The authors would like to thank Dr. Jay Pepose for helping teaching the model to us. This work was supported by National Institutes of Health Grants EY11885 (PMS), EY21247 (PMS) and an unrestricted grant from Research to Prevent Blindness to Department of Ophthalmology.

Animal Care Note: Analgesics are not used in this model as they are anti-inflammatory and thus would invalidate the model.
1. Preparation of Virus
<ol>
	<li>Grow HSV-1 on Vero cells (80% confluent) using a starting dilution of 0.01 multiplicity of infection (in T-150 flask, about 5 x 105 plaque forming units) for 3-4 days until all of cells have rounded-up and are easily dislodged by hitting the flask.</li>
	<li>Remove media to sterile centrifuge tubes and centrifuge in Sorvall Legend RT at 4 &deg;C and 3,500 rpm for 15 min. After removing supernatant (see 1.3), resuspend large pellet from each 50 ml tube with 5 ml of media total. Sonicate for 1 min in two 30 sec bursts.</li>
	<li>Remove supernatant and put into 50 ml sterile Oak Ridge tubes and centrifuge at 9,000 rpm, for 1 hr at 4 &deg;C in a Beckman J2-21 centrifuge. This is to produce a small viral pellet. Discard the supernatant.</li>
	<li>Combine sonicate from 1.2 with pellet from 1.3 and sonicate again for 45 sec. Centrifuge in Sorvall Legend RT at 1,500 rpm for 5 min at 4 &deg;C. Save the supernatant. This constitutes the virus stock which is aliquoted and stored at -70 &deg;C.</li>
	<li>Titer virus on Vero cells. I usually plate 100 out to 10-8 dilution (each being a 10-fold dilution) 2x from 2 separate dilution sets. Titration of virus is performed on 12-well sterile plates.</li>
</ol>
2. Mouse Infection
<ol>
	<li>Inject each mouse with 0.1 ml of anesthetic cocktail/20 g mouse body weight (Ketamine, 60 mg/kg + Xylazine 5 mg/kg which is diluted in HBSS). This cocktail is used because it is one of the safest means of anesthesia when proper dosages are used and the effects of this drug are very short-lived.</li>
	<li>When mice are anesthetized scratch the cornea of the right eye with a 30 gauge needle using a dissecting microscope to ensure that the cornea is not perforated.</li>
	<li>Each mouse received an intraperitoneal injection of 1 ml of pooled human serum (Sigma, Temecula, Calif.; anti-HSV reactivity with an effective dose for 50% viral neutralization of 1:800) in order to protect corneas from damage during primary infection.</li>
	<li>Number the mice with either ear clips or by ear punch.</li>
	<li>After all of the mice have been numbered; using a 20 &mu;l pipettor, we infect each eye with 106 PFU (5 &mu;l). We infect only one eye and typically the right eye. We also place 5 &mu;l of HBSS to the other eye to keep it moist while they are anesthetized. 5 ul is sufficient to maintain hydration of the eyes since the procedures are performed in less than 10 min, and the animals are dosed with anesthetic accordingly. Infection is confirmed by swabbing mice 3 days post-infection with a sterile cotton applicator that was hydrated in 1 ml of Vero media. Then 100 &mu;l is added to Vero cells grown in 48-well plates. These plates are monitoring daily for cytopathic effects (cpe).</li>
</ol>
3. Reactivation of Mice from Latency
<ol>
	<li>Mice are anesthetized at least 5 weeks following primary infection. It should be noted that we have reactivated mice up to one year following primary infection and have not observed significant differences in response.</li>
	<li>Once anesthetized they are placed TM20 Chromato-Vu transilluminator, which emits UV-B at a peak wavelength of 302 nm such that only a single eye is exposed to the UV-B light. Each mouse is exposed to 250 mJ of UV-B light cm2.</li>
	<li>Reactivation is determined by swabbing eyes with sterile cotton applicator that is first placed in 1 ml of Vero media on Day 0 (Before UV-B exposure to control for spontaneous shedders) and then on days 1 to 7 post-UV-B irradiation. The swab material is evaluated as described in 2.5). For those swabs that have infectious virus the amount of virus is tittered by a standard plaque assay using 12 well plates.</li>
</ol>
4. Clinical Evaluation
<ol>
	<li>Mice are evaluated for clinical eye disease by a masked observer using a binocular dissecting microscope.</li>
	<li>Corneal opacity is rated on a scale of 0 to 4, where 0 indicates clear stroma, 1 indicates mild stromal opacification, 2 indicates moderate opacity with discernible iris features, 3 indicates dense opacity with loss of defined iris detail except pupil margins, and 4 indicates total opacity with no posterior view.</li>
	<li>Neovascularization is rated on a scale of 1 to 8 by dividing the cornea into 4 equal quadrants and determining the extent of vascularization in each of these quadrants.</li>
	<li>Blepharitis is measured as follows: 0, no lesions; 1, minimal eyelid swelling; 2, moderate swelling and crusty ocular discharge; 3, severe swelling, moderate periocular hair loss, and skin lesions; and 4, severe swelling with eyes crusted shut, severe periocular hair loss, and skin lesions.</li>
	<li>Evidence of encephalitis included hunched back, ruffled hair, and obvious neurologic abnormalities. Mice are euthanized when they display significant signs of encephalitis.</li>
</ol>
5. Representative Results
The recurrent model which was described above was first published by Shimeld, et al. 1-3. They tested and our laboratory has been using a modified version of this model to publish many manuscripts over the years 4-15. The model was used to define the role that the cytokine interferon-&gamma; plays in recurrent HSV-1 disease 10. As shown in Figure 3, mice lacking IFN&gamma; displayed worse corneal disease than did wild-type mice 14. It was also used successfully to define the therapeutic value of several different vaccine constructs 6,10,11. Note that in one case the vaccine tested worked well prophylactically but did not prove to be therapeutically effective 6. However, when a replication-incompetent viral vaccine was tested, it was not only effective prophylactically, but was also very effective therapeutically 10,11, see Figure 5 in reference 10. More recently we have used this model to determine if gender differences were detectable in mice undergoing recurrent HSK. As Figure 1 demonstrates, male C57BL/6 mice display significantly less corneal opacity than do female C57BL/6 mice. Likewise, when corneal neovascularization was evaluated, male mice demonstrated significantly less new vessel growth in the cornea than did female mice (Figure 2). We are currently testing whether this phenotype is strain specific by performing similar analysis in other strains of mice. We will also determine whether the difference is due to the lack of testosterone or the presence of estrogen.
<img alt="Figure 1" src="/files/ftp_upload/4276/4276fig1.jpg" /> 
 Figure 1. Corneal disease in male and female C57BL/6 mouse strains following UV-B induced reactivation. Latently infected mice were induced to reactivate with UV-B irradiation and mice were monitored for corneal opacity for 35 days. The numbers of mice used for these studies were as follows: males, n = 15; females, n = 15. Results indicate mean &plusmn; SEM. *There was significantly greater virus-induced disease in female C57BL/6 mice for days 14-35 (P = 0.001 to 0.01).
<img alt="Figure 2" src="/files/ftp_upload/4276/4276fig2.jpg" /> 
 Figure 2. Corneal disease in male and female C57BL/6 mouse strains following UV-B induced reactivation. Latently infected mice were induced to reactivate with UV-B irradiation and mice were monitored for corneal neovascularization for 35 days. The numbers of mice used for these studies were as follows: males, n = 15; females, n = 15. Results indicate mean &plusmn; SEM. *There was significantly greater virus-induced disease in female C57BL/6 mice for days 14-28 (P = 0.001 to 0.01).

<ol>
	<li>Shimeld, C., Hill, T. J., Blyth, B., Easty, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+model+of+recurrent+herpetic+eye+disease+in+mice.">An improved model of recurrent herpetic eye disease in mice.</a> Curr. Eye Res. 8, 1193-1205 (1989).</li><li>Shimeld, C., Hill, T. J., Blyth, W. A., Easty, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactivation+of+latent+infection+and+induction+of+recurrent+herpetic+eye+disease+in+mice.">Reactivation of latent infection and induction of recurrent herpetic eye disease in mice.</a> J. Gen. Virol. 71, 397-404 (1990).</li><li>Shimeld, C., Hill, T. J., Blyth, W. A., Easty, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Passive+immunization+protects+the+mouse+eye+from+damage+after+herpes+simplex+virus+infection+by+limiting+spread+of+virus+in+the+nervous+system.">Passive immunization protects the mouse eye from damage after herpes simplex virus infection by limiting spread of virus in the nervous system.</a> J. Gen. Virol. 71, 681-687 (1990).</li><li>Laycock, K. A., Lee, S. F., Brady, R. H., Pepose, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+a+murine+model+of+recurrent+herpes+simplex+viral+keratitis+induced+by+ultraviolet+B+radiation.">Characterization of a murine model of recurrent herpes simplex viral keratitis induced by ultraviolet B radiation.</a> Invest. Ophthalmol. Vis. Sci. 32, 2741-2746 (1991).</li><li>Keadle, T. L., Stuart, 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=IL-10+ameliorates+corneal+disease+in+a+mouse+model+of+recurrent+herpetic+keratitis.">IL-10 ameliorates corneal disease in a mouse model of recurrent herpetic keratitis.</a> Microbial Path. 38, 13-21 (2005).</li><li>Keadle, T. L., Laycock, K. A., Miller, J. K., Hook, K. K., Fenoglio, E. D., Francotte, M., Slaoui, M., Stuart, P. M., Pepose, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+of+a+recombinant+glycoprotein+D+subunit+vaccine+on+the+development+of+primary+and+recurrent+ocular+infection+with+herpes+simplex+virus+type+1+in+mice.">Efficacy of a recombinant glycoprotein D subunit vaccine on the development of primary and recurrent ocular infection with herpes simplex virus type 1 in mice.</a> J. Inf. Dis. 176, 331-338 (1997).</li><li>Keadle, T. L., Laycock, K. A., Pepose, J. S., Stuart, 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=Proinflammatory+cytokines+IL-1+and+TNF-a+are+required+for+recurrent+herpetic+keratitis+in+NIH+mice.">Proinflammatory cytokines IL-1 and TNF-a are required for recurrent herpetic keratitis in NIH mice.</a> Invest. Ophth. Vis. Sci. 41, 96-102 (2000).</li><li>Keadle, T. L., Usui, N., Laycock, K. A., Kumano, Y., Pepose, J. S., Stuart, 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=Corneal+cytokine+expression+in+a+murine+model+recurrent+herpetic+stromal+keratitis.">Corneal cytokine expression in a murine model recurrent herpetic stromal keratitis.</a> Ocular Immunol. Inflam. 9, 193-205 (2001).</li><li>Keadle, T. L., Morris, J. L., Pepose, J. S., Stuart, 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=CD4++and+CD8++cells+are+key+participants+in+the+development+of+recurrent+herpetic+stromal+keratitis+in+mice.">CD4+ and CD8+ cells are key participants in the development of recurrent herpetic stromal keratitis in mice.</a> Microbial Path. 32, 255-262 (2002).</li><li>Keadle, T. L., Morrison, L. A., Morris, J. L., Pepose, J. S., Stuart, 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=Therapeutic+immunization+with+a+virion+host+shutoff-defective,+replication-incompetent+herpes+simplex+virus+type+1+strain+limits+recurrent+herpetic+ocular+infection.">Therapeutic immunization with a virion host shutoff-defective, replication-incompetent herpes simplex virus type 1 strain limits recurrent herpetic ocular infection.</a> J. Virol. 76, 3615-3625 (2002).</li><li>Keadle, T. L., Laycock, K. A., Morris, J. L., Leib, D. A., Morrison, L. A., Pepose, J. S., Stuart, 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=Therapeutic+vaccination+with+vhs(-)+herpes+simplex+virus+reduces+the+severity+of+recurrent+herpetic+stromal+keratitis+in+mice.">Therapeutic vaccination with vhs(-) herpes simplex virus reduces the severity of recurrent herpetic stromal keratitis in mice.</a> J. Gen. Virol. 83, 2361-2365 (2002).</li><li>Keadle, T. L., Morris, J. L., Stuart, 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=The+effects+of+aminoguanidine+on+primary+and+recurrent+ocular+herpes+simplex+virus+infection.">The effects of aminoguanidine on primary and recurrent ocular herpes simplex virus infection.</a> Nitric Oxide. 13, 247-253 (2005).</li><li>Stuart, P. M., Morris, J. E., Sidhu, M., Keadle, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CCL3+protects+mice+from+corneal+pathology+during+recurrent+HSV-1+infection.">CCL3 protects mice from corneal pathology during recurrent HSV-1 infection.</a> Front. Biosci. 13, 4407-4415 (2008).</li><li>Keadle, T. L., Alexander, D. E., Leib, D. A., Stuart, 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=Interferon+gamma+is+not+required+for+recurrent+herpetic+stromal+keratitis.">Interferon gamma is not required for recurrent herpetic stromal keratitis.</a> Virology. 380, 46-51 (2008).</li><li>Carr, D. J., Austin, B. A., Halford, W. P., Stuart, 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=Delivery+of+Interferon-gamma+by+an+adenovirus+vector+blocks+herpes+simplex+virus+Type+1+reactivation+in+vitro+and+in+vivo+independent+of+RNase+L+and+double-stranded+RNA-dependent+protein+kinase+pathways.">Delivery of Interferon-gamma by an adenovirus vector blocks herpes simplex virus Type 1 reactivation in vitro and in vivo independent of RNase L and double-stranded RNA-dependent protein kinase pathways.</a> J. Neuroimmunol. 206, 39-43 (2009).</li></ol>

No conflicts of interest declared.

The recurrent model of herpetic stromal keratitis (HSK) described here enables the investigator to study human HSK in a model that is more consistent with that which is observed during human disease. Thus, the model's strengths are that disease occurs in the context of an immune system that has already by stimulated during primary disease. Since these mice already have an immune response to HSV-1, the factors that reactivate that immune response are likely different from those that originally generated it. Therefore, the...

<table><tbody><tr><td>DMEM</td><td>Sigma</td><td>D5796</td><td></td></tr><tr><td>Fetal Bovine Serum</td><td>Atlanta Biologicals</td><td>S11150</td><td></td></tr><tr><td>Human Serum</td><td>Sigma</td><td>S7023</td><td></td></tr><tr><td>L-Glutamine</td><td>Cellgro</td><td>25-005-C1</td><td></td></tr><tr><td>Pen/ Strep</td><td>Sigma</td><td>P4333</td><td></td></tr><tr><td>Fungizone</td><td>Invitrogen</td><td>15290018</td><td></td></tr><tr><td>Centrifuge</td><td>Sorvall</td><td>Legend RT</td><td></td></tr><tr><td>Centrifuge</td><td>Beckman</td><td>52-21</td><td></td></tr><tr><td>Transilluminatior</td><td>UVP</td><td>95-0452-02</td><td></td></tr><tr><td>Sonicatior</td><td>Branson</td><td>Sonifier 450</td><td></td></tr><tr><td>Oak Ridge Tubes</td><td>Nalgene</td><td>Z 720410</td><td></td></tr><tr><td>Flasks- 7150</td><td>Corning</td><td>430823</td><td></td></tr><tr><td>Plates- 12 well</td><td>Corning</td><td>CLS 3513</td><td></td></tr><tr><td>Plates- 48 well</td><td>Corning</td><td>CLS 3548</td><td></td></tr><tr><td>Sterile Conical Tubes- 30 ml</td><td>Corning</td><td>CLS 430828</td><td></td></tr><tr><td>Sterile Cotton-tipped Applicators</td><td>Fisher</td><td>23-400-125</td><td></td></tr><tr><td>30G Needles</td><td>Becton-Dickinson</td><td>305106</td><td></td></tr><tr><td>25G Needles</td><td>BD</td><td>305122</td><td></td></tr><tr><td>10 ml Syringe</td><td>BD</td><td>309602</td><td></td></tr><tr><td>10 ml Syringe</td><td>BD</td><td>309604</td><td></td></tr></tbody></table>

recurrent herpetic stromal keratitis in mice, a model for studying human hsk

Herpetic eye disease, termed herpetic stromal keratitis (HSK), is a potentially blinding infection of the cornea that results in over 300,000 clinical visits each year for treatment. Between 1 and 2 percent of those patients with clinical disease will experience loss of vision of the infected cornea. The vast majority of these cases are the result of reactivation of a latent infection by herpes simplex type I virus and not due to acute disease. Interestingly, the acute infection is the model most often used to study this disease. However, it was felt that a recurrent model of HSK would be more reflective of what occurs during clinical disease. The recurrent animal models for HSK have employed both rabbits and mice. The advantage of rabbits is that they experience reactivation from latency absent any known stimulus. That said, it is difficult to explore the role that many immunological factors play in recurrent HSK because the rabbit model does not have the immunological and genetic resources that the mouse has. We chose to use the mouse model for recurrent HSK because it has the advantage of there being many resources available and also we know when reactivation will occur because reactivation is induced by exposure to UV-B light. Thus far, this model has allowed those laboratories using it to define several immunological factors that are important to this disease. It has also allowed us to test both therapeutic and vaccine efficacy.

Watch this Scientific Journal Video about Recurrent Herpetic Stromal Keratitis in Mice, a Model for Studying Human HSK at JoVE.com

Recurrent Herpetic Stromal Keratitis in Mice, a Model for Studying Human HSK

Most studies of herpetic corneal disease use a primary infection model. However, primary infection with HSV-1 does not typically lead to human disease. Here we describe a recurrent model of herpetic corneal disease, which more closely mimics human disease.

Herpetic eye disease, termed herpetic stromal keratitis (HSK), is a potentially blinding infection of the cornea that results in over 300,000 clinical ...

recurrent-herpetic-stromal-keratitis-mice-model-for-studying-human

Research

JoVE Journal

Immunology and Infection

11.9K Views.  Saint Louis University. Most studies of herpetic corneal disease use a primary infection model. However, primary infection with HSV-1 does not typically lead to human disease. Here we describe a recurrent model of herpetic corneal disease, which more closely mimics human disease.

Video: Recurrent Herpetic Stromal Keratitis in Mice, a Model for Studying Human HSK

Ex Vivo Organotypic Corneal Model of Acute Epithelial Herpes Simplex Virus Type I Infection

Herpes keratitis is one of the most severe pathologies associated with the herpes simplex virus-type 1 (HSV-1). Herpes keratitis is currently the leading cause of both cornea-derived and infection-associated blindness in the developed world. Typical presentation of herpes keratitis includes infection of the corneal epithelium and sometimes the deeper corneal stroma and endothelium, leading to such permanent corneal pathologies as scarring, thinning, and opacity 1.
Corneal HSV-1 infection is traditionally studied in two types of experimental models. The in vitro model, in which cultured monolayers of corneal epithelial cells are infected in a Petri dish, offers simplicity, high level of replicability, fast experiments, and relatively low costs. On the other hand, the in vivo model, in which animals such as rabbits or mice are inoculated directly in the cornea, offers a highly sophisticated physiological system, but has higher costs, longer experiments, necessary animal care, and a greater degree of variability. 
In this video article, we provide a detailed demonstration of a new ex vivo model of corneal epithelial HSV-1 infection, which combines the strengths of both the in vitro and the in vivo models. The ex vivo model utilizes intact corneas organotypically maintained in culture and infected with HSV-1. The use of the ex vivo model allows for highly physiologically-based conclusions, yet it is rather inexpensive and requires time commitment comparable to that of the in vitro model.

Ex Vivo Organotypic Corneal Model of Acute Epithelial Herpes Simplex Virus Type I Infection

In this video article we describe the use of a new ex vivo model of acute herpes simplex virus type I corneal epithelial infection.

Herpes keratitis is one of the most severe pathologies associated with the herpes simplex virus-type 1 (HSV-1).  Herpes keratitis is currently the leading ...

Neuroscience

A Laser-induced Mouse Model of Chronic Ocular Hypertension to Characterize Visual Defects

Glaucoma, frequently associated with elevated intraocular pressure (IOP), is one of the leading causes of blindness. We sought to establish a mouse model of ocular hypertension to mimic human high-tension glaucoma. Here laser illumination is applied to the corneal limbus to photocoagulate the aqueous outflow, inducing angle closure. The changes of IOP are monitored using a rebound tonometer before and after the laser treatment. An optomotor behavioral test is used to measure corresponding changes in visual capacity. The representative result from one mouse which developed sustained IOP elevation after laser illumination is shown. A decreased visual acuity and contrast sensitivity is observed in this ocular hypertensive mouse. Together, our study introduces a valuable model system to investigate neuronal degeneration and the underlying molecular mechanisms in glaucomatous mice.

Chronic ocular hypertension is induced using laser photocoagulation of the trabecular meshwork in mouse eyes. The intraocular pressure (IOP) is elevated for several months after laser treatment. The decrease of visual acuity and contrast sensitivity of experimental animals are monitored using the optomotor test.

Glaucoma, frequently associated with elevated intraocular pressure (IOP), is one of the leading causes of blindness. We sought to establish a mouse model ...

Medicine

Ex Vivo Infection of Murine Epidermis with Herpes Simplex Virus Type 1

To enter its human host, herpes simplex virus type 1 (HSV-1) must overcome the barrier of mucosal surfaces, skin, or cornea. HSV-1 targets keratinocytes during initial entry and establishes a primary infection in the epithelium, which is followed by latent infection of neurons. After reactivation, viruses can become evident at mucocutaneous sites that appear as skin vesicles or mucosal ulcers. How HSV-1 invades skin or mucosa and reaches its receptors is poorly understood. To investigate the invasion route of HSV-1 into epidermal tissue at the cellular level, we established an ex vivo infection model of murine epidermis, which represents the site of primary and recurrent infection in skin. The assay includes the preparation of murine skin. The epidermis is separated from the dermis by dispase II treatment. After floating the epidermal sheets on virus-containing medium, the tissue is fixed and infection can be visualized at various times postinfection by staining infected cells with an antibody against the HSV-1 immediate early protein ICP0. ICP0-expressing cells can be observed in the basal keratinocyte layer already at 1.5 hr postinfection. With longer infection times, infected cells are detected in suprabasal layers, indicating that infection is not restricted to the basal keratinocytes, but the virus spreads to other layers in the tissue. Using epidermal sheets of various mouse models, the infection protocol allows determining the involvement of cellular components that contribute to HSV-1 invasion into tissue. In addition, the assay is suitable to test inhibitors in tissue that interfere with the initial entry steps, cell-to-cell spread and virus production. Here, we describe the ex vivo infection protocol in detail and present our results using nectin-1- or HVEM-deficient mice.

Ex Vivo Infection of Murine Epidermis with Herpes Simplex Virus Type 1

The skin is one target tissue of the human pathogen herpes simplex virus type 1 (HSV-1). To explore the invasion route of HSV-1 into tissue, we established an ex vivo infection model of murine epidermal sheets which represent the outermost layer of skin.

To enter its human host, herpes simplex virus type 1 (HSV-1) must overcome the barrier of mucosal surfaces, skin, or cornea. HSV-1 targets keratinocytes ...

Establishment of the Dual Humanized TK-NOG Mouse Model for HIV-associated Liver Pathogenesis

Despite the increased life expectancy of patients infected with human immunodeficiency virus-1 (HIV-1), liver disease has emerged as a common cause of their morbidity. The liver immunopathology caused by HIV-1 remains elusive. Small xenograft animal models with human hepatocytes and human immune system can recapitulate the human biology of the disease&#39;s pathogenesis. Herein, a protocol is described to establish a dual humanized mouse model through human hepatocytes and CD34+ hematopoietic stem/progenitor cells (HSPCs) transplantation, to study liver immunopathology as observed in HIV-infected patients. To achieve dual reconstitution, male TK-NOG (NOD.Cg-Prkdcscid Il2rgtm1Sug Tg(Alb-TK)7-2/ShiJic) mice are intraperitoneally injected with ganciclovir (GCV) doses to eliminate mouse transgenic liver cells, and with treosulfan for nonmyeloablative conditioning, both of which facilitate human hepatocyte (HEP) engraftment and human immune system (HIS) development. Human albumin (ALB) levels are evaluated for liver engraftment, and the presence of human immune cells in blood detected by flow cytometry confirms the establishment of human immune system. The model developed using the protocol described here resembles multiple components of liver damage from HIV-1 infection. Its establishment could prove to be essential for studies of hepatitis virus co-infection and for the evaluation of antiviral and antiretroviral drugs.

This protocol provides a reliable method to establish humanized mice with both human immune system and liver cells. Dual reconstituted immunodeficient mice achieved via intrasplenic injection of human hepatocytes and CD34+ hematopoietic stem cells are susceptible to human immunodeficiency virus-1 infection and recapitulate liver damage as observed in HIV-infected patients.

Despite the increased life expectancy of patients infected with human immunodeficiency virus-1 (HIV-1), liver disease has emerged as a common cause of ...

Chronic, Acute, and Reactivated HIV Infection in Humanized Immunodeficient Mouse Models

Humanized NOD/SCID/IL-2 receptor &#947;-chainnull mice recapitulate some features of human immunity, which can be exploited in basic and pre-clinical research on infectious diseases. Described here are three models of humanized immunodeficient mice for studying the dynamics of HIV infection. The first is based on the intrahepatic injection of CD34+ hematopoietic stem cells in newborn mice, which allows for the reconstitution of several blood and lymphoid tissue-confined cells, followed by infection with a reference HIV strain. This model allows monitoring for up to 36 weeks post-infection and is hence called the chronic model. The second and third models are referred to as the acute and reactivation models, in which peripheral blood mononuclear cells are intraperitoneally injected in adult mice. In the acute model, cells from a healthy donor are engrafted through the intraperitoneal route, followed by infection with a reference HIV strain. Finally, in the reactivation model, cells from an HIV-infected donor under antiretroviral therapy are engrafted via the intraperitoneal route. In this case, a drug-free environment in the mouse allows for virus reactivation and an increase in viral load. The protocols provided here describe the conventional experimental approach for humanized, immunodeficient mouse models of HIV infection.

Described here are three experimental approaches for studying the dynamics of HIV infection in humanized mice. The first permits the study of chronic infection events, whereas the two latter allows for the study of acute events after primary infection or viral reactivation.

Humanized NOD/SCID/IL-2 receptor &#947;-chainnull mice recapitulate some features of human immunity, which can be exploited in basic and pre-clinical ...

Mouse Footpad Inoculation Model to Study Viral-Induced Neuroinflammatory Responses

This protocol describes a footpad inoculation model used to study the initiation and development of neuroinflammatory responses during alphaherpesvirus infection in mice. As alphaherpesviruses are main invaders of the peripheral nervous system (PNS), this model is suitable to characterize the kinetics of viral replication, its spread from the PNS to CNS, and associated neuroinflammatory responses. The footpad inoculation model allows virus particles to spread from a primary infection site in the footpad epidermis to sensory and sympathetic nerve fibers that innervate the epidermis, sweat glands, and dermis. The infection spreads via the sciatic nerve to the dorsal root ganglia (DRG) and ultimately through the spinal cord to the brain. Here, a mouse footpad is inoculated with pseudorabies virus (PRV), an alphaherpesvirus closely related to herpes simplex virus (HSV) and varicella-zoster virus (VZV). This model demonstrates that PRV infection induces severe inflammation, characterized by neutrophil infiltration in the footpad and DRG. High concentrations of inflammatory cytokines are subsequently detected in homogenized tissues by ELISA. In addition, a strong correlation is observed between PRV gene and protein expression (via qPCR and IF staining) in DRG and the production of pro-inflammatory cytokines. Therefore, the footpad inoculation model provides a better understanding of the processes underlying alphaherpesvirus-induced neuropathies and may lead to the development of innovative therapeutic strategies. In addition, the model can guide research on peripheral neuropathies, such as multiple sclerosis and associated viral-induced damage to the PNS. Ultimately, it can serve as a cost-effective in vivo tool for drug development.

The footpad inoculation model is a valuable tool for characterizing viral-induced neuroinflammatory responses in vivo. In particular, it provides a clear assessment of viral kinetics and associated immunopathological processes initiated in the peripheral nervous system.

This protocol describes a footpad inoculation model used to study the initiation and development of neuroinflammatory responses during alphaherpesvirus ...

Porcine Corneal Tissue Explant to Study the Efficacy of Herpes Simplex Virus-1 Antivirals

Viruses and bacteria can cause a variety of ocular surface defects and degeneration such as wounds and ulcers through corneal infection. With a seroprevalence that ranges from 60-90% worldwide, the Herpes Simplex Virus type-1 (HSV-1) commonly causes mucocutaneous lesions of the orofacial region which also manifest as lesions and infection-associated blindness. While current antiviral drugs are effective, emergence of resistance and persistence of toxic side-effects necessitates development of novel antivirals against this ubiquitous pathogen. Although in vitro assessment provides some functional data regarding an emerging antiviral, they do not demonstrate the complexity of ocular tissue in vivo. However, in vivo studies are expensive and require trained personnel, especially when working with viral agents. Hence ex vivo models are efficient yet inexpensive steps for antiviral testing. Here we discuss a protocol to study infection by HSV-1 using porcine corneas ex vivo and a method to treat them topically using existing and novel antiviral drugs. We also demonstrate the method to perform a plaque assay using HSV-1. The methods detailed may be used to conduct similar experiments to study infections that resemble the HSV-1 pathogen.

We describe the use of a porcine cornea to test the antiviral efficacy of experimental drugs.

Viruses and bacteria can cause a variety of ocular surface defects and degeneration such as wounds and ulcers through corneal infection. With a ...

Contact Hypersensitivity as a Murine Model of Allergic Contact Dermatitis

Contact hypersensitivity (CHS) is an experimental model of allergic contact dermatitis (ACD) that can be studied in mice. This study aims to present an objective laboratory method that may help to study the CHS reaction in mice, which can be measured and quantified by various tests. To induce CHS, on day "0", mice were sensitized on a previously shaved spot by abdominal skin painting with the hapten 2,4,6-trinitrochlorobenzene (TNCB) in an acetone-ethanol mixture, whereas negative control mice were sham sensitized with vehicle alone-acetone-ethanol mixture. On day "4", the baseline ear thickness was measured with a micrometer prior to the elicitation of CHS (challenge) by painting both ears with diluted TNCB both in the test and control groups. After 24 h, the ear swelling was measured with a micrometer. CHS is an example of a T cell-mediated immune response that causes swelling in inflamed tissue, peaking 24 h after the skin challenge with the same hapten. An increase in ear edema correlated with augmented ear weight, myeloperoxidase (MPO) activity, pro-inflammatory cytokine concentration in the ear extracts, increased thickening of the edematous dermis in the histological examination, and ear vascular permeability. There was also an increase in the concentration of TNP-specific IgG1 antibodies in the sera of the test group when compared with the control mice. Additionally, CHS can be successfully transferred with the CHS-effector cells obtained from donors previously sensitized with TNCB. The CHS-effector cells were administered intravenously into na&#239;ve recipient mice, which were subsequently challenged with the same diluted hapten. Ear swelling was measured with a micrometer 24 h later.

Contact hypersensitivity (CHS) is a murine experimental model of allergic contact dermatitis (ACD). CHS is based on sensitization with reactive hapten by painting the shaved skin of the chest and abdomen, with a subsequent ear skin challenge with a diluted hapten, causing a swelling reaction that is assessed in various ways.

Contact hypersensitivity (CHS) is an experimental model of allergic contact dermatitis (ACD) that can be studied in mice. This study aims to present an ...

A Mouse Model of Mechanotransduction-driven, Human-like Hypertrophic Scarring

Hypertrophic scarring (HTS) is an abnormal process of wound healing that results in excessive scar tissue formation. Over the past decade, we have demonstrated that mechanotransduction&#8212;the conversion of mechanical stimuli into cellular responses&#8212;drives excessive fibrotic scar healing. A mouse model to assess human-like hypertrophic scarring would be an essential tool for examining various therapeutics and their ability to reduce scarring and improve healing. Specifically, our laboratory has developed a murine wound model that increases mechanical strain to promote human-like HTS. This&#160;protocol utilizes biomechanical loading devices, made from modified 13 mm palatal expanders, whose arms are placed on either side of the incision and distracted incrementally apart in order to apply continuous tension across the wound bed during healing. Over nearly two decades of use, this model has been significantly advanced to improve efficacy and reproducibility. Using the murine HTS model, significant dermal fibrotic scars can be induced to be histologically comparable to human hypertrophic scars. This murine model provides an environment to develop biologics involved in the treatment of HTS and mechanotransduction-related conditions such as foreign body response.

This protocol will explain how to establish a hypertrophic scarring murine model that increases mechanotransduction signaling to simulate human-like scarring. This method involves increasing mechanical tension across a healing incision in a mouse and using a specialized device to create reproducible, excessive scar tissue for detailed histological and bioinformatic analyses.

Hypertrophic scarring (HTS) is an abnormal process of wound healing that results in excessive scar tissue formation. Over the past decade, we have ...

Bioengineering

Corneal Sensory Fiber Damage Protocols for Axon Regeneration Studies

Three Strategies to Induce Neurotrophic Keratitis and Nerve Regeneration in Murine Cornea

The cornea is a transparent tissue that covers the eye and is crucial for clear vision. It is the most innervated tissue in the body. This innervation provides sensation and trophic function to the eye and contributes to preserving corneal integrity. The pathological disruption of this innervation is termed neurotrophic keratitis. This can be triggered by injury to the eye, surgery, or disease. In this study, we propose three different protocols for inflicting damage on the innervation in ways that recapitulate the three types of cases generally encountered in the clinic.
The first method consists in making an abrasion of the epithelium with an ophthalmic burr. This involves the removal of the epithelial layer, the free nerve endings, and the subbasal plexus in a manner similar to the photorefractive keratectomy surgery performed in the clinic. The second method&#160;only targets the innervation by sectioning it at the periphery with a biopsy punch, maintaining the integrity of the epithelium. This method is similar to the first steps of lamellar keratoplasty and leads to a degeneration of the innervation followed by regrowth of the axons in the central cornea. The last method damages the innervation of a transgenic mouse model using a multiphoton microscope, which specifically localizes the site of cauterization of the fluorescent nerve fibers. This method inflicts the same damage as photokeratitis, an overexposure to UV light.
This study describes different options for investigating the physiopathology of corneal innervation, particularly the degeneration and regeneration of the axons. Promoting regeneration is crucial for avoiding such complications as epithelium defects or even perforation of the cornea. The proposed models can help test new pharmacological molecules or gene therapy that enhance nerve regeneration and limit disease progression.

Author Spotlight: Advancing Corneal Innervation Research Through Innovative Models 

Here, we propose three different methods of damaging the sensory fibres innervating the cornea. These methods facilitate the study of axon regeneration in mice. These three methods, which are adaptable to other animal models, are ideal for the study of corneal innervation physiology and regeneration.

The cornea is a transparent tissue that covers the eye and is crucial for clear vision. It is the most innervated tissue in the body. This innervation ...

Recurrent Herpetic Stromal Keratitis in Mice, a Model for Studying Human HSK

Summary

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Chronic, Acute, and Reactivated HIV Infection in Humanized Immunodeficient Mouse Models

Mouse Footpad Inoculation Model to Study Viral-Induced Neuroinflammatory Responses

Porcine Corneal Tissue Explant to Study the Efficacy of Herpes Simplex Virus-1 Antivirals

Contact Hypersensitivity as a Murine Model of Allergic Contact Dermatitis

A Mouse Model of Mechanotransduction-driven, Human-like Hypertrophic Scarring

Three Strategies to Induce Neurotrophic Keratitis and Nerve Regeneration in Murine Cornea