Sin Nombre Viral RNA Load in Patients with the Hantavirus Cardiopulmonary Syndrome

To address the role of viral load in pathogenesis in patients with hantavirus cardiopulmonary syndrome (HCPS), we quantified Sin Nombre virus S segment viral RNA in plasma samples from 27 acutely-ill patients. For six patients we examined viral load in matched plasma, urine, and/or tracheal aspirate throughout the time when patients were in intensive care. Peak titers in plasma reached 1.8x106 copies/ml; none had viral RNA in urine. Titers in tracheal aspirates did not exceed 8x104/ml. We found a statistically significant association (P\u3c 0.005) between plasma viral RNA levels at admission and the severity of disease. Of those with plasma viral RNA titers above the threshold for assay sensitivity (5000 copies/ml), those with mild-moderate and severe disease had an average of 27,800 and 438,545 copies/ml, respectively. These results suggest that patients with high viral loads on admission are more likely to have severe disease

Inquérito sorológico para infecções por arbovírus em animais silvestres de áreas rurais do Estado de São Paulo, Brasil

A serosurvey was conducted in wild animals captured close to two areas where hantavirus cardiopulmonary syndrome (HCPS) occurred in São Paulo State, Brazil. Serum samples from a total of 43 mammals were tested for antibodies reactive with Sin Nombre (SN) hantavirus using a strip immunoblot assay. RNAs from the blood clots of the positive samples were submitted to reverse transcriptase-polymerase chain reaction (RT-PCR). Two rodents of the genus Oligoryzomys were positive for hantavirus antibodies. These animals were captured in the Iguape region and represented 16.7% (2/12) of the sera from rodents and 100.0% (2/2) of the Oligoryzomys captured in that area. RT-PCR failed to amplify any viral cDNA. These results are in agreement with other data that suggest that members of this genus are important reservoirs of hantaviruses in Brazil.Realizou-se inquérito sorológico em animais silvestres capturados em áreas próximas a duas regiões do Estado de São Paulo, Brasil, onde ocorreram casos de Síndrome Cardiopulmonar por Hantavírus (HCPS). Pesquisou-se a presença de anticorpos para o vírus Sin Nombre (SNV) em amostras de soro de 43 mamíferos, utilizando-se a técnica de Strip Immunoblot Assay (SIA). Empregou-se a técnica de reação em cadeia de polimerase - transcriptase reversa (RT-PCR) nos coágulos sangüíneos dos espécimes positivos. Dois roedores do gênero Oligoryzomys apresentaram anticorpos para hantavírus. Esses animais foram capturados na região de Iguape e representavam 16,7% (2/12) dos roedores e 100,0% dos Oligoryzomys capturados naquela área. O RT-PCR não detectou cDNA viral nas amostras. Os resultados estão de acordo com outros trabalhos que sugerem que membros desse gênero são importantes reservatórios de hantavírus no Brasil

Neutralizing Antibodies and Sin Nombre Virus RNA after Recovery from Hantavirus Cardiopulmonary Syndrome

Patients who later have a mild course of hantavirus cardiopulmonary syndrome (HCPS) are more likely to exhibit a high titer of neutralizing antibodies against Sin Nombre virus (SNV), the etiologic agent of HCPS, at the time of hospital admission. Because administering plasma from patients who have recovered from HCPS to those in the early stages of disease may be an advantageous form of passive immunotherapy, we examined the neutralizing antibody titers of 21 patients who had recovered from SNV infection. Even 1,000 days after admission to the hospital, 6 of 10 patients had titers of 800 or higher, with one sample retaining a titer of 3,200 after more than 1,400 days. None of the convalescent-phase serum samples contained detectable viral RNA. These results confirm that patients retain high titers of neutralizing antibodies long after recovery from SNV infection

Profiling helper T cell subset gene expression in deer mice

BACKGROUND: Deer mice (Peromyscus maniculatus) are the most common mammals in North America and are reservoirs for several zoonotic agents, including Sin Nombre virus (SNV), the principal etiologic agent of hantavirus cardiopulmonary syndrome (HCPS) in North America. Unlike human HCPS patients, SNV-infected deer mice show no overt pathological symptoms, despite the presence of virus in the lungs. A neutralizing IgG antibody response occurs, but the virus establishes a persistent infection. Limitations of detailed analysis of deer mouse immune responses to SNV are the lack of reagents and methods for evaluating such responses. RESULTS: We developed real-time PCR-based detection assays for several immune-related transcription factor and cytokine genes from deer mice that permit the profiling of CD4(+ )helper T cells, including markers of Th1 cells (T-bet, STAT4, IFNγ, TNF, LT), Th2 cells (GATA-3, STAT6, IL-4, IL-5) and regulatory T cells (Fox-p3, IL-10, TGFβ1). These assays compare the expression of in vitro antigen-stimulated and unstimulated T cells from individual deer mice. CONCLUSION: We developed molecular methods for profiling immune gene expression in deer mice, including a multiplexed real-time PCR assay for assessing expression of several cytokine and transcription factor genes. These assays should be useful for characterizing the immune responses of experimentally- and naturally-infected deer mice

Sin Nombre Virus Infection in Field Workers, Colorado, USA

We report 2 cases of Sin Nombre virus (SNV) infection in field workers, possibly contracted through rodent bites. Screening for antibodies to SNV in rodents trapped in 2 seasons showed that 9.77% were seropositive. Quantitative real-time PCR showed that 2 of 79 deer mice had detectable titers of SNV RNA

Hantavirus Prevalence in the IX Region of Chile

An epidemiologic and seroprevalence survey was conducted (n=830) to assess proportion of persons exposed to hantavirus in IX Region Chile, which accounts for 25% of reported cases of hantavirus cardiopulmonary syndrome. This region has three geographic areas with different disease incidences and a high proportion of aboriginals. Serum samples were tested for immunoglobulin (Ig) G antibodies by enzyme-linked immunosorbent assay against Sin Nombre virus N antigen by strip immunoblot assay against Sin Nombre, Puumala, Río Mamoré, and Seoul N antigens. Samples from six patients were positive for IgG antibodies reactive with Andes virus; all patients lived in the Andes Mountains. Foresting was also associated with seropositivity; but not sex, age, race, rodent exposure, or farming activities. Exposure to hantavirus varies in different communities of IX Region. Absence of history of pneumonia or hospital admission in persons with specific IgG antibodies suggests that infection is clinically inapparent

Incidence Rate for Hantavirus Infections without Pulmonary Syndrome, Panama

During 2001–2007, to determine incidence of all hantavirus infections, including those without pulmonary syndrome, in western Panama, we conducted 11 communitywide surveys. Among 1,129 persons, antibody prevalence was 16.5%–60.4%. Repeat surveys of 476 found that patients who seroconverted outnumbered patients with hantavirus pulmonary syndrome by 14 to 1

Tick-, mosquito-, and rodent-borne parasite sampling designs for the National Ecological Observatory Network

Parasites and pathogens are increasingly recognized as significant drivers of ecological and evolutionary change in natural ecosystems. Concurrently, transmission of infectious agents among human, livestock, and wildlife populations represents a growing threat to veterinary and human health. In light of these trends and the scarcity of long-term time series data on infection rates among vectors and reservoirs, the National Ecological Observatory Network (NEON) will collect measurements and samples of a suite of tick-, mosquito-, and rodent-borne parasites through a continental-scale surveillance program. Here, we describe the sampling designs for these efforts, highlighting sampling priorities, field and analytical methods, and the data as well as archived samples to be made available to the research community. Insights generated by this sampling will advance current understanding of and ability to predict changes in infection and disease dynamics in novel, interdisciplinary, and collaborative ways. (Résumé d'auteur

Tick-, Mosquito-, and Rodent-Borne Parasite Sampling Designs for the National Ecological Observatory Network [Special Feature: NEON Design]

Parasites and pathogens are increasingly recognized as significant drivers of ecological and evolutionary change in natural ecosystems. Concurrently, transmission of infectious agents among human, livestock, and wildlife populations represents a growing threat to veterinary and human health. In light of these trends and the scarcity of long-term time series data on infection rates among vectors and reservoirs, the National Ecological Observatory Network (NEON) will collect measurements and samples of a suite of tick-, mosquito-, and rodent-borne parasites through a continental-scale surveillance program. Here, we describe the sampling designs for these efforts, highlighting sampling priorities, field and analytical methods, and the data as well as archived samples to be made available to the research community. Insights generated by this sampling will advance current understanding of and ability to predict changes in infection and disease dynamics in novel, interdisciplinary, and collaborative ways