Expression of recombinant Araraquara Hantavirus nucleoprotein in insect cells and its use as an antigen for immunodetection compared to the same antigen expressed in Escherichia coli

<p>Abstract</p> <p>Background</p> <p>Antigens for Hantavirus serological tests have been produced using DNA recombinant technology for more than twenty years. Several different strategies have been used for that purpose. All of them avoid the risks and difficulties involved in multiplying Hantavirus in the laboratory. In Brazil, the Araraquara virus is one of the main causes of Hantavirus Cardio-Pulmonary Syndrome (HCPS).</p> <p>Methods</p> <p>In this investigation, we report the expression of the N protein of the Araraquara Hantavirus in a Baculovirus Expression System, the use of this protein in IgM and IgG ELISA and comparison with the same antigen generated in <it>E. coli</it>.</p> <p>Results</p> <p>The protein obtained, and purified in a nickel column, was effectively recognized by antibodies from confirmed HCPS patients. Comparison of the baculovirus generated antigen with the N protein produced in <it>E. coli </it>showed that both were equally effective in terms of sensitivity and specificity.</p> <p>Conclusions</p> <p>Our results therefore indicate that either of these proteins can be used in serological tests in Brazil.</p

Neutralising antibodies for West Nile virus in horses from Brazilian Pantanal

Despite evidence of West Nile virus (WNV) activity in Colombia, Venezuela and Argentina, this virus has not been reported in most South American countries. In February 2009, we commenced an investigation for WNV in mosquitoes, horses and caimans from the Pantanal, Central-West Brazil. The sera of 168 horses and 30 caimans were initially tested using a flaviviruses-specific epitope-blocking enzyme-linked immunosorbent assay (blocking ELISA) for the detection of flavivirus-reactive antibodies. The seropositive samples were further tested using a plaque-reduction neutralisation test (PRNT90) for WNV and its most closely-related flaviviruses that circulate in Brazil to confirm the detection of specific virus-neutralising antibodies. Of the 93 (55.4%) blocking ELISA-seropositive horse serum samples, five (3%) were seropositive for WNV, nine (5.4%) were seropositive for St. Louis encephalitis virus, 18 (10.7%) were seropositive for Ilheus virus, three (1.8%) were seropositive for Cacipacore virus and none were seropositive for Rocio virus using PRNT90, with a criteria of > four-fold antibody titre difference. All caimans were negative for flaviviruses-specific antibodies using the blocking ELISA. No virus genome was detected from caiman blood or mosquito samples. The present study is the first report of confirmed serological evidence of WNV activity in Brazil

Inquérito soroepidemiológico para pesquisa de infecções por arbovírus em moradores de reserva ecológica Serological survey on arbovirus infection in residents of ecological reserve

OBJETIVO: Inquéritos sorológicos têm evidenciado ampla circulação de arbovírus causadores de doença humana na Região do Vale do Ribeira, São Paulo, Brasil. Com o propósito de estabelecer a prevalência de infecções por esses agentes em reserva ecológica, localizada naquela área, pesquisou-se a presença de anticorpos, bem como suas possíveis associações com características individuais e familiares dos investigados. MÉTODOS: Pesquisaram-se anticorpos para os antígenos dos vírus Rocio (ROC), Ilhéus (ILH), encefalite de St. Louis (SLE), encefalites eqüinas do leste (EEE), oeste (WEE) e venezuelana (VEE), em 182 pessoas pertencentes a 58 famílias residentes na Estação Ecológica de Juréia-Itatins, utilizando-se testes de inibição de hemaglutinação e neutralização com redução de placas. Usou-se Mac-Elisa para pesquisar anticorpos IgM para os vírus ROC, ILH e EEE. RESULTADOS: Foi observada a presença de anticorpos para todos os arbovírus testados, com exceção do vírus WEE. A prevalência total de anticorpos foi 26,9% (21,4% para alfavírus e 12,6% para flavivírus). Não foram encontrados anticorpos IgM. Entre as várias características pesquisadas dos indivíduos e de suas famílias, a idade, a ocupação, a naturalidade e o hábito de entrar na mata mostraram-se estatisticamente associados a infecções por arbovírus (p<0,05). CONCLUSÕES: Existe intensa circulação de arbovírus patogênicos, especialmente do alfavírus VEE, na população estudada. Aparentemente, a principal forma de exposição a vetores de arbovírus nessa população é o hábito de entrar na mata. Sugerem-se outras investigações sobre a responsabilidade de aves atuando como amplificadores de vírus dentro dos domicílios.<br>OBJECTIVE: Serological inquires conducted in the Ribeira Valley, S. Paulo State, Brazil, showed an intense circulation of pathogenic arboviruses in the region. The goal was to verify the prevalence of arboviral infections in people living at the local ecological, and its potential association with these population' individual and familiar characteristics. METHODS: The study was carried out among 182 persons of 58 families to identify the presence of antibodies to the following viruses: Rocio (ROC), Ilheus (ILH), Eastern equine encephalitis virus (EEE), Western equine encephalitis virus (WEE), Venezuelan equine encephalitis virus (VEE) and St. Louis encephalitis virus (SLE). Inhibition hemagglutination test and plaque reduction neutralization test were the laboratory assays of choice. MAC-ELISA was used to identify IgM antibodies to ROC, ILH and EEE viruses. RESULTS: The prevalence of antibodies was 26.9% (21.4% to alphavirus and 12.6% to flavivirus). There were no antibodies to WEE virus. IgM antibodies were not observed suggesting no recent infection in study population. Among the characteristics investigated, age, occupation, place of birth and the habit of going into the forest were shown to be statistically associated with arboviral infection (p<0.05). CONCLUSIONS: It was observed an intense circulation of pathogenic arboviruses, especially VEE. It seems the habit of going into the forest is the most important factor to this population exposure to the mosquito vectors of arboviruses. The results suggest the need of further investigation to clarify the role of birds as arbovirus infection amplificators indoors