13 research outputs found
Genomic characterization and seroprevalence studies on alphaviruses in Uruguay
Alphaviruses (Togaviridae) are arboviruses frequently associated with emerging infectious diseases. In this study, we aimed to investigate the presence of alphaviruses in Uruguay by detecting the viral genome in mosquitoes and neutralizing antibodies in equines. A total of 3,575 mosquitoes were analyzed for alphavirus genome detection. Serologic studies were performed on 425 horse sera by plaque reduction neutralization test (PRNT80) against Venezuelan equine encephalitis virus (VEEV) subtype IAB, Pixuna virus (PIXV), Rio Negro virus (RNV), western equine encephalitis virus (WEEV), and Madariaga virus (MADV). Mosquitoes belonging to six genera were captured and 82.9% were identified as Culex pipiens. Two Cx. pipiens pools collected in Fray Bentos and Las Toscas localities were alphavirus positive, and phylogenetic analyses showed that the sequences grouped into two different clusters: the lineage I of eastern equine encephalitis virus and RNV (VEEV complex), respectively. Plaque reduction neutralization test assays showed antibodies against strains of the VEEV complex, MADV, and WEEV. Rio Negro virus was the most geographically widespread virus, showing higher seroprevalences (up to 20%). Seroprevalences against VEEV IAB ranged between 4.6% and 13%; antibodies against PIXV, WEEV, and MADV were less frequent (3–4%). In conclusion, RNV exhibited the highest seroprevalence in horses, a wide geographical distribution, and viral genome was detected in Cx. pipiens mosquitoes. Madariaga virus had a low seroprevalence in equines, but an epizootic lineage typical of North America was detected in Cx. pipiens mosquitoes. Taken together, our results show that alphaviruses are present in Uruguay with variable occurrence and geographical distribution being a potential threat for human and equine health
Rapid, Specific Detection of Alphaviruses from Tissue Cultures Using a Replicon-Defective Reporter Gene Assay
We established a rapid, specific technique for detecting alphaviruses using a replicon-defective reporter gene assay derived from the Sindbis virus XJ-160. The pVaXJ expression vector containing the XJ-160 genome was engineered to form the expression vectors pVaXJ-EGFP expressing enhanced green fluorescence protein (EGFP) or pVaXJ-GLuc expressing Gaussia luciferase (GLuc). The replicon-defective reporter plasmids pVaXJ-EGFPΔnsp4 and pVaXJ-GLucΔnsp4 were constructed by deleting 1139 bp in the non-structural protein 4 (nsP4) gene. The deletion in the nsP4 gene prevented the defective replicons from replicating and expressing reporter genes in transfected BHK-21 cells. However, when these transfected cells were infected with an alphavirus, the non-structural proteins expressed by the alphavirus could act on the defective replicons in trans and induce the expression of the reporter genes. The replicon-defective plasmids were used to visualize the presence of alphavirus qualitatively or detect it quantitatively. Specificity tests showed that this assay could detect a variety of alphaviruses from tissue cultures, while other RNA viruses, such as Japanese encephalitis virus and Tahyna virus, gave negative results with this system. Sensitivity tests showed that the limit of detection (LOD) of this replicon-defective assay is between 1 and 10 PFU for Sindbis viruses. These results indicate that, with the help of the replicon-defective alphavirus detection technique, we can specifically, sensitively, and rapidly detect alphaviruses in tissue cultures. The detection technique constructed here may be well suited for use in clinical examination and epidemiological surveillance, as well as for rapid screening of potential viral biological warfare agents
Viral etiology of acute respiratory infections among children in Porto Alegre, RS, Brazil Etiologia viral das infecções respiratórias agudas em Porto Alegre, RS, Brasil
Although acute respiratory infections (ARIs) are a major cause of child morbidity and mortality in Southern Brazil, little information is available on their seasonality and viral etiology. This study was conducted on children under 5 years of age with ARI to assess viral etiology in the State of Rio Grande do Sul, from 1990 to 1992. A total of 862 nasopharyngeal secretion (NPS) samples were tested using indirect immunofluorescence. The results showed that 316 (36.6%) NPS samples were positive: 26.2% for RSV, 6% for adenovirus, 1.7% for influenzaviruses, 1.5% for parainfluenzaviruses, and 1.2% for mixed infection. The mean viral prevalence rates in out-patient services, emergency wards, and in-patient hospital wards were 26.7%, 53% and 42.3%, respectively. Respiratory syncytial virus (RSV) and adenovirus accounted for 91.4 % of the viral diagnoses. RSV was more frequent in children under one year of age at the three levels of health care and was prevalent in infants under six months. Adenovirus was the most prevalent pathogen in hospitalized children, in 1992. Influenza A virus showed an increased prevalence with age among out-patient children. This study shows the annual occurence of viral respiratory infections in the coldest months, with a significant annual variation in the frequency of RSV infection.<br>Embora as IRAs sejam importante causa de morbidade e mortalidade infantil no sul do Brasil, poucas e esparsas informações sĂŁo disponĂveis sobre sazonalidade e etiologia viral. Este estudo foi realizado em crianças menores de 5 anos de idade com IRAs para avaliar a importância da etiologia viral no Rio Grande do Sul, no perĂodo de 1990 a 1992. Foram processadas 862 secreções de nasofaringe, por imunofluorescĂŞncia indireta. Os resultados mostraram que 316 (36,6%) amostras foram positivas: 26,2% para vĂrus respiratĂłrio sincicial (VRS), 6% para adenovĂrus, 1,7% para vĂrus influenza, 1,5% para vĂrus parainfluenza e 1,2% para infecção mista. As mĂ©dias das prevalĂŞncias virais nos serviços de ambulatĂłrio, emergĂŞncia e hospitalizados foram de 26,7%, 53% e 42,3%, respectivamente. VRS e adenovĂrus foram responsáveis por 91,4% dos diagnĂłsticos virolĂłgicos positivos. O VRS foi mais freqĂĽente em menores de 1 ano, nos trĂŞs nĂveis de atenção Ă saĂşde, sendo mais prevalente em menores de 6 meses. O adenovĂrus foi o patĂłgeno mais prevalente em crianças hospitalizadas em 1992. O vĂrus influenza A mostrou uma tendĂŞncia de acrĂ©scimo da positividade com o aumento da idade nas crianças de ambulatĂłrio. Este estudo mostrou a ocorrĂŞncia anual de infecções respiratĂłrias virais nos meses frios, com variação anual significativa na freqĂĽĂŞncia da infecção por VRS
Impact of human metapneumovirus infection on in and outpatients for the years 2006-2008 in Southern Brazil
The human metapneumovirus (hMPV), member of the Paramyxoviridae family, has been reported as an important agent involved with acute respiratory infections (ARIs). The aim of this study is to identify hMPV as the etiological agent of ARIs on in and outpatients in the city of Curitiba, Southern Brazil, and describe clinical data of hMPV subtyping. A retrospective study was performed in 1,572 respiratory samples over a period of three years. hMPV was detected by reverse transcription-polymerase chain reaction and subtyping was performed by nucleotide sequencing. hMPV was present in 61 (3.9%) samples and subtypes A1, A2a, B1 and B2 were detected. The incidence of hMPV was higher in outpatients (5.9%), whose mean age was 19.7 years (range 6 months-75 years old), than in inpatients (3%), whose mean age was 7.6 months (range 1 month-26 years old). The outpatients had upper respiratory tract infections with flu-like symptoms and all hospitalized children had lower respiratory tract infections. A pediatric patient died from complications associated with hMPV A2a infection. hMPV has been reported as a respiratory pathogen in all age groups. No correlation was observed between viral subtype and disease severity in the samples of this study
Arbovirus researchers unite: expanding genomic surveillance for an urgent global need
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