Name: humanized nod/scid/il2r&#947;null (hu-nsg) mouse model for hiv replication and latency studies
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This work was supported by the National Institutes of Health [grant numbers R01AI29329, R01AI42552 and R01HL07470 to J.J.R.] and National Cancer Institute of the National Institutes of Health [grant number P30CA033572 to support City of Hope Integrative Genomics, Analytical Pharmacology, and Analytical Cytometry Cores]. The following reagent was obtained through the NIH AIDS Research and Reference Reagent Program, Division of AIDS, NIAID, NIH: HIV BaL virus.

All animal care and procedures have been performed according to protocols reviewed and approved by the City of Hope Institutional Animal Care and Use Committee (IACUC) held by the principal investigator of this study (Dr. John Rossi, IACUC #12034). Human fetal liver tissue was obtained from Advanced Bioscience Resources (Alameda, CA), a nonprofit organization, in accordance with federal and state regulations. The vendor has its own Institutional Review Board (IRB) and is compliant with human subject protection requiremen...

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Immunocompromised mice engrafted with human cells/tissue present human-like physiological characteristics and are a tremendous value for pathology, pathophysiology, and immunology studies concerning human-specific diseases. Among multiple strains of immunocompromised mice, the NOD.Cg-PrkdcscidIl2rgtm1Wji (NSG) model is the most immunodeficient due to its lack of both innate and adaptive immunity, as well as ablated mouse-specific cytokine signaling3,<sup c...

Because establishing suitable animal models for human diseases is key to finding a cure, appropriate animals models have long been pursued and improved over time. Multiple strains of immunocompromised murine models have been developed that permit the engraftment of human cells and/or tissues and the subsequent execution of humanized functions1,2. Such humanized mouse models are critical for investigations of human-specific diseases3,4,5.
Acquired immune deficiency syndrome (AIDS) resulting from infection with human immunodeficiency virus (HIV) is one example. Prior to the establishment of humanized mouse models, ethical and technical limitations confined HIV/AIDS preclinical animal studies to non-human primates3. However, the high expenses and requirements for specialized care for such animal hinder HIV/AIDS studies in typical academic settings. HIV primarily infects human CD4+ T-cells and impacts the development and immune responses of other human immune cells such as B-cells, macrophages, and dendritic cells6; therefore, small animal models transplanted with functional human immune systems are in high demand.
A breakthrough came in 1988, when CB17-scid mice with a Prkdcscid mutation were developed and showed successful engraftment of the human immune system1. The Prkdcscid mutation results in defective T- and B-cell functions and an ablated adaptive immune system in mice, thereby enabling the engraftment of human peripheral blood mononuclear cells (PBMCs), hematopoietic stem cells (HSCs), and fetal hematopoietic tissues7,8. Nonetheless, low levels of engraftment are frequently observed in this model; possible causes are 1) residual innate immune activity modulated via natural killer (NK)-cells and 2) the late-stage development of mouse T- and B-cells (leakiness)5. The subsequent development of the non-obese diabetic (NOD)-scid mouse model achieved dramatic down-regulation of NK-cell activity; thus, it is able to support a higher level and more sustainable engraftment of human immune system components9. To further suppress or impede development of innate immunity, mouse models bearing truncation or total knockout of the interleukin-2 receptor &#947;-chain (Il2rg) in the (NOD)-scid background were established. Il2rg, also known as common cytokine-receptor &#947;-chain, is an indispensable component of various cytokine receptors10,11,12,13. Strains such as NOD.Cg-PrkdcscidIl2rgtm1Wji (NSG) and NODShi.Cg-PrkdcscidIl2rgtm1Sug (NOG) present robust disruption of mouse cytokine signaling and complete ablation of NK-cell development, in addition to severe impairment of adaptive immunity14,15,16.
Three humanized mouse models bearing a scid mutation and Il2rg knockout are frequently employed in HIV/AIDS research: the BLT (Bone marrow/Liver/Thymus) model, the PBL (Peripheral Blood Leukocyte) model, and the SRC (SCID Repopulating Cell) model3. The BLT model is created via surgical transplantation of human fetal liver and thymus under the mouse kidney capsule accompanied with intravenous injection of fetal liver HSCs3,17,18. The BLT mouse model offers high engraftment efficacy, development of human hematopoietic cells in all lineages, and establishment of a strong human immune system; additionally, T-cells are educated in a human autologous thymus and exhibit HLA-restricted immune responses4,5,17,19. However, the requirement for surgical procedures remains the major drawback of the BLT model. The PBL mouse model is established by intravenous injection with human peripheral lymphoid cells. The PBL model offers convenience and yields successful T-cell engraftment, but its application is limited due to insufficient B-cell and myeloid cell engraftment, low engraftment levels overall, and the onset of severe graft-versus-host disease (GVHD)3,20. The SRC mouse model is established through injection of human HSCs into newborn or young adult SCID mice. It exhibits average engraftment efficiency above 25% (assessed as peripheral blood CD45 percentage) and supports the multiple-lineage development of injected HSCs and the elaboration of an innate human immune system. However, the limitation of the SRC model is that the T-cell response is mouse H2-restricted instead of human HLA-restricted14,21.
The SRC mouse model is considered a facile and reliable model for preclinical HIV/AIDS small animal studies, exemplified by the consistent engraftment of a human immune system and successful hematopoietic development. We previously reported the establishment of a NSG Hu-SRC-SCID (hu-NSG) mouse model and described its application in HIV replication and latency studies22,23,24. This hu-NSG mouse model exhibits high levels of bone marrow homing, susceptibility to HIV infection, and recapitulation of HIV infection and pathogenesis. Additionally, the hu-NSG mouse model responds appropriately to combinatorial antiretroviral therapy (cART) and recapitulates plasma viral rebound upon cART withdrawal, confirming the establishment of an HIV latency reservoir25,26,27. This HIV latency reservoir is further substantiated by the production of replication-competent HIV viruses ex vivo induced by human resting CD4+ T-cells isolated from infected and cART-treated hu-NSG mice.
Herein, we describe the detailed protocol for establishment of the hu-NSG mouse model from neonatal NSG mice, including procedures related to HIV infection and cART treatment for latency development. We expect this protocol to offer a new set of approaches in HIV animal studies regarding HIV virology, latency, and treatment.

<table>
	<tbody>
		<tr>
			<td>CD34 MicroBead Kit, human</td>
			<td>MiltenyiBiotec</td>
			<td>130-046-703</td>
			<td></td>
		</tr>
		<tr>
			<td>CryoStor CS2</td>
			<td>Stemcell Technologies</td>
			<td>07932</td>
			<td></td>
		</tr>
		<tr>
			<td>NOD.Cg-PrkdcscidIl2rgtm1Wji </td>
			<td>The Jackson Laboratory</td>
			<td>005557</td>
			<td>Order breeders instead of experimental mice</td>
		</tr>
		<tr>
			<td>IsoFlo</td>
			<td>Patterson Veterinary</td>
			<td>07-806-3204</td>
			<td>Order through animal facility, restricted item</td>
		</tr>
		<tr>
			<td>Clidox disinfectant</td>
			<td>Fisher Sicentific</td>
			<td>NC9189926</td>
			<td></td>
		</tr>
		<tr>
			<td>Wescodyne</td>
			<td>Fisher Sicentific</td>
			<td>19-818-419</td>
			<td></td>
		</tr>
		<tr>
			<td>Hamilton 80508 syringe/needle</td>
			<td>Hamilton</td>
			<td>80508</td>
			<td>Custom made</td>
		</tr>
		<tr>
			<td>Blood collection tube (K2EDTA)</td>
			<td>BD Bioscience</td>
			<td>367843</td>
			<td></td>
		</tr>
		<tr>
			<td>Blood collection tube (Heparin)</td>
			<td>BD Bioscience</td>
			<td>365965</td>
			<td></td>
		</tr>
		<tr>
			<td>Capillary tube (Heparinized)</td>
			<td>Fisher Sicentific</td>
			<td>22-362574</td>
			<td></td>
		</tr>
		<tr>
			<td>Red Blood Cell Lysis Buffer</td>
			<td>Sigma Aldrich</td>
			<td>11814389001</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAamp Viral RNA mini kit</td>
			<td>Qiagen</td>
			<td>52906</td>
			<td></td>
		</tr>
		<tr>
			<td>TaqMan Fast VIrus 1-step Master Mix</td>
			<td>Thermofisher</td>
			<td>4444434</td>
			<td></td>
		</tr>
		<tr>
			<td>HIV-1 P24 ELISA (5 Plate kit)</td>
			<td>PerkinElmer</td>
			<td>NEK050B001KT</td>
			<td></td>
		</tr>
		<tr>
			<td>IgG from human serum</td>
			<td>Sigma Aldrich</td>
			<td>I4506-100MG</td>
			<td></td>
		</tr>
		<tr>
			<td>IgG from mouse serum</td>
			<td>Sigma Aldrich</td>
			<td>I5381-10MG</td>
			<td></td>
		</tr>
		<tr>
			<td>BB515 Mouse Anti-Human CD45 (clone HI30)</td>
			<td>BD Biosciences</td>
			<td>564586</td>
			<td>RRID: AB_2732068, LOT 6347696</td>
		</tr>
		<tr>
			<td>PE-Cy7 Mouse Anti-Human CD3 (Clone SK7)</td>
			<td>BD Biosciences</td>
			<td>557851</td>
			<td>RRID: AB_396896, LOT 6021877</td>
		</tr>
		<tr>
			<td>Pacific Blue Mouse Anti-Human CD4 (Clone RPA-T4)</td>
			<td>BD Biosciences</td>
			<td>558116</td>
			<td>RRID: AB_397037, LOT 6224744</td>
		</tr>
		<tr>
			<td>BUV395 Mouse Anti-Human CD8 (Clone RPA-T8)</td>
			<td>BD Biosciences</td>
			<td>563795</td>
			<td>RRID: AB_2722501, LOT 6210668</td>
		</tr>
		<tr>
			<td>APC-Alexa Fluor 750 Mouse Anti-Human CD14 (TuK4)</td>
			<td>ThermoFisher</td>
			<td>MHCD1427</td>
			<td>RRID: AB_10373536, LOT 1684947A</td>
		</tr>
		<tr>
			<td>PE Mouse Anti-Human CD19 (SJ25-C1)</td>
			<td>ThermoFisher</td>
			<td>MHCD1904</td>
			<td>RRID: AB_10373382, LOT 1725304B</td>
		</tr>
	</tbody>
</table>

humanized nod/scid/il2r&#947;null (hu-nsg) mouse model for hiv replication and latency studies

Ethical regulations and technical challenges for research in human pathology, immunology, and therapeutic development have placed small animal models in high demand. With a close genetic and behavioral resemblance to humans, small animals such as the mouse are good candidates for human disease models, through which human-like symptoms and responses can be recapitulated. Further, the mouse genetic background can be altered to accommodate diverse demands. The NOD/SCID/IL2r&#947;null (NSG) mouse is one of the most widely used immunocompromised mouse strains; it allows engraftment with human hematopoietic stem cells and/or human tissues and the subsequent development of a functional human immune system. This is a critical milestone in understanding the prognosis and pathophysiology of human-specific diseases such as HIV/AIDS and aiding the search for a cure. Herein, we report a detailed protocol for generating a humanized NSG mouse model (hu-NSG) by hematopoietic stem cell transplantation into a radiation-conditioned neonatal NSG mouse. The hu-NSG mouse model shows multi-lineage development of transplanted human stem cells and susceptibility to HIV-1 viral infection. It also recapitulates key biological characteristics in response to combinatorial antiretroviral therapy (cART).

Flow cytometry analysis is frequently performed to validate the purity of isolated HSCs, evaluate engraftment levels, profile immune responses to viral infection, and survey cART efficacy. A typical antibody panel contains 4-6 individual fluorescently labeled antibodies; thus, a flow cytometer with multiple lasers and a wide selection of filters is crucial for achieving accurate results.
For initial engraftment validation, the h...

Watch this Scientific Journal Video about Humanized NOD/SCID/IL2rÎ³null hu-NSG Mouse Model for HIV Replication and Latency Studies at JoVE.com

Humanized NOD/SCID/IL2r&#947;null (hu-NSG) Mouse Model for HIV Replication and Latency Studies

This protocol provides a method to establish humanized mice (hu-NSG) via intrahepatic injection of human hematopoietic stem cells into radiation-conditioned neonatal NSG mice. The hu-NSG mouse is susceptible to HIV infection and combinatorial antiretroviral therapy (cART) and serves as a suitable pathophysiological model for HIV replication and latency investigations.

Ethical regulations and technical challenges for research in human pathology, immunology, and therapeutic development have placed small animal models in ...

These matters can help answer key questions in HIV/AIDS research, such as the molecular mechanism and the prognosis of HIV infection, and how and where the latency reservoir is established. The advantage of this technique is that it is non-invasive, and established a hu-NSG mice that must treat a multi-lineage development over transplanted human stem cells that are susceptible to HIV infection and are receptive to cART. Begin by filtering a digested, human, fetal, liver tissue, slurry sample through a sterile, 70 micrometer, nylon, mesh strainer to obtain a single cell suspension, and enrich for CD34+HSCs by magnetic activated cell sorting according to the manufacturer's instructions.After counting, re-suspend the HSC at a two-times-ten-to-the-seventh viable cells per milliliter concentration in fresh DPBS on ice. Next place an entire neonatal human NOD/SCID/gamma or NSG mouse litter into a sterile, pie-shaped, irradiation cage, and treat the animals with 200 to 250 centigrades of gamma ray from a cesium-137 radiation source. Then load the cells into a custom-made, Hamilton 80508 50-microliter syringe equipped with a 30-gauge needle, and inject each neonatal animal directly into the liver with five-times-ten-to-the-fifth viable human CD34+HSCs and 25 microliters of DPBS.Ten-to-twelve weeks post infection, spin down retro-orbital, peripheral, blood samples from each mouse by centrifugation, and transfer the plasma supernates to microcentrifuge tubes for negative 80 degrees Celsius storage as experimentally appropriate. For HSC engraftment validation, re-suspend the pellets with 200 microliters of red blood cell lysis buffer, and pull the cell suspensions in a 1.5 millimeter microcentrifuge tube for a ten-minute incubation at room temperature. Then collect the remaining white blood cells by centrifugation for two washes in 0.5 milliliters of fresh, 0.01 percent bovine serum albumin, or BSA, in DPBS per wash.After the second wash, block the cells with 100 microliters of blocking cocktail for twenty minutes at 4 degrees Celsius followed by labeling with the appropriate anti-body cocktail of interest at a 2 microliters of anti-body per one-times-one-to-the-sixth cells concentration. After 30 minutes at 4 degrees Celsius, wash the cells two times in fresh DPBS plus BSA, and evaluate the peripheral blood samples by flow cytometry according to standard protocols to quantify the percentage of human CD45+CD3+CD14+or CD19+cells per sample. Then calculate the ratio of CD4+to-CD8+T cells, and assess the viral load with in the plasma samples according to standard, quantitative, reverse transcriptase, PCR protocols.To assess the effects of HIV infection, deliver HIV bale virus to anesthetized, human, NSG mice with a greater than 20 percent human CD45+cell population in their peripheral blood, at a 200 nanograms of P24 per mouse concentration via intraperitoneal administration, collecting blood samples via retro-orbital bleeding every two weeks, and analyze both the CD4-to-CD8 ratio and the plasma viral load, as demonstrated. For viral suppression validation supply the infected, human NSG animals with fresh, combinatorial, anti-retroviral therapy, or cART, in sweetened water every week for 4 weeks, collecting blood samples via retro-orbital bleeding every two weeks and analyze both the CD4-to-CD8 ratio and the plasma viral load as demonstrated. To asses the viral rebound when the plasma viral loads are below the detection limit and the CD4-to-CD8 ratio is restored between 1.5 and 2.5 collect peripheral blood samples through retro-orbital bleeding every 2 weeks after cART withdrawal and evaluate the samples as demonstrated.During the initial engraftment validation, the human CD45+cell count should range from 20 to 80 percent, and the subsets of human leukocytes should appear as discrete populations by flow cytometric analysis. The ratio of CD4+to-CD8+cells remains between 1.5 and 2.5 in healthy individuals while significant CD4+T cell depletion is typically observed upon viral infection. Notably, the healthy ratio is restored in response to cART treatment.The detection of plasma viral loads by quantitative RT PCR throughout the course of the infection and the cART regimen can be plotted and used to evaluate the efficiency of the viral delivery and the anti-viral treatment, respectively. Though this method can provide insight into HIV/AIDS virology studies and therapeutic development, it can also be applied to other studies related to human disease, such as cancer, diabetes, and auto-immune diseases. The hu-NSG mouse model development paved the way for researchers in immunology and oncology to explore a new dysfunction and pathology in humans, particularly mechanistic and therapeutic studies targeting HIV chronic infection and the latency reservoir.

humanized-nodscidil2rnull-hu-nsg-mouse-model-for-hiv-replication

Research

JoVE Journal

Immunology and Infection

Dissecting Host-virus Interaction in Lytic Replication of a Model Herpesvirus

In response to viral infection, a host develops various defensive responses, such as activating innate immune signaling pathways that lead to antiviral cytokine production1,2. In order to colonize the host, viruses are obligate to evade host antiviral responses and manipulate signaling pathways. Unraveling the host-virus interaction will shed light on the development of novel therapeutic strategies against viral infection.
Murine &gamma;HV68 is closely related to human oncogenic Kaposi's sarcoma-associated herpesvirus and Epsten-Barr virus3,4. &gamma;HV68 infection in laboratory mice provides a tractable small animal model to examine the entire course of host responses and viral infection in vivo, which are not available for human herpesviruses. In this protocol, we present a panel of methods for phenotypic characterization and molecular dissection of host signaling components in &gamma;HV68 lytic replication both in vivo and ex vivo. The availability of genetically modified mouse strains permits the interrogation of the roles of host signaling pathways during &gamma;HV68 acute infection in vivo. Additionally, mouse embryonic fibroblasts (MEFs) isolated from these deficient mouse strains can be used to further dissect roles of these molecules during &gamma;HV68 lytic replication ex vivo.
Using virological and molecular biology assays, we can pinpoint the molecular mechanism of host-virus interactions and identify host and viral genes essential for viral lytic replication. Finally, a bacterial artificial chromosome (BAC) system facilitates the introduction of mutations into the viral factor(s) that specifically interrupt the host-virus interaction. Recombinant &gamma;HV68 carrying these mutations can be used to recapitulate the phenotypes of &gamma;HV68 lytic replication in MEFs deficient in key host signaling components. This protocol offers an excellent strategy to interrogate host-pathogen interaction at multiple levels of intervention in vivo and ex vivo.
Recently, we have discovered that &gamma;HV68 usurps an innate immune signaling pathway to promote viral lytic replication5. Specifically, &gamma;HV68 de novo infection activates the immune kinase IKK&beta; and activated IKK&beta; phosphorylates the master viral transcription factor, replication and transactivator (RTA), to promote viral transcriptional activation. In doing so, &gamma;HV68 efficiently couples its transcriptional activation to host innate immune activation, thereby facilitating viral transcription and lytic replication. This study provides an excellent example that can be applied to other viruses to interrogate host-virus interaction.

We describe a protocol to identify key roles of host signaling molecules in lytic replication of a model herpesvirus, gamma herpesvirus 68 (&gamma;HV68). Utilizing genetically modified mouse strains and embryonic fibroblasts for &gamma;HV68 lytic replication, the protocol permits both phenotypic characterization and molecular interrogation of virus-host interactions in viral lytic replication.

In response to viral infection, a host develops various defensive responses, such as activating innate immune signaling pathways that lead to antiviral ...

Using the BLT Humanized Mouse as a Stem Cell based Gene Therapy Tumor Model

Small animal models such as mice have been extensively used to study human disease and to develop new therapeutic interventions. Despite the wealth of information gained from these studies, the unique characteristics of mouse immunity as well as the species specificity of viral diseases such as human immunodeficiency virus (HIV) infection led to the development of humanized mouse models. The earlier models involved the use of C. B 17 scid/scid mice and the transplantation of human fetal thymus and fetal liver termed thy/liv (SCID-hu) 1, 2 or the adoptive transfer of human peripheral blood leukocytes (SCID-huPBL) 3. Both models were mainly utilized for the study of HIV infection.
One of the main limitations of both of these models was the lack of stable reconstitution of human immune cells in the periphery to make them a more physiologically relevant model to study HIV disease. To this end, the BLT humanized mouse model was developed. BLT stands for bone marrow/liver/thymus. In this model, 6 to 8 week old NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) immunocompromised mice receive the thy/liv implant as in the SCID-hu mouse model only to be followed by a second human hematopoietic stem cell transplant 4. The advantage of this system is the full reconstitution of the human immune system in the periphery. This model has been used to study HIV infection and latency 5-8.
We have generated a modified version of this model in which we use genetically modified human hematopoietic stem cells (hHSC) to construct the thy/liv implant followed by injection of transduced autologous hHSC 7, 9. This approach results in the generation of genetically modified lineages. More importantly, we adapted this system to examine the potential of generating functional cytotoxic T cells (CTL) expressing a melanoma specific T cell receptor. Using this model we were able to assess the functionality of our transgenic CTL utilizing live positron emission tomography (PET) imaging to determine tumor regression (9).
The goal of this protocol is to describe the process of generating these transgenic mice and assessing in vivo efficacy using live PET imaging. As a note, since we use human tissues and lentiviral vectors, our facilities conform to CDC NIH guidelines for Biosafety Level 2 (BSL2) with special precautions (BSL2+). In addition, the NSG mice are severely immunocompromised thus, their housing and maintenance must conform to the highest health standards (<a href="http://jaxmice.jax.org/research/immunology/005557-housing.html" target="_blank">http://jaxmice.jax.org/research/immunology/005557-housing.html</a>).

The generation and characterization of tumor specific T cells using humanized mice is described here. Human thymic tissue and genetically modified human hematopoietic stem cells are transplanted into immunocompromised mice. This results in the reconstitution of an engineered human immune system allowing for in vivo examination of anti-tumor immune responses.

Small animal models such as mice have been extensively used to study human  disease and to develop new therapeutic interventions. Despite the wealth of  ...

Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature

Neisseria meningitidis causes a severe, frequently fatal sepsis when it enters the human blood stream. Infection leads to extensive damage of the blood vessels resulting in vascular leak, the development of purpuric rashes and eventual tissue necrosis. Studying the pathogenesis of this infection was previously limited by the human specificity of the bacteria, which makes in vivo models difficult. In this protocol, we describe a humanized model for this infection in which human skin, containing dermal microvessels, is grafted onto immunocompromised mice. These vessels anastomose with the mouse circulation while maintaining their human characteristics. Once introduced into this model, N. meningitidis adhere exclusively to the human vessels, resulting in extensive vascular damage, inflammation and in some cases the development of purpuric rash. This protocol describes the grafting, infection and evaluation steps of this model in the context of N. meningitidis infection. The technique may be applied to numerous human specific pathogens that infect the blood stream.

Neisseria meningitidis is a human specific pathogen that infects blood vessels. In this protocol human microvessels are introduced into a mouse by grafting human skin onto immunocompromised mice. Bacteria adhere extensively to the human vessels, leading to vascular damage and development of the purpuric rash typically observed in human cases.

Neisseria meningitidis causes a severe, frequently fatal sepsis when it enters the human blood stream. Infection leads to extensive damage of the blood ...

Pairwise Growth Competition Assay for Determining the Replication Fitness of Human Immunodeficiency Viruses

In vitro fitness assays are essential tools for determining viral replication fitness for viruses such as HIV-1. Various measurements have been used to extrapolate viral replication fitness, ranging from the number of viral particles per infectious unit, growth rate in cell culture, and relative fitness derived from multiple-cycle growth competition assays. Growth competition assays provide a particularly sensitive measurement of fitness since the viruses are competing for cellular targets under identical growth conditions. There are several experimental factors to consider when conducting growth competition assays, including the multiplicity of infection (MOI), sampling times, and viral detection and fitness calculation methods. Each factor can affect the end result and hence must be considered carefully during the experimental design. The protocol presented here includes steps from constructing a new recombinant HIV-1 clone to performing growth competition assays and analyzing the experimental results. This protocol utilizes experimental parameter values previously shown to yield consistent and robust results. Alternatives are discussed, as some parameters need to be adjusted according to the cell type and viruses being studied. The protocol contains two alternative viral detection methods to provide flexibility as the availability of instruments, reagents and expertise varies between laboratories.

Growth competition between nearly isogenic viruses provides a sensitive measurement for determining relative replication fitness. The protocols described here include the construction of recombinant HIV-1 clones, virus propagation and growth competition and analysis methods optimized to yield sensitive and consistent results.

In vitro fitness assays are essential tools for determining viral replication fitness for viruses such as HIV-1. Various measurements have been used to ...

Measurement of In Vitro Integration Activity of HIV-1 Preintegration Complexes

HIV-1 envelope proteins engage cognate receptors on the target cell surface, which leads to viral-cell membrane fusion followed by the release of the viral capsid (CA) core into the cytoplasm. Subsequently, the viral Reverse Transcriptase (RT), as part of a namesake nucleoprotein complex termed the Reverse Transcription Complex (RTC), converts the viral single-stranded RNA genome into a double-stranded DNA copy (vDNA). This leads to the biogenesis of another nucleoprotein complex, termed the pre-integration complex (PIC), composed of the vDNA and associated virus proteins and host factors. The PIC-associated viral integrase (IN) orchestrates the integration of the vDNA into the host chromosomal DNA in a temporally and spatially regulated two-step process. First, the IN processes the 3&#39; ends of the vDNA in the cytoplasm and, second, after the PIC traffics to the nucleus, it mediates integration of the processed vDNA into the chromosomal DNA. The PICs isolated from target cells acutely infected with HIV-1 are functional in vitro, as they are competent to integrate the associated vDNA into an exogenously added heterologous target DNA. Such PIC-based in vitro integration assays have significantly contributed to delineating the mechanistic details of retroviral integration and to discovering IN inhibitors. In this report, we elaborate upon an updated HIV-1 PIC assay that employs a nested real-time quantitative Polymerase Chain Reaction (qPCR)-based strategy for measuring the in vitro integration activity of isolated native PICs.

Measurement of In Vitro Integration Activity of HIV-1 Preintegration Complexes

This report describes an in vitro assay for measuring the human immunodeficiency virus type 1 (HIV-1) preintegration complex (PIC)-associated integration activity in the cytoplasmic extracts of acutely infected cells. The integration of PIC-associated HIV-1 DNA into heterologous target DNA is quantified by using a nested real-time polymerase chain reaction strategy.

HIV-1 envelope proteins engage cognate receptors on the target cell surface, which leads to viral-cell membrane fusion followed by the release of the ...

Influenza A Virus Studies in a Mouse Model of Infection

Influenza viruses cause over 500,000 deaths worldwide1 and are associated with an annual cost of 12 - 14 billion USD in the United States alone considering direct medical and hospitalization expenses and work absenteeism2. Animal models are crucial in Influenza A virus (IAV) studies to evaluate viral pathogenesis, host-pathogen interactions, immune responses, and the efficacy of current and/or novel vaccine approaches as well as antivirals. Mice are an advantageous small animal model because their immune system is evolutionarily similar to that found in humans, they are available from commercial vendors as genetically identical subjects, there are multiple strains that can be exploited to evaluate the genetic basis of infections, and they are relatively inexpensive and easy to manipulate. To recapitulate IAV infection in humans via the airways, mice are first anesthetized prior to intranasal inoculation with infectious IAVs under proper biosafety containment. After infection, the pathogenesis of IAVs is determined by monitoring daily the morbidity (body weight loss) and mortality (survival) rate. In addition, viral pathogenesis can also be evaluated by assessing virus replication in the upper (nasal mucosa) or lower (lungs) respiratory tract of infected mice. Humoral responses upon IAV infection can be rapidly evaluated by non-invasive bleeding and secondary antibody detection assays aimed at detecting the presence of total or neutralizing antibodies. Here, we describe the common methods used to infect mice intranasally (i.n) with IAV and evaluate pathogenesis, humoral immune responses and protection efficacy.

Influenza A viruses (IAVs) are important human respiratory pathogens. To understand the pathogenicity of IAVs and to perform preclinical testing of novel vaccine approaches, animal models mimicking human physiology are required. Here, we describe techniques to evaluate IAV pathogenesis, humoral responses and vaccine efficacy using a mouse model of infection.

Influenza viruses cause over 500,000 deaths worldwide1 and are associated with an annual cost of 12 - 14 billion USD in the United States alone ...

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 ...

High Throughput In Vitro Assessment of Latency Reversing Agents on HIV Transcription and Splicing

HIV remains incurable due to the existence of a reservoir of cells that harbors stable and latent form of the virus, which stays invisible to the immune system and is not targeted by the current antiretroviral therapy (cART). Transcription and splicing have been shown to reinforce HIV-1 latency in resting CD4+ T cells. Reversal of latency by the use of latency reversal agents (LRAs) in the &#34;shock and kill&#34; approach has been studied extensively in an attempt to purge this reservoir but has thus far not shown any success in clinical trials due to the lack of development of adequate small molecules that can efficiently perturb this reservoir. The protocol presented here provides a method for reliably and efficiently assessing latency reversal agents (LRAs) on HIV transcription and splicing. This approach is based on the use of an LTR-driven dual color reporter that can simultaneously measure the effect of an LRA on transcription and splicing by flow cytometry. The protocol described here is adequate for adherent cells as well as the cells in suspension. It is useful for testing a large number of drugs in a high throughput system. The method is technically simple to implement and cost-effective. In addition, the use of flow cytometry allows the assessment of cell viability and thus drug toxicity at the same time.

A high throughput protocol for functional assessment of HIV efficient reactivation and clearance of latent proviruses is described and applied by testing the impact of interventions on HIV transcription and splicing. Representative results of the effect of latency reversing agents on LTR-driven transcription and splicing are provided.

HIV remains incurable due to the existence of a reservoir of cells that harbors stable and latent form of the virus, which stays invisible to the immune ...

Identification of Nucleolar Factors During HIV-1 Replication Through Rev Immunoprecipitation and Mass Spectrometry

The HIV-1 infectious cycle requires viral protein interactions with host factors to facilitate viral replication, packaging, and release. The infectious cycle further requires the formation of viral/host protein complexes with HIV-1 RNA to regulate the splicing and enable nucleocytoplasmic transport. The HIV-1 Rev protein accomplishes the nuclear export of HIV-1 mRNAs through multimerization with intronic cis-acting targets - the Rev response element (RRE). A nucleolar localization signal (NoLS) exists within the COOH-terminus of the Rev arginine-rich motif (ARM), allowing the accumulation of Rev/RRE complexes in the nucleolus. Nucleolar factors are speculated to support the HIV-1 infectious cycle through various other functions in addition to mediating mRNA-independent nuclear export and splicing. We describe an immunoprecipitation method of wild-type (WT) Rev in comparison to Rev nucleolar mutations (deletion and single-point Rev-NoLS mutations) in the presence of HIV-1 replication for mass spectrometry. Nucleolar factors implicated in the nucleocytoplasmic transport (nucleophosmin B23 and nucleolin C23), as well as cellular splicing factors, lose interaction with Rev in the presence of Rev-NoLS mutations. Various other nucleolar factors, such as snoRNA C/D box 58, are identified to lose interaction with Rev mutations, yet their function in the HIV-1 replication cycle remain unknown. The results presented here demonstrate the use of this approach for the identification of viral/host nucleolar factors that maintain the HIV-1 infectious cycle. The concepts used in this approach are applicable to other viral and disease models requiring the characterization of understudied pathways.

Here we describe Rev immunoprecipitation in the presence of HIV-1 replication for mass spectrometry. The methods described can be used for the identification of nucleolar factors involved in the HIV-1 infectious cycle and are applicable to other disease models for the characterization of understudied pathways.

The HIV-1 infectious cycle requires viral protein interactions with host factors to facilitate viral replication, packaging, and release. The infectious ...

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 ...