hu-SCID Mice Research Articles

Cowpox Helped Against Smallpox; Will the Goat Lentivirus (Caprine Arthritis Encephalitis Virus) Help Against HIV-1?

AIDS Research and Human RetrovirusesVol. 31, No. 6 Images in HIV ResearchCowpox Helped Against Smallpox; Will the Goat Lentivirus (Caprine Arthritis Encephalitis Virus) Help Against HIV-1?Yahia Chebloune, Maha Moussa, Géraldine Arrode-Brusés, and Jean GagnonYahia CheblouneSearch for more papers by this author, Maha MoussaSearch for more papers by this author, Géraldine Arrode-BrusésSearch for more papers by this author, and Jean GagnonSearch for more papers by this authorPublished Online:29 May 2015https://doi.org/10.1089/aid.2015.0010AboutSectionsView articleView Full TextPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail View article"Cowpox Helped Against Smallpox; Will the Goat Lentivirus (Caprine Arthritis Encephalitis Virus) Help Against HIV-1?." AIDS Research and Human Retroviruses, 31(6), pp. 577–578FiguresReferencesRelatedDetailsCited byComparative Analysis of Tat-Dependent and Tat-Deficient Natural Lentiviruses29 September 2015 | Veterinary Sciences, Vol. 2, No. 4 Volume 31Issue 6Jun 2015 InformationCopyright 2015, Mary Ann Liebert, Inc.To cite this article:Yahia Chebloune, Maha Moussa, Géraldine Arrode-Brusés, and Jean Gagnon.Cowpox Helped Against Smallpox; Will the Goat Lentivirus (Caprine Arthritis Encephalitis Virus) Help Against HIV-1?.AIDS Research and Human Retroviruses.Jun 2015.577-578.http://doi.org/10.1089/aid.2015.0010Published in Volume: 31 Issue 6: May 29, 2015Online Ahead of Print:April 6, 2015PDF download

Using human-severe combined immunodeficiency (hu-SCID) mice as a model for testing allergenicity of genetically modified organisms (GMOs)

Background GM peas expressing the alpha-amylase inhibitor (AAI) protein derived from common Tendergreen bean were created to protect them against infestation by pea weevils. Although animal models are used for studying allergenicity of GM containing foods, the correlation with human allergy remains controversial. Methods Our aim in this study was to establish a humanized mouse model to study GMOs by adoptively transferring peripheral blood mononuclear cells from AAI-specific IgE-positive legume allergic and non-allergic individuals into SCID mice. These mice were then gavaged twice weekly for 1 month with GM pea, non-transgenic pea and Tendergreen bean seed meal suspensions or PBS. Subsequently, mice were administered 1 dose of the purified AAI protein or PBS intranasally as a read out for an in vivo allergic response. Seventy-two hours later, no eosinophilia or mucus hypersecretion were observed in the lungs of mice treated with PBS or fed the non-transgenic peas. Results In contrast, hu-SCID mice derived from allergic and nonallergic donors had intense allergic lung inflammation and mucus over production illustrating that AAI-containing seed meal feeding primed for allergic immune responses. However, there were no differences in the responses between hu-SCID mice derived from allergic and nonallergic donors. Because both donors had anti-AAI antibodies, we hypothesize that they were both sensitized to AAI and thus indistinguishable when their cells were exposed to AAI during feeding in the humanized mice. Conclusion

Blockade of PD-1/PD-L1 immune checkpoint during DC vaccination induces potent protective immunity against breast cancer in hu-SCID mice

Immune checkpoints, such as the PD-1/PD-L1 pathway, negatively interfere in the efficiency of dendritic cell (DC) vaccination in cancer immunotherapy. In this study, we demonstrated that the blockade of PD-L1 signaling could promote DC maturation, proliferation, and IL-12 secretion, augment DC primed T cell response and reverse tumor cell dampened T cell impairment. Blockade of PD-L1 signaling during DC vaccination showed better therapeutic effects than classic DC vaccination by preventing tumor growth and prolonging survival times in a breast tumor-bearing hu-SCID model. Taken together, suppressing immune checkpoints during DC vaccination might be a more efficient strategy for cancer therapy.

Vaccination with immature dendritic cells combined with CD40 mAb induces protective immunity against B lymphoma in hu-SCID mice

Dendritic cells (DCs) pulsed by tumor antigens have been widely used as tumor vaccines to specifically trigger the cytotoxicity of CD8+ T cells. But the tumor microenviroment with enriched immunosuppressants hampered DC maturation and co-stimulation. CD40/CD40L signaling, one of the most important co-stimulatory molecules is capable of effectively skewing the immune response by promoting DCs maturation and co-stimulation. To establish a novel specific immunotherapeutic approach for the use of DC vaccine in the treatment of B lymphoma, hu-SCID mice bearing B lymphoma were vaccinated by different combination of tumor antigen pulsed DC or imDC vaccines and immune-enhancing agencies such as agonist CD40 mAb and T cells. The results of immature DCs combined with agonistic CD40 mAb were encouraging with achievement of tumor regression and induction of antigen-specific immune responses. These findings demonstrated the potential utility of imDC-based tumor vaccination combining with agonistic CD40 mAb in the treatment of malignant lymphoma.

Targeted ablation of human CD30 positive cells with an anti-CD30-MMAE antibody-drug conjugate (SGN-35) in vivo inhibits antigen-specific secondary immune responses (50.17)

Abstract CD30 is a member of the tumor necrosis factor receptor superfamily whose normal physiologic expression is restricted primarily to relatively small subpopulations of activated T- and B-cells. In abnormal physiologic states, CD30 has been found on inflammatory cells in patients with a variety of chronic inflammatory diseases such as atopic dermatitis and asthma. In addition, malignant Reed-Sternberg and anaplastic large cell lymphoma cells express particularly high levels of CD30. Cells expressing CD30 have been shown to be activated and produce cytokines during inflammatory responses. SGN-35 is an antibody-drug conjugate that binds to human CD30, ablates CD30+ tumor cells in vitro, and strongly inhibits growth of HL and ALCL tumors in vivo. In the present study, the effects of SGN-35 on antigen specific secondary immune responses were evaluated. Compared to untreated cells, SGN-35 induced a dose-dependent inhibition of T cell proliferation, with maximum inhibition of 70% following antigen stimulation in vitro. In the hu-SCID mouse tetanus toxoid model, antigen-specific immunoglobulin responses in SGN-35 treated mice were much lower compared to untreated controls (p=0.0019). Taken together, these data demonstrate specific targeting of subsets of activated lymphocytes and suggest that SGN-35 may be employed clinically to decrease antigen specific cells and immunoglobulin that damage tissue in autoimmune and inflammatory diseases.

Antibody to the dendritic cell surface activation antigen CD83 prevents acute graft-versus-host disease

Allogeneic (allo) hematopoietic stem cell transplantation is an effective therapy for hematological malignancies but it is limited by acute graft-versus-host disease (GVHD). Dendritic cells (DC) play a major role in the allo T cell stimulation causing GVHD. Current immunosuppressive measures to control GVHD target T cells but compromise posttransplant immunity in the patient, particularly to cytomegalovirus (CMV) and residual malignant cells. We showed that treatment of allo mixed lymphocyte cultures with activated human DC-depleting CD83 antibody suppressed alloproliferation but preserved T cell numbers, including those specific for CMV. We also tested CD83 antibody in the human T cell–dependent peripheral blood mononuclear cell transplanted SCID (hu-SCID) mouse model of GVHD. We showed that this model requires human DC and that CD83 antibody treatment prevented GVHD but, unlike conventional immunosuppressants, did not prevent engraftment of human T cells, including cytotoxic T lymphocytes (CTL) responsive to viruses and malignant cells. Immunization of CD83 antibody-treated hu-SCID mice with irradiated human leukemic cell lines induced allo antileukemic CTL effectors in vivo that lysed 51Cr-labeled leukemic target cells in vitro without further stimulation. Antibodies that target activated DC are a promising new therapeutic approach to the control of GVHD.

HTLV-1 Infection of Human Hematopoietic Stem Cells Induces a Novel T Cell Lymphoma in Humanized SCID Mice

Human T-lymphotropic virus type-1 (HTLV-1) is a human retrovirus linked to cancer and is the etiologic agent of Adult T-cell leukemia/lymphoma (ATLL), an aggressive CD4+/CD25+ T cell malignancy. The early molecular events induced by HTLV-1 infection as well as the role of various viral genes in the induction of leukemia remain unclear, predominantly due to the lack of an animal model that recapitulates ATLL development. HTLV-1 infection of humanized NOD/SCID mice (HTLV-1- HU-SCID) was achieved by inoculation of NOD/SCID mice with CD34+ hematopoietic progenitor cells and stem cells (CD34+ HP/HSCs) infected ex vivo with HTLV-1. HTLV-1-HU-NOD/SCIDmice consistently developed CD4+CD25+ T cell lymphomas with clinical characteristics associated with ATLL and infected mice showed hyperproliferation of infected human stem cells (CD34+CD38−) in the bone marrow. Inoculation of NOD/SCID mice withCD34+ HP/HSCs transduced with a lentivirus vector (LV) expressing the HTLV-1oncoprotein (Tax1) also developed CD4+CD25+ lymphomas. The HTLV-1 bZIP protein(HBZ), encoded by the minus strand of the HTLV-1 genome, is expressed in all ATLL cells and has been implicated in the maintenance of leukemogenesis. HBZ has previously been previously shown to interact with numerous cellular factors and can modulate Tax1 activity in vitro. To establish the role of HBZ in HTLV-1 replication and leukemogenesis in vivo, HU-SCID mice were infected with an infectious proviral clone lacking functional HBZ (HTLV-1ΔHBZ). HTLV-1ΔHBZ-infected HU-SCID mice developed lymphoproliferations with an immature preleukemic CD4−CD8−CD90+ phenotype starting at ~10 weeks post-reconstitution. In contrast wild type HTLV-1 infection reproducibly induces a mature CD4+CD25+ CD90− lymphoma. Lymphoma cells successfully engrafted naïve NOD/SCID mice when injected into the peritoneal cavity and these cells maintain the expression of viral proteins, gp46env and p19gag. HTLV-1 infection of CD34+ HP/HSCs and the recapitulation of a lymphoma similar to ATLL in HU-NOD/SCID mice suggest that hematopoietic stem cells provide a relevant cellular target and viral reservoir in vivo and that infection of these cells contribute to viral lymphomagenesis in humans. The HTLV-1-HU-SCID mouse model presents a compelling in vivo model to characterize molecular initiation and progression of events in the generation of ATL and to establish the role of HTLV-1 auxiliary proteins in viral pathogenesis.

Novel In Vivo Model for the Study of Human Immunodeficiency Virus Type 1 Transcription Inhibitors: Evaluation of New 6-Desfluoroquinolone Derivatives

Two novel 6-desfluoroquinolone derivatives, HM-12 and HM-13, were evaluated for anti-human immunodeficiency virus (anti-HIV) activity in acutely, chronically, and latently HIV type 1 (HIV-1)-infected cell cultures and were found to behave as potent HIV-1 transcription inhibitors. In order to extend this result in vivo, we developed an artificial hu-SCID mouse model for HIV-1 latency based on SCID mice engrafted with latently HIV-1-infected promyelocytic OM-10.1 cells in which HIV-1 can be reactivated in vivo by the administration of human tumor necrosis factor alpha (hTNF-alpha). Treating these SCID mice with HM-12 or HM-13 prior to hTNF-alpha stimulation resulted in a pronounced suppressive effect on viral reactivation. Since both quinolone derivatives were able to inhibit the reactivation of HIV-1 from this artificial viral reservoir in vivo, we provide encouraging evidence for the use of quinolones in the control of HIV-1 infections.

SBAFF mutants induce neutralizing antibodies against BAFF

B cell activating factor belonging to the TNF family (BAFF) is a novel member of the tumor necrosis factor (TNF) ligand family and plays an important role in B lymphocyte maturation and survival. Overexpression of BAFF is closely involved in the pathogenesis and progression of many kinds of autoimmune disorders; therefore, BAFF has been considered as an ideal therapeutic target for these conditions. In this study, we generated several candidate immune inhibitors of human BAFF by conjugating foreign immunodominant T-helper cell (Th) epitopes to the N- or C-terminus of five BAFF mutants. The recombined proteins were successfully expressed in Escherichia coli ( E. coli) and purified by Ni-NTA chromatography. BALB/c mice immunized with the recombinant proteins produced high levels of anti-BAFF antibodies, and their sera inhibited the lymphocyte proliferation-inducing activity of recombinant soluble BAFF and natural soluble BAFF. Moreover, antibodies cross-reactive with BAFF were detected in sera from hu-SCID mice immunized with the recombinant proteins. These results indicated that the recombinant BAFF mutants modified with Th epitopes could induce neutralizing antibodies against BAFF in vivo. This study may provide a valuable strategy for treating BAFF-associated autoimmune diseases.

IgM-enriched human intravenous immunoglobulin suppresses T lymphocyte functionsin vitroand delays the activation of T lymphocytes in hu-SCID mice

Previous studies of an experimental human immunoglobulin preparation for intravenous use, containing normal pooled IgM (IVIgM), have shown its beneficial therapeutic effect in experimental autoimmune diseases. The mechanisms of its immunomodulatory activity remain however, poorly understood. In the experiments reported here, IVIgM inhibited the proliferation of various autonomously growing human lymphoid cell lines in vitro, as well as of MLR- and of PHA-stimulated human T-lymphocytes. These effects of IVIgM were observed at non-apoptotic concentrations and were stronger on a molar basis than those of normal pooled IgG for intravenous use (IVIg). Both preparations, when administered to SCID mice, repopulated with human peripheral blood mononuclear cells, delayed the expression of the early activation marker CD69 on both human CD4+ and CD8+ T-lymphocytes, activated by the mouse antigenic environment. The data obtained show that normal pooled human IgM exerts a powerful antiproliferative effect on T-cells that is qualitatively similar but quantitatively superior to that of therapeutic IVIg. Our results suggest that infusions with IVIgM might have a significant beneficial immunomodulating activity in patients with selected autoimmune diseases.

Porcine cell microchimerism but lack of productive porcine endogenous retrovirus (PERV) infection in naive and humanized SCID-beige mice treated with porcine peripheral blood mononuclear cells

Pigs are considered a suitable source of cells and organs for xenotransplantation. All known strains of pigs contain porcine endogenous retrovirus (PERV) and PERV released by porcine cells may infect human cells in vitro and severe-combined immunodeficient (SCID) mice in vivo. Humanized SCID (hu-SCID) mice develop immune response to porcine antigens. Here we investigated PERV transmission in humanized SCID-beige mice using porcine peripheral blood mononuclear cells (PBMC) as the donor tissue (and the source of PERV). Mice were infused in the peritoneal cavity with 1.5–3.0×10 7 unfractionated human PBMC. Unfractionated porcine PBMC (1.5–3.0×10 7 cell/mouse) were infused to the mice simultaneously with human PBMC or 3 weeks after human PBMC infusion. The treated mice were monitored for weight and skin changes, donor cell chimerism, anti-pig antibodies and PERV transmission. All humanized mice tested 5–12 weeks after human PBMC transplantation were macrochimeric (up to 40% of cells in blood) for human cells, where 99% of the human cells were T-lymphocytes. Although human B lymphocytes were very rare in the blood of humanized mice at that point, the mice were positive for human anti-pig natural antibodies. The control SCID-beige mice or mice treated with porcine PBMC alone were negative for anti-porcine antibodies. Approximately 70% of the humanized mice treated with porcine PBMC were also microchimeric for porcine cells. Although some tissue samples of these mice were positive for PERV DNA in the absence of porcine DNA indicating PERV infection, the infection was non-productive as PERV transcripts were not detectable in those tissues. PERV infection of human and mouse cells in vitro by co-culturing with porcine PBMC was also non-productive. Humanized SCID-beige mice suffered weight loss and occasional minor skin changes due to graft vs. host disease caused by human PBMC but none of the mice showed observable effect attributable to the apparent PERV infection alone.

Increased airway responsiveness, allergy-type-I skin responses and systemic anaphylaxis in a humanized-severe combined immuno-deficiency mouse model.

In patients with allergic bronchial asthma, a strong relationship between elevated serum IgE antibody titres and the development of increased airway responsiveness (AR) has been demonstrated. To further elucidate the relationship between human (hu) IgE and development of increased AR, we developed an in vivo model utilizing immuno-compromised severe combined immuno-deficiency (SCID) mice. SCID mice were either reconstituted with peripheral blood mononuclear cells (PBMC) from non-atopic, healthy or atopic individuals sensitized against house dust mite allergen (Der p), or passively sensitized with plasma from non-atopic, healthy or atopic individuals. In both systems, atopic hu-SCID mice developed increased AR. The following results suggest that these responses were mediated via IgE antibodies: increased AR did not occur after transfer of either PBMC or IgE-negative plasma from non-atopic individuals; increased AR occurred simultaneous with increased serotonin release detected 15 min after allergen-aerosol challenge in bronchoalveolar lavage fluid; and increased AR required at least two allergen-aerosol challenges. SCID mice reconstituted with serum containing anti-Der p IgE antibodies developed positive immediate-type skin test responses to intradermal injection of Der p as well as anti-hu-IgE antibody. In addition, IgE binding to skin mast cells was demonstrated by immunohistochemistry. Furthermore, intravenous challenge of hu anti-Der p positive SCID mice with Der p resulted in systemic anaphylaxis. These data provide evidence that passive immunization of SCID mice with hu IgE alters AR and that T cells and eosinophils were not a requirement for the development of increased AR in this model.

Anti-nerve growth factor Ab abrogates macrophage-mediated HIV-1 infection and depletion of CD4+ T lymphocytes in hu-SCID mice.

Infection by HIV-1 causes persistent, long-term high virus production in macrophages. Major evidence, both in humans and in primate models, shows the crucial role of macrophages in sustaining virus production and in mediating a cytopathic effect on bystander CD4+ T lymphocytes and neuronal cells. In the present study, we used severe combined immunodeficient (SCID) mice engrafted with human peripheral blood lymphocytes (hu-PBL-SCID mice) to investigate the in vivo effect of HIV-1-infected macrophages on virus spread and CD4+ T lymphocyte depletion, and the ability of a mAb against nerve growth factor (NGF, a neurokine essential for the survival of HIV-1-infected macrophages) to suppress the pathogenetic events mediated by infected macrophages. Injection of mice with as few as 500 HIV-exposed macrophages causes (i) complete depletion of several millions of autologous CD4+ T lymphocytes, (ii) sustained HIV viremia, and (iii) spreading of HIV-1 DNA in mouse lymphoid organs. In contrast, in vivo treatment with an anti-NGF Ab completely abrogates all effects mediated by HIV-infected macrophages. Taken together, the results demonstrate the remarkable power of macrophages in sustaining in vivo HIV-1 infection, and that such a phenomenon can be specifically abrogated by an anti-NGF Ab. This may open new perspectives of experimental approaches aimed at selectively eliminating persistently infected macrophages from the bodies of HIV-infected patients.

Inhibition of vaginal transmission of HIV-1 in hu-SCID mice by the non-nucleoside reverse transcriptase inhibitor TMC120 in a gel formulation.

The development of drugs that can be used as topical microbicides is currently recognized as a priority area of research. A preclinical evaluation of the potential effectiveness of TMC120, a non-nucleoside reverse transcriptase inhibitor (NNRTI), as a topical microbicide to prevent vaginal HIV-1 transmission in a humanized severe combined immunodeficient (hu-SCID) mouse model. Reconstituted mice received an intravaginal application of a TMC120-containing gel 20 min prior to a non-invasive vaginal challenge with cell-associated HIV. The possible cytotoxic effect of TMC120-containing-gel on lymphocytes was assessed and their in vivo migration was followed using fluorescently labelled human lymphocytes. Systemic infection was monitored by p24 antigen detection in culture supernatant from cocultured intraperitoneal cells using antigen capture enzyme-linked immunosorbent assay test and by the presence of integrated proviral HIV-1 DNA in DNA extracted from spleen cells. In vivo migration of labelled lymphocytes was examined by analysis of cells isolated from regional lymph nodes. In this model, systemic infection was successfully inhibited by the presence of TMC120-containing gel at vaginal level. The in vivo migration of human lymphocytes from the vagina to regional lymph nodes, following the deposition of TMC120-containing gel, excluded the possibility that inhibition of systemic infection was a result of NNRTI toxicity. Vaginal transmission of HIV was successfully prevented by the application of a gel formulation containing TMC120. This is the first evidence of the in vivo effectiveness of a microbicide preparation containing an NNRTI against cell-associated HIV.

ACh Receptor Protein Drives Primary and Memory Autoantibody Responses in Chimeric Human-SCID Mice

The native antigen that drives the T-helper cells regulating production of muscle acetylcholine receptor (AChR) autoantibodies is unknown. Human T cell lines activated by autoantigens in vitro are of unproven relevance to B cell help. Here we report the functional interaction and unprecedented longevity of AChR-specific human T and B lymphocytes residing in SCID mice. Lymphoid cells from myasthenia gravis (MG) patients and healthy subjects were injected ip. Recombinant human AChR-α1-subunit-1–210 was injected after day 75. Human AChR-specific Ig was produced rapidly in MG-SCID mice challenged once. Only 1 of 32 control hu-SCID mice produced AChR-specific Ig. This required multiple immunizations, was initially cross-reactive with Torpedo AChR, and had a slow course. Thus, memory T and B lymphocytes specific for human AChR-α1-subunit are readily demonstrable in MG patients, interact to produce autoantibody of the same restricted specificity found in the donor's serum, and are long-lived without exogenous autoantigen challenge. In healthy subjects, AChR-specific lymphocytes are infrequent and exhibit naive response characteristics, including apparent affinity maturation of Ig specificity.

Vaginal transmission of HIV-1 in hu-SCID mice: a new model for the evaluation of vaginal microbicides.

To develop an animal model of vaginal transmission of HIV-1 for the evaluation of vaginal microbicides. Vaginal infection was performed in SCID mice reconstituted with 4 x 107 human peripheral blood lymphocytes (hu-PBL) by non-invasive vaginal administration. The hu-PBL were previously infected in vitro with a non-syncytium (NSI) strain of HIV-1 (SF162) (hu-PBL-SCID). Lymphocyte migration in vivo was examined using fluorescently labelled human lymphocytes. The percentage of CD4 T cells, plasma viral load and p24 antigen were evaluated using fluorescent activated cell sorting (FACS), the Amplicor HIV-1 monitor kit and enzyme-linked immunosorbent assay, respectively. Polymerase chain reaction (PCR) analysis was performed on DNA extracted from spleen and lymph nodes. For in vivo migration of labelled lymphocytes, the mice were sacrificed after 4, 24 and 48 h; vaginae and local lymph nodes were removed, snap frozen with OCT, sectioned and examined by fluorescent microscopy and FACS. HIV transmission was established using virus-infected cells inoculated vaginally, as shown by FACS, HIV viral load, p24 and PCR results. Labelled cells were easily located within the vaginal tissues after 4 h. However, few or no cells could be identified after 24 or 48 h at the vaginal level, whereas labelled cells could be detected at the level of regional lymph nodes. Because of its simplicity and practical features compared with other animal models, the vaginal HIV-infected hu-SCID mouse model may prove useful to test the activity of compounds against cell-associated HIV and, possibly, other sexually transmitted diseases.

Antibacterial effect of human V gamma 2V delta 2 T cells in vivo.

V gamma 2V delta 2 cells, a class of T cells found only in primates, are reactive to nonpeptide organophosphate and alkylamine antigens secreted by bacteria and parasites. These cells make up 2-5% percent of human peripheral blood T cells but expand to make up 8-60% of peripheral blood T cells during bacterial and parasitic infections. We show here, using a chimeric severe combined immunodeficiency (SCID) mouse (hu-SCID) model, that human V gamma 2V delta 2 T cells mediate resistance to extracellular gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli and Morganella morganii) bacteria, as assessed by survival, body weight, bacterial loads, and histopathology. Surprisingly, this bacterial resistance was evident 1 day after infection, and bacteria were cleared well before gamma delta T cell expansion was detected 6 days after infection. Decreased resistance in V delta 2 T cell-depleted hu-SCID mice correlated with decreased serum IFN-gamma titers. Intravenous treatment of infected, reconstituted hu-SCID mice with pamidronate, a human V gamma 2V delta 2 T cell-specific aminobisphosphonate antigen, markedly increased the in vivo antibacterial effect of V gamma 2V delta 2 T cells. Therefore, this large pool of antigen-specific, yet immediately reactive memory human V gamma 2V delta 2 T cells is likely to be an important mediator of resistance against extracellular bacterial infection and may bridge the gap between innate and acquired immunity.

Hu-SCID: A model for the evaluation of vaginal microbicides

There is a need of new approaches to test and develop vaginal microbicides with antiviral specificity. We are studying a hu-SCID mouse animal model of vaginal transmission of HIV-1. Vaginal infection was performed using SCID mice reconstituted intraperitoneally with 3 × 107 human PBMC. At day 0 the mice were treated with 5mg of progestin and followed at day 7 by a non invasive vaginal administration of 1 × 106 PBMC previously infected in vitro with NSI stain of HIV-1. Systemic infection was investigated after two weeks post-inoculation collecting different samples: plasma, spleen cells, lymph-nodes cells, peritoneal cells and supernatants from lavage. Plasma viral load and p24 antigen detection were evaluated by using the amplicor HIV-1 monitor kit and cocoltivation, respectively. Polymerase chain reaction (PCR) analysis was performed on DNA extracted from tissues (spleen, lymph-nodes, peritoneal cells) to determine the presence of proviral copies using specific primers for HIV-1. In our experiments transmission was established using NSI virus infected cells inoculated vaginally as shown by either PCR results or plasma and peritoneal fluid viral load and p24 antigen detection. This hu-SCID mouse model may prove useful to test the activity of compounds against HIV and sexually transmitted diseases.

Gastric ulcers in SCID mice induced by Helicobacter pylori infection after transplanting lymphocytes from patients with gastric lymphoma

Background & Aims: Several studies have indicated that host factors are important in Helicobacter pylori–induced gastroduodenal diseases. We examined the pathological role of host immune responses in H. pylori infection by reconstituting components of the human immune system into severe combined immunodeficient (SCID) mice by transplantation of peripheral blood mononuclear cells (PBMCs) from H. pylori–infected patients. Methods: PBMCs obtained from patients with mucosa-associated lymphoid tissue (MALT) lymphoma were injected intraperitoneally into SCID mice, designated MALToma-hu-SCID mice. One month after transplantation, H. pylori was administered orally to the mice. The mice were killed and examined for pathological changes and immunologic features. Results: Human lymphocytes were detected in hu-SCID mice, and T- and B-cell functions were preserved for 1 month. Administration of H. pylori led to gastric ulcers with bleeding in the MALToma-hu-SCID mice. The gastric mucosa of control mice injected with Escherichia coli or transplanted with PBMCs from patients with peptic ulcers or gastritis or from healthy volunteers showed no pathological changes. Conclusions: Host immune responses against H. pylori appear to be involved in the development of gastric ulcers in patients who have MALT lymphoma. GASTROENTEROLOGY 1999;117:893-899

Two Neutralizing Human Anti-RSV Antibodies: Cloning, Expression, and Characterization

Respiratory syncytial virus (RSV) infection is a major problem in the newborn and aging populations. Fully human monoclonal antibodies with the ability to neutralize RSV could have a major impact on the immunotherapy of the disease. The generation of human antibodies has been difficult because there exists no general way to activate B cells against an antigen of choice in vitro. Human spleen cells from individuals exposed to RSV were used to repopulate SCID mice. Hu-SCID mice were boosted with RSV fusion (F)-protein and subsequently developed B cell tumors. The tumors were removed and cultured and subcloned in vitro, using a feeder layer of CD154-expressing T cells. Two of these tumors produced the antibodies designated RF-1 and RF-2. VL genes were isolated by standard PCR techniques, however, it was necessary to use high-temperature reverse transcriptase to clone the VH genes. RF-1 and RF-2 VH genes were both found to be closely related members of the VH2 family. Vk genes originated from the VK III family. RF-1 and RF-2 recombinant antibodies expressed in CHO cells (cRF-1 and cRF-2) were found to have affinities for RSV F-protein of 0.1 nM and 0.07 nM, respectively, and both were able to neutralize several A and B subtypes of RSV. The technique of immortalizing human B lymphocytes, by passage in SCID mice and expression as recombinant antibodies in CHO cells, provides a method by which high-affinity human antibodies can be developed for immunotherapy of viral diseases.