Hantavirus infection prevalence in wild rodents and human anti-hantavirus serological profiles from different geographic areas of South Brazil.

Paraná state presents the fourth highest number of accumulated cases of hantavirus pulmonary syndrome in Brazil. To map the risk areas for hantavirus transmission we carried out a study based on rodent trapping and determined the anti-hantavirus seroprevalence in these animals and in the inhabitants of these localities. Overall seroprevalence in rodents and humans were 2.5% and 2.4%, respectively. Eighty-two percent of the seropositive rodents were genetically analyzed. Phylogenetic analyses revealed that hantaviruses from rodent samples cluster with Araucária (Juquitiba-like) or Jaborá hantavirus genotypes. The Jaborá strain was identified in Akodon serrensis and Akodon montensis, whereas the Araucária strain was detected in Oligoryzomys nigripes, Oxymycterus judex, A. montensis, and Akodon paranaensis, with the latter species being identified for the first time as a natural host. These findings expose the complex relationships between virus and reservoirs in Brazil, which could have an impact on hantavirus transmission dynamics in nature and human epidemiology.

Laboratory diagnosis, epidemiology, and clinical outcomes of pandemic influenza A and community respiratory viral infections in southern Brazil.

Community respiratory viruses (CRVs) are commonly associated with seasonal infections. They have been associated with higher morbidity and mortality among children, elderly individuals, and immunosuppressed patients. In April 2009, the circulation of a new influenza A virus (FLUA H1N1v) was responsible for the first influenza pandemic of this century. We report the clinical and epidemiological profiles of inpatients infected with CRVs or with FLUA H1N1v at a tertiary care hospital in southern Brazil. In addition, we used these profiles to evaluate survivor and nonsurvivor patients infected with FLUA H1N1v. Multiplex reverse transcription-PCR (RT-PCR) and real time RT-PCR were used to detect viruses in inpatients with respiratory infections. Record data from all patients were reviewed. A total of 171 patients were examined over a period of 16 weeks. Of these, 39% were positive for FLUA H1N1v, 36% were positive for CRVs, and 25% were negative. For the FLUA H1N1v- and CRV-infected patients, epidemiological data regarding median age (30 and 1.5 years), myalgia (44% and 13%), need for mechanical ventilation (44% and 9%), and mortality (35% and 9%) were statistically different. In a multivariate analysis comparing survivor and nonsurvivor patients infected with influenza A virus H1N1, median age and creatine phosphokinase levels were significantly associated with a severe outcome. Seasonal respiratory infections are a continuing concern. Our results highlight the importance of studies on the prevalence and severity of these infections and that investments in programs of clinical and laboratory monitoring are essential to detect the appearance of new infective agents.

Production and characterization of monoclonal antibodies against the recombinant nucleoprotein of Araucaria hantavirus.

Hantaviruses are rodent-borne RNA viruses that cause hemorrhagic fever with renal syndrome (HFRS) or hantavirus pulmonary syndrome (HPS). From the first detection of infection in Brazil in 1993 until 2009, 1161 cases of HPS have been reported, with mortality rates of around approximately 40%. Currently, due to the absence of a vaccine or specific antiviral therapy, the only way to reduce mortality by hantavirus infection is a fast and precise diagnosis that allows for supportive clinical health care. To improve the detection of hantavirus infection, we developed monoclonal antibodies (Mabs) against the nucleoprotein (rNDelta85) of the Araucaria hantavirus strain (ARAUV). The specificity of generated Mabs for rNDelta85 was demonstrated by western blot, indirect immunofluorescence and immunohistochemistry. These are the first monoclonal antibodies to be produced and characterized against the South American hantavirus strain, and may be of special interest in the development of diagnostic assays and epidemiological studies.

Phylogenetic characterization of hantaviruses from wild rodents and hantavirus pulmonary syndrome cases in the state of Parana (southern Brazil).

Over 1,100 cases of hantavirus pulmonary syndrome (HPS) have occurred in Brazil since 1993, but little is known about Brazilian hantaviruses, and many of their rodent hosts remain unknown. The Araucaria hantavirus (ARAUV) was described recently from HPS patients from Paraná, in southern Brazil, but its host could not be identified. In this study, rodents were captured from regions with high HPS prevalence to address this issue. ARAUV RNA was detected in three distantly related rodent species: Oligoryzomys nigripes, Oxymycterus judex and Akodon montensis. Furthermore, a specimen of A. montensis was infected with a Jaborá-like virus, implying that A. montensis can be infected by at least two different hantaviruses. The presence of the same hantavirus strain in three different rodent species and the co-circulation of two different strains in the same rodent species highlight the potential for genomic reassortment, which could have an impact on hantavirus transmission dynamics in nature and on human epidemiology.

Evidence for the co-circulation of dengue virus type 3 genotypes III and V in the Northern region of Brazil during the 2002-2004 epidemics.

The reintroduction of dengue virus type 3 (DENV-3) in Brazil in 2000 and its subsequent spread throughout the country was associated with genotype III viruses, the only DENV-3 genotype isolated in Brazil prior to 2002. We report here the co-circulation of two different DENV-3 genotypes in patients living in the Northern region of Brazil during the 2002-2004 epidemics. Complete genomic sequences of viral RNA were determined from these epidemics, and viruses belonging to genotypes V (Southeast Asia/South Pacific) and III were identified. This recent co-circulation of different DENV-3 genotypes in South America may have implications for pathological and epidemiological dynamics.

Evidence for the co-circulation of dengue virus type 3 genotypes III and V in the Northern region of Brazil during the 2002-2004 epidemics

The reintroduction of dengue virus type 3 (DENV-3) in Brazil in 2000 and its subsequent spread throughout the country was associated with genotype III viruses, the only DENV-3 genotype isolated in Brazil prior to 2002. We report here the co-circulation of two different DENV-3 genotypes in patients living in the Northern region of Brazil during the 2002-2004 epidemics. Complete genomic sequences of viral RNA were determined from these epidemics, and viruses belonging to genotypes V (Southeast Asia/South Pacific) and III were identified. This recent co-circulation of different DENV-3 genotypes in South America may have implications for pathological and epidemiological dynamics.

Expression profile of interferon stimulated genes in central nervous system of mice infected with dengue virus Type-1.

Dengue virus (DENV) infection can cause a self-limiting disease (dengue fever) or a more severe clinical presentation known as dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). Furthermore, data from recent dengue epidemics in Brazil indicate that the neurological manifestations are becoming more prevalent. However, the neuropathogenesis of dengue are not well understood. The balance between viral replication efficiency and innate immunity--in opposition during the early stages of infection--determines the clinical outcome of DENV infection. In this study, we investigated the effects of DENV infection on the transcription profile of the central nervous system (CNS) of mice. We observed in infected mice the up-regulation of 151 genes possibly involved in neuropathogenesis of dengue. Conversely, they may have a protective effect. Ingenuity Systems software analysis demonstrated, that the main pathways modulated by DENV infection in the mouse CNS are involved in interferon signaling and antigen presentation.

Dengue neurovirulence in mice: identification of molecular signatures in the E and NS3 helicase domains.

Recent observations indicate that the clinical profile of dengue virus (DENV) infection is changing, and that neurological manifestations are becoming frequent. The neuro pathogenesis of dengue, and the contribution of viral and host factors to the disease are not well understood. To define the amino acid substitutions in DENV potentially implicated in the acquisition of a neurovirulent phenotype we used a murine model to characterize two neuroadapted strains of DENV-1, FGA/NA a5c (previously obtained), and FGA/NA P6 (recently obtained). Only three amino acid substitutions were identified in the neurovirulent strains, mapping to the E and NS3 helicase domains. These mutations enhanced the ability of neuroadapted viral strains to replicate in the CNS of infected mice, causing extensive damage with leptomeningitis and encephalitis.