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Method Article
This protocol describes a novel method to deliver oral combinational antiretroviral drugs that successfully suppress HIV-1 RNA replication in humanized mice.
The human immunodeficiency virus (HIV-1) pandemic continues to spread unabated worldwide, and currently, there is no vaccine available against HIV. Although combinational antiretroviral therapy (cART) has been successful in suppressing viral replication, it cannot completely eradicate the reservoir from HIV-infected individuals. A safe and effective cure strategy for HIV infection will require multipronged methods, and therefore the advancements of animal models for HIV-1 infection are pivotal for the development of HIV cure research. Humanized mice recapitulate key features of HIV-1 infection. The humanized mouse model can be infected by HIV-1 and viral replication can be controlled with cART regimens. Moreover, cART interruption results in a prompt viral rebound in humanized mice. However, administration of cART to the animal can be ineffective, difficult, or toxic, and many clinically relevant cART regimens are unable to be optimally utilized. Along with being potentially unsafe for researchers, administration of cART by a commonly used intensive daily injection procedure induces stress by physical restraint of the animal. The novel oral cART method to treat HIV-1 infected humanized mice described in this article resulted in suppression of viremia below the detection level, increased rate of CD4+ restoration, and improved overall health in HIV-1 infected humanized mice.
The life expectancy of chronic human immunodeficiency virus (HIV)-infected individuals has significantly improved with combinational antiretroviral treatment (cART)1,2. cART successfully reduces the HIV-1 replication and increases CD4+ T cell counts to normalcy in the majority of HIV-1 chronically infected participants3, resulting in improved overall health and dramatically reduced disease progression4. However, the latent HIV-1 reservoir is established even when ART is initiated during acute infection5,6,7. Reservoirs persist over years during ART and rapid viral rebound after ART interruption is well-documented8,9. People living with HIV on ART are also predisposed to a higher risk of comorbidities such as cardiovascular disease, cancer, and neuro disorders10,11,12. Therefore, a functional cure for HIV is needed. Animal models for HIV-1 infection offer obvious advantages in developing and validating novel HIV cure strategies13,14,15. Humanized mice, as a small animal model, can provide multilineage human immune cell reconstitution in different tissues, which allows for the close study of HIV infection16,17,18,19. Among humanized models, the humanized bone marrow-liver-thymus (BLT) model successfully recapitulates chronic HIV-1 infection as well as functional human immune responses to HIV-1 infection20,21,22,23,24. Therefore, the humanized BLT mouse model has been widely used to investigate various aspects in the HIV research field. Humanized BLT mice are not only well-established models for the recapitulation of persistent HIV-1 infection and pathogenesis, but also consequential tools for the evaluation of cell therapy-based intervention strategies. The current authors and others have demonstrated that the humanized BLT mice model recapitulates persistent HIV-1 infection and pathogenesis25,26,27 and provides tools to evaluate cell therapy-based intervention strategies 28,29,30,31,32,33.
cART regimens consisting of combinations of antiretroviral drugs that are taken daily suppress HIV-1 replication to the point that the viral load in successfully treated individuals remains undetectable over long term34. The outcomes of treating HIV-infected humanized mice with clinically relevant cART regimens resemble those observed in HIV-1 infected ART-treated individuals22: HIV-1 levels are suppressed below the limits of detection and interruption of cART results in a rebound of HIV replication from the latent reservoir35. Subcutaneous (SC)27,36,37 or intraperitoneal (IP)37,38,39 injection is the route commonly used for cART treatment in humanized mice. However, intensive daily injection induces stress to animals by physical restraint40. It is also labor-intensive and potentially unsafe for researchers due to increased exposure to HIV while using sharps. Oral administration is ideal to mimic the absorption, distribution, and excretion of cART drugs that are taken by HIV-1-infected individuals. Oral administration typically involves customized and often laborious procedures to put the antiretroviral drugs in sterilized (necessary due to the immunodeficiency of the mice) food24,37,41 or water42,43,44,45,46, which may or may not be chemically compatible with many antiretroviral drugs, or result in something the mice would not readily eat or drink (which would affect dose and drug levels in the body). The novel peroral cART administration method proposed here surpasses previous delivery attempts due to its compatibility with different types of antiretroviral drugs, safety and ease of preparation and administration, and reduction of animal stress and anxiety resulting from the daily injection.
Tenofovir disoproxil fumarate (TDF), Elvitegravir (ELV), and Raltegravir (RAL) are poorly water-soluble drugs. Interestingly, increased bioavailability of TDF is observed with fatty foods, suggesting that competitive inhibition of lipases by fatty food may provide certain protection for TDF47. Therefore, DietGel Boost cups were selected to replace regular rodent chow as the method of delivery based on their modest fat content (20.3 g per 100 g) as compared to regular rodent chow (10 g per 100 g) and a typical mouse high-fat diet (40-60 g per 100 g)48. The total weight of one cup is 75 g; thus, each cup will contain the amount of food, and therefore drug, sufficient for five mice over 3 days.
Anonymized human fetal tissue was acquired commercially. Animal research was carried out according to protocols approved by the University of California, Los Angeles, and (UCLA) Animal Research Committee (ARC) in accordance with all federal, state, and local guidelines. Specifically, all the experiments were carried out in accordance with the recommendations and guidelines for housing and care of laboratory animals of the National Institutes of Health (NIH) and the Association for the Assessment and Accreditation of Laboratory Animal Care (AALAC) International under UCLA ARC Protocol Number 2010-038-02B. All surgeries were performed under ketamine (100 mg/kg)/xylazine (5 mg/kg) and isoflurane anesthesia (2-3 vol%) and all efforts were made to minimize animal pain and discomfort.
1. Humanized mice infected with HIV-1
NOTE: Humanized mice were constructed as previously described in30,31,49. The protocol is briefly described below.
2. Preparation of ART drugs
3. Administration of ART drugs to HIV-1 infected mice
4. Monitor viral load by real-time PCR
5. Assess CD4/CD8 ratios by flow cytometry
Assuming an average mouse weighing 25 g consumes 4 g of food per day, the daily drug dose through oral intake corresponds to 2.88 mg/kg TFV, 83 mg/kg FTC, and 768 mg/kg RAL. To test whether the optimized food regimen is toxic and influences overall health compared to daily injection of cART, mice weight was monitored weekly before and during cART through oral or subcutaneous injection. There were no significant weight differences before cART administration in each group (Figure 1). However, ...
An oral cART administration method is developed here for HIV-1 infected humanized mice by combining three antiretroviral drugs within high nutrient food. Compared to administration by daily injections, oral delivery is easier to use, limits administration frequency, reduces animal handling, minimizes stress, and improves safety55. Up to this point, only a few studies in humanized mice24,37,41 have used fo...
SK is a founder of CDR3 Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
We would like to thank Drs. Romas Geleziunas and Jeff Murry and the people at Gilead for providing the antiretroviral drugs used in this study. This work was funded by NCI 1R01CA239261-01 (to Kitchen), NIH Grants P30AI28697 (the UCLA CFAR Virology Core, Gene and Cell Therapy Core, and Humanized Mouse Core), U19AI149504 (PIs: Kitchen & Chen), CIRM DISC2-10748, NIDA R01DA-52841 (to Zhen), NIAID R2120200174 (PIs: Xie & Zhen), IRACDA K12 GM106996 (Carrillo). This work was also supported by the UCLA AIDS Institute, the James B. Pendleton Charitable Trust, and the McCarthy Family Foundation.
Name | Company | Catalog Number | Comments |
60 mm petri dish | Thermo Scientific Nunc | 150288 | For aliquoting ART food |
APC anti-human CD8 Antibody | Biolegend | 344722 | For flow cytometry |
BD LSRFortessa | BD biosciences | For flow data collection | |
CD34 microbeads | Miltenyi Biotec | 130-046-702 | For NSG-BLT mice generation |
Centrifuge tubes | Falcon | 14-432-22 | For dissolving ART |
DietGel Boost | ClearH2O | 72-04-5022 | For making ART food |
Elvitegravir | Gilead | Gifted from Gilead | |
Emtricitabine | Gilead | Gifted from Gilead | |
FITC anti-human CD3 Antibody | Biolegend | 317306 | For flow cytometry |
Flowjo software | FlowJo | For flow cytometry data analysis | |
HIV-1 forward primer: 5′-CAATGGCAGCAATTTCACCA-3′; | IDT | Customized | For viral load RT-PCR |
HIV-1 probe: 5′-[6-FAM]CCCACCAACAGGCGGCCT TAACTG [Tamra-Q]-3′; | IDT | Customized | For viral load RT-PCR |
HIV-1 reverse primer: 5′-GAATGCCAAATTCCTGCTTGA-3′; | IDT | Customized | For viral load RT-PCR |
Human fetal tissue | Advanced Bioscience Resources, Inc | ||
Mice, strain NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ | The Jackson Laboratory | 5557 | For constructing the humanized mice |
Pacific Blue anti-human CD45 | Biolegend | 304022 | For flow cytometry |
PerCP anti-human CD4 Antibody | Biolegend | 300528 | For flow cytometry |
QIAamp Viral RNA Kits | Qiagen | 52904 | For measuring viral load |
Raltegravir | Merck | Gifted from Merck | |
Sterile cell scrapers | Thermo Scientific | 179693 | For aliquoting ART food |
TaqMan RNA-To-Ct 1-Step Kit | Applied Biosystems | 4392653 | For plasma viral load detection |
Tenofovir disoproxil fumarate | Gilead | Gifted from Gilead | |
Trimethoprim-Sulfamethoxazole | Pharmaceutical Associates | NDC 0121-0854-16 | For keeping ART food sterile. Each 5mL teaspoon contains 200 mg Sulfamethoxazole, USP 40 mg Trimethoprim, USP NMT 0.5% Alcohol |
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