animals with 40 milligrams per kilogram of diminazine aceturate intraperitoneally to clear the peripheral parasitemia. After imaging the animals on day 35, place the excised brains onto a section of black plastic and pripet 50 micro-liters of 15 milligrams per milliliter of luciferin over the tissues. Then, image the brain using the same settings as demonstrated for the whole animal imaging.To quantify the degree of bio luminescence within specific regions of interest, or ROIs, select the ROI tool within the imaging software and create a rectangular ROI for the whole animal quantitation. Position the ROI over the mouse image from the tip of the nose to the base of the tail, and using the same size box for every animal and every time point, measure the total flux. To evaluate the ROI of the brain alone, create a circular ROI and place it over the animal's head region.Repeat for each animal and measure the total flux. Then, using the image with the highest bio luminescence and the image adjust tab on the tool palette, select a logarithmic scale and an appropriate color scale minimum and maximum for the image and apply this scale to all of the images within the experiment. The infection development can be following in vivo by sequential measurements of the bio luminescence to determine the degree of infection in the animals over the course of an experiment.As the infection progresses, an increase in the bio luminescence can be observed in all of the animals over the first 21 days as the signal becomes more disseminated and intense, with the highest regions of bio luminescence apparent in the spleen area. On day 21, the mice are treated with diminazine aceturate post-imaging, as just demonstrated, resulting in only low levels of bio luminescence present in the brain by day 28, as the peripheral infection is cleared. On day 35, the signal is not only still present in the head region, but has also become more intense, indicating a possible brain infection.Quantitation of both the peripheral parasitemia and bio luminescence allows the evaluation of the disease kinetics. For example, in this experiment, at day 7 a high bio luminescence signal of one times 10 to the 8th photons per second was observed, while the observed parasitemia was very low within the blood films generated on the same day. At day 28, the parasitemia became undetectable in the blood films due to the diminazene aceturate treatment administered on day 21, while the bio luminescence continued to remain above background levels until day 35, representing the bio luminescence observed in the head region and confirming the higher sensitivity of the bio luminescence analysis over the blood filming.Bio uminescence imaging of the brain itself reveals differences in the infection burden between animals, which does not appear to localize to specific anatomical regions of the tissue. While attempting this procedure it's important to remember to obtain a good range of exposure times to ensure quality imaging data, as overexposure, for example, negatively impacts important localization detail. Following this procedure, other downstream methods like quantitative PCR and immunohistochemistry can be performed to answer additional questions about brain parasite burden and parasite localization.After it's development, this technique paved the way for researchers in the field of trypanosome biology to perform drug evaluation within 90 days of infection, due to improved sensitivity of relapse detection. After watching this video, you should have a good understanding of how to use bio luminescence imaging of TB brucei infection to follow the disease progression from the blood to the late stage infection of the brain.

bioluminescence-imaging-to-detect-late-stage-infection-african

Research

JoVE Journal

Immunology and Infection

7.7K Views.  London School of Hygiene & Tropical Diseases. The overall goal of this protocol is to use in vivo live imaging to track a real-time trypanosome infection, visualizing the early blood to the late brain infection stages in the mouse, mimicking the clinical sleeping sickness progression. This method can help answer key questions in the trypanosome biology field, identifying potential new therapeutic treatments and evaluating the efficacy against the infection. The main advantage of this technique is that the drug evaluation can be establish...