St. Louis encephalitis vírus: first isolation from a human in São Paulo state, Brasil Vírus da encefalite São Luis: primeiro isolamento de humano no Estado de São Paulo, Brasil

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Iray M. Rocco, Cecília L.S. Santos, Ivani Bisordi, Selma M.C.N. Petrella, Luiz E. Pereira, Renato P. Souza, Terezinha L.M. Coimbra, Thirsa A.F. Bessa, Fabiola M. Oshiro, Luciana B.Q. Lima, Matheus P. Cerroni, Antonia T. Marti, Vera M. Barbosa, Gizelda Katz, Akemi Suzuki
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP) 2005
• Subjects: Saint Louis encephalitis; Flavivirus; Virus isolation; RT/PCR; Genomic sequencing; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Aguda; Arctic; St. Louis
• Online Access: https://doi.org/10.1590/S0036-46652005000500008; https://doaj.org/article/56846f0c120b4e499c30ff49bd658615

This paper reports the isolation of St. Louis encephalitis virus (SLEV) from a febrile human case suspected to be dengue, in São Pedro, São Paulo State. A MAC-ELISA done on the patient's acute and convalescent sera was inconclusive and hemagglutination inhibition test detected IgG antibody for flaviviruses. An indirect immunofluorescent assay done on the C6/36 cell culture inoculated with the acute serum was positive for flaviviruses but negative when tested with dengue monoclonal antibodies. RNA extracted from the infected cell culture supernatant was amplified by RT-PCR in the presence of NS5 universal flavivirus primers and directly sequenced. Results of BLAST search indicated that this sequence shares 93% nucleotide similarity with the sequence of SLEV (strain-MSI.7), confirmed by RT-PCR performed with SLEV specific primers. Since SLEV was identified as the cause of human disease, it is necessary to improve surveillance in order to achieve early detection of this agent in the state of São Paulo and in Brazil. This finding is also an alert to health professionals about the need for more complete clinical and epidemiological investigations of febrile illnesses as in the reported case. SLEV infections can be unrecognized or confused with other ones caused by an arbovirus, such as dengue. O presente estudo relata o isolamento do vírus da encefalite São Luis (SLEV) de um caso febril humano suspeito de dengue, em São Pedro, Estado de São Paulo. MAC-ELISA realizado com soros das fases aguda e convalescente foi inconclusivo e anticorpos IgG foram detectados por inibição da hemaglutinação para flavivirus. Imunofluorescência indireta com cultura de células C6/36 inoculadas com soro da fase aguda foi positivo para flavivirus mas negativo quando testado com anticorpos monoclonais para dengue. O RNA extraído de cultura de células infectadas foi amplificado na presença de primers universais para o gênero Flavivirus, deduzidos de uma região da proteína não estrutural 5 e diretamente sequenciado. Os resultados da pesquisa ...