1
|
Kim J, Behzadi ES, Nehring M, Carver S, Cowan SR, Conry MK, Rawlinson JE, VandeWoude S, Miller CA. Combination Antiretroviral Therapy and Immunophenotype of Feline Immunodeficiency Virus. Viruses 2023; 15:822. [PMID: 37112803 PMCID: PMC10146003 DOI: 10.3390/v15040822] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 04/29/2023] Open
Abstract
Feline Immunodeficiency Virus (FIV) causes progressive immune dysfunction in cats similar to human immunodeficiency virus (HIV) in humans. Although combination antiretroviral therapy (cART) is effective against HIV, there is no definitive therapy to improve clinical outcomes in cats with FIV. This study therefore evaluated pharmacokinetics and clinical outcomes of cART (2.5 mg/kg Dolutegravir; 20 mg/kg Tenofovir; 40 mg/kg Emtricitabine) in FIV-infected domestic cats. Specific pathogen free cats were experimentally infected with FIV and administered either cART or placebo treatments (n = 6 each) for 18 weeks, while n = 6 naïve uninfected cats served as controls. Blood, saliva, and fine needle aspirates from mandibular lymph nodes were collected to quantify viral and proviral loads via digital droplet PCR and to assess lymphocyte immunophenotypes by flow cytometry. cART improved blood dyscrasias in FIV-infected cats, which normalized by week 16, while placebo cats remained neutropenic, although no significant difference in viremia was observed in the blood or saliva. cART-treated cats exhibited a Th2 immunophenotype with increasing proportions of CD4+CCR4+ cells compared to placebo cats, and cART restored Th17 cells compared to placebo-treated cats. Of the cART drugs, dolutegravir was the most stable and long-lasting. These findings provide a critical insight into novel cART formulations in FIV-infected cats and highlight their role as a potential animal model to evaluate the impact of cART on lentiviral infection and immune dysregulation.
Collapse
Affiliation(s)
- Jeffrey Kim
- Comparative Medicine Research Unit, School of Medicine, University of Louisville, Louisville, KY 40292, USA
| | - Elisa S. Behzadi
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Mary Nehring
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Scott Carver
- School of Natural Sciences, University of Tasmania, Hobart, TAS 7001, Australia
| | - Shannon R. Cowan
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Megan K. Conry
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Jennifer E. Rawlinson
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Sue VandeWoude
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Craig A. Miller
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078, USA
| |
Collapse
|
2
|
Differences in Env and Gag protein expression patterns and epitope availability in feline immunodeficiency virus infected PBMC compared to infected and transfected feline model cell lines. Virus Res 2017; 227:249-260. [PMID: 27836726 DOI: 10.1016/j.virusres.2016.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 11/05/2016] [Accepted: 11/05/2016] [Indexed: 11/21/2022]
Abstract
Env and Gag are key components of the FIV virion that are targeted to the plasma membrane for virion assembly. They are both important stimulators and targets of anti-FIV immunity. To investigate and compare the expression pattern and antigenic changes of Gag and Env in various research models, infected PBMC (the natural FIV host cells) and GFox, and transfected CrFK were stained over time with various Env and Gag specific MAbs. In FIV infected GFox and PBMC, Env showed changes in epitope availability for antibody binding during processing and trafficking, which was not seen in transfected CrFK. Interestingly, epitopes exposed on intracellular Env and Env present on the plasma membrane of CrFK and GFox seem to be hidden on plasma membrane expressed Env of FIV infected PBMC. A kinetic follow up of Gag and Env expression showed a polarization of both Gag and Env expression to specific sites at the plasma membrane of PBMC, but not in other cell lines. In conclusion, mature trimeric cell surface expressed Env might be antigenically distinct from intracellular monomeric Env in PBMC and might possibly be unrecognizable by feline humoral immunity. In addition, Env expression is restricted to a small area on the plasma membrane and co-localizes with a large moiety of Gag, which may represent a preferred FIV budding site, or initiation of virological synapses with direct cell-to-cell virus transmission.
Collapse
|
3
|
Abstract
In humans and mouse models, Foxp3(+) regulatory T cells are known to control all aspects of immune responses. However, only limited information exists on these cells' role in diseases of other animals. In this review, we cover the most important features and different types of regulatory T cells, which include those that are thymus-derived and peripherally induced, the mechanisms by which they control immune responses by targeting effector T cells and antigen-presenting cells, and most important, their role in animal health and diseases including cancer, infections, and other conditions such as hypersensitivities and autoimmunity. Although the literature regarding regulatory T cells in domestic animal species is still limited, multiple articles have recently emerged and are discussed. Moreover, we also discuss the evidence suggesting that regulatory T cells might limit the magnitude of effector responses, which can have either a positive or negative result, depending on the context of animal and human disease. In addition, the issue of plasticity is discussed because plasticity in regulatory T cells can result in the loss of their protective function in some microenvironments during disease. Lastly, the manipulation of regulatory T cells is discussed in assessing the possibility of their use as a treatment in the future.
Collapse
|
4
|
Miller MM, Akaronu N, Thompson EM, Hood SF, Fogle JE. Modulating DNA methylation in activated CD8+ T cells inhibits regulatory T cell-induced binding of Foxp3 to the CD8+ T Cell IL-2 promoter. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2015; 194:990-8. [PMID: 25548225 PMCID: PMC4297683 DOI: 10.4049/jimmunol.1401762] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have previously demonstrated that CD4(+)CD25(+) regulatory T cells (Tregs) activated during the course of feline immunodeficiency virus (FIV) infection suppress CD8(+) CTL function in a TGF-β-dependent fashion, inhibiting IFN-γ and IL-2 production and inducing G1 cell-cycle arrest. In this article, we describe the molecular events occurring at the IL-2 promoter leading to suppression of IL-2 production. These experiments demonstrate that Foxp3 induced by lentivirus-activated Tregs in the CD8(+) target cells binds to the IL-2 promoter, actively repressing IL-2 transcription. We further demonstrate that the chronic activation of CD8(+) T cells during FIV infection results in chromatin remodeling at the IL-2 promoter, specifically, demethylation of CpG residues. These DNA modifications occur during active transcription and translation of IL-2; however, these changes render the IL-2 promoter permissive to Foxp3-induced transcriptional repression. These data help explain, in part, the seemingly paradoxical observations that CD8(+) T cells displaying an activation phenotype exhibit altered antiviral function. Further, we demonstrate that blocking demethylation of CpG residues at the IL-2 promoter inhibits Foxp3 binding, suggesting a potential mechanism for rescue and/or reactivation of CD8(+) T cells. Using the FIV model for lentiviral persistence, these studies provide a framework for understanding how immune activation combined with Treg-mediated suppression may affect CD8(+) T cell IL-2 transcription, maturation, and antiviral function.
Collapse
Affiliation(s)
- Michelle M Miller
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607
| | - Nnenna Akaronu
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607
| | - Elizabeth M Thompson
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607
| | - Sylvia F Hood
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607
| | - Jonathan E Fogle
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607
| |
Collapse
|
5
|
Roukaerts IDM, Theuns S, Taffin ERL, Daminet S, Nauwynck HJ. Phylogenetic analysis of feline immunodeficiency virus strains from naturally infected cats in Belgium and The Netherlands. Virus Res 2014; 196:30-6. [PMID: 25449575 DOI: 10.1016/j.virusres.2014.10.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 10/15/2014] [Accepted: 10/25/2014] [Indexed: 11/19/2022]
Abstract
Feline immunodeficiency virus (FIV) is a major pathogen in feline populations worldwide, with seroprevalences up to 26%. Virus strains circulating in domestic cats are subdivided into different phylogenetic clades (A-E), based on the genetic diversity of the V3-V4 region of the env gene. In this report, a phylogenetic analysis of the V3-V4 env region, and a variable region in the gag gene was made for 36 FIV strains isolated in Belgium and The Netherlands. All newly generated gag sequences clustered together with previously known clade A FIV viruses, confirming the dominance of clade A viruses in Northern Europe. The same was true for the obtained env sequences, with only one sample of an unknown env subtype. Overall, the genetic diversity of FIV strains sequenced in this report was low. This indicates a relatively recent introduction of FIV in Belgium and The Netherlands. However, the sample with an unknown env subtype indicates that new introductions of FIV from unknown origin do occur and this will likely increase genetic variability in time.
Collapse
Affiliation(s)
- Inge D M Roukaerts
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Sebastiaan Theuns
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Elien R L Taffin
- Department of Small Animal Medicine and Clinical Biology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Sylvie Daminet
- Department of Small Animal Medicine and Clinical Biology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Hans J Nauwynck
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
| |
Collapse
|
6
|
Veiga-Parga T, Sehrawat S, Rouse BT. Role of regulatory T cells during virus infection. Immunol Rev 2014; 255:182-96. [PMID: 23947355 DOI: 10.1111/imr.12085] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The host response to viruses includes multiple cell types that have regulatory function. Most information focuses on CD4(+) regulatory T cells that express the transcription factor Foxp3(+) (Tregs), which are the topic of this review. We explain how viruses through specific and non-specific means can trigger the response of thymus-derived natural Tregs as well as induce Tregs. The latter derive under appropriate stimulation conditions either from uncommitted precursors or from differentiated cells that convert to become Tregs. We describe instances where Tregs appear to limit the efficacy of antiviral protective immunity and other, perhaps more common, immune-mediated inflammatory conditions, where the Tregs function to limit the extent of tissue damage that occurs during a virus infection. We discuss the controversial roles that Tregs may play in the pathogenesis of human immunodeficiency and hepatitis C virus infections. The issue of plasticity is discussed, as this may result in Tregs losing their protective function when present in inflammatory environments. Finally, we mention approaches used to manipulate Treg numbers and function and assess their current value and likely future success to manage the outcome of virus infection, especially those that are responsible for chronic tissue damage.
Collapse
Affiliation(s)
- Tamara Veiga-Parga
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA
| | | | | |
Collapse
|
7
|
Miller MM, Petty CS, Tompkins MB, Fogle JE. CD4+CD25+ T regulatory cells activated during feline immunodeficiency virus infection convert T helper cells into functional suppressors through a membrane-bound TGFβ / GARP-mediated mechanism. Virol J 2014; 11:7. [PMID: 24438223 PMCID: PMC3902059 DOI: 10.1186/1743-422x-11-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 01/09/2014] [Indexed: 12/22/2022] Open
Abstract
Background We and others have previously reported that cell membrane-bound TGFβ (mTGFβ) on activated T regulatory (Treg) cells mediates suppressor function. Current findings suggest that a novel protein known as Glycoprotein A Repetitions Predominant (GARP) anchors mTGFβ to the Treg cell surface and facilitates suppressor activity. Recently, we have described that GARP+TGFβ+ Treg cells expand during the course of FIV infection. Because Treg cells are anergic and generally exhibit poor proliferative ability, we asked how Treg homeostasis is maintained during the course of feline immunodeficiency virus (FIV) infection. Results Here, we report that Treg cells from FIV+ cats express GARP and mTGFβ and convert T helper (Th) cells into phenotypic and functional Treg cells. Th to Treg conversion was abrogated by anti-TGFβ or anti-GARP treatment of Treg cells or by anti-TGFβRII treatment of Th cells, suggesting that Treg cell recruitment from the Th pool is mediated by TGFβ/TGFβRII signaling and that cell-surface GARP plays a major role in this process. Conclusions These findings suggest Th to Treg conversion may initiate a cascade of events that contributes to the maintenance of virus reservoirs, progressive Th cell immunosuppression, and the development of immunodeficiency, all of which are central to the pathogenesis of AIDS lentivirus infections.
Collapse
Affiliation(s)
| | | | | | - Jonathan E Fogle
- Immunology Program, North Carolina State University, Raleigh NC, USA.
| |
Collapse
|
8
|
Chumbley LB, Boudreaux CE, Coats KS. Aberrant placental immune parameters in the feline immunodeficiency virus (FIV)-infected cat suggest virus-induced changes in T cell function. Virol J 2013; 10:238. [PMID: 23870389 PMCID: PMC3723510 DOI: 10.1186/1743-422x-10-238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 07/11/2013] [Indexed: 11/12/2022] Open
Abstract
Background Immune activity during pregnancy must be tightly regulated to ensure successful pregnancy. This regulation includes the suppression of inflammatory activity that could target the semi-allogeneic fetus. Tregs are immunosuppressive; Th17 cells are pro-inflammatory. A precise balance in the two cell populations is critical to pregnancy maintenance, while dysregulation in this balance accompanies compromised pregnancy in humans and mice. FIV is known to target Tregs preferentially in the infected cat. Therefore, it may be hypothesized that FIV infection alters the placental Treg/Th17 cell balance resulting in aberrant immunomodulator expression by these cells and consequent pregnancy perturbation. Methods RNA was purified from random sections of whole placental tissues collected from both uninfected and FIV-infected queens at early pregnancy, including tissues from viable and nonviable fetuses. Real time qPCR was performed to quantify expression of intranuclear markers of Tregs (FoxP3) and Th17 cells (RORγ); cytokine products of Tregs (IL-10 and TGF-β), Th17 cells (IL-2, IL-6, and IL-17a), and macrophages (IL-1β); and the FIV gag gene. Pairwise comparisons were made to evaluate coexpression patterns between the cytokines and between the cytokines and the virus. Results Both FoxP3 and RORγ were reduced in placentas of infected animals. Neither infection status nor fetal viability affected placental expression of IL-1β. However, fetal nonviability was associated with reduced levels of all other cytokines. Infection and fetal nonviability impacted coexpression of various cytokine pairs. No obvious bias toward Treg or Th17 cells was observed. Conclusions FIV infection coupled with fetal nonviability alters expression patterns of T cell cytokines. These data suggest that functionally altered placental T cell leukocyte populations may occur in the infected queen and possibly contribute to fetal nonviability.
Collapse
Affiliation(s)
- Lyndon Bart Chumbley
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA
| | | | | |
Collapse
|
9
|
McDonnel SJ, Sparger EE, Murphy BG. Feline immunodeficiency virus latency. Retrovirology 2013; 10:69. [PMID: 23829177 PMCID: PMC3707804 DOI: 10.1186/1742-4690-10-69] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/27/2013] [Indexed: 12/18/2022] Open
Abstract
Despite highly effective anti-retroviral therapy, HIV is thought to persist in patients within long-lived cellular reservoirs in the form of a transcriptionally inactive (latent) integrated provirus. Lentiviral latency has therefore come to the forefront of the discussion on the possibility of a cure for HIV infection in humans. Animal models of lentiviral latency provide an essential tool to study mechanisms of latency and therapeutic manipulation. Of the three animal models that have been described, the feline immunodeficiency virus (FIV)-infected cat is the most recent and least characterized. However, several aspects of this model make it attractive for latency research, and it may be complementary to other model systems. This article reviews what is known about FIV latency and chronic FIV infection and how it compares with that of other lentiviruses. It thereby offers a framework for the usefulness of this model in future research aimed at lentiviral eradication.
Collapse
Affiliation(s)
- Samantha J McDonnel
- Department of Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California, Davis, 4206 Vet Med 3A, Davis, CA 95616, USA.
| | | | | |
Collapse
|
10
|
Infection with feline immunodeficiency virus directly activates CD4+ CD25+ T regulatory cells. J Virol 2013; 87:9373-8. [PMID: 23760252 DOI: 10.1128/jvi.00996-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lentivirus infection activates CD4(+) CD25(+) T regulatory (Treg) cells. Activation of Treg cells may be due to direct virus infection or chronic antigenic stimulation. Herein we demonstrate that in vitro feline immunodeficiency virus (FIV) infection, but not UV-inactivated virus, activates Treg cells as measured by immunosuppressive function and upregulation of GARP, FoxP3, and membrane-bound transforming growth factor β (TGF-β). These data demonstrate for the first time that AIDS lentiviruses infect and activate Treg cells, potentially contributing to immune dysfunction.
Collapse
|
11
|
Miller MM, Fogle JE, Ross P, Tompkins MB. Feline glycoprotein A repetitions predominant anchors transforming growth factor beta on the surface of activated CD4(+)CD25(+) regulatory T cells and mediates AIDS lentivirus-induced T cell immunodeficiency. AIDS Res Hum Retroviruses 2013; 29:641-51. [PMID: 23373523 DOI: 10.1089/aid.2012.0322] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Using the feline immunodeficiency virus (FIV) model for AIDS-lentivirus infection, our laboratory has previously demonstrated that T regulatory (Treg) cell-mediated immune T and B cell dysfunction contributes to lentivirus persistence and chronic disease through membrane bound transforming growth factor beta (mTGFb). Studying Treg cells in the context of infection has been problematic as no inducible marker for activated Treg cells had been identified. However, recent reports in human Treg studies have described a novel protein, glycoprotein A repetitions predominant (GARP), as a unique marker of activated human Treg cells that anchors mTGFb. Herein we extend these studies to the feline Treg system, identifying feline GARP and demonstrating that human and feline GARP proteins are homologous in structure, expression pattern, and ability to form a complex with TGFb. We further demonstrate that GARP and TGFb form a complex on the surface of activated Treg cells and that these GARP(+)TGFb(+) Treg cells are highly efficient suppressor cells. Analysis of expression of this Treg activation marker in the FIV-AIDS model reveals an up-regulation of GARP expressing Treg cells during chronic FIV infection. We demonstrate that the GARP(+) Treg cells from FIV-infected cats suppress T helper cells in vivo and that blocking GARP or TGFb eliminates this suppression. These data suggest that GARP is expressed in complex with TGFb on the surface of activated Treg cells and plays an important role in TGFb(+) Treg-mediated T cell immune suppression during lentivirus infection.
Collapse
Affiliation(s)
- Michelle M. Miller
- Immunology Program, North Carolina State University, Raleigh, North Carolina
- Department of Population Health and Pathobiology, North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina
| | - Jonathan E. Fogle
- Immunology Program, North Carolina State University, Raleigh, North Carolina
- Department of Population Health and Pathobiology, North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina
| | - Peter Ross
- Immunology Program, North Carolina State University, Raleigh, North Carolina
- Department of Clinical Sciences, North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina
| | - Mary B. Tompkins
- Immunology Program, North Carolina State University, Raleigh, North Carolina
- Department of Population Health and Pathobiology, North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina
| |
Collapse
|
12
|
Hartmann K, Stengel C, Klein D, Egberink H, Balzarini J. Efficacy and adverse effects of the antiviral compound plerixafor in feline immunodeficiency virus-infected cats. J Vet Intern Med 2012; 26:483-90. [PMID: 22551322 DOI: 10.1111/j.1939-1676.2012.00904.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 01/04/2012] [Accepted: 01/27/2012] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Bicyclam derivatives inhibit feline immunodeficiency virus (FIV) replication through selective blockage of chemokine receptor CXCR4. HYPOTHESIS/OBJECTIVES CXCR4 antagonist plerixafor (AMD3100, 1,1'-bis-1,4,8,11-tetraazacyclotetradekan) alone or combination with adefovir (PMEA, 9-(2-phosphonylmethoxyethyl)adenine) safe and effective for treating FIV-infected cats. ANIMALS Forty naturally FIV-infected, privately owned cats. MATERIALS AND METHODS Prospective, placebo-controlled, double-blind clinical trial. Cats randomly classified into 4 treatment groups. Received AMD3100, PMEA, AMD3100 in combination with PMEA, or placebo for 6 weeks. Clinical and laboratory parameters, including CD4(+) and CD8(+) cell counts, FIV proviral and viral load measured by quantitative polymerase chain reaction (qPCR) evaluated. Additionally, FIV isolates from cats treated with AMD3100 tested for drug resistance. RESULTS FIV-infected cats treated with AMD3100 caused significant decrease in proviral load compared to placebo group (2.3 ± 3.8% to 1.9 ± 3.1%, of blood lymphocytes P < .05), but did not lead to improvement of clinical or immunological variables; it caused a decrease in serum magnesium concentration without clinical signs. No development of resistance of FIV isolates to AMD3100 found during treatment period. PMEA administration improved stomatitis (stomatitis score [degree 1 - 100] PMEA group: 23 ± 19 to 11 ± 10, P < .001; AMD3100 + PMEA group: 12 ± 17 to 3 ± 5, P < .05), but did not decrease proviral or viral load and caused anemia (RBC [× 10(6) /μL] PMEA group: 9.07 ± 1.60 to 6.22 ± 2.16, P < .05; AMD3100 ± PMEA group: 8.80 ± 1.23 to 5.84 ± 1.58, P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE Administration of CXCR4 antagonists, as AMD3100, can induce reduction of proviral load and may represent viable treatment of FIV-infected cats. Combination treatment with PMEA not recommended.
Collapse
Affiliation(s)
- K Hartmann
- Clinic of Small Animal Medicine, LMU University of Munich, Munich, Germany.
| | | | | | | | | |
Collapse
|
13
|
Feline immunodeficiency virus in South America. Viruses 2012; 4:383-396. [PMID: 22590677 PMCID: PMC3347033 DOI: 10.3390/v4030383] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 02/22/2012] [Accepted: 02/24/2012] [Indexed: 12/16/2022] Open
Abstract
The rapid emergence of AIDS in humans during the period between 1980 and 2000 has led to extensive efforts to understand more fully similar etiologic agents of chronic and progressive acquired immunodeficiency disease in several mammalian species. Lentiviruses that have gene sequence homology with human immunodeficiency virus (HIV) have been found in different species (including sheep, goats, horses, cattle, cats, and several Old World monkey species). Lentiviruses, comprising a genus of the Retroviridae family, cause persistent infection that can lead to varying degrees of morbidity and mortality depending on the virus and the host species involved. Feline immunodeficiency virus (FIV) causes an immune system disease in domestic cats (Felis catus) involving depletion of the CD4+ population of T lymphocytes, increased susceptibility to opportunistic infections, and sometimes death. Viruses related to domestic cat FIV occur also in a variety of nondomestic felids. This is a brief overview of the current state of knowledge of this large and ancient group of viruses (FIVs) in South America.
Collapse
|
14
|
Patel JR, Heldens JGM, Bakonyi T, Rusvai M. Important mammalian veterinary viral immunodiseases and their control. Vaccine 2012; 30:1767-81. [PMID: 22261411 PMCID: PMC7130670 DOI: 10.1016/j.vaccine.2012.01.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 01/03/2012] [Accepted: 01/05/2012] [Indexed: 11/16/2022]
Abstract
This paper offers an overview of important veterinary viral diseases of mammals stemming from aberrant immune response. Diseases reviewed comprise those due to lentiviruses of equine infectious anaemia, visna/maedi and caprine arthritis encephalitis and feline immunodeficiency. Diseases caused by viruses of feline infectious peritonitis, feline leukaemia, canine distemper and aquatic counterparts, Aleutian disease and malignant catarrhal fever. We also consider prospects of immunoprophylaxis for the diseases and briefly other control measures. It should be realised that the outlook for effective vaccines for many of the diseases is remote. This paper describes the current status of vaccine research and the difficulties encountered during their development.
Collapse
Affiliation(s)
- J R Patel
- Jas Biologicals Ltd, 12 Pembroke Avenue, Denny Industrial Estate, Waterbeach, Cambridge CB25 9QR, UK.
| | | | | | | |
Collapse
|
15
|
Holmes D, Gao J, Su L. Foxp3 inhibits HDAC1 activity to modulate gene expression in human T cells. Virology 2011; 421:12-8. [PMID: 21974802 DOI: 10.1016/j.virol.2011.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 07/05/2011] [Accepted: 09/01/2011] [Indexed: 01/08/2023]
Abstract
We have previously reported that HIV-1 preferentially infects Foxp3+ Treg cells in vitro and in vivo, and Foxp3 enhances the HIV-1 LTR expression through epigenetic mechanisms in T cells. We report here that histone deacetylase inhibitor (HDACi) failed to further enhance HIV gene expression in FoxP3+ T cells. We discovered that Foxp3 inhibited cellular HDAC activity in T cells, and mutations in the forkhead domain that ablate Foxp3 function also abolished its ability to inhibit HDAC. When co-expressed, Foxp3 specifically inhibited the deacetylase activity of HDAC1. We further showed that Foxp3 was associated with HDAC1, and mutations in the forkhead domain that ablate Foxp3 function in Treg cells also inhibited Foxp3 association with and inhibition of HDAC1. Finally, Foxp3 failed to enhance HIV-1 gene expression in human T cells expressing HDAC1-specific shRNA. We conclude that Foxp3 modulates gene expression in human T cells at least partly by inhibiting HDAC1 activity.
Collapse
Affiliation(s)
- Derek Holmes
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | | | | |
Collapse
|
16
|
Hartmann K. Clinical aspects of feline immunodeficiency and feline leukemia virus infection. Vet Immunol Immunopathol 2011; 143:190-201. [PMID: 21807418 PMCID: PMC7132395 DOI: 10.1016/j.vetimm.2011.06.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses with a global impact on the health of domestic cats. The two viruses differ in their potential to cause disease. FIV can cause an acquired immunodeficiency syndrome that increases the risk of developing opportunistic infections, neurological diseases, and tumors. In most naturally infected cats, however, FIV itself does not cause severe clinical signs, and FIV-infected cats may live many years without any health problems. FeLV is more pathogenic, and was long considered to be responsible for more clinical syndromes than any other agent in cats. FeLV can cause tumors (mainly lymphoma), bone marrow suppression syndromes (mainly anemia) and lead to secondary infectious diseases caused by suppressive effects of the virus on bone marrow and the immune system. Today, FeLV is less important as a deadly infectious agent as in the last 20 years prevalence has been decreasing in most countries.
Collapse
Affiliation(s)
- Katrin Hartmann
- Clinic of Small Animal Medicine, LMU University of Munich, Veterinaerstrasse 13, 80539 Munich, Germany.
| |
Collapse
|
17
|
Scott VL, Shack LA, Eells JB, Ryan PL, Donaldson JR, Coats KS. Immunomodulator expression in trophoblasts from the feline immunodeficiency virus (FIV)-infected cat. Virol J 2011; 8:336. [PMID: 21729293 PMCID: PMC3152912 DOI: 10.1186/1743-422x-8-336] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 07/05/2011] [Indexed: 12/22/2022] Open
Abstract
Background FIV infection frequently compromises pregnancy under experimental conditions and is accompanied by aberrant expression of some placental cytokines. Trophoblasts produce numerous immunomodulators that play a role in placental development and pregnancy maintenance. We hypothesized that FIV infection may cause dysregulation of trophoblast immunomodulator expression, and aberrant expression of these molecules may potentiate inflammation and compromise pregnancy. The purpose of this project was to evaluate the expression of representative pro-(TNF-α, IFN-γ, IL-1β, IL-2, IL-6, IL-12p35, IL-12p40, IL-18, and GM-CSF) and anti-inflammatory cytokines (IL-4, IL-5, and IL-10); CD134, a secondary co-stimulatory molecule expressed on activated T cells (FIV primary receptor); the chemokine receptor CXCR4 (FIV co-receptor); SDF-1α, the chemokine ligand to CXCR4; and FIV gag in trophoblasts from early-and late-term pregnancy. Methods We used an anti-cytokeratin antibody in immunohistochemistry to identify trophoblasts selectively, collected these cells using laser capture microdissection, and extracted total RNA from the captured cell populations. Real time, reverse transcription-PCR was used to quantify gene expression. Results We detected IL-4, IL-5, IL-6, IL-1β, IL-12p35, IL-12p40, and CXCR4 in trophoblasts from early-and late-term pregnancy. Expression of cytokines increased from early to late pregnancy in normal tissues. A clear, pro-inflammatory microenvironment was not evident in trophoblasts from FIV-infected queens at either stage of pregnancy. Reproductive failure was accompanied by down-regulation of both pro-and anti-inflammatory cytokines. CD134 was not detected in trophoblasts, and FIV gag was detected in only one of ten trophoblast specimens collected from FIV-infected queens. Conclusion Feline trophoblasts express an array of pro-and anti-inflammatory immunomodulators whose expression increases from early to late pregnancy in normal tissues. Non-viable pregnancies were associated with decreased expression of immunomodulators which regulate trophoblast invasion in other species. The detection of FIV RNA in trophoblasts was rare, suggesting that the high rate of reproductive failure in FIV-infected queens was not a direct result of viral replication in trophoblasts. The influence of placental immune cells on trophoblast function and pregnancy maintenance in the FIV-infected cat requires additional study.
Collapse
Affiliation(s)
- Veronica L Scott
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA
| | | | | | | | | | | |
Collapse
|
18
|
Isolation and partial characterization of Brazilian samples of feline immunodeficiency virus. Virus Res 2011; 160:59-65. [PMID: 21619902 DOI: 10.1016/j.virusres.2011.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 05/06/2011] [Accepted: 05/10/2011] [Indexed: 11/21/2022]
Abstract
Feline immunodeficiency virus (FIV) causes a slow progressive degeneration of the immune system which eventually leads to a disease comparable to acquired immune deficiency syndrome (AIDS) in humans. FIV has extensive sequence variation, a typical feature of lentiviruses. Sequence analysis showed that diversity was not evenly distributed throughout the genome, but was greatest in the envelope gene, env. The virus enters host cells via a sequential interaction, initiated by the envelope glycoprotein (env) binding the primary receptor molecule CD134 and followed by a subsequent interaction with chemokine co-receptor CXCR4. The purpose of this study was to isolate and characterize isolates of FIV from an open shelter in São Paulo, Brazil. The separated PBMC from 11 positive cats were co-cultured with MYA-1 cells. Full-length viral env glycoprotein genes were amplified and determined. Chimeric feline × human CD134 receptors were used to investigate the receptor utilization of 17 clones from Brazilian isolates of FIV. Analyses of the sequence present of molecular clones showed that all clones grouped within subtype B. In contrast to the virulent primary isolate FIV-GL8, expression of the first cysteine-rich domain (CRD1) of feline CD134 in the context of human CD134 was sufficient for optimal receptor function for all Brazilian FIV isolates tested.
Collapse
|
19
|
Garden O, Pinheiro D, Cunningham F. All creatures great and small: regulatory T cells in mice, humans, dogs and other domestic animal species. Int Immunopharmacol 2011; 11:576-88. [DOI: 10.1016/j.intimp.2010.11.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 11/01/2010] [Indexed: 12/12/2022]
|
20
|
Mikkelsen SR, Long JM, Zhang L, Galemore ER, VandeWoude S, Dean GA. Partial regulatory T cell depletion prior to acute feline immunodeficiency virus infection does not alter disease pathogenesis. PLoS One 2011; 6:e17183. [PMID: 21364928 PMCID: PMC3045403 DOI: 10.1371/journal.pone.0017183] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 01/23/2011] [Indexed: 11/18/2022] Open
Abstract
Feline immunodeficiency virus (FIV) infection in cats follows a disease course similar to HIV-1, including a short acute phase characterized by high viremia, and a prolonged asymptomatic phase characterized by low viremia and generalized immune dysfunction. CD4(+)CD25(hi)FoxP3(+) immunosuppressive regulatory T (Treg) cells have been implicated as a possible cause of immune dysfunction during FIV and HIV-1 infection, as they are capable of modulating virus-specific and inflammatory immune responses. Additionally, the immunosuppressive capacity of feline Treg cells has been shown to be increased during FIV infection. We have previously shown that transient in vivo Treg cell depletion during asymptomatic FIV infection reveals FIV-specific immune responses suppressed by Treg cells. In this study, we sought to determine the immunological influence of Treg cells during acute FIV infection. We asked whether Treg cell depletion prior to infection with the highly pathogenic molecular clone FIV-C36 in cats could alter FIV pathogenesis. We report here that partial Treg cell depletion prior to FIV infection does not significantly change provirus, viremia, or CD4(+) T cell levels in blood and lymphoid tissues during the acute phase of disease. The effects of anti-CD25 mAb treatment are truncated in cats acutely infected with FIV-C36 as compared to chronically infected cats or FIV-naïve cats, as Treg cell levels were heightened in all treatment groups included in the study within two weeks post-FIV infection. Our findings suggest that the influence of Treg cell suppression during FIV pathogenesis is most prominent after Treg cells are activated in the environment of established FIV infection.
Collapse
Affiliation(s)
- S. Rochelle Mikkelsen
- Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Julie M. Long
- Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Lin Zhang
- Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Erin R. Galemore
- Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Sue VandeWoude
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Gregg A. Dean
- Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
21
|
Scott VL, Boudreaux CE, Lockett NN, Clay BT, Coats KS. Cytokine dysregulation in early- and late-term placentas from feline immunodeficiency virus (FIV)-infected cats. Am J Reprod Immunol 2010; 65:480-91. [PMID: 20825375 DOI: 10.1111/j.1600-0897.2010.00919.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PROBLEM Experimental infection of cats with FIV-B-2542 produces high rates of fetal infection and reproductive failure. We hypothesized that dysregulation of placental cytokine expression occurs in FIV-infected queens, and aberrant expression potentiates inflammation and impacts pregnancy outcome. Our purpose was to quantify expression of representative pro-inflammatory cytokines (IL-6, IL-12p35, and IL-1β), IL-10 (anti-inflammatory), and the chemokine SDF-1α in early- and late-term placental tissues. METHOD OF STUDY Real-time reverse transcriptase PCR was used to measure gene expression in placental tissues. RESULTS Increased expression of IL-6 and IL-12p35 and decreased expression of IL-10 occurred in FIV-infected tissues at early pregnancy; at late gestation, IL-6 expression increased and IL-1β and SDF-1α decreased. At late pregnancy, IL-6 expression positively correlated with FIV load. IL-12:IL-10 ratios were higher in infected tissues at early, but not late pregnancy. Fetal non-viability accompanied decreased IL-12p35 and SDF-1α expression at both stages and decreased IL-12:IL-10 ratio at late pregnancy. CONCLUSION FIV infection caused a pro-inflammatory placental microenvironment at early, but not late pregnancy.
Collapse
Affiliation(s)
- Veronica L Scott
- Department of Biological Sciences, Mississippi State University, MS 39762, USA
| | | | | | | | | |
Collapse
|
22
|
Lockett NN, Scott VL, Boudreaux CE, Clay BT, Pruett SB, Ryan PL, Coats KS. Expression of regulatory T cell (Treg) activation markers in endometrial tissues from early and late pregnancy in the feline immunodeficiency virus (FIV)-infected cat. Placenta 2010; 31:796-802. [PMID: 20674972 DOI: 10.1016/j.placenta.2010.06.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 06/25/2010] [Accepted: 06/29/2010] [Indexed: 11/26/2022]
Abstract
Regulatory T cells (Tregs) support pregnancy maintenance by suppressing placental inflammation, while diminished Treg function may accompany reproductive failure. Experimental FIV infection frequently results in vertical transmission and increased pregnancy failure in the cat. The mechanism of reproductive compromise is unknown. We hypothesized that FIV infection alters endometrial Treg population dynamics and function, potentiating vertical transmission and reproductive failure. RNA collected from early and late gestation reproductive tissue and fetuses from FIV infected and control cats was probed for expression of FIV gag and Treg markers CD25, FOXP3, and CTLA4, using real time reverse-transcriptase (RT)-PCR. Frequent placental and fetal infection and reproductive failure were detected at early and late pregnancy. Expression of FOXP3 and CTLA4 was higher in early gestation tissues from control cats. FIV infection significantly reduced expression of FOXP3 and CTLA4 at early, but not late pregnancy. At late pregnancy, CTLA4 was expressed to higher levels in infected tissues. The number of tissues with decreased co-expression of FOXP3 and CTLA4 was significant in infected cats at early pregnancy. No significant changes in CD25 expression occurred between FIV-infected and control animals at early or late pregnancy. Differences in Treg marker expression were not significant between viable and non-viable pregnancies in infected cats. The detection of Treg markers in these feline tissues provides the first evidence of feline endometrial Tregs and suggests that such cells diminish as pregnancy progresses. These cells may be depleted or rendered less functional by viral infection, but understanding their role in pregnancy requires further study.
Collapse
Affiliation(s)
- N N Lockett
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
In vivo depletion of CD4(+)CD25(hi) regulatory T cells is associated with improved antiviral responses in cats chronically infected with feline immunodeficiency virus. Virology 2010; 403:163-72. [PMID: 20471053 DOI: 10.1016/j.virol.2010.04.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 03/22/2010] [Accepted: 04/19/2010] [Indexed: 11/22/2022]
Abstract
Regulatory T (Treg) cells are activated and suppress immune responses during infection, and are characterized as CD4(+)CD25(hi)FOXP3(+). Ex vivo studies demonstrate that Treg cells potentially suppress anti-HIV-1 T cell responses. Lentivirus-induced CD4(+)CD25(hi) Treg cells were first described in feline immunodeficiency virus (FIV)-infected cats. In the present study we demonstrate that anti-feline CD25 monoclonal antibody (mAb) therapy depletes Treg cells in FIV-infected cats for 4 weeks and does not exacerbate viral replication or proinflammatory cytokine production. Significant FIV-specific immune responses are revealed in Treg cell-depleted cats. These anti-FIV effector cells exist prior to Treg cell depletion and are not expanded while Treg cells are depleted. Importantly, cats receiving the Treg cell-depleting mAb are able to produce a robust humoral response to new antigen. We propose that short-term in vivo Treg cell depletion during chronic HIV-1 infection could provide a window of opportunity for therapeutic vaccination in individuals with controlled viral replication.
Collapse
|
24
|
Fogle JE, Mexas AM, Tompkins WA, Tompkins MB. CD4(+)CD25(+) T regulatory cells inhibit CD8(+) IFN-gamma production during acute and chronic FIV infection utilizing a membrane TGF-beta-dependent mechanism. AIDS Res Hum Retroviruses 2010; 26:201-16. [PMID: 20156102 DOI: 10.1089/aid.2009.0162] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
CD8(+) lymphocytes are critical to the control and elimination of viral pathogens. Impaired CD8(+) responses are well recognized in lentiviral infections; however, the mechanisms underlying CD8(+) impairment remain elusive. Using the feline immunodeficiency virus (FIV) model for human AIDS, we reported previously that CD4(+)CD25(+) Treg cells in both the acute and long-term, asymptomatic phase of infection are constitutively activated and suppress CD4(+)CD25(-) T cell responses. In the current study, we have demonstrated that CD4(+)CD25(+) Treg cells suppress CD8(+) responses to immune stimulation during both the acute and chronic, asymptomatic phase of FIV infection and that the mechanism of suppression may be mediated by membrane-associated TGF-beta (mTGF-beta) on CD4(+)CD25(+) lymphocytes. Depletion of CD4(+)CD25(+) lymphocytes from lymph node suspensions significantly enhanced production of IFN-gamma during the acute phase of infection and coculture of CD8(+) lymphocytes with CD4(+)CD25(+) lymphocytes resulted in suppression of CD8(+) IFN-gamma during both the acute and chronic stages of infection. FACS analysis indicated that there was TGF-betaRII upregulation on CD8(+) cells from FIV(+) cats during the acute and chronic stage of infection. In addition, there was upregulation of mTGF-beta on the CD4(+)CD25(+) subset in chronically infected cats. In support of activation of the TGF-beta signaling pathway, Western blotting showed Smad 2 phosphorylation in CD8(+) targets following CD4(+)CD25(+)/CD8(+) coculture. These results demonstrate the suppressive effect CD4(+)CD25(+) Treg cells have on the CD8(+) immune response during the acute and chronic stages of FIV infection and suggest that the mechanism of suppression may be mediated by mTGF-beta.
Collapse
Affiliation(s)
- Jonathan E. Fogle
- Immunology Program, Department of Population Health and Pathobiology, North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina 27606
| | - Angela M. Mexas
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Wayne A. Tompkins
- Immunology Program, Department of Population Health and Pathobiology, North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina 27606
| | - Mary B. Tompkins
- Immunology Program, Department of Population Health and Pathobiology, North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina 27606
| |
Collapse
|
25
|
Wongyanin P, Buranapraditkun S, Chokeshai-Usaha K, Thanawonguwech R, Suradhat S. Induction of inducible CD4+CD25+Foxp3+ regulatory T lymphocytes by porcine reproductive and respiratory syndrome virus (PRRSV). Vet Immunol Immunopathol 2009; 133:170-82. [PMID: 19709757 DOI: 10.1016/j.vetimm.2009.07.012] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 07/01/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
Abstract
Increases in numbers or activities of regulatory T lymphocytes (Tregs) have been linked to the establishments of several persistent infections. It has been previously shown that porcine reproductive and respiratory syndrome virus (PRRSV) can negatively modulate the host immune responses, resulting in persistent infection and secondary immunodeficiency. Recently, the existence of porcine CD4(+)CD25(+) Tregs has been demonstrated. We investigated the effect of PRRSV on the CD4(+)CD25(+) Tregs. The CD4(+)CD25(+)Foxp3(+) T lymphocytes in the peripheral blood mononuclear cells (PBMCs) were identified, using the anti-human anti-Foxp3 monoclonal antibody. In vitro culture of porcine PBMC in the presence of PRRSV, but not classical swine fever virus, significantly increased the numbers of Foxp3(+) lymphocytes, particularly in the CD4(+)CD25(high) subpopulation. The time-course study revealed that PRRSV significantly increased the numbers of viral-specific CD4(+)CD25(high)Foxp3(+) subpopulation in the culture starting from 12h through the end of the observation period. Consistent to the results obtained by flow cytometry, enhanced Foxp3 gene expression was observed in the PBMC cultured with PRRSV in a time-course manner. The presence of monocyte-derived DC in the co-culture significantly enhanced the induction of CD4(+)CD25(+) Foxp3(+) T lymphocytes. The PRRSV-induced CD4(+)CD25(high) T lymphocytes exhibited suppressive activity when co-cultured with PHA-activated, autologous peripheral blood leukocytes, indicating the suppressive activity of the PRRSV-specific Tregs. In addition, PRRSV exposure significantly increased the numbers of PRRSV-specific CD4(+)CD25(+)Foxp3(+) subpopulation in the PBMC of infected pigs at 10 days post-infection. In summary, the results indicated that PRRSV could increase the numbers of viral-specific, inducible regulatory T lymphocytes in the porcine PBMC, both in vitro and in vivo. The findings suggested the novel immunomodulatory mechanism induced by PRRSV.
Collapse
Affiliation(s)
- P Wongyanin
- Interdisciplinary Program of Medical Microbiology, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand
| | | | | | | | | |
Collapse
|
26
|
Abstract
FoxP3(+)CD4(+)CD25(+) regulatory T (Treg) cells are implicated in a number of pathologic processes including elevated levels in cancers and infectious diseases, and reduced levels in autoimmune diseases. Treg cells are activated to modulate immune responses to avoid over-reactive immunity. However, conflicting findings are reported regarding relative levels of Treg cells during HIV-1 infection and disease progression. The role of Treg cells in HIV-1 diseases (aberrant immune activation) is poorly understood due to lack of a robust model. We summarize here the regulation and function of Foxp3 in Treg cells and in modulating HIV-1 replication. Based on recent findings from SIV/monkey and HIV/humanized mouse models, a model of the dual role of Treg cells in HIV-1 infection and immuno-pathogenesis is discussed.
Collapse
|
27
|
Mexas AM, Fogle JE, Tompkins WA, Tompkins MB. CD4+CD25+ regulatory T cells are infected and activated during acute FIV infection. Vet Immunol Immunopathol 2008; 126:263-72. [PMID: 18799222 DOI: 10.1016/j.vetimm.2008.08.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 07/31/2008] [Accepted: 08/13/2008] [Indexed: 10/21/2022]
Abstract
HIV-induced AIDS may be mediated by the activation of immunosuppressive CD4+CD25+ T regulatory cells (Treg cells). Treg cells have been shown to regulate CD4+ and CD8+ immune responses to HIV and FIV antigens in vitro. We tested the hypothesis that Treg cells become infected and activated during the acute infection with FIV leading to the suppression of CD4+ T helper cell responses. Cats were experimentally infected with FIV-NCSU1 and blood and lymph node cells were collected at weekly intervals following inoculation. Real-time RT-PCR was used to determine plasma viremia and the relative expression of FIV, FoxP3, TGF-beta, and GAPDH mRNA copies in CD4+CD25+ and CD4+CD25- T cell subsets. Flow cytometry was used to assess the absolute numbers of each cell type and the expression of surface TGF-beta and intracellular FoxP3 in CD4+CD25+ and CD4+CD25- T cells at each time-point. Treg suppression of IL-2 production in CD4+ T helper cells was assessed by ELISPOT assays. Our results showed that peak viremia occurred at 2 weeks post infection and correlated with maximal infectivity in CD4+CD25+ T cell populations. FIV-gag-mRNA levels were higher in CD4+CD25+ T cells than CD4+CD25- T cells throughout the acute phase of infection. Induction of FoxP3 and TGF-beta indicated activation of Treg cells during the acute stage infection, which was confirmed by Treg cell suppression of IL-2 production by CD4+ Th cells in an ELISPOT assay. Our findings support the hypothesis that early activation of Treg immunosuppressor function may limit an effective anti-FIV response, contributing to the establishment of chronic infection and the immunodeficiency caused by this virus.
Collapse
Affiliation(s)
- Angela M Mexas
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606, United States
| | | | | | | |
Collapse
|
28
|
Willett BJ, Hosie MJ. Chemokine receptors and co-stimulatory molecules: unravelling feline immunodeficiency virus infection. Vet Immunol Immunopathol 2008; 123:56-64. [PMID: 18289703 DOI: 10.1016/j.vetimm.2008.01.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Feline immunodeficiency virus (FIV) infection of the domestic cat induces an immunodeficiency characterised by a gradual depletion of CD4+ T-helper lymphocytes. The virus targets T-helper cells by way of an interaction between its envelope glycoprotein (Env) and the cell surface molecule CD134 (OX40), a member of the nerve growth factor receptor/tumour necrosis factor receptor superfamily. The Env-CD134 interaction is a necessary prerequisite for the subsequent interaction with CXCR4, the only chemokine receptor identified to date to act as a co-receptor for FIV. As T-helper cell expression of CD134 and CXCR4 is restricted to activated cells, FIV targets selectively antigen-specific T-helper cells. With disease progression the cell tropism of the virus expands; this may be the result of changes in the way in which Env interacts with CD134, a less stringent Env-CD134 interaction enabling the Env to interact more readily with CXCR4 and thus broadening the cell tropism of virus. In contrast, viruses that are present in early infection may have a narrower cell tropism, reflecting a more stringent interaction with CD134. Accordingly, "early" viruses may target CD134-expressing cells more efficiently and be more resistant to neutralising antibody. It is these early viruses that may be transmitted and should be considered as candidates for the development of vaccine regimes and novel therapeutic agents.
Collapse
Affiliation(s)
- Brian J Willett
- Retrovirus Research Laboratory, Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsen Road, Glasgow G61 1QH, United Kingdom.
| | | |
Collapse
|
29
|
Elder JH, Sundstrom M, de Rozieres S, de Parseval A, Grant CK, Lin YC. Molecular mechanisms of FIV infection. Vet Immunol Immunopathol 2008; 123:3-13. [PMID: 18289701 DOI: 10.1016/j.vetimm.2008.01.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Feline immunodeficiency virus (FIV) is an important viral pathogen worldwide in the domestic cat, which is the smallest animal model for the study of natural lentivirus infection. Thus, understanding the molecular mechanisms by which FIV carries out its life cycle and causes an acquired immune deficiency syndrome (AIDS) in the cat is of high priority. FIV has an overall genome size similar to HIV, the causative agent of AIDS in man, and shares with the human virus genomic features that may serve as common targets for development of broad-based intervention strategies. Specific targets include enzymes encoded by the two lentiviruses, such as protease (PR), reverse transcriptase (RT), RNAse H, and integrase (IN). In addition, both FIV and HIV encode Vif and Rev elements essential for virus replication and also share the use of the chemokine receptor CXCR4 for entry into the host cell. The following review is a brief overview of the current state of characterization of the feline/FIV model and development of its use for generation and testing of anti-viral agents.
Collapse
Affiliation(s)
- John H Elder
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States.
| | | | | | | | | | | |
Collapse
|
30
|
Scott VL, Burgess SC, Shack LA, Lockett NN, Coats KS. Expression of CD134 and CXCR4 mRNA in term placentas from FIV-infected and control cats. Vet Immunol Immunopathol 2008; 123:90-6. [PMID: 18295905 DOI: 10.1016/j.vetimm.2008.01.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Feline immunodeficiency virus (FIV) causes a natural infection of domestic cats that resembles HIV-1 in pathogenesis and disease progression. Feline AIDS is characterized by depression of the CD4+ T cell population and fatal opportunistic infections. Maternal-fetal transmission of FIV readily occurs under experimental conditions, resulting in infected viable kittens and resorbed or arrested fetal tissues. Although both FIV and HIV use the chemokine receptor CXCR4 as a co-receptor, FIV does not utilize CD4 as the primary receptor. Rather, CD134 (OX40), a T cell activation antigen and co-stimulatory molecule, is the primary receptor for FIV. We hypothesized that placental expression of CD134 and CXCR4 may render the placenta vulnerable to FIV infection, possibly facilitating efficient vertical transmission of FIV, and impact pregnancy outcome. The purpose of this project was to quantify the relative expression of CD134 and CXCR4 mRNA from the term placentas of three groups of cats: uninfected queens producing viable offspring, experimentally-infected queens producing only viable offspring, and experimentally-infected queens producing viable offspring among mostly non-viable fetuses. Total RNA was extracted from term placental tissues from all groups of cats. Real-time one-step reverse transcriptase-PCR was used to measure gene expression. The FIV receptors CD134 and CXCR4 were expressed in all late term feline placental tissues. Placentas from FIV-infected queens producing litters of only viable offspring expressed more CD134 and CXCR4 mRNA than those from uninfected queens, suggesting that infection may cause upregulation of the receptors. On the other hand, placentas from FIV-infected cats with non-successful pregnancies expressed similar levels of CD134 mRNA and slightly less CXCR4 mRNA than those from uninfected queens. Thus, it appears that cells expressing these receptors may play a role in pregnancy maintenance.
Collapse
Affiliation(s)
- Veronica L Scott
- Department of Biological Sciences, Mississippi State University, P.O. Box GY, Mississippi State, Mississippi 39762, United States
| | | | | | | | | |
Collapse
|
31
|
Smithberg SR, Fogle JE, Mexas AM, Reckling SK, Lankford SM, Tompkins MB, Dean GA. In vivo depletion of CD4+CD25+ regulatory T cells in cats. J Immunol Methods 2007; 329:81-91. [PMID: 17980384 DOI: 10.1016/j.jim.2007.09.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 09/11/2007] [Accepted: 09/29/2007] [Indexed: 11/19/2022]
Abstract
To establish a characterized model of regulatory T cell (Treg) depletion in the cat we assessed the kinetics of depletion and rebound in peripheral and central lymphoid compartments after treatment with anti-CD25 antibody as determined by cell surface markers and FOXP3 mRNA expression. An 82% decrease in circulating CD4+CD25+ Tregs was observed by day 11 after treatment. CD4+CD25+ cells were also reduced in the thymus (69%), secondary lymphoid tissues (66%), and gut (67%). Although CD4+CD25+ cells rebound by day 35 post-treatment, FOXP3 levels remain depressed suggesting anti-CD25 antibody treatment has a sustainable diminutive effect on the Treg population. To determine whether CD25+ Treg depletion strategies also deplete activated CD25+ effector cells, cats were immunized with feline immunodeficiency virus (FIV) p24-GST recombinant protein, allowing them to develop a measurable memory response, prior to depletion with anti-CD25 antibody. Anti-FIV p24-GST effector cell activity in peripheral blood after depletion was sustained as determined by antigen-specific T cell proliferation and humoral responses against FIV p24-GST with an ELISA for antigen-specific feline IgG. Furthermore, development of an anti-mouse response in Treg-depleted cats was similar to control levels indicating the retained capacity to respond to a novel antigen. We conclude that despite alterations in CD25+ cell levels during depletion, the feline immune system remains functional. We demonstrate here a model for the study of disease pathogenesis in the context of reduced numbers of immunosuppressive CD4+CD25+ Tregs throughout the feline immune system.
Collapse
Affiliation(s)
- S Rochelle Smithberg
- Center for Comparative Medicine and Translational Research and Department of Molecular Biomedical Sciences, 4700 Hillsborough Street, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA
| | | | | | | | | | | | | |
Collapse
|
32
|
Willett BJ, McMonagle EL, Logan N, Spiller OB, Schneider P, Hosie MJ. Probing the interaction between feline immunodeficiency virus and CD134 by using the novel monoclonal antibody 7D6 and the CD134 (Ox40) ligand. J Virol 2007; 81:9665-79. [PMID: 17609274 PMCID: PMC2045395 DOI: 10.1128/jvi.01020-07] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The feline immunodeficiency virus (FIV) targets activated CD4-positive helper T cells preferentially, inducing an AIDS-like immunodeficiency in its natural host species, the domestic cat. The primary receptor for FIV is CD134, a member of the tumor necrosis factor receptor superfamily, and all primary viral strains tested to date use CD134 for infection. We examined the expression of CD134 in the cat using a novel anti-feline CD134 monoclonal antibody (MAb), 7D6, and showed that as in rats and humans, CD134 expression is restricted tightly to CD4+, and not CD8+, T cells, consistent with the selective targeting of these cells by FIV. However, FIV is also macrophage tropic, and in chronic infection the viral tropism broadens to include B cells and CD8+ T cells. Using 7D6, we revealed CD134 expression on a B220-positive (B-cell) population and on cultured macrophages but not peripheral blood monocytes. Moreover, macrophage CD134 expression and FIV infection were enhanced by activation in response to bacterial lipopolysaccharide. Consistent with CD134 expression on human and murine T cells, feline CD134 was abundant on mitogen-stimulated CD4+ T cells, with weaker expression on CD8+ T cells, concordant with the expansion of FIV into CD8+ T cells with progression of the infection. The interaction between FIV and CD134 was probed using MAb 7D6 and soluble CD134 ligand (CD134L), revealing strain-specific differences in sensitivity to both 7D6 and CD134L. Infection with isolates such as PPR and B2542 was inhibited well by both 7D6 and CD134L, suggesting a lower affinity of interaction. In contrast, GL8, CPG, and NCSU were relatively refractory to inhibition by both 7D6 and CD134L and, accordingly, may have a higher-affinity interaction with CD134, permitting infection of cells where CD134 levels are limiting.
Collapse
Affiliation(s)
- Brian J Willett
- Retrovirus Research Laboratory, Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow, United Kingdom.
| | | | | | | | | | | |
Collapse
|
33
|
Holmes D, Knudsen G, Mackey-Cushman S, Su L. FoxP3 enhances HIV-1 gene expression by modulating NFkappaB occupancy at the long terminal repeat in human T cells. J Biol Chem 2007; 282:15973-80. [PMID: 17416586 PMCID: PMC4418638 DOI: 10.1074/jbc.m702051200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
FoxP3 determines the development of CD4+CD25+ regulatory T (Treg) cells and represses interleukin-2 (IL-2) expression in Treg cells. However, human immunodeficiency virus type 1 (HIV-1) infects and replicates efficiently in FoxP3+ Treg cells. We report that, while inhibiting IL-2 gene expression, FoxP3 enhances gene expression from HIV-1 long terminal repeat (LTR). This FoxP3 activity requires both the N- and C-terminal domains and is inactivated by human IPEX (immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome) mutations. FoxP3 enhances HIV-1 LTR via its specific NFkappaB binding sequences in an NFkappaB-dependent fashion in T cells but not in HEK293 cells. FoxP3 decreases level of histone acetylation at the interleukin-2 locus but not at the HIV-1 LTR. Although NFkappaB nuclear translocation is not altered, FoxP3 enhances NFkappaB-p65 binding to HIV-1 LTR. These data suggest that FoxP3 modulates gene expression in a promoter sequence-dependent fashion by modulating chromatin structure and NFkappaB activity. HIV-1 LTR has evolved to both highjack the T-cell activation pathway for expression and to resist FoxP3-mediated suppression of T-cell activation.
Collapse
Affiliation(s)
- Derek Holmes
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599-7295
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295
| | - Geoffry Knudsen
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295
| | - Stephanie Mackey-Cushman
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295
| | - Lishan Su
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599-7295
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina 27599-7295
| |
Collapse
|
34
|
Yamamoto JK, Pu R, Sato E, Hohdatsu T. Feline immunodeficiency virus pathogenesis and development of a dual-subtype feline-immunodeficiency-virus vaccine. AIDS 2007; 21:547-63. [PMID: 17314517 DOI: 10.1097/qad.0b013e328013d88a] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
35
|
VandeWoude S, Apetrei C. Going wild: lessons from naturally occurring T-lymphotropic lentiviruses. Clin Microbiol Rev 2006; 19:728-62. [PMID: 17041142 PMCID: PMC1592692 DOI: 10.1128/cmr.00009-06] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Over 40 nonhuman primate (NHP) species harbor species-specific simian immunodeficiency viruses (SIVs). Similarly, more than 20 species of nondomestic felids and African hyenids demonstrate seroreactivity against feline immunodeficiency virus (FIV) antigens. While it has been challenging to study the biological implications of nonfatal infections in natural populations, epidemiologic and clinical studies performed thus far have only rarely detected increased morbidity or impaired fecundity/survival of naturally infected SIV- or FIV-seropositive versus -seronegative animals. Cross-species transmissions of these agents are rare in nature but have been used to develop experimental systems to evaluate mechanisms of pathogenicity and to develop animal models of HIV/AIDS. Given that felids and primates are substantially evolutionarily removed yet demonstrate the same pattern of apparently nonpathogenic lentiviral infections, comparison of the biological behaviors of these viruses can yield important implications for host-lentiviral adaptation which are relevant to human HIV/AIDS infection. This review therefore evaluates similarities in epidemiology, lentiviral genotyping, pathogenicity, host immune responses, and cross-species transmission of FIVs and factors associated with the establishment of lentiviral infections in new species. This comparison of consistent patterns in lentivirus biology will expose new directions for scientific inquiry for understanding the basis for virulence versus avirulence.
Collapse
Affiliation(s)
- Sue VandeWoude
- Department of Microbiology, Immunology and Pathology, College of Veterinary and Biomedical Sciences, Colorado State University, Fort Collins, CO 80538-1619, USA
| | | |
Collapse
|
36
|
Robertson SJ, Hasenkrug KJ. The role of virus-induced regulatory T cells in immunopathology. SPRINGER SEMINARS IN IMMUNOPATHOLOGY 2006; 28:51-62. [PMID: 16841143 PMCID: PMC7079961 DOI: 10.1007/s00281-006-0019-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Accepted: 05/17/2006] [Indexed: 12/14/2022]
Abstract
In recent years, regulatory T cells have received increased attention for their role in immune responses to microbial infections. The list of microbial pathogens associated with regulatory T cell responses is growing rapidly and includes bacteria, viruses, parasites, and fungi. As the biology of regulatory T cells is revealed, we are discovering that their induction during infection is a normal aspect of immunity, necessary to limit collateral damage from inflammatory responses and aggressive immunological effectors. Thus, these cells play a critical role in maintaining the delicate balance between preventing immunopathology and allowing the immune response to clear infections. While generally successful, there are notable exceptions where regulatory T cell-mediated suppression appears to be responsible for allowing certain viruses to establish and maintain a persistent state. In this review, we will discuss our current understanding of what virus-induced regulatory T cells are, how they are induced, and what mechanisms they use to suppress immunity. The complex role of Tregs in regulating immunity to viral infections, and the consequences their activity has on disease is illustrated by a review of specific viral infections including hepatitis C virus and human immunodeficiency virus.
Collapse
Affiliation(s)
- Shelly J. Robertson
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th St., Hamilton, MT 59840 USA
| | - Kim J. Hasenkrug
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th St., Hamilton, MT 59840 USA
| |
Collapse
|
37
|
Kinkade A, Ware CF. The DARC conspiracy--virus invasion tactics. Trends Immunol 2006; 27:362-7. [PMID: 16807107 DOI: 10.1016/j.it.2006.06.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2006] [Revised: 05/12/2006] [Accepted: 06/12/2006] [Indexed: 11/25/2022]
Abstract
Is there a "conspiracy" at work among viral pathogens? Apparently, yes. Rabies virus, lenti- and retroviruses, and herpesviruses, the "co-conspirators", target select members of the tumor necrosis factor (TNF) receptor superfamily to invade the cells of their host. The intrigue deepens, as several reports have revealed that the viral envelope proteins interact with the cellular TNF receptor in a highly conserved region of previously unknown function. Targeting of this region by diverse pathogens suggests that a selective advantage is acquired. This advantage might involve regulation of the immune response, because recent investigations of the herpesvirus entry receptor demonstrated that this conserved region engages an inhibitory co-receptor governing T-cell activation.
Collapse
Affiliation(s)
- April Kinkade
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
| | | |
Collapse
|
38
|
Willett BJ, McMonagle EL, Ridha S, Hosie MJ. Differential utilization of CD134 as a functional receptor by diverse strains of feline immunodeficiency virus. J Virol 2006; 80:3386-94. [PMID: 16537606 PMCID: PMC1440405 DOI: 10.1128/jvi.80.7.3386-3394.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The feline homologue of CD134 (fCD134) is the primary binding receptor for feline immunodeficiency virus (FIV), targeting the virus preferentially to activated CD4+ helper T cells. However, with disease progression, the cell tropism of FIV broadens such that B cells and monocytes/macrophages become significant reservoirs of proviral DNA, suggesting that receptor utilization may alter with disease progression. We examined the receptor utilization of diverse strains of FIV and found that all strains tested utilized CD134 as the primary receptor. Using chimeric feline x human CD134 receptors, the primary determinant of receptor function was mapped to the first cysteine-rich domain (CRD1) of fCD134. For the PPR and B2542 strains, the replacement of CDR1 of fCD134 (amino acids 1 to 64) with human CD134 (hCD134) alone was sufficient to confer nearly optimal receptor function. However, evidence of differential utilization of CD134 was revealed, since strains GL8, CPGammer (CPG41), TM2, 0827, and NCSU1 required determinants in the region spanning amino acids 65 to 85, indicating that these strains may require a more stringent interaction for infection to proceed.
Collapse
Affiliation(s)
- Brian J Willett
- Retrovirus Research Laboratory, Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, United Kingdom.
| | | | | | | |
Collapse
|
39
|
Vahlenkamp TW, Tompkins MB, Tompkins WAF. The role of CD4+CD25+ regulatory T cells in viral infections. Vet Immunol Immunopathol 2005; 108:219-25. [PMID: 16126280 DOI: 10.1016/j.vetimm.2005.07.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Many virus infections result in the suppression of one or more functions of the immune system. Multiple mechanisms have been proposed to explain viral-induced immunosuppression, including an imbalance in the cellular Th1/Th2 or cytokine profile, induction of anergy, depletion of effector cells and most recently the activation of CD4+CD25+ regulatory T (T reg) cells. CD4+CD25+ T reg cells are a subset of circulating CD4+ T cells with suppressive properties. CD4+CD25+ T reg cells were first identified in mice as cells capable of maintaining self-tolerance by suppressing autoreactive T cells. This review focuses on interactions between CD4+CD25+ T reg cells and viral pathogens. Most cases in which CD4+CD25+ T reg cells participate in response to infection reported so far involve chronic or persistent viral infections. Examples have been growing recently and include members of different viral families including retroviridae, herpesviridae and picornaviridae. It is currently not known how microbes are recognized by CD4+CD25+ T reg cells and whether exoantigen-specific T reg cells are of the same lineage as self-reacting natural T reg cells or represent peripherally induced counterparts derived from CD4+CD25- T cells. The findings that T reg cells influence the functional immunity during viral infections, however, might indicate that, in some cases, virus-specific T reg cells not only influence immune pathology or prevent pathogen elimination but also can promote a generalized state of immunosuppression in vivo such that the host is more susceptible to secondary infections with other pathogens or has reduced resistance to tumors. Conceivably, the activities of T reg cells might be one of the contributing reasons why it has been difficult so far to produce effective vaccines against some persisting viral infections.
Collapse
Affiliation(s)
- Thomas W Vahlenkamp
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Boddenblick 5a, 17493 Greifswald-Insel Riems, Germany.
| | | | | |
Collapse
|
40
|
Coats KS. The Feline Immunodeficiency Virus-Infected Cat: A Model for Lentivirus-induced Placental Immunopathology and Reproductive Failure (Mini-Review). Am J Reprod Immunol 2005; 54:169-85. [PMID: 16135008 DOI: 10.1111/j.1600-0897.2005.00296.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
PROBLEM Pediatric human immunodeficiency virus (HIV) infection is largely a result of transplacental transmission, and pregnancy perturbation is more frequent in HIV-infected women. Dysregulation of placental immunology may occur during HIV infection, possibly facilitating HIV vertical transfer and miscarriage. The (FIV)-infected cat is a useful small-animal model for HIV pathogenesis because the viruses share common biological and clinical features. Transplacental transmission is readily achieved experimentally, resulting in a high proportion of infected offspring and frequent reproductive failure. METHOD OF STUDY We are using this model to examine lentivirus-induced placental immunopathology to determine the role aberrant immunology plays in intrauterine transmission and pregnancy perturbation. RESULTS Kittens were cesarean delivered from FIV-B-2542-infected and control queens at week 8 gestation (1 week short of term), and placental and fetal specimens were collected. On average, control queens delivered 3.8 kittens/litter, and 1 of 31 kittens (3.2%) was non-viable. FIV-infected queens produced 2.7 kittens/litter with 15 of 25 fetuses (60%) non-viable. The virus was detected in 14 of 15 placentas (93%) and 21 of 22 fetuses (95%) using polymerase chain reaction (PCR). Using a one-step, real time reverse transcriptase (RT)-PCR, we measured expression of representative placental T helper 1 (Th1) cytokines, interleukin (IL)-1beta and interferon (IFN)-gamma, a Th2 cytokine, IL-10, and chemokine receptor CXCR4. A comparison of placental cytokine expression between infected and control queens did not reveal differences between the two groups. However, elevated expression of Th1 cytokines and increased Th1/Th2 ratios (IL-1beta/IL-10) occurred in placentas from resorptions, indicating that increased placental Th1 cytokine expression was associated with pregnancy failure in the FIV-infected cat. CONCLUSION The potential to establish efficient FIV in utero transmission, coupled with the parallels in immunopathology between FIV-infected cats and HIV-infected humans, suggests the usefulness of the FIV-infected cat as a cost-effective, small-animal model to study lentivirus-induced immunopathology, transplacental infection, and reproductive failure.
Collapse
Affiliation(s)
- Karen S Coats
- Department of Biological Sciences and College of Veterinary Medicine, Mississippi State University, PO Box GY, MS 39762, USA.
| |
Collapse
|