St. Louis encephalitis vírus: first isolation from a human in São Paulo state, Brasil

Revista do Instituto de Medicina Tropical de São Paulo

Iray M. Rocco²  Cecília L.s. Santos²  Ivani Bisordi²  Selma M.c.n. Petrella²  Luiz E. Pereira²  Renato P. Souza²  Terezinha L.m. Coimbra²  Thirsa A.f. Bessa¹  Fabiola M. Oshiro²  Luciana B.q. Lima²  Matheus P. Cerroni²  Antonia T. Marti²  Vera M. Barbosa²  Gizelda Katz¹  Akemi Suzuki² 

[1] ,Instituto Adolfo LutzSão Paulo SP ,Brasil

关键词: Saint Louis encephalitis;    Flavivirus;    Virus isolation;    RT/PCR;    Genomic sequencing;   

DOI  :  10.1590/S0036-46652005000500008

来源: SciELO

【 摘 要 】

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.

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