Mouse STAT2 Restricts Early Dengue Virus Replication

Human postmortem studies of natural dengue virus (DENV) infection have reported systemically distributed viral antigen. Although it is widely accepted that DENV infects mononuclear phagocytes, the sequence in which specific tissues and cell types are targeted remains uncharacterized. We previously reported that mice lacking alpha/beta and gamma interferon receptors permit high levels of DENV replication and show signs of systemic disease (T. R. Prestwood et al., J. Virol. 82:8411-8421, 2008). Here we demonstrate that within 6 h, DENV traffics to and replicates in both CD169؉ and SIGN-R1 ؉ macrophages of the splenic marginal zone or draining lymph node, respectively, following intravenous or intrafootpad inoculation. Subsequently, high levels of replication are detected in F4/80 ؉ splenic red pulp macrophages and in the bone marrow, lymph nodes, and Peyer's patches. Intravenously inoculated mice begin to succumb to dengue disease 72 h after infection, at which time viral replication occurs systemically, except in lymphoid tissues. In particular, high levels of replication occur in CD68؉ macrophages of the kidneys, heart, thymus, and gastrointestinal tract. Over the course of infection, proportionately large quantities of DENV traffic to the liver and spleen. However, late during infection, viral trafficking to the spleen decreases, while trafficking to the liver, thymus, and kidneys increases. The present study demonstrates that macrophage populations, initially in the spleen and other lymphoid tissues and later in nonlymphoid tissues, are major targets of DENV infection in vivo.T he four serotypes of dengue virus (DENV1 to DENV4) belong to the Flaviviridae family and cause a mosquito-borne febrile illness in more than 50 million people per year. In nearly 500,000 cases per year, individuals develop severe hemorrhage and sometimes shock, resulting in more than 25,000 deaths annually (12). The 10.7-kb positive-stranded RNA genome of DENV encodes a polyprotein that is cleaved into 3 structural proteins, the envelope (E), the premembrane/membrane (prM/M), and the capsid (C), and 7 nonstructural (NS) proteins, NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5. During replication, all DENV proteins and both positive-and negative-sense DENV RNAs are produced intracellularly, while only positive-sense RNA, the structural proteins, and NS1 are known to be secreted at high levels. Thus, based on current knowledge, NS proteins, with the exception of NS1, are restricted predominantly to cells in which DENV replicates.The cellular tropism of DENV has been investigated in humans (2, 5, 6, 8, 13, 15, 16, 25, 29) and mice (3, 9, 20, 38). In human studies, DENV antigen has been reported in the skin, liver, brain, kidney, spleen, lymph nodes, lungs, stomach, and intestines (2,5,6,8,13,15,16,25,29). These studies have mainly relied upon detection of secreted DENV antigens, which may actually localize elsewhere, complicating the interpretation of results. Recently two studies detected DENV NS antigen in the lymph nodes, spleen, liver, and ...

Section: Discussioncontrasting

confidence: 52%

Trafficking and Replication Patterns Reveal Splenic Macrophages as Major Targets of Dengue Virus in Mice

Prestwood

May

Plummer

et al. 2012

“…tagonize key innate immune restriction signaling molecules in mouse cells and in mice, including MITA (also known as STING) (85,86) and STAT2 (87,88). Passive transfer studies in our mouse models of DENV-4 infection correlated with in vitro neutralization data: poor inhibitory activity in vitro against DENV-4 H-241…”

Section: Discussionmentioning

confidence: 64%

Functional Analysis of Antibodies against Dengue Virus Type 4 Reveals Strain-Dependent Epitope Exposure That Impacts Neutralization and Protection

Sukupolvi-Petty

Brien

Austin

et al. 2013

g Although prior studies have characterized the neutralizing activities of monoclonal antibodies (MAbs) against dengue virus (DENV) serotypes 1, 2, and 3 (DENV-1, DENV-2, and DENV-3), few reports have assessed the activity of MAbs against DENV-4. Here, we evaluated the inhibitory activity of 81 new mouse anti-DENV-4 MAbs. We observed strain-and genotype-dependent differences in neutralization of DENV-4 by MAbs mapping to epitopes on domain II (DII) and DIII of the envelope (E) protein. Several anti-DENV-4 MAbs inefficiently inhibited at least one strain and/or genotype, suggesting that the exposure or sequence of neutralizing epitopes varies within isolates of this serotype. Remarkably, flavivirus cross-reactive MAbs, which bound to the highly conserved fusion loop in DII and inhibited infection of DENV-1, DENV-2, and DENV-3, more weakly neutralized five different DENV-4 strains encompassing the genetic diversity of the serotype after preincubation at 37°C. However, increasing the time of preincubation at 37°C or raising the temperature to 40°C enhanced the potency of DII fusion loop-specific MAbs and some DIII-specific MAbs against DENV-4 strains. Prophylaxis studies in two new DENV-4 mouse models showed that neutralization titers of MAbs after preincubation at 37°C correlated with activity in vivo. Our studies establish the complexity of MAb recognition against DENV-4 and suggest that differences in epitope exposure relative to other DENV serotypes affect antibody neutralization and protective activity. Dengue virus (DENV) is a member of the Flaviviridae family of RNA viruses and is genetically related to other human pathogens of global concern, including yellow fever, West Nile (WNV), and Japanese encephalitis viruses. In nature, DENV disease occurs exclusively in humans after Aedes aegypti or Aedes albopictus mosquito inoculation, with clinical disease ranging from a debilitating febrile illness (dengue fever [DF]) to a life-threatening hemorrhagic and capillary leak syndrome (dengue hemorrhagic fever [DHF]/dengue shock syndrome [DSS]). No approved antiviral treatment is currently available, although candidate tetravalent vaccines are in advanced clinical trials (reviewed in references 1 and 2). Because of the increased geographic range of its mosquito vectors, urbanization, and international travel, DENV continues to spread worldwide and now causes an estimated 390 million infections and 500,000 cases of DHF/DSS per year, with 3.6 billion people at risk (3, 4). Given that the most advanced live-attenuated DENV vaccine candidate showed a poor 30% overall efficacy rate in a recently published phase 2b clinical trial (5), there is an urgent need for understanding the correlates of protection, especially those of neutralizing antibodies.DENV is an enveloped virus with a single-stranded, positivepolarity RNA genome. Based on experiments with DENV-1 and DENV-2 isolates, the mature DENV virion is ϳ500 Å in diameter with a highly organized outer protein shell, a 50-Å lipid membrane bilayer, and a nucleocapsid core ...

“…As well as the AG129 mice (11), mice lacking signaling elements downstream of the IFN receptors (IFNRs) (STAT1/ 2), and STAT1 IFNAR double knockout mice are all highly susceptible to DENV infection (12,13). Mice deficient in just the type I IFN receptor are also susceptible to high-titer DENV challenge (14), while mice lacking the type II IFN receptor alone can resist even large doses of DENV without developing significant viremia or pathology (14,15).…”

mentioning

confidence: 99%

Type I Interferon Signals in Macrophages and Dendritic Cells Control Dengue Virus Infection: Implications for a New Mouse Model To Test Dengue Vaccines

Züst

Toh

Valdés

et al. 2014

Dengue virus (DENV) infects an estimated 400 million people every year, causing prolonged morbidity and sometimes mortality. Development of an effective vaccine has been hampered by the lack of appropriate small animal models; mice are naturally not susceptible to DENV and only become infected if highly immunocompromised. -cell response to viral infection, compared to a weak response in IFNAR؊/؊ mice. Furthermore, mice lacking IFNAR on either CD11c ؉ or LysM ؉ cells were also sufficiently immunocompetent to raise a protective immune response to a candidate subunit vaccine against DENV-2. These data demonstrate that mice with conditional deficiencies in expression of the IFNAR represent improved models for the study of DENV immunology and screening of vaccine candidates. IMPORTANCEDengue virus infects 400 million people every year worldwide, causing 100 million clinically apparent infections, which can be fatal if untreated. Despite many years of research, there are no effective vaccine and no antiviral treatment available for dengue. Development of vaccines has been hampered in particular by the lack of a suitable small animal model. Mouse models used to test dengue vaccine are deficient in interferon (IFN) type I signaling and severely immunocompromised and therefore likely not ideal for the testing of vaccines. In this study, we explored alternative models lacking the IFN receptor only on certain cell types. We show that mice lacking the IFN receptor on either CD11c-or LysM-expressing cells (conditional IFNAR mice) are susceptible to dengue virus infection. Importantly, we demonstrate that conditional IFN receptor knockout mice generate a better immune response to live virus and a candidate dengue vaccine compared to IFNAR mice and are resistant to subsequent challenge. D engue virus (DENV, a member of the Flaviviridae family, is a mosquito-borne pathogen that infects approximately 400 million people every year (1, 2). Each of the four DENV serotypes causes a spectrum of clinical symptoms ranging from mild fever to potentially fatal manifestations of dengue shock syndrome. DENV causes an acute infection with high fever, which usually resolves after 5 to 7 days. At this time, most patients have cleared the high virus load. Intriguingly, however, this is also the time point when some patients start to develop vascular leakage, which, if untreated, can lead to a collapse of the metabolism and organ failure. The frequency, severity, and geographical spread of cases has increased over the past decades (3, 4), and DENV infection is now considered a leading cause of morbidity in the tropics.There are no effective treatments for dengue fever, and the development of a vaccine has been hampered by the lack of suitable small animal models. Wild-type (wt) mice are not susceptible to infection with field strains of DENV, and while viral replication in these animals can be forced by intracranial injections of hightiter mouse-adapted DENV strains, the resulting clinical disease bears little resemblance to dengue fev...