The authors acknowledge the help from the staff of Laboratory Animal Medicine, University of Nevada, Reno. MM received funding from Nevada INBRE.

The protocol (Number-00682) outlined below is approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Nevada Reno and follows the guidelines of the University of Nevada, Reno&#39;s animal research ethics committee. Briefly, mice were anesthetized with isoflurane and a nose cone was used for maintaining continuous isoflurane levels for 20 min. A vet ointment was used to prevent drying of eyes under anesthesia. Toe pinch was used to ascertain the anesthesia level and breathing rate was measured throughout the procedure. Mice were kept in individual cages and monitored until consciousness was regained. Mice were used only once for tick feeding and were euthanized post tick recovery. Euthanasia was carried out by the Laboratory of Animal Medicine staff personnel. CO2 and cervical dislocation were used for euthanizing animals.
NOTE: Working on ticks requires use of complete personal protective equipment. For counting immature ticks, wear white lab coats, long nitrile gloves to cover the sleeve opening of the lab coat capped with rubber bands, and closed-toe shoes. For infesting mice with ticks, use a hair net, disposable coveralls, long-sleeved gloves over the sleeves, and foot covers. Use white or light colored coveralls to detect wayward ticks. Periodically check gloves and sleeves for ticks.
1. Preparing Room for Animal Housing
<ol>
	<li>Designate a separate room to house mice infested with ticks. Place a sticky mat or double-sided carpet tape outside and inside the door to prevent accidental tick escape.</li>
</ol>
2. Counting Ticks for Mouse Infestation
<ol>
	<li>Put double-sided tape all around the top edges of a 7&#34; x 5&#34; x 14&#34; plastic container and fill with water to approximately 2 cm.</li>
	<li>Place another small box or Petri dish in the center of the container and fill with water to 1 cm creating a &#34;moat&#34; around this container</li>
	<li>Store the vial containing larvae or nymphs inside the Petri dish.</li>
	<li>Use a fine paint brush to remove larvae or nymphs from the vial and count under the microscope. Count 50 larvae or 25 nymphs into separate scintillation vials. Cover the vials immediately with nylon mesh or organdy cloth screen and close with rubber bands.</li>
</ol>
3. Infesting Mice with Immature Ticks
<ol>
	<li>Use a white or light colored work bench and stick double-sided tape around the perimeter of the work area.</li>
	<li>Anesthetize mouse with isoflurane. Check level of anesthesia by toe pinch. Once anesthetized, transfer the mouse to a heating pad covered with paper towels and attach to a nose cone for continued isoflurane supply.</li>
	<li>Apply petroleum jelly-based eye ointment to avoid dryness. Note the breathing pattern of the mouse to adjust isoflurane levels (80 - 230 breaths per min is normal., Reduce isoflurane level if breathing rate is less than 80 breaths per min to avoid killing the animal).</li>
	<li>Take one vial of 50 larvae or 25 nymphs and place ticks under the fur on the head between the ears with a paint brush (Figure 1). Keep mouse under anesthesia for 20 min following placement to give enough time for ticks to attach.</li>
	<li>Move the mouse to a standard, plastic shoe box-type disposable mouse cage with static lids and white bedding. Provide toys, water, and food ad libitum as per normal mouse care.</li>
	<li>Store the mouse cage within a larger rat or gerbil cage lined with double-sided sticky tape around top edges. Fill the outer cage with 3 cm of water (Figure 2).</li>
</ol>
4. Collecting Ticks from Mice
<ol>
	<li>Immature ticks detach between days 3 and 6 of feeding. Check the cages and water moat for engorged ticks every day after day 3.</li>
	<li>Collect detached ticks from the cage between days 4 and 6. Use a paint brush or soft forceps for picking up engorged ticks and store in clean scintillation vials capped with nylon mesh cloth secured with rubber bands.</li>
	<li>Anesthetize and check mouse on day 7 for any remaining attached ticks.</li>
	<li>Check the bedding, food trough, and water bottle for engorged ticks on day 7. Euthanize mice following the procedure as described above. Autoclave the disposable cages, bedding, water bottle, and food trough to avoid any escaping unfed ticks.</li>
</ol>
5. Storage of Fed Ticks
<ol>
	<li>Maintain engorged ticks at 90% humidity, 20 &#176;C, and a 12:12 light:dark cycle in a humidity and temperature controlled incubator until molting occurs. This may take approximately 12 to 18 weeks to occur.</li>
	<li>While high humidity promotes tick survival, it also makes the ticks prone to fungal overgrowth. Check the fed ticks under the microscope at least once a week for mold. If detected, wash survivors in 70% ethanol for 5 min., rinse in water, transfer to a filter paper to dry, and transfer to new, clean vials.</li>
</ol>

<ol>
	<li>Gleim, E. R., 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=Factors+associated+with+tick+bites+and+pathogen+prevalence+in+ticks+parasitizing+humans+in+Georgia,+USA.">Factors associated with tick bites and pathogen prevalence in ticks parasitizing humans in Georgia, USA.</a> Parasites &amp;amp; Vectors. 9 (125), 1-13 (2016).</li><li>Krober, T., Guerin, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+feeding+assays+for+hard+ticks.">In vitro feeding assays for hard ticks.</a> Trends Parasitol. 23 (9), 445-449 (2007).</li><li>Kuhnert, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feeding+of+Hard+Ticks+In+Vitro:+New+Perspectives+for+Rearing+and+for+the+Identification+of+Systemic+Acaricides.">Feeding of Hard Ticks In Vitro: New Perspectives for Rearing and for the Identification of Systemic Acaricides.</a> ALTEX. 13 (2), 76-87 (1996).</li><li>Voigt, W. 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=In+vitro+feeding+of+instars+of+the+ixodid+tick+Amblyomma+variegaturn+on+skin+membranes+and+its+application+to+the+transmission+of+Theileria+mutans+and+Cowdria+ruminantium.">In vitro feeding of instars of the ixodid tick Amblyomma variegaturn on skin membranes and its application to the transmission of Theileria mutans and Cowdria ruminantium.</a> Parasitol. 107, 257-263 (1993).</li><li>Gregson, J. D., Smith, C. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ticks.">Ticks.</a> Insect Colonization and Mass Production. , 49-72 (1966).</li><li>Sonenshine, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biology of Ticks. 2, (1993).</li><li>Bouchard, K. R., Wikel, S. K., Marquaedt, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Care,+maintenance,+and+experimental+infestation+of+ticks+in+the+laboratory+setting.">Care, maintenance, and experimental infestation of ticks in the laboratory setting.</a> Biology of Disease Vectors. , 705-711 (2005).</li><li>Schumaker, T. S., Barros, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Life+cycle+of+Ornithodoros+(Alectorobius)+talaje.+(Acari:Argasidae)+in+laboratory.">Life cycle of Ornithodoros (Alectorobius) talaje. (Acari:Argasidae) in laboratory.</a> J Med Entomol. 32, 249-254 (1995).</li><li>Banks, C. W., Oliver, J. H., Hopla, C. E., Dotson, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laboratory+life+cycle+of+Ixodes+woodi+(Acari:Ixodidae).">Laboratory life cycle of Ixodes woodi (Acari:Ixodidae).</a> J. Med. Entomol. 35, 177-179 (1998).</li><li>James, A. M., Oliver, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feeding+and+host+preference+of+immature+Ixodes+dammini,I.scapularis,and+I.pacificus.(Acari:Ixodidae).">Feeding and host preference of immature Ixodes dammini,I.scapularis,and I.pacificus.(Acari:Ixodidae).</a> J. Med. Entomol. 27, 324-330 (1990).</li></ol>

The authors have nothing to disclose.

Critical Steps within the Protocol
It is important to have several levels of safety measures when rearing ticks to avoid accidental escape. Use of sticky tape and a water moat are critical to ensure safety. It is important to keep the anesthetized mouse on a heating pad to keep the body temperature constant. We also found that shaving the mouse does not provide any extra benefit for tick attachment. An individual mouse can be kept in the same cage for one week in a designated &#34;tick room&#34; ...

Ticks are obligate hematophagous ectoparasites of vertebrates and are distributed worldwide. In the United States, at least 11 species of ticks are vectors of pathogens of public health importance1. Ixodes scapularis is responsible for transmission of several pathogens such as the causative agents of Lyme disease (Borrelia burgdorferi) relapsing fever (B. miyamotoi), human granulocytic anaplasmosis (Anaplasma phagocytophilum), and babesiosis (Babesia spp.). Despite the importance of I. scapularis as a disease vector, collecting these arachnids in abundance from the wild for studies in the lab is not always feasible. Therefore, the production of healthy laboratory-reared ticks is essential to studies on tick biology, and tick-pathogen interactions.
The life cycle of all hard ticks (family Ixodidae), including I. scapularis, consists of the egg and three active stages: larva, nymph, and adult. Each active stage feeds on a vertebrate host. The complex interactions that take place between ticks and their hosts over several days of attachment and feeding are nearly impossible to replicate using artificial feeders, and are unlikely to provide enough numbers of fed ticks for mass rearing2,3,4. Therefore, live mice and rabbits are used most frequently as hosts for rearing immature (larvae and nymphs), and mature stages (adults) of ticks, respectively. The requirement of multiple hosts for blood feeding during each developmental stage complicates tick rearing, and is time and cost intensive5,6,7. Most tick rearing protocols require keeping mice in a suspended wire grid floor cage7,8 or in a cylindrical cage of such dimensions that the animal cannot move freely and groom itself6,9,10.
These cylindrical cages are later transferred to a shoebox cage with a wire grid. Engorged, detached ticks are then collected from the water underneath. However, this method results in exposing fed ticks to water contaminated with urine and feces that can increase fungal growth and tick mortality9. In addition, it increases the possibility of tick escape from the water trough, as well as causing stress to mice. To circumvent these problems, we here demonstrate larval tick feeding on mice within plastic shoebox-type disposable cages. This method allows the normal behavior of mice, increases engorged tick recovery, and decreases tick mortality due to contamination.

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rearing ixodes scapularis, the black-legged tick: feeding immature stages on mice

Ixodes scapularis, the vector of Lyme disease, is one of the most important disease vectors in the eastern and Midwestern United States. This species is a three host tick that requires a blood meal from a vertebrate host for each development stage, and the adult females require a blood meal for reproduction. Larval ticks attach to their host for 3 - 5 days for feeding and drop off the host when fully engorged. This dependency on several different hosts and the lengthy attachment time for engorgement complicates tick rearing in the laboratory setting. However, to understand tick biology and tick-pathogen interactions, the production of healthy, laboratory-reared ticks is essential. Here, we demonstrate a simple, cost-effective protocol for immature tick feeding on mice. We modified the existing protocols for decreased stress on mice and increased tick feeding success and survival by using disposable cages without mesh bottoms to avoid contact of ticks with water contaminated with mice urine and feces.

We modified existing tick rearing protocols6,10 for improved feeding efficiency and reduced stress on the mouse host. The results demonstrate that the standard shoebox style mouse cages are well suited for tick rearing. The white bedding provided a good contrast for easy collection of fed ticks. Most ticks climbed up the walls of the containers after feeding and were easy to collect. In addition, the tight fitted lid of the dispos...

Watch this Scientific Journal Video about Rearing Ixodes scapularis, the Black-legged Tick: Feeding Immature Stages on Mice at JoVE.com

Rearing Ixodes scapularis, the Black-legged Tick: Feeding Immature Stages on Mice

The production of healthy laboratory-reared ticks is essential to studies on tick biology, and tick-pathogen interactions. Here we demonstrate a simple protocol for immature tick feeding that is cost-effective and less stressful to mice.

Rearing Ixodes scapularis, the Black-legged Tick: Feeding Immature Stages on Mice

Ixodes scapularis, the vector of Lyme disease, is one of the most important disease vectors in the eastern and Midwestern United States. This species is a ...

rearing-ixodes-scapularis-black-legged-tick-feeding-immature-stages

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Immunology and Infection

11.9K Views.  University of Nevada, Reno. The production of healthy laboratory-reared ticks is essential to studies on tick biology, and tick-pathogen interactions. Here we demonstrate a simple protocol for immature tick feeding that is cost-effective and less stressful to mice.

Video: Rearing Ixodes scapularis, the Black-legged Tick: Feeding Immature Stages on Mice

Methods for Rapid Transfer and Localization of Lyme Disease Pathogens Within the Tick Gut

Lyme disease is caused by infection with the spirochete pathogen Borrelia burgdorferi, which is maintained in nature by a tick-rodent infection cycle 1. A tick-borne murine model 2 has been developed to study Lyme disease in the laboratory. While na&iacute;ve ticks can be infected with B. burgdorferi by feeding them on infected mice, the molting process takes several weeks to months to complete. Therefore, development of more rapid and efficient tick infection techniques, such as a microinjection-based procedure, is an important tool for the study of Lyme disease 3,4. The procedure requires only hours to generate infected ticks and allows control over the delivery of equal quantities of spirochetes in a cohort of ticks. This is particularly important as the generation of B. burgdorferi infected ticks by the natural feeding process using mice fails to ensure 100% infection rate and potentially results in variation of pathogen burden amongst fed ticks. Furthermore, microinjection can be used to infect ticks with B. burgdorferi isolates in cases where an attenuated strain is unable to establish infection in mice and thus can not be naturally acquired by ticks 5. This technique can also be used to deliver a variety of other biological materials into ticks, for example, specific antibodies or double stranded RNA 6. In this article, we will demonstrate the microinjection of nymphal ticks with in vitro-grown B. burgdorferi. We will also describe a method for localization of Lyme disease pathogens in the tick gut using confocal immunofluorescence microscopy.

Lyme disease research studies often require generation of ticks infected with the pathogen Borrelia burgdorferi, a process that typically takes several weeks. Here we demonstrate a microinjection-based tick infection procedure that can be accomplished within hours. We also demonstrate an immunofluorescence method for in situ localization of B. burgdorferi within ticks.

Lyme disease is caused by infection with the spirochete pathogen Borrelia burgdorferi, which is maintained in nature by a tick-rodent infection cycle 1.  ...

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne relapsing fever (Borrelia spp.), Rocky Mountain Spotted fever (Rickettsia rickettsii), ehrlichiosis (Ehrlichia chaffeensis and E. equi), anaplasmosis (Anaplasma phagocytophilum), encephalitis (tick-borne encephalitis virus), babesiosis (Babesia spp.), Colorado tick fever (Coltivirus), and tularemia (Francisella tularensis) 1-8. To be properly transmitted into the host these infectious agents differentially regulate gene expression, interact with tick proteins, and migrate through the tick 3,9-13. For example, the Lyme disease agent, Borrelia burgdorferi, adapts through differential gene expression to the feast and famine stages of the tick's enzootic cycle 14,15. Furthermore, as an Ixodes tick consumes a bloodmeal Borrelia replicate and migrate from the midgut into the hemocoel, where they travel to the salivary glands and are transmitted into the host with the expelled saliva 9,16-19.
As a tick feeds the host typically responds with a strong hemostatic and innate immune response 11,13,20-22. Despite these host responses, I. scapularis can feed for several days because tick saliva contains proteins that are immunomodulatory, lytic agents, anticoagulants, and fibrinolysins to aid the tick feeding 3,11,20,21,23. The immunomodulatory activities possessed by tick saliva or salivary gland extract (SGE) facilitate transmission, proliferation, and dissemination of numerous tick-borne pathogens 3,20,24-27. To further understand how tick-borne infectious agents cause disease it is essential to dissect actively feeding ticks and collect tick saliva. This video protocol demonstrates dissection techniques for the collection of hemolymph and the removal of salivary glands from actively feeding I. scapularis nymphs after 48 and 72 hours post mouse placement. We also demonstrate saliva collection from an adult female I. scapularis tick.

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

The collection of infected tick hemolymph, salivary glands, and saliva is important to study how tick-borne pathogens cause disease. In this protocol we demonstrate how to collect hemolymph and salivary glands from feeding Ixodes scapularis nymphs. We also demonstrate saliva collection from female I. scapularis adults.

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne ...

Rearing and Injection of Manduca sexta Larvae to Assess Bacterial Virulence

Manduca sexta, commonly known as the tobacco hornworm, is considered a significant agricultural pest, feeding on solanaceous plants including tobacco and tomato. The susceptibility of M. sexta larvae to a variety of entomopathogenic bacterial species1-5, as well as the wealth of information available regarding the insect's immune system6-8, and the pending genome sequence9 make it a good model organism for use in studying host-microbe interactions during pathogenesis. In addition, M. sexta larvae are relatively large and easy to manipulate and maintain in the laboratory relative to other susceptible insect species. Their large size also facilitates efficient tissue/hemolymph extraction for analysis of the host response to infection.
The method presented here describes the direct injection of bacteria into the hemocoel (blood cavity) of M. sexta larvae. This approach can be used to analyze and compare the virulence characteristics of various bacterial species, strains, or mutants by simply monitoring the time to insect death after injection. This method was developed to study the pathogenicity of Xenorhabdus and Photorhabdus species, which typically associate with nematode vectors as a means to gain entry into the insect. Entomopathogenic nematodes typically infect larvae via natural digestive or respiratory openings, and release their symbiotic bacterial contents into the insect hemolymph (blood) shortly thereafter10. The injection method described here bypasses the need for a nematode vector, thus uncoupling the effects of bacteria and nematode on the insect. This method allows for accurate enumeration of infectious material (cells or protein) within the inoculum, which is not possible using other existing methods for analyzing entomopathogenesis, including nicking11 and oral toxicity assays12. Also, oral toxicity assays address the virulence of secreted toxins introduced into the digestive system of larvae, whereas the direct injection method addresses the virulence of whole-cell inocula.
The utility of the direct injection method as described here is to analyze bacterial pathogenesis by monitoring insect mortality. However, this method can easily be expanded for use in studying the effects of infection on the M. sexta immune system. The insect responds to infection via both humoral and cellular responses. The humoral response includes recognition of bacterial-associated patterns and subsequent production of various antimicrobial peptides7; the expression of genes encoding these peptides can be monitored subsequent to direct infection via RNA extraction and quantitative PCR13. The cellular response to infection involves nodulation, encapsulation, and phagocytosis of infectious agents by hemocytes6. To analyze these responses, injected insects can be dissected and visualized by microscopy13, 14.

Rearing and Injection of Manduca sexta Larvae to Assess Bacterial Virulence

The method described here utilizes direct injection of entomopathogenic bacteria into the hemocoel of Manduca sexta insect larvae. M. sexta is a commercially available and well-studied insect. Thus, this method represents a simple approach to analyzing host-bacterial interactions from the perspective of one or both partners.

Manduca sexta, commonly known as the tobacco hornworm, is considered a significant agricultural pest, feeding on solanaceous plants including tobacco and ...

Feeding of Ticks on Animals for Transmission and Xenodiagnosis in Lyme Disease Research

Transmission of the etiologic agent of Lyme disease, Borrelia burgdorferi, occurs by the attachment and blood feeding of Ixodes species ticks on mammalian hosts. In nature, this zoonotic bacterial pathogen may use a variety of reservoir hosts, but the white-footed mouse (Peromyscus leucopus) is the primary reservoir for larval and nymphal ticks in North America. Humans are incidental hosts most frequently infected with B. burgdorferi by the bite of ticks in the nymphal stage. B. burgdorferi adapts to its hosts throughout the enzootic cycle, so the ability to explore the functions of these spirochetes and their effects on mammalian hosts requires the use of tick feeding. In addition, the technique of xenodiagnosis (using the natural vector for detection and recovery of an infectious agent) has been useful in studies of cryptic infection. In order to obtain nymphal ticks that harbor B. burgdorferi, ticks are fed live spirochetes in culture through capillary tubes. Two animal models, mice and nonhuman primates, are most commonly used for Lyme disease studies involving tick feeding. We demonstrate the methods by which these ticks can be fed upon, and recovered from animals for either infection or xenodiagnosis.

Lyme disease is the most commonly-reported vector-borne disease in North America. The causative agent, Borrelia burgdorferi is a spirochete bacterium transmitted by Ixodid ticks. Transmission and detection of infection in animal models is optimized by the use of tick feeding, which we describe here.

Transmission of the etiologic agent of Lyme disease, Borrelia burgdorferi, occurs by the  attachment and blood feeding of Ixodes species ticks on ...

Measuring Local Anaphylaxis in Mice

Allergic responses are the result of the activation of mast cells and basophils, and the subsequent release of vasoactive and proinflammatory mediators. Exposure to an allergen in a sensitized individual can result in clinical symptoms that vary from minor erythema to life threatening anaphylaxis. In the laboratory, various animal models have been developed to understand the mechanisms driving allergic responses. Herein, we describe a detailed method for measuring changes in vascular permeability to quantify localized allergic responses. The local anaphylaxis assay was first reported in the 1920s, and has been adapted from the technique published by Kojima et al. in 20071. In this assay, mice sensitized to OVA are challenged in the left ear with vehicle and in the right ear with OVA. This is followed by an intravenous injection of Evans Blue dye. Ten min after injecting Evans Blue, the animal is euthanized and the dye that has extravasated into the ears is extracted overnight in formamide. The absorbance of the extracted dye is then quantified with a spectrophotometer. This method reliably results in a visual and quantifiable manifestation of a local allergic response.

Allergic responses, characterized by the activation of mast cells and basophils, are driven by the cross-linking of IgE and release of proinflammatory mediators. A quantitative assessment of allergic responses can be achieved by using Evans Blue dye to monitor changes in vascular permeability after allergen challenge.

Allergic responses are the result of the activation of mast cells and basophils, and the subsequent release of vasoactive and proinflammatory mediators. ...

Generation of Immature, Mature and Tolerogenic Dendritic Cells with Differing Metabolic Phenotypes

Immune response results from a complex interplay between the antigen non-specific innate immune system and the antigen specific adaptive immune system. The immune system is a constant balance in maintaining tolerance to self-molecules and reacting rapidly to pathogens. Dendritic cells (DCs) are powerful professional antigen presenting cells that link the innate immune system to the adaptive immune system and balance the adaptive response between self and non-self. Depending on the maturation signals, immature dendritic cells can be selectively stimulated to differentiate into immunogenic or tolerogenic DCs. Immunogenic dendritic cells provide proliferation signals to antigen-specific T cells for clonal expansion; while tolerogenic dendritic cells regulate tolerance by antigen-specific T-cell deletion or clonal expansion of regulatory T-cells. Due to this unique property, dendritic cells are highly sought after as therapeutic agents for cancer and autoimmune diseases. Dendritic cells can be loaded with specific antigens in vitro and injected into the human body to mount a specific immune response both immunogenic and tolerogenic. This work presents a means to generate in vitro from monocytes, immature monocyte derived dendritic cells (moDCs), tolerogenic and mature moDCs that differ in surface marker expression, function and metabolic phenotypes.

Immature dendritic cells can be selectively differentiated into tolerogenic or mature dendritic cells to regulate the balance between immunity and tolerance. This work presents a means to generate from immature monocyte derived dendritic cells (moDCs), in vitro tolerogenic and mature moDCs that differ in metabolic phenotypes.

Immune response results from a complex interplay between the antigen non-specific innate immune system and the antigen specific adaptive immune system. ...

Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle

Currently, it is possible to construct recombinant forms of various viruses, such as human immunodeficiency virus 1 (HIV-1) and hepatitis C virus (HCV), that carry foreign genes such as a reporter or marker protein in their genomes. These recombinant viruses usually faithfully mimic the life cycle of the original virus in infected cells and exhibit the same host range dependence. The development of a recombinant virus enables the efficient screening of inhibitors and the identification of specific host factors. However, to date the construction of recombinant hepatitis B virus (HBV) has been difficult because of various experimental limitations. The main limitation is the compact genome size of HBV, and a fairly strict genome size that does not exceed 1.3 genome sizes, that must be packaged into virions. Thus, the size of a foreign gene to be inserted should be smaller than 0.4 kb if no deletion of the genome DNA is to be performed. Therefore, to overcome this size limitation, the deletion of some HBV DNA is required. Here, we report the construction of recombinant HBV encoding a reporter gene to monitor the early stage of the HBV replication cycle by replacing part of the HBV core-coding region with the reporter gene by deleting part of the HBV pol coding region. Detection of recombinant HBV infection, monitored by the reporter activity, was highly sensitive and less expensive than detection using the currently available conventional methods to evaluate HBV infection. This system will be useful for a number of applications including high-throughput screening for the identification of anti-HBV inhibitors, host factors and virus-susceptible cells.

Here we describe a newly developed hepatitis B virus (HBV) reporter system to monitor the early stages of the HBV life cycle. This simplified in vitro system will aid in the screening of anti-HBV agents using a high-throughput strategy.

Currently, it is possible to construct recombinant forms of various viruses, such as human immunodeficiency virus 1 (HIV-1) and hepatitis C virus (HCV), ...

Fluorescence-based Neuraminidase Inhibition Assay to Assess the Susceptibility of Influenza Viruses to The Neuraminidase Inhibitor Class of Antivirals

The neuraminidase (NA) inhibitors are the only class of antivirals approved for the treatment and prophylaxis of influenza that are effective against currently circulating strains. In addition to their use in treating seasonal influenza, the NA inhibitors have been stockpiled by a number of countries for use in the event of a pandemic. It is therefore important to monitor the susceptibility of circulating influenza viruses to this class of antivirals. There are different types of assays that can be used to assess the susceptibility of influenza viruses to the NA inhibitors, but the enzyme inhibition assays using either a fluorescent substrate or a chemiluminescent substrate are the most widely used and recommended. This protocol describes the use of a fluorescence-based assay to assess influenza virus susceptibility to NA inhibitors. The assay is based on the NA enzyme cleaving the 2&#8242;-(4-Methylumbelliferyl)-&#945;-D-N-acetylneuraminic acid (MUNANA) substrate to release the fluorescent product 4-methylumbelliferone (4-MU). Therefore, the inhibitory effect of an NA inhibitor on the influenza virus NA is determined based on the concentration of the NA inhibitor that is required to reduce 50% of the NA activity, given as an IC50 value.

We describe the use of a phenotypic fluorescence-based neuraminidase inhibition assay to assess the susceptibility of influenza A and B viruses to the neuraminidase inhibitor class of antivirals.

The neuraminidase (NA) inhibitors are the only class of antivirals approved for the treatment and prophylaxis of influenza that are effective against ...

Phenotypic Analysis of Rodent Malaria Parasite Asexual and Sexual Blood Stages and Mosquito Stages

Recent advances in genetics and systems biology technologies have promoted our understanding of the biology of malaria parasites on the molecular level. However, effective malaria parasite targets for vaccine and chemotherapy development are still limited. This is largely due to the unavailability of relevant and practical in vivo infection models for human Plasmodium species, most notably for P.&#160;falciparum and P. vivax. Therefore, rodent malaria species have been extensively used as practical alternative in vivo models for malaria vaccine, drug targeting, immune response, and functional characterization studies of conserved Plasmodiumspp. genes. Indeed, rodent malaria models have proven to be invaluable, especially for exploring mosquito transmission and liver stage biology, and were indispensable for immunological studies. However, there are discrepancies in the methods used to evaluate the phenotypes of transgenic and wild-type asexual and sexual blood-stage parasites.&#160;Examples of these discrepancies are the choice of an intravenous vs. intraperitoneal infection of rodents with blood-stage parasites and the evaluation of male gamete exflagellation. Herein, we detail standardized experimental methods to evaluate the phenotypes of asexual and sexual blood stages in transgenic parasites expressing reporter-gene or wild-type rodent malaria parasite species. We also detail the methods to evaluate the phenotypes of malaria parasite mosquito stages (gametes, ookinetes, oocysts, and sporozoites) inside Anopheles mosquito vectors. These methods are detailed and simplified here for the lethal and non-lethal strains of P. berghei and P. yoelii but can also be applied with some adjustments to P. chabaudi and P. vinckei rodent malaria species.

Due to the striking similarities of the life cycle and biology of rodent malaria parasites to human malaria parasites, rodent malaria models have become indispensable for malaria research. Herein, we standardized some of the most important techniques used in the phenotypic analysis of wild-type and transgenic rodent malaria species.

Recent advances in genetics and systems biology technologies have promoted our understanding of the biology of malaria parasites on the molecular level. ...

Generating Recombinant Avian Herpesvirus Vectors with CRISPR/Cas9 Gene Editing

Herpesvirus of turkeys (HVT) is an ideal viral vector for the generation of recombinant vaccines against a number of avian diseases, such as avian influenza (AI), Newcastle disease (ND), and infectious bursal disease (IBD), using bacterial artificial chromosome (BAC) mutagenesis or conventional recombination methods. The clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 system has been successfully used in many settings for gene editing, including the manipulation of several large DNA virus genomes. We have developed a rapid and efficient CRISPR/Cas9-mediated genome editing pipeline to generate recombinant HVT. To maximize the potential use of this method, we present here detailed information about the methodology of generating recombinant HVT expressing the VP2 protein of IBDV. The VP2 expression cassette is inserted into the HVT genome via an NHEJ (nonhomologous end-joining)-dependent repair pathway. A green fluorescence protein (GFP) expression cassette is first attached to the insert for easy visualization and then removed via the Cre-LoxP system. This approach offers an efficient way to introduce other viral antigens into the HVT genome for the rapid development of recombinant vaccines.

Herpesvirus of turkeys (HVT) is widely used as a vector platform for the generation of recombinant vaccines against a number of avian diseases. This article describes a simple and rapid approach for the generation of recombinant HVT-vectored vaccines using an integrated NHEJ-CRISPR/Cas9 and Cre-Lox system.