Name: evaluation of host-pathogen responses and vaccine efficacy in mice
Uploaded: 2019-02-22T13:30:00
Description: Watch this Scientific Journal Video about Evaluation of Host-Pathogen Responses and Vaccine Efficacy in Mice at JoVE.com

This work was supported by 1R01AI125560-01 and start-up funds from The Ohio State University.

All experiments with live animals were conducted following a protocol approved by The Ohio State University IACUC in accordance with IACUC guidelines. C57BL/6 mice were used in all immunizations and infections. Both male and female mice are used in each group as per NIH guidelines. The number of animals per group was determined by power calculations based on the predicted differences in outcome among experimental groups. For example, 8 mice per group will yield 80% power at &#945; = 0.05 (2-sided) for a 2-sample t</e...

The comprehensive protocol described here to study vaccine-induced immunity to B. pertussis infection will also permit evaluation of host responses to a variety of other pathogens. The protocol discusses methods to deliver immunizations, determine vaccine efficacy following pathogen challenge, and parallel dissection of immune function. In adapting the protocol in order to study other pathogens, several parameters would need to be modified. These include, but are not limited to, the mode of animal anesthesia, va...

Vaccines represent one of the greatest public health achievements of the 20th century, yet we still do not fully understand the mechanisms by which successful vaccines stimulate protective immunity. The identification of molecular signatures (e.g., cell activation markers, expansion of cellular subtypes, and patterns of gene expression) induced after vaccination provides a plethora of information for predicting and generating an efficacious immune response. The complexity of host-pathogen responses cannot be adequately replicated using in vitro cell culture systems1. In vivo vaccine models are designed to concomitantly evaluate multiple immune cell types within the host. This provides an advantage when characterizing vaccine antigen processing and presentation, differential cytokine secretion, and expansion of immune cells. The protocol described here provides a detailed method to determine vaccine efficacy through evaluation of the systemic and local immune responses and quantification of pathogen burden in tissues of interest. The example provided here tests the efficacy of an experimental vaccine for the pathogen Bordetella pertussis (B. pertussis).
B. pertussis is a gram-negative bacterium that is the etiological agent of the respiratory disease whooping cough (pertussis)2,3. Close contact with infected individuals (symptomatic or asymptomatic) leads to transmission, colonization, and disease. Despite significant global vaccine coverage4, pertussis is considered a resurging disease in many nations around the world and is a major cause of preventable childhood deaths5,6,7,8. In 2015, B. pertussis and pertussis were included in the National Institute of Allergy and infectious Diseases (NIAID) emerging infectious pathogen/disease list, emphasizing the need for development of a better vaccine that confers long-lived protective immunity.
Currently, an active area of investigation to control pertussis resurgence is development of a next-generation acellular pertussis vaccine (aPV) with an optimal combination of novel adjuvants and antigens to mimic the immune response elicited by the whole-cell pertussis vaccine (wPV)9. Using the protocol described, we recently reported that the modification of a current FDA-approved aPV by the addition of a novel adjuvant, Bordetella colonization factor A (BcfA), resulted in more efficient reduction of B. pertussis bacterial load from mouse lungs10,11. This increased protection was accompanied by the skewing of an alum-induced Th1/Th2 immune response to the more protective Th1/Th17 immune profile10. This protocol is detailed and comprehensive, enabling the investigator to obtain maximal information through concurrent evaluation of host and immune responses to a variety of pathogens.
The protocol described here follows the representative vaccine schedule, shown in Figure 1, to ensure optimal host immune responses.

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		<tr height="21">
			<td height="21" style="height:21px;width:333px;">2L induction chamber</td>
			<td style="width:175px;">Vet Equip</td>
			<td style="width:119px;">941444</td>
			<td style="width:307px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Fluriso</td>
			<td style="width:175px;">Vet One</td>
			<td style="width:119px;">V1 501017</td>
			<td>any brand is appropriate</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Bordet Gengou Agar Base</td>
			<td style="width:175px;">BD bioscience</td>
			<td style="width:119px;">248200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Casein</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:119px;">C-7078</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Casamino acids</td>
			<td style="width:175px;">VWR</td>
			<td style="width:119px;">J851-500G</td>
			<td>Strainer Scholte (SS) media components</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:333px;">L-Glutamic acid</td>
			<td style="width:175px;">Research Products Int</td>
			<td style="width:119px;">G36020-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">L-Proline</td>
			<td style="width:175px;">Research Products Int</td>
			<td style="width:119px;">P50200-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Sodium Chloride</td>
			<td style="width:175px;">Fisher</td>
			<td style="width:119px;">BP358-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Potassium Phosphate monobasic</td>
			<td style="width:175px;">Fisher</td>
			<td style="width:119px;">BP362-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Potassium Chloride</td>
			<td style="width:175px;">Fisher</td>
			<td style="width:119px;">P217-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Magnesium Chloride hexahydrate</td>
			<td style="width:175px;">Fisher</td>
			<td style="width:119px;">M2670-500G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Calcium Chloride</td>
			<td style="width:175px;">Fisher</td>
			<td style="width:119px;">C75-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Tris base</td>
			<td style="width:175px;">Fisher</td>
			<td style="width:119px;">BP153-1</td>
			<td></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:333px;">L-cysteine HCl</td>
			<td style="width:175px;">Fisher</td>
			<td style="width:119px;">BP376-100</td>
			<td>SS media suplements</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Ferrous Sulfate heptahydrate</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:119px;">F-7002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Niacin</td>
			<td style="width:175px;">Research Products Int</td>
			<td style="width:119px;">N20080-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Glutathione</td>
			<td style="width:175px;">Research Products Int</td>
			<td style="width:119px;">G22010-25</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:333px;">Ascorbic acid</td>
			<td style="width:175px;">Research Products Int</td>
			<td style="width:119px;">A50040-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">RPMI 1640</td>
			<td style="width:175px;">ThermoFisher Scientific</td>
			<td>11875093</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">FBS</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:119px;">F2442-500mL</td>
			<td>&#160;any US source, non-heat inactivated</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">gentamicin</td>
			<td style="width:175px;">ThermoFisher Scientific</td>
			<td>15710064</td>
			<td style="width:307px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">B-mercaptoethanol</td>
			<td style="width:175px;">Fisher&#160;</td>
			<td style="width:119px;">BP176-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">15mL dounce tissue grinder</td>
			<td style="width:175px;">Wheaton</td>
			<td>357544</td>
			<td>any similar brand is appropriate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Cordless Hand Homogenizer</td>
			<td style="width:175px;">Kontes/Sigma&#160;</td>
			<td style="width:119px;">Z359971-1EA</td>
			<td>any similar brand is appropriate</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:333px;">Instruments - scissors, curve scissors, forceps, fine forceps, triangle spreaders</td>
			<td style="width:175px;"></td>
			<td style="width:119px;"></td>
			<td>any brand is appropriate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">3mL syringes</td>
			<td style="width:175px;">BD bioscience</td>
			<td style="width:119px;">309657</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">15mL conical tubes</td>
			<td style="width:175px;">Fisher&#160;</td>
			<td style="width:119px;">339651</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">1.5mL microfuge tubes</td>
			<td style="width:175px;">Denville</td>
			<td style="width:119px;">C2170</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">70um cell strainers</td>
			<td style="width:175px;">Fisher&#160;</td>
			<td style="width:119px;">22363548</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">60mm plates</td>
			<td style="width:175px;">ThermoFisher Scientific</td>
			<td style="width:119px;">130181</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">48-well tissue culture plates</td>
			<td style="width:175px;">ThermoFisher Scientific</td>
			<td>08-772-1C</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:333px;">1mL insulin syringe 28G1/2</td>
			<td style="width:175px;">Fisher Scientific/Excel Int.</td>
			<td style="width:119px;">14-841-31</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Mouse IFN-gamma ELISA Ready-SET-Go! Kit</td>
			<td style="width:175px;">Invitrogen / eBioscience</td>
			<td style="width:119px;">50-173-21</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:333px;">Mouse IL-17 ELISA Ready-SET-Go! Kit</td>
			<td style="width:175px;">Invitrogen / eBioscience</td>
			<td style="width:119px;">50-173-77</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:333px;">Mouse IL-5 ELISA Ready-SET-Go! Kit</td>
			<td style="width:175px;">Invitrogen / eBioscience</td>
			<td style="width:119px;">50-172-09</td>
			<td></td>
		</tr>
	</tbody>
</table>

evaluation of host-pathogen responses and vaccine efficacy in mice

Vaccines are a 20th century medical marvel. They have dramatically reduced the morbidity and mortality caused by infectious diseases and contributed to a striking increase in life expectancy around the globe. Nonetheless, determining vaccine efficacy remains a challenge. Emerging evidence suggests that the current acellular vaccine (aPV) for Bordetella pertussis (B. pertussis) induces suboptimal immunity. Therefore, a major challenge is designing a next-generation vaccine that induces protective immunity without the adverse side effects of a whole-cell vaccine (wPV). Here we describe a protocol that we used to test the efficacy of a promising, novel adjuvant that skews immune responses to a protective Th1/Th17 phenotype and promotes a better clearance of a B. pertussis challenge from the murine respiratory tract. This article describes the protocol for mouse immunization, bacterial inoculation, tissue harvesting, and analysis of immune responses. Using this method, within our model, we have successfully elucidated crucial mechanisms elicited by a promising, next-generation acellular pertussis vaccine. This method can be applied to any infectious disease model in order to determine vaccine efficacy.

The model described shows a method to evaluate vaccine efficiency and immune responses during host-pathogen interactions. Figure 1 depicts the representative vaccine schedule used to immunize and infect mice and harvest tissues for analysis. Figure 2 demonstrates the setup of the anesthesia system employed to induce mice, enabling investigators to deliver immunizations and bacterial inoculums. Figure 3</stron...

Watch this Scientific Journal Video about Evaluation of Host-Pathogen Responses and Vaccine Efficacy in Mice at JoVE.com

Evaluation of Host-Pathogen Responses and Vaccine Efficacy in Mice

Here we present an elegant protocol for in vivo evaluation of vaccine effectiveness and host immune responses. This protocol can be adapted for vaccine models that study viral, bacterial, or parasitic pathogens.

Vaccines are a 20th century medical marvel. They have dramatically reduced the morbidity and mortality caused by infectious diseases and contributed to a ...

The protocol enables the evaluation of host responses to a variety of pathogens and vaccine formulations. The main advantage of this technique is that it allows the evaluation of bacterial burden and immune responses in vivo, using a tractable animal model. Demonstrating this procedure is Kacy Yount, a graduate student from my laboratory.For immunization, confirm a lack of response to toe pinch in an anesthetized, six-to-twelve-week-old mouse, and load a one milliliter insulin syringe, equipped with a 28.5 gauge needle with a 0.1 milliliter of the vaccine of interest. Holding the syringe at a 45 degree angle, with the bevel facing up, insert the needle approximately five millimeters into the deltoid of the mouse, and inject the vaccine. Keep the needle inserted in the muscle for five to ten seconds, then rotate the syringe 180 degrees, so that the bevel is facing down to create a seal, and to prevent vaccine leakage, before slowly retracting the needle from the injection site.Then return the mouse to its cage, with monitoring, until full recovery. About two weeks after boosting, infect immunized mice. Grasp an anesthetized mouse by the scruff of the dorsal thorax, behind the shoulder blades and neck, and position the mouse upright to access the nose.Using a 200 microliter pipette tip, slowly apply 20 to 25 microliters of the bacterial inoculum of interest to each nare of the animal, holding the mouse until the entire inoculum has been inhaled. Then deliver an equal volume of sterile PBS to one group of mice as a negative control. At the appropriate experimental end point, place an infected mouse ventral side up on a dissection board, and secure the limbs.Wet the body with 70%ethanol, and use forceps to clasp the skin below the abdomen in the center of the pelvis. Using sharp scissors, make a vertical cut up to the mandible, and dissect the skin from the peritoneal wall. Move the skin to the sides of the carcass to create an unobstructed field for sterile organ harvest, and grasp the intact peritoneum below the ribcage, at or near the liver.Cut the peritoneum toward the ribcage to expose the lower digestive tract, and move the colon to the left to reveal the spleen. Using curved forceps, grasp the spleen, and dissect away the connective tissue with scissors. Then place the spleen in a 15 milliliter conical tube containing 3 milliliters of RPMI, and 5%fetal bovine serum on ice.Use forceps to stabilize the ribcage at the xyphoid process, and cut open the diaphragm. The lungs should deflate, and fall towards the spine. Cut open the ribcage at the sides to remove the breastplate, and cut the pulmonary arteries and veins to isolate and remove the superior lobe of the right lung.Fix the lobe in a 15 milliliter conical tube of 10%neutral buffered formalin at room temperature for at least 24 hours, and isolate the remaining lobes of the right and left lungs. Then place lobes in a 15 milliliter conical tube, containing two milliliters of 1%casein in PBS on ice. Use a one milliliter pipetman with tip to collect the blood filling the chest cavity, and transfer the blood into a pre-labeled 1.5 milliliter microcentrifuge tube on ice.Remove the parotid, sublingual, and submaxillary glands and lymph nodes covering the trachea, and open and remove the protective membranes surrounding the trachea. Using fine forceps and scissors, carefully separate the trachea from the esophagus, and any other connective tissue from the top of the collarbones to the bottom of the mandible. Use forceps to hold the trachea, and cut the trachea at top of the clavicle.Pull down the trachea to maximize the elasticity, and cut the trachea at the bottom of the mandible, right above the larynx, isolating about one centimeter of tissue. Then place the organ in a pre-labeled 1.5 milliliter microcentrifuge tube, containing 0.3 milliliters of 1%casein in PBS on ice. Now turn the mouse for clear access to the nose, and spray the head with 70%ethanol.Manually grasp the animal directly behind the skull, and use scissors to cut away the soft flesh of the snout, starting from the bottom of the nose and moving upward. Remove the fur, skin, and whiskers from around the nose, and insert the tips of a curved pair of scissors into the nares with the curves pointed downward. Cut open the nasal passage towards the eyes, creating a V-like formation.Then use fine forceps to collect the nasal septum, and soft tissue within the formation, and place the tissue in a pre-labeled 1.5 milliliter microcentrifuge tube containing 0.3 milliliters of 1%casein in PBS, on ice. To process the lung tissue, transfer the entire lung sample tube contents into a sterile 15 milliliter Dounce homogenizer, and use a pestle to homogenize the tissue. Dissociate the sample until no large particles of tissue remain, and return the homogenized suspension to the original 15 milliliter tube.Remove a 0.3 milliliter aliquot for plating colony forming units, and collect the rest of the homogenate by centrifugation. Aliquot 0.5 milliliters of supernatant into pre-labeled microcentrifuge tubes for storage at 20 degrees Celsius until cytokine expression analysis by Eliza. Then, serially dilute 0.1 milliliter aliquots of the set aside homogenized lung suspension in 0.9 milliliters of sterile PBS per dilution, and use a sterile triangle spreader to plate 0.1 milliliter of each empirically chosen dilution onto pre-labeled 10%Bordet-Gengou plus streptomycin plates.Here, representative optical density 600 measurements and calculations to achieve a one optical density bacterial suspension, to prepare a one hundredfold diluted bacterial inoculum to be delivered to mice, are shown. After seven days of vaccine antigen stimulation, immunized spleen cells from the combination vaccine group produce interferon gamma, and IL17, while significantly down regulating IL5, promoting a T helper, one T helper 17 polarization of the immune response during a B pertussis infection. Colony forming unit enumeration of bacteria recovered from respiratory tract issues of a B pertussis infected mouse can be used to assess the protective effects of the vaccine of interest.Work as quickly and as efficiently as possible in order to avoid tissue necrosis, and store the isolated tissue on ice to preserve the viability of the recovered bacteria. ELISpot flow cytometry and DNA and RNA isolation can be performed to evaluate immune cells, analyte production, and to enable epigenetic and transcriptomic analyses. When working with infectious agents such as Bordetella pertussis, it's important to remember to wear the appropriate PPE, and work in a certified biosafety cabinet in order prevent pathogen transmission.This protocol details CFU enumeration from the respiratory tract, specifically the nasal pharynx. To address questions in the vaccine and infectious disease fields about targeting bacterial colonization in the nose.

evaluation-of-host-pathogen-responses-and-vaccine-efficacy-in-mice

Research

JoVE Journal

Immunology and Infection

Use of an Optical Trap for Study of Host-Pathogen Interactions for Dynamic Live Cell Imaging

Dynamic live cell imaging allows direct visualization of real-time interactions between cells of the immune system1, 2; however, the lack of spatial and temporal control between the phagocytic cell and microbe has rendered focused observations into the initial interactions of host response to pathogens difficult. Historically, intercellular contact events such as phagocytosis3 have been imaged by mixing two cell types, and then continuously scanning the field-of-view to find serendipitous intercellular contacts at the appropriate stage of interaction. The stochastic nature of these events renders this process tedious, and it is difficult to observe early or fleeting events in cell-cell contact by this approach. This method requires finding cell pairs that are on the verge of contact, and observing them until they consummate their contact, or do not. To address these limitations, we use optical trapping as a non-invasive, non-destructive, but fast and effective method to position cells in culture.
Optical traps, or optical tweezers, are increasingly utilized in biological research to capture and physically manipulate cells and other micron-sized particles in three dimensions4. Radiation pressure was first observed and applied to optical tweezer systems in 19705, 6, and was first used to control biological specimens in 19877. Since then, optical tweezers have matured into a technology to probe a variety of biological phenomena8-13.
We describe a method14 that advances live cell imaging by integrating an optical trap with spinning disk confocal microscopy with temperature and humidity control to provide exquisite spatial and temporal control of pathogenic organisms in a physiological environment to facilitate interactions with host cells, as determined by the operator. Live, pathogenic organisms like Candida albicans and Aspergillus fumigatus, which can cause potentially lethal, invasive infections in immunocompromised individuals15, 16 (e.g. AIDS, chemotherapy, and organ transplantation patients), were optically trapped using non-destructive laser intensities and moved adjacent to macrophages, which can phagocytose the pathogen. High resolution, transmitted light and fluorescence-based movies established the ability to observe early events of phagocytosis in living cells. To demonstrate the broad applicability in immunology, primary T-cells were also trapped and manipulated to form synapses with anti-CD3 coated microspheres in vivo, and time-lapse imaging of synapse formation was also obtained. By providing a method to exert fine spatial control of live pathogens with respect to immune cells, cellular interactions can be captured by fluorescence microscopy with minimal perturbation to cells and can yield powerful insight into early responses of innate and adaptive immunity.

A method is described to individually select, manipulate, and image live pathogens using an optical trap coupled to a spinning disk microscope. The optical trap provides spatial and temporal control of organisms and places them adjacent to host cells. Fluorescence microscopy captures dynamic intercellular interactions with minimal perturbation to cells.

Dynamic live cell imaging allows direct visualization of real-time interactions between cells of the immune system1, 2; however, the lack of spatial and ...

Use of the EpiAirway Model for Characterizing Long-term Host-pathogen Interactions

Nontypeable Haemophilus influenzae (NTHi) are human-adapted Gram-negative bacteria that can cause recurrent and chronic infections of the respiratory mucosa 1; 2. To study the mechanisms by which these organisms survive on and inside respiratory tissues, a model in which successful long-term co-culture of bacteria and human cells can be performed is required. We use primary human respiratory epithelial tissues raised to the air-liquid interface, the EpiAirway model (MatTek, Ashland, MA). These are non-immortalized, well-differentiated, 3-dimensional tissues that contain tight junctions, ciliated and nonciliated cells, goblet cells that produce mucin, and retain the ability to produce cytokines in response to infection. 
This biologically relevant in vitro model of the human upper airway can be used in a number of ways; the overall goal of this method is to perform long-term co-culture of EpiAirway tissues with NTHi and quantitate cell-associated and internalized bacteria over time. As well, mucin production and the cytokine profile of the infected co-cultures can be determined. This approach improves upon existing methods in that many current protocols use submerged monolayer or Transwell cultures of human cells, which are not capable of supporting bacterial infections over extended periods3. For example, if an organism can replicate in the overlying media, this can result in unacceptable levels of cytotoxicity and loss of host cells, arresting the experiment. The EpiAirway model allows characterization of long-term host-pathogen interactions. Further, since the source for the EpiAirway is normal human tracheo-bronchial cells rather than an immortalized line, each is an excellent representation of actual human upper respiratory tract tissue, both in structure and in function4.
For this method, the EpiAirway tissues are weaned off of anti-microbial and anti-fungal compounds for 2 days prior to delivery, and all procedures are performed under antibiotic-free conditions. This necessitates special considerations, since both bacteria and primary human tissues are used in the same biosafety cabinet, and are co-cultured for extended periods.

This method allows characterization of extended bacterial co-culture with EpiAirways, primary human respiratory epithelial tissue grown at the air-liquid interface, a biologically relevant in vitro model. The approach can be used with any microbe that is amenable to long-term co-culture.

Nontypeable Haemophilus influenzae  (NTHi) are human-adapted Gram-negative bacteria that can cause recurrent and chronic infections of the respiratory ...

A Comparative Approach to Characterize the Landscape of Host-Pathogen Protein-Protein Interactions

Significant efforts were gathered to generate large-scale comprehensive protein-protein interaction network maps. This is instrumental to understand the pathogen-host relationships and was essentially performed by genetic screenings in yeast two-hybrid systems. The recent improvement of protein-protein interaction detection by a Gaussia luciferase-based fragment complementation assay now offers the opportunity to develop integrative comparative interactomic approaches necessary to rigorously compare interaction profiles of proteins from different pathogen strain variants against a common set of cellular factors.
This paper specifically focuses on the utility of combining two orthogonal methods to generate protein-protein interaction datasets: yeast two-hybrid (Y2H) and a new assay, high-throughput Gaussia princeps protein complementation assay (HT-GPCA) performed in mammalian cells.
A large-scale identification of cellular partners of a pathogen protein is performed by mating-based yeast two-hybrid screenings of cDNA libraries using multiple pathogen strain variants. A subset of interacting partners selected on a high-confidence statistical scoring is further validated in mammalian cells for pair-wise interactions with the whole set of pathogen variants proteins using HT-GPCA. This combination of two complementary methods improves the robustness of the interaction dataset, and allows the performance of a stringent comparative interaction analysis. Such comparative interactomics constitute a reliable and powerful strategy to decipher any pathogen-host interplays.

This article focuses on the identification of high-confident interaction datasets between host and pathogen proteins using a combination of two orthogonal methods: yeast two-hybrid followed by a high-throughput interaction assay in mammalian cells called HT-GPCA.

Significant efforts were gathered to generate  large-scale comprehensive protein-protein interaction network maps. This is  instrumental to understand the ...

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. typhimurium bacteria are quickly detected and phagocytized by macrophages, and contained in vesicles known as phagosomes in order to be degraded. Isolation of S. typhimurium-containing phagosomes have been widely used to study how S. typhimurium infection alters the process of phagosome maturation to prevent bacterial degradation. Classically, the isolation of bacteria-containing phagosomes has been performed by sucrose gradient centrifugation. However, this process is time-consuming, and requires specialized equipment and a certain degree of dexterity. Described here is a simple and quick method for the isolation of S. typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin-streptavidin-conjugated magnetic beads. Phagosomes obtained by this method can be suspended in any buffer of choice, allowing the utilization of isolated phagosomes for a broad range of assays, such as protein, metabolite, and lipid analysis. In summary, this method for the isolation of S. typhimurium-containing phagosomes is specific, efficient, rapid, requires minimum equipment, and is more versatile than the classical method of isolation by sucrose gradient-ultracentrifugation.

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

We describe here a simple and quick method for the isolation of Salmonella typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin and streptavidin.

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. ...

A Suction Blister Protocol to Study Human T-cell Recall Responses In Vivo

Cutaneous antigen-recall models allow for studies of human memory responses in vivo. When combined with skin suction blister (SB) induction, this model offers accessibility to rare populations of antigen-specific T-cells representative of the cellular memory response as well as the cytokine microenvironment in situ.
This report describes the practical procedure of a cutaneous recall, an SB induction, and a harvest of antigen-specific T-cells. To exemplify the method, the tuberculin skin test is used for antigenic recall in individuals who, prior to this study, underwent a Bacillus Calmette-Gu&#233;rin vaccination against an infection with Mycobacterium tuberculosis. Finally, examples of multiplex and flow cytometric analyses of SB specimens are provided, illustrating high fractions of antigen-specific polyfunctional CD4+ T-cells available by this sampling method compared with cells isolated from the blood.
The method described here is safe and minimally invasive, provides a unique opportunity to study both innate and adaptive immune responses in vivo, and may be beneficial to a broad community of researchers working with cell-mediated immunity and human memory responses, in the context of vaccine development.

A Suction Blister Protocol to Study Human T-cell Recall Responses In Vivo

Here, we provide a demonstration of the suction blister cutaneous recall model. The model allows a simple access to study human in vivo adaptive immune responses, for instance in the context of vaccine development.

Cutaneous antigen-recall models allow for studies of human memory responses in vivo. When combined with skin suction blister (SB) induction, this model ...

Characterization of Thymus-dependent and Thymus-independent Immunoglobulin Isotype Responses in Mice Using Enzyme-linked Immunosorbent Assay

Antibodies, also termed as immunoglobulins (Ig), secreted by differentiated B lymphocytes, plasmablasts/plasma cells, in humoral immunity provide a formidable defense against invading pathogens via diverse mechanisms. One major goal of vaccination is to induce protective antigen-specific antibodies to prevent life-threatening infections. Both thymus-dependent (TD) and thymus-independent (TI) antigens can elicit robust antigen-specific IgM responses and can also induce the production of isotype-switched antibodies (IgG, IgA and IgE) as well as the generation of memory B cells with the help provided by antigen presenting cells (APCs). Here, we describe a protocol to characterize TD and TI Ig isotype responses in mice using enzyme-linked immunosorbent assay (ELISA). In this protocol, TD and TI Ig responses are elicited in mice by intraperitoneal (i.p.) immunization with hapten-conjugated model antigens TNP-KLH (in alum) and TNP-polysaccharide (in PBS), respectively. To induce TD memory response, a booster immunization of TNP-KLH in alum is given at 3 weeks after the first immunization with the same antigen/adjuvant. Mouse sera are harvested at different time points before and after immunization. Total serum Ig levels and TNP-specific antibodies are subsequently quantified using Ig isotype-specific Sandwich and indirect ELISA, respectively. In order to correctly quantify the serum concentration of each Ig isotype, the samples need to be appropriately diluted to fit within the linear range of the standard curves. Using this protocol, we have consistently obtained reliable results with high specificity and sensitivity. When used in combination with other complementary methods such as flow cytometry, in vitro culture of splenic B cells and immunohistochemical staining (IHC), this protocol will allow researchers to gain a comprehensive understanding of antibody responses in a given experimental setting.

In this paper, we describe a protocol to characterize T-dependent and T-independent immunoglobulin (Ig) isotype responses in mice using ELISA. This method used alone or in combination with flow cytometry will allow researchers to identify differences in B cell-mediated Ig isotype responses in mice following T-dependent and T-independent antigen immunization.

Antibodies, also termed as immunoglobulins (Ig), secreted by differentiated B lymphocytes, plasmablasts/plasma cells, in humoral immunity provide a ...

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1-/- Mice

The Zika virus (ZIKV) can induce inflammation in immunoprivileged organs (e.g., the brain and testis), leading to the Guillain-Barr&#233; syndrome and damaging the testes. During an infection with the ZIKV, immune cells have been shown to infiltrate into the tissues. However, the cellular mechanisms that define the protection and/or immunopathogenesis of these immune cells during a ZIKV infection are still largely unknown. Herein, we describe methods to evaluate the virus-specific T-cell functionality in these immunoprivileged organs of ZIKV-infected mice. These methods include a) a ZIKV infection and vaccine inoculation in Ifnar1-/- mice; b) histopathology, immunofluorescence, and immunohistochemistry assays to detect the virus infection and inflammation in the brain, testes, and spleen; c) the preparation of a tetramer of ZIKV-derived T-cell epitopes; d) the detection of ZIKV-specific T cells in the monocytes isolated from the brain, testes, and spleen. Using these approaches, it is possible to detect the antigen-specific T cells that have infiltrated into the immunoprivileged organs and to evaluate the functions of these T cells during the infection: potential immune protection via virus clearance and/or immunopathogenesis to exacerbate the inflammation. These findings may also help to clarify the contribution of T cells induced by the immunization against ZIKV.

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1-/- Mice

A protocol to evaluate antigen-specific T-cell responses in the immunoprivileged organs of the Ifnar1-/- murine model for the Zika virus (ZIKV) infection is described. This method is pivotal for investigating the cellular mechanisms of the protection and immunopathogenesis of ZIKV vaccines and is also valuable for their efficacy evaluation.

The Zika virus (ZIKV) can induce inflammation in immunoprivileged organs (e.g., the brain and testis), leading to the Guillain-Barr&#233; syndrome and ...

Infection of Zebrafish Larvae with Aspergillus Spores for Analysis of Host-Pathogen Interactions

Invasive aspergillosis (IA) is one of&#160;the most common fungal infections among immunocompromised individuals. Despite the availability of antifungal drugs, IA can cause &#62;50% mortality in infected immunocompromised patients. It is crucial to determine both host and pathogen factors that contribute to infection susceptibility and low survival rates in infected patients in order to develop novel therapeutics. Innate immune responses play a pivotal role in recognition and clearance of Aspergillus spores, though little is known about the exact cellular and molecular mechanisms. Reliable models are required to investigate detailed mechanistic interactions between the host and pathogen. The optical clarity and genetic tractability of zebrafish larvae make them an intriguing model&#160;to study host-pathogen interactions of multiple human bacterial and fungal infections in a live and intact host. This protocol describes a larval zebrafish Aspergillus infection model. First, Aspergillus spores are isolated and injected into the zebrafish hindbrain ventricle via microinjection. Then, chemical inhibitors such as immunosuppressive drugs are added directly to the larval water. Two methods to monitor the infection in injected larvae are described, including the 1) homogenization of larvae for colony forming unit (CFU) enumeration and 2) a repeated, daily live imaging setup. Overall, these techniques can be used to mechanistically analyze the progression of Aspergillus infection in vivo and can be applied to different host backgrounds and Aspergillus strains to interrogate host-pathogen interactions.

Infection of Zebrafish Larvae with Aspergillus Spores for Analysis of Host-Pathogen Interactions

This protocol describes an Aspergillus infection model in zebrafish larvae. Aspergillus spores are microinjected into the hindbrain of larvae, and chemical treatment is used to induce immunosuppression. Infection progression is monitored via a daily imaging setup to monitor fungal growth and immune responses as well as enumeration of live spores by colony forming unit plating.

Invasive aspergillosis (IA) is one of&#160;the most common fungal infections among immunocompromised individuals. Despite the availability of antifungal ...

Label-Free Quantitative Proteomics Workflow for Discovery-Driven Host-Pathogen Interactions

The technological achievements of mass spectrometry (MS)-based quantitative proteomics opens many undiscovered avenues for analyzing an organism&#8217;s global proteome under varying conditions. This powerful strategy applied to the interactions of microbial pathogens with the desired host comprehensively characterizes both perspectives towards infection. Herein, the workflow describes label-free quantification (LFQ) of the infectome of Cryptococcus neoformans, a fungal facultative intracellular pathogen that is the causative agent of the deadly disease cryptococcosis, in the presence of immortalized macrophage cells. The protocol details the proper protein preparation techniques for both pathogen and mammalian cells within a single experiment, resulting in appropriate peptide submission for liquid-chromatography (LC)-MS/MS analysis. The high throughput generic nature of LFQ allows a wide dynamic range of protein identification and quantification, as well as transferability to any host-pathogen infection setting, maintaining extreme sensitivity. The method is optimized to catalogue extensive, unbiased protein abundance profiles of a pathogen within infection-mimicking conditions. Specifically, the method demonstrated here provides essential information on C. neoformans pathogenesis, such as protein production necessary for virulence and identifies critical host proteins responding to microbial invasion.

Here, we present a protocol to profile the interplay between host and pathogen during infection by mass spectrometry-based proteomics. This protocol uses label-free quantification to measure changes in protein abundance of both host (e.g., macrophages) and pathogen (e.g., Cryptococcus neoformans) in a single experiment.

The technological achievements of mass spectrometry (MS)-based quantitative proteomics opens many undiscovered avenues for analyzing an organism&#8217;s ...

Double Labeling Immunofluorescence using Antibodies from the Same Species to Study Host-Pathogen Interactions

Nowadays, it is possible to find a wide range of molecular tools available to study parasite-host cell interactions. However, some limitations exist to obtain commercial monoclonal or polyclonal antibodies that recognize specific cell structures and proteins in parasites. Besides, there are few commercial antibodies available to label trypanosomatids. Usually, polyclonal antibodies against parasites are prepared in-house and could be more challenging to use in combination with other antibodies produced in the same species. Here, the protocol demonstrates how to use polyclonal and monoclonal antibodies raised in the same species to perform double labeling immunofluorescence to study host cell and pathogen interactions. To achieve the double labeling immunofluorescence, it is crucial to incubate first the mouse polyclonal antibody and then follow the incubation with the secondary mouse IgG antibody conjugated to any fluorochrome. After that, an additional blocking step is necessary to prevent any trace of the primary antibody from being recognized by the next secondary antibody. Then, a mouse monoclonal antibody and its specific IgG subclass secondary antibody conjugated to a different fluorochrome are added to the sample at the appropriate times. Additionally, it is possible to perform triple labeling immunofluorescence using a third antibody raised in a different species. Also, structures such as nuclei and actin can be stained subsequently with their specific compounds or labels. Thus, these approaches presented here can be adjusted for any cell whose sources of primary antibodies are limited.

Here, the protocol describes how to perform double labeling immunofluorescence using primary antibodies raised in the same species to study host-pathogen interactions. Also, it can include the third antibody from a different host in this protocol. This approach can be made in any cell type and pathogens.

Nowadays, it is possible to find a wide range of molecular tools available to study parasite-host cell interactions. However, some limitations exist to ...