Sin Nombre Research Articles

Hantavirus Infections among Overnight Visitors to Yosemite National Park, California, USA, 2012

In summer 2012, an outbreak of hantavirus infections occurred among overnight visitors to Yosemite National Park in California, USA. An investigation encompassing clinical, epidemiologic, laboratory, and environmental factors identified 10 cases among residents of 3 states. Eight case-patients experienced hantavirus pulmonary syndrome, of whom 5 required intensive care with ventilatory support and 3 died. Staying overnight in a signature tent cabin (9 case-patients) was significantly associated with becoming infected with hantavirus (p<0.001). Rodent nests and tunnels were observed in the foam insulation of the cabin walls. Rodent trapping in the implicated area resulted in high trap success rate (51%), and antibodies reactive to Sin Nombre virus were detected in 10 (14%) of 73 captured deer mice. All signature tent cabins were closed and subsequently dismantled. Continuous public awareness and rodent control and exclusion are key measures in minimizing the risk for hantavirus infection in areas inhabited by deer mice.

Why is the Four Corners a hotspot for hantavirus?

Sin Nombre virus (SNV) is a hantavirus hosted almost exclusively by deer mice (Peromyscus maniculatus) that causes high (∼40%) mortality in humans. Transmission patterns of SNV in natural host populations are not well understood and, as such, represent a knowledge gap that has significant implications for human health. Since its identification in the early 1990s, the Four Corners region of the southwestern United States (i.e. geographic area encompassing southeastern UT, northeastern AZ, southwestern CO and northwestern NM) has remained a “hotspot” for SNV infections in both deer mice and humans; however, the reason for this skewed geographic distribution of SNV remains unclear. Therefore, our objective was to observe regional patterns of SNV prevalence in deer mice along a latitudinal gradient in the Four Corners region and determine the extent to which prevalence is influenced by factors including deer mouse density, small mammal diversity, vegetation cover, plant moisture content, soil pH and soil water content. Although we did not find a significant correlation between SNV prevalence and small mammal species diversity, SNV prevalence and deer mouse density were positively correlated. We found no relationship between soil pH and SNV prevalence; however, there was a strong negative correlation between SNV prevalence and soil water content. We also found strong positive correlations between SNV prevalence and total vegetation cover and between SNV prevalence and plant moisture content. Collectively, our results suggest that SNV prevalence is driven primarily by increased deer mouse densities and that deer mice are more likely to be associated with habitats that have higher plant moisture content, as well as greater total vegetation cover. Our results also indicate that, whereas soil pH is not a direct predictor of SNV prevalence, sites with dry soils at pH levels close to the optimal for SNV (6.9) that also contain high densities of deer mice may be hantavirus “hot spots”.

An Innate Immunity-Regulating Virulence Determinant Is Uniquely Encoded within the Andes Virus Nucleocapsid Protein

ABSTRACTAndes virus (ANDV) is the only hantavirus known to spread from person to person and shown to cause highly lethal hantavirus pulmonary syndrome (HPS) in patients and Syrian hamsters. Hantaviruses replicate in human endothelial cells and accomplish this by restricting the early induction of beta interferon (IFN-β)- and IFN-stimulated genes (ISGs). Our studies reveal that the ANDV nucleocapsid (N) protein uniquely inhibits IFN signaling responses directed by cytoplasmic double-stranded RNA (dsRNA) sensors RIG-I and MDA5. In contrast, N proteins from Sin Nombre, New York-1, and Prospect Hill hantaviruses had no effect on RIG-I/MDA5-directed transcriptional responses from IFN-β-, IFN-stimulated response element (ISRE)-, or κB-containing promoters. Ablating a potential S-segment nonstructural open reading frame (ORF) (NSs) within the ANDV plasmid expressing N protein failed to alter IFN regulation by ANDV N protein. Further analysis demonstrated that expressing the ANDV N protein inhibited downstream IFN pathway activation directed by MAVS, TBK1, and IκB kinase ε (IKKε) but failed to inhibit transcriptional responses directed by constitutive expression of active interferon regulatory factor IRF3-5D or after stimulation by alpha interferon (IFN-α) or tumor necrosis factor alpha (TNF-α). Consistent with IFN pathway-specific regulation, the ANDV N protein inhibited TBK1-directed IRF3 phosphorylation (phosphorylation of serine 396 [pS396]) and TBK1 autophosphorylation (pS172). Collectively, these findings indicate that the ANDV N inhibits IFN signaling responses by interfering with TBK1 activation, upstream of IRF3 phosphorylation and NF-κB activation. Moreover, our findings reveal that ANDV uniquely carries a gene encoding a virulence determinant within its N protein that is capable of restricting ISG and IFN-β induction and provide a rationale for the novel pathogenesis and spread of ANDV.

Prognostic Factors in Hantavirus Infections

The hantaviruses classified in Hantavirus genus of Bunyaviridae family, may cause two different types of clinical conditions, namely hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). Mortality may reach up to 40% in these infections. Hantavirus subtypes (Sin Nombre, Hantaan, Seoul, Puumala, Dobrava, etc) with different virulences represent one of the most significant factors affecting the mortality. Additionally, many other factors including age, gender, humoral immune response, genetic factors, patient's clinical and laboratory findings, transfusion, mechanical ventilation requirement, antiviral treatment and immunotherapy administered to the patient are prognostically important. Increasing age had an unfavorable effect on mortality. While the disease is commonly observed in the male gender, mortality rate is higher in the female gender. The higher the emergent neutralizing antibody response, the virus spread, the number of the infected cells and the cytotoxic T lymphocyte-mediated injury will be lower. The requirement for dialysis is reported to be higher with a poorer prognosis in individuals with HLA-B8, -DR3, -DQ2 alleles, and those with HLA-B27 allele usually experience a milder clinical course. Clinically, the risk of mortality increases in patients with multiple, central nervous system hemorrhage, sepsis, disseminated intravascular coagulation (DIC) and secondary infection. The presence of adult respiratory distress syndrome (ARDS), the requirement for mechanical ventilation, the presence of dyspnea and hemoconcentration in HPS are reported to be the most important prognostic factors associated with death. The correlation of severity and the transfusion requirement with mortality was demonstrated. High serum levels of white blood cells, blood urea nitrogen (BUN), creatinine phophokinase (CPK), C-reactive protein (CRP), prothrombin time (PT), activated partial thromboplastin time (aPTT), D-dimer and INR (International normalized ratio) are prognostic factors that increase the mortality risk. Hemodialysis support is particularly important in cases infected with Hantaan and Dobrava viruses. Respiratory support and mechanical ventilation can be life-saving in HPS cases. Extracorporeal membrane oxygenation support has been demonstrated to have a favorable contribution to the patient survival in HPS. While there are some human and animal trials showing that ribavirin reduces the severity of HFRS, hemodialysis requirement and mortality, its efficacy for HPS has not yet been demonstrated. As a result, a proper evaluation of the prognostic factors will provide physicians a perspective with respect to the disease course and the necessary treatment approach.

Twenty-Year Summary of Surveillance for Human Hantavirus Infections, United States

In the past 20 years of surveillance for hantavirus in humans in the United States, 624 cases of hantavirus pulmonary syndrome (HPS) have been reported, 96% of which occurred in states west of the Mississippi River. Most hantavirus infections are caused by Sin Nombre virus, but cases of HPS caused by Bayou, Black Creek Canal, Monongahela, and New York viruses have been reported, and cases of domestically acquired hemorrhagic fever and renal syndrome caused by Seoul virus have also occurred. Rarely, hantavirus infections result in mild illness that does not progress to HPS. Continued testing and surveillance of clinical cases in humans will improve our understanding of the etiologic agents involved and the spectrum of diseases.

The Intracellular Cargo Receptor ERGIC-53 Is Required for the Production of Infectious Arenavirus, Coronavirus, and Filovirus Particles

SummaryArenaviruses and hantaviruses cause severe human disease. Little is known regarding host proteins required for their propagation. We identified human proteins that interact with the glycoproteins (GPs) of a prototypic arenavirus and hantavirus and show that the lectin endoplasmic reticulum (ER)-Golgi intermediate compartment 53 kDa protein (ERGIC-53), a cargo receptor required for glycoprotein trafficking within the early exocytic pathway, associates with arenavirus, hantavirus, coronavirus, orthomyxovirus, and filovirus GPs. ERGIC-53 binds to arenavirus GPs through a lectin-independent mechanism, traffics to arenavirus budding sites, and is incorporated into virions. ERGIC-53 is required for arenavirus, coronavirus, and filovirus propagation; in its absence, GP-containing virus particles form but are noninfectious, due in part to their inability to attach to host cells. Thus, we have identified a class of pathogen-derived ERGIC-53 ligands, a lectin-independent basis for their association with ERGIC-53, and a role for ERGIC-53 in the propagation of several highly pathogenic RNA virus families.

Increased Detection of Sin Nombre Hantavirus RNA in Antibody-Positive Deer Mice from Montana, USA: Evidence of Male Bias in RNA Viremia

Hantaviruses are widespread emergent zoonotic agents that cause unapparent or limited disease in their rodent hosts, yet cause acute, often fatal pulmonary or renal infections in humans. Previous laboratory experiments with rodent reservoir hosts indicate that hantaviruses can be cleared from host blood early in the infection cycle, while sequestered long term in various host organs. Field studies of North American deer mice (Peromyscus maniculatus), the natural reservoir of Sin Nombre hantavirus, have shown that viral RNA can be transiently detected well past the early acute infection stage, but only in the minority of infected mice. Here, using a non-degenerate RT-PCR assay optimized for SNV strains known to circulate in Montana, USA, we show that viral RNA can be repeatedly detected on a monthly basis in up to 75% of antibody positive deer mice for periods up to 3–6 months. More importantly, our data show that antibody positive male deer mice are more than twice as likely to have detectable SNV RNA in their blood as antibody positive females, suggesting that SNV-infected male deer mice are more likely to shed virus and for longer periods of time.

Role of nucleocapsid protein of hantaviruses in intracellular traffic of viral glycoproteins

To understand the role of nucleocapsid protein (NP) of hantaviruses in viral assembly, the effect of NP on intracellular traffic of viral glycoproteins Gn and Gc was investigated. Double staining of viral and host proteins in Hantaan virus (HTNV)-infected Vero E6 cells showed that Gn and Gc were localized to cis-Golgi, in which virus particles are thought to be formed. When HTNV Gn and Gc were expressed by a plasmid encoding glycoprotein precursor (GPC), which is posttranslationaly cleaved into Gn and Gc, Gn was localized to cis-Golgi, whereas Gc showed diffuse distribution in the cytoplasm in 32.9% of Gc-positive cells. The ratio of the diffused Gc-positive cells was significantly decreased to 15.0% by co-expression of HTNV NP. Co-expression of HTNV GPC with NPs of other hantaviruses, such as Seoul virus, Puumala virus and Sin Nombre virus, also reduced the ratios of diffused Gc-positive cells to 13.5%, 25.2%, and 11.6%, respectively. Among amino- and carboxyl-terminally truncated HTNV NPs, NP75-429, NP116-429, NP1-333, NP1-233, and NP1-155 possessed activity to reduce the ratio of diffused Gc-positive cells, while NP155-429 and NP1-116 did not. NP30-429 has partial activity. These results indicate that amino acid region 116–155 of NP is important for the activity, although amino acid region 1-30 is partially related. Truncation of the HTNV Gc cytoplasmic tail caused an increase in diffused Gc-positive cells. In addition, the effect of coexpression of HTNV NP was weakened. These results suggest that HTNV NP has a role to promote Golgi localization of Gc through a mechanism possibly mediated by the Gc cytoplasmic tail.

The adaptive immune response does not influence hantavirus disease or persistence in the Syrian hamster

Pathogenic New World hantaviruses cause severe disease in humans characterized by a vascular leak syndrome, leading to pulmonary oedema and respiratory distress with case fatality rates approaching 40%. Hantaviruses infect microvascular endothelial cells without conspicuous cytopathic effects, indicating that destruction of the endothelium is not a mechanism of disease. In humans, high levels of inflammatory cytokines are present in the lungs of patients that succumb to infection. This, along with other observations, suggests that disease has an immunopathogenic component. Currently the only animal model available to study hantavirus disease is the Syrian hamster, where infection with Andes virus (ANDV), the primary agent of disease in South America, results in disease that closely mimics that seen in humans. Conversely, inoculation of hamsters with a passaged Sin Nombre virus (SNV), the virus responsible for most cases of disease in North America, results in persistent infection with high levels of viral replication. We found that ANDV elicited a stronger innate immune response, whereas SNV elicited a more robust adaptive response in the lung. Additionally, ANDV infection resulted in significant changes in the blood lymphocyte populations. To determine whether the adaptive immune response influences infection outcome, we depleted hamsters of CD4(+) and CD8(+) T cells before infection with hantaviruses. Depletion resulted in inhibition of virus-specific antibody responses, although the pathogenesis and replication of these viruses were unaltered. These data show that neither hantavirus replication, nor pathogenesis caused by these viruses, is influenced by the adaptive immune response in the Syrian hamster.

The role of behavioural heterogeneity on infection patterns: implications for pathogen transmission

Animals infected with pathogens often differ in behaviour from their uninfected counterparts, and these differences may be key to understanding zoonotic pathogen transmission. To explore behavioural heterogeneity and its role in pathogen transmission, we studied deer mice, Peromyscus maniculatus, under field conditions. Deer mice are the natural host of Sin Nombre virus (SNV), a zoonotic pathogen with high human mortality. We live-trapped mice in May, July and September of 2009 and 2010, marked captures with passive integrated transponder (PIT) tags, recorded physical characteristics and collected blood samples for SNV analysis. For 4 nights after each trapping session, we observed behaviour with a novel surveillance system of nine camera stations, each consisting of a foraging tray, infrared camera, PIT antenna and data logger. We found that deer mice infected with SNV (30.0%) engaged more frequently in behaviours that increased the probability of intraspecific encounters and SNV transmission than did uninfected deer mice. When deer mice were categorized as bold (31.7%) or shy (68.3%) based on these behaviours, bold behaviour was predictive of positive SNV status. Bold deer mice were three times more likely to be infected with SNV than were shy deer mice. These results suggest that a small percentage of bold individuals are responsible for a majority of SNV transmission events, and that behavioural phenotype is an important consideration in transmission dynamics of zoonotic diseases.

Rapid parallel flow cytometry assays of active GTPases using effector beads

We describe a rapid assay for measuring the cellular activity of small guanine triphosphatases (GTPases) in response to a specific stimulus. Effector-functionalized beads are used to quantify in parallel multiple GTP-bound GTPases in the same cell lysate by flow cytometry. In a biologically relevant example, five different Ras family GTPases are shown for the first time to be involved in a concerted signaling cascade downstream of receptor ligation by Sin Nombre hantavirus.

The biopolitical aesthetic: toward a post-biopolitical subject

In this article I argue that the biopolitical aesthetic can be explored through various anxious tensions between politicization of life and the necessity of killing. I read five films (Gattaca, Children of Men, Valhalla Rising, Sin Nombre, and Essential Killing) in order to cultivate four exemplary tensions: one, Kill or be Killed; two, Kill to Live More; three, Live More to Kill; and finally, four, Kill and be Killed. I conclude by asking whether a post-biopolitical subject can emerge from within this final biopolitical tension whereby, instead of circulating life as freedom, it is killing that is now primarily circulated as life. I conclude with the post-biopolitical subject of indifference and its implications for approaching security beyond the anxieties of both geopolitical and biopolitical aesthetics.

A novel Sin Nombre virus DNA vaccine and its inclusion in a candidate pan-hantavirus vaccine against hantavirus pulmonary syndrome (HPS) and hemorrhagic fever with renal syndrome (HFRS)

Sin Nombre virus (SNV; family Bunyaviridae, genus Hantavirus) causes a hemorrhagic fever known as hantavirus pulmonary syndrome (HPS) in North America. There have been approximately 200 fatal cases of HPS in the United States since 1993, predominantly in healthy working-age males (case fatality rate 35%). There are no FDA-approved vaccines or drugs to prevent or treat HPS. Previously, we reported that hantavirus vaccines based on the full-length M gene segment of Andes virus (ANDV) for HPS in South America, and Hantaan virus (HTNV) and Puumala virus (PUUV) for hemorrhagic fever with renal syndrome (HFRS) in Eurasia, all elicited high-titer neutralizing antibodies in animal models. HFRS is more prevalent than HPS (>20,000 cases per year) but less pathogenic (case fatality rate 1–15%). Here, we report the construction and testing of a SNV full-length M gene-based DNA vaccine to prevent HPS. Rabbits vaccinated with the SNV DNA vaccine by muscle electroporation (mEP) developed high titers of neutralizing antibodies. Furthermore, hamsters vaccinated three times with the SNV DNA vaccine using a gene gun were completely protected against SNV infection. This is the first vaccine of any kind that specifically elicits high-titer neutralizing antibodies against SNV. To test the possibility of producing a pan-hantavirus vaccine, rabbits were vaccinated by mEP with an HPS mix (ANDV and SNV plasmids), or HFRS mix (HTNV and PUUV plasmids), or HPS/HFRS mix (all four plasmids). The HPS mix and HFRS mix elicited neutralizing antibodies predominantly against ANDV/SNV and HTNV/PUUV, respectively. Furthermore, the HPS/HFRS mix elicited neutralizing antibodies against all four viruses. These findings demonstrate a pan-hantavirus vaccine using a mixed-plasmid DNA vaccine approach is feasible and warrants further development.

Antiviral Efficacy of Favipiravir against Two Prominent Etiological Agents of Hantavirus Pulmonary Syndrome

Hantavirus pulmonary syndrome (HPS) is caused by infection with several Sigmodontinae- and Neotominae-borne hantaviruses and has a case fatality rate of 30 to 50%. Humans often become infected by inhalation of materials contaminated with virus-laden rodent urine or saliva, although human-to-human transmission has also been documented for Andes virus (ANDV). The ability to transmit via aerosolization, coupled with the high mortality rates and lack of therapeutic options, makes the development of medical countermeasures against HPS imperative. In the present study, we evaluated the efficacy of the broad-spectrum antiviral agent favipiravir (T-705) against Sin Nombre virus (SNV) and ANDV, the predominant causes of HPS in North and South America, respectively. In vitro, T-705 potently inhibited SNV and ANDV, as evidenced by decreased detection of viral RNA and reduced infectious titers. For both viruses, the 90% effective concentration was estimated at ≤5 μg/ml (≤31.8 μM). In the lethal ANDV hamster model, daily administration of oral T-705 at 50 or 100 mg/kg of body weight diminished the detection of viral RNA and antigen in tissue specimens and significantly improved survival rates. Oral T-705 therapy remained protective against HPS when treatment was initiated prior to the onset of viremia. No disease model for SNV exists; however, using a hamster-adapted SNV, we found that daily administration of oral T-705 significantly reduced the detection of SNV RNA and antigen in tissue specimens, suggesting that the compound would also be effective against HPS in North America. Combined, these results suggest that T-705 treatment is beneficial for postexposure prophylaxis against HPS-causing viruses and should be considered for probable exposures.

Hantavirus (Bunyaviridae: Hantavirus) en roedores murinos de Sincelejo, departamento de Sucre

Los hantavirus, asociados a roedores de la subfamilia Sigmodontinae, son patógenosemergentes causantes de la zoonosis Síndrome Cardiopulmonar por Hantavirus (SCPH) en las Américas. Hasta la fecha, en Colombia no se han confirmado casos de la enfermedad; sin embargo, se ha demostrado la evidencia serológica de exposición a hantavirus en roedores y humanos de dos departamentos de la RegiónCaribe, y la detección molecular de genoma viral en muestras de tejido de roedores en Antioquia. El objetivo de esta investigación fue determinar la frecuencia de anticuerpos específicos contra hantavirus en roedores de la ciudad de Sincelejo, departamento de Sucre. Los muestreos de los animales fueron realizados con trampas Sherman, desde marzo hasta julio de 2009. Los anticuerpos IgG específicos contra el Virus Sin Nombre (VSN) fueron detectados en muestras de plasma medianteensayo de inmunoabsorción ligado aenzimas (ELISA indirecto). Secapturaron 61 roedores distribuidos en tres especies, de las cuales Mus musculusfue la más abundante (91.8%). Del total de animales analizados, un único ejemplar, clasificado dentrode la especie Rattusrattus (seroprevalencia de 1.64%), resultó positivo a hantavirus. Los hallazgos evidenciaron seropositividad a hantavirus en roedores de la subfamilia Murinae en Colombia. La detección de anticuerpos contra el virus refuerza la hipótesis que sugiere la circulación de al menos un hantavirus en roedores del norte colombiano.

Impact of the Yosemite Hantavirus Outbreak on Hantavirus Antibody Testing at a National Reference Laboratory

In conjunction with the 2012 Yosemite hantavirus outbreak, the number of sera our facility tested for hantavirus antibodies increased. We tracked test results and used the data set to determine if a more efficient testing algorithm was possible. Sera were screened using laboratory-developed pan-hantavirus IgG and IgM enzyme immunoassays (EIAs), with an index of >1.10 defined as positive. Sera that were IgM positive by screening (screen IgM(+)) were tested for Sin Nombre virus (SNV)-specific IgM using a laboratory-developed EIA; screen IgM(+) IgG(+) sera were also tested for SNV IgG using a laboratory-developed immunoblot assay. SNV antibody-positive samples were sent to state public health laboratories (PHL) or the CDC for confirmation. Of 3,946 sera tested from July through December 2012, 205 were screen IgM(+) IgG negative (IgG(-)); 7/205 were SNV IgM(+), but only 1/5 sent to PHL/CDC was confirmed as SNV IgM(+). Of 61 screen IgM(+) IgG(+) sera, 16 were SNV antibody positive; 13/16 sera (from 11 patients) went to PHL/CDC, where SNV infection was confirmed for all patients. Of 12 confirmed patients, 7 had been exposed at Yosemite. A modified algorithm defining screen indices of ≥2.00 as positive identified 11/12 confirmed cases while reducing the number of sera requiring SNV-specific antibody testing by 65%; the patient missed was not tested until 3 months after the onset of symptoms. Hantavirus antibody testing at our facility identified 12 SNV-infected patients, including 7 exposed at Yosemite. Some screen IgM(+) IgG(-) SNV IgM(+) results were false positives, emphasizing the value of PHL/CDC confirmatory testing. We identified a modified algorithm requiring analysis of fewer specimens for SNV-specific antibodies without loss of sensitivity.

The Central American transnational imaginary: Defining the transnational and gendered contours of Central American immigrant experience

In this article, I explore recent cultural production about and by Central Americans in the United States, including the independent film Sin nombre, Sirias's novel, Bernardo and the Virgin, and the autobiographical account, December Sky: Beyond My Undocumented Life by Cortez-Davis. Drawing on José Saldivar's conceptualization of a “transnational imaginary,” I contend that these cultural works contribute to the formation and continuous redefinition of an emergent Central American transnational imaginary. In so doing, they provide insight into the identities and multiple subject positions taking shape among Central American immigrants in the United States. Moreover, because in all of these texts women play a central role, these works also call attention to the gendered dimensions and implications of such processes.

Predominant Th2 cytokine gene expression in lymph node cell cultures from Andes virus-infected deer mice (Peromyscus maniculatus) (P6316)

Abstract Deer mice (Peromyscus maniculatus) are the principal reservoir hosts of Sin Nombre virus (SNV), while long-tailed pygmy rice rats (Oligoryzomys longicaudatus) are the principal reservoir hosts of Andes virus (ANDV). These viruses cause the great majority of hantavirus cardiopulmonary syndrome cases in North and South America. The disease in humans is principally an inflammatory immunopathology that results in a pronounced capillary leak syndrome with a 36% fatality rate due to cardiogenic shock. In contrast, infection of rodent reservoirs with their hantaviruses results in life-long persistence, without signs of disease, that appears to be mediated by regulatory T cells. Deer mice are experimentally susceptible to ANDV; however, they clear infection within 56 days. We infected deer mice with SNV or ANDV for 14 days and examined the immune responses to each virus. Lymph node cells from infected deer mice were harvested and cultured with viral antigens to examine expression of 94 immune-related genes by real-time PCR. We found that most of the same genes were expressed in both SNV- and ANDV-infected deer mice; however, the magnitude of gene expression, particularly Th2 genes, were significantly greater in lymph node cells from ANDV-infected deer mice. Together, these results suggest a quantitative effect occurs in the host response to a reservoir hantavirus (SNV) compared to a nonreservoir hantavirus (ANDV) and is associated with persistence or clearance.

Expression profiling of lymph node cells from deer mice infected with Andes virus

BackgroundDeer mice (Peromyscus maniculatus) are the principal reservoir hosts of Sin Nombre virus (SNV), the cause of the great majority of hantavirus cardiopulmonary syndrome (HCPS) cases in North America. SNV, like all hantaviruses with their reservoirs, causes persistent infection without pathology in deer mice and appear to elicit a regulatory T cell response. Deer mice are also susceptible to Andes virus (ANDV), which causes the great majority of HCPS cases in South America, but they clear infection by 56 days post infection without signs of disease.ResultsWe examined lymph node cell responses of deer mice infected with ANDV to determine expression profiles upon in vitro recall challenge with viral antigen. Because the deer mouse genome is currently unannotated, we developed a bioinformatics pipeline to use known lab mouse (Mus musculus) cDNAs to predict genes within the deer mouse genome and design primers for quantitative PCR (http://dna.publichealth.uga.edu/BlastPrimer/BlastPrimer.php). Of 94 genes examined, 20 were elevated, the plurality of which were Th2-specific, whereas 12 were downregulated. Other expressed genes represented Th1, regulatory T cells and follicular helper T cells, and B cells, but not Th17 cells, indicating that many cellular phenotypes participate in the host response to Andes virus.ConclusionsThe ability to examine expression levels of nearly any gene from deer mice should allow direct comparison of infection with SNV or ANDV to determine the immunological pathways used for clearance of hantavirus infection in a reservoir host species.

Indirect Immunofluorescence Assay for the Simultaneous Detection of Antibodies against Clinically Important Old and New World Hantaviruses

In order to detect serum antibodies against clinically important Old and New World hantaviruses simultaneously, multiparametric indirect immunofluorescence assays (IFAs) based on biochip mosaics were developed. Each of the mosaic substrates consisted of cells infected with one of the virus types Hantaan (HTNV), Puumala (PUUV), Seoul (SEOV), Saaremaa (SAAV), Dobrava (DOBV), Sin Nombre (SNV) or Andes (ANDV). For assay evaluation, serum IgG and IgM antibodies were analyzed using 184 laboratory-confirmed hantavirus-positive sera collected at six diagnostic centers from patients actively or previously infected with the following hantavirus serotypes: PUUV (Finland, n=97); SEOV (China, n=5); DOBV (Romania, n=7); SNV (Canada, n=23); ANDV (Argentina and Chile, n=52). The control panel comprised 89 sera from healthy blood donors. According to the reference tests, all 184 patient samples were seropositive for hantavirus-specific IgG (n=177; 96%) and/or IgM (n=131; 72%), while all control samples were tested negative. In the multiparametric IFA applied in this study, 183 (99%) of the patient sera were IgG and 131 (71%) IgM positive (accordance with the reference tests: IgG, 96%; IgM, 93%). Overall IFA sensitivity for combined IgG and IgM analysis amounted to 100% for all serotypes, except for SNV (96%). Of the 89 control sera, 2 (2%) showed IgG reactivity against the HTNV substrate, but not against any other hantavirus. Due to the high cross-reactivity of hantaviral nucleocapsid proteins, endpoint titrations were conducted, allowing serotype determination in >90% of PUUV- and ANDV-infected patients. Thus, multiparametric IFA enables highly sensitive and specific serological diagnosis of hantavirus infections and can be used to differentiate PUUV and ANDV infection from infections with Murinae-borne hantaviruses (e.g. DOBV and SEOV).