title: DETECTION OF HUMAN ANTI-ZIKA VIRUS IgG BY ELISA USING AN ANTIGEN FROM in vitro INFECTED VERO CELLS: PRELIMINARY RESULTS.
abstract: Zika virus (ZKV) infection is a huge public health problem in Brazil because of the increased incidence of microcephaly in neonates from infected mothers. Detection of specific IgG antibodies in maternal serum samples constitutes an important approach for diagnosing ZKV infection and evaluating its relationship with neonatal microcephaly. However, as there is no serological test produced in Brazil to detect IgM and IgG antibodies against ZKV, we sought to examine specific IgG in serum samples from patients or suspected mothers to detect previous infection and to test for specificity with regard to flaviviral infections occurring in the same area. Brazilian Zika virus native antigens were obtained from infected Vero cell layers or free virions in the culture medium and then used in ELISA. We tested sera from eight ZKV RNA-diagnosed infected patients (ZKVR), seven neonates with microcephaly and their mothers after delivery (MM), 140 dengue virus IgM-positive (DM) and IgG (DG)-positive patients, and 100 yellow fever (YF)-vaccinated patients. According to the ELISA, ZKVR samples were mostly positive (7/8), and all the MM serum samples were positive for ZKV IgG (7/7). In contrast, cross-reactions for dengue or yellow fever-vaccinated patients were observed, including DM (48/95), DG (10/45) or YF (3/100) serum samples; however, these cross-reactions exhibited low antigen avidity so that 6 M urea largely removed this cross-reactivity, with only a few cross-reacting samples remaining (8/140). ELISA based on extracted virions was much more specific, with all ZKVR (8/8) and MM sera being positive for ZKV IgG (7/7) and only borderline cross-reactivity found for DM (6/95), DG (3/45) or YF (4/100)-vaccinated serum samples. This technique (ELISA) can identify specific IgG in ZKV-infected patients and may be helpful in diagnosing congenital infetions after maternal RNA virus clearance or in epidemiological studies.
authors.affiliation: Universidade de São Paulo, Instituto de Medicina Tropical de São Paulo, Laboratório de Virologia, São Paulo, SP, Brasil.
authors.forename: Laura Masami
authors.initials: LM
authors.lastname: Sumita
authors.affiliation: Universidade de São Paulo, Instituto de Medicina Tropical de São Paulo, Laboratório de Protozoologia, São Paulo, SP, Brasil.
authors.forename: Jaqueline Polizeli
authors.initials: JP
authors.lastname: Rodrigues
authors.affiliation: Universidade de São Paulo, Instituto de Medicina Tropical de São Paulo, Laboratório de Virologia, São Paulo, SP, Brasil.
authors.forename: Noely Evangelista
authors.initials: NE
authors.lastname: Ferreira
authors.affiliation: Universidade de São Paulo, Instituto de Medicina Tropical de São Paulo, Laboratório de Virologia, São Paulo, SP, Brasil.
authors.forename: Alvina Clara
authors.initials: AC
authors.lastname: Felix
authors.affiliation: Universidade de São Paulo, Instituto de Medicina Tropical de São Paulo, Laboratório de Virologia, São Paulo, SP, Brasil.
authors.forename: Nathalia Caroline Santiago
authors.initials: NC
authors.lastname: Souza
authors.affiliation: Universidade de São Paulo, Instituto de Medicina Tropical de São Paulo, Laboratório de Virologia, São Paulo, SP, Brasil.
authors.forename: Clarisse Martins
authors.initials: CM
authors.lastname: Machado
authors.affiliation: Universidade de São Paulo, Instituto de Medicina Tropical de São Paulo, Laboratório de Protozoologia, São Paulo, SP, Brasil.
authors.forename: Heitor Franco de Andrade
authors.initials: HF
authors.lastname: Júnior
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood* / Q000276:immunology; D000918:Antibody Specificity; D000956:Antigens, Viral / Q000276:immunology*; D002522:Chlorocebus aethiops; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D014709:Vero Cells; D000071244:Zika Virus / Q000276:immunology* / Q000648:ultrastructure; D000071243:Zika Virus Infection / Q000175:diagnosis*
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D000939:Epitopes; D007074:Immunoglobulin G; D007075:Immunoglobulin M