title: Results of a Zika Virus (ZIKV) Immunoglobulin M-Specific Diagnostic Assay Are Highly Correlated With Detection of Neutralizing Anti-ZIKV Antibodies in Neonates With Congenital Disease.
abstract: BACKGROUND
  Usually, immunoglobulin M (IgM) serologic analysis is not sufficiently specific to confirm Zika virus (ZIKV) infection. However, since IgM does not cross the placenta, it may be a good marker of infection in neonates.
  
  
  METHODS
  We tested blood from 42 mothers and neonates with microcephaly and collected cerebrospinal fluid (CSF) specimens from 30 neonates. Molecular assays were performed for detection of ZIKV, dengue virus, and chikungunya virus; IgM enzyme-linked immunosorbent assays and plaque-reduction neutralization tests (PRNTs) were performed to detect ZIKV and dengue virus. No control neonates without microcephaly were evaluated.
  
  
  RESULTS
  Among neonates, all 42 tested positive for ZIKV IgM: 38 of 42 serum specimens (90.5%) were positive, whereas 30 of 30 CSF specimens (100%) were positive. ZIKV IgM-specific ELISA ratios, calculated as the mean optical density (OD) of the test sample when reacted on viral antigen divided by the mean OD of the negative control when reacted with viral antigen, were higher in CSF specimens (median, 14.9 [range, 9.3-16.4]) than in serum (median, 8.9 [range, 2.1-20.6]; P = .0003). All ZIKV IgM-positive results among the neonates were confirmed by the detection of neutralizing antibodies. Mother/neonate pairs with primary ZIKV infection had neutralizing antibodies to ZIKV only, and mother/neonate pairs with ZIKV virus infection secondary to infection with another flavivirus had high titers of neutralizing antibodies to ZIKV. Among secondary infections, median titers in serum were 2072 (range, 232-12 980) for mothers and 2730 (range, 398-12 980) for neonates (P < .0001), and the median titer in CSF was 93 (range, 40-578) among neonates (P < .0001).
  
  
  CONCLUSIONS
  Among neonates, detection of ZIKV IgM in serum is confirmatory of congenital ZIKV infection, and detection of ZIKV IgM in CSF is confirmatory of neurologic infection. Therefore, we recommend testing for ZIKV IgM in neonates suspected of having congenital ZIKV infection and performance of PRNTs in equivocal cases.
authors.affiliation: Department of Virology, Aggeu Magalhães Research Center, Fundação Oswaldo Cruz.
authors.forename: Marli T
authors.initials: MT
authors.lastname: Cordeiro
authors.affiliation: Department of Clinical Medicine, Federal University of Pernambuco.
authors.forename: Carlos A A
authors.initials: CA
authors.lastname: Brito
authors.affiliation: Department of Virology, Aggeu Magalhães Research Center, Fundação Oswaldo Cruz.
authors.forename: Lindomar J
authors.initials: LJ
authors.lastname: Pena
authors.affiliation: Department of Virology, Aggeu Magalhães Research Center, Fundação Oswaldo Cruz.
authors.forename: Priscila M S
authors.initials: PM
authors.lastname: Castanha
authors.affiliation: Department of Virology, Aggeu Magalhães Research Center, Fundação Oswaldo Cruz.
authors.forename: Laura H V G
authors.initials: LH
authors.lastname: Gil
authors.affiliation: Department of Virology, Aggeu Magalhães Research Center, Fundação Oswaldo Cruz.
authors.forename: Kennya G S
authors.initials: KG
authors.lastname: Lopes
authors.affiliation: Department of Virology, Aggeu Magalhães Research Center, Fundação Oswaldo Cruz.
authors.forename: Rafael
authors.initials: R
authors.lastname: Dhalia
authors.affiliation: Department of Pediatrics, Instituto de Medicina Integral Professor Fernando Figueira.
authors.forename: Jucille A
authors.initials: JA
authors.lastname: Meneses
authors.affiliation: Department of Pediatrics, Instituto de Medicina Integral Professor Fernando Figueira.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Ishigami
authors.affiliation: Department of Pediatrics, Instituto de Medicina Integral Professor Fernando Figueira.
authors.forename: Luisa M
authors.initials: LM
authors.lastname: Mello
authors.affiliation: Central Public Health Laboratory, Secretaria de Saúde do Estado de Pernambuco, Recife, Brazil.
authors.forename: Liciana X E
authors.initials: LX
authors.lastname: Alencar
authors.affiliation: Central Public Health Laboratory, Secretaria de Saúde do Estado de Pernambuco, Recife, Brazil.
authors.forename: Klarissa M
authors.initials: KM
authors.lastname: Guarines
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, United Kingdom.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rodrigues
authors.affiliation: Department of Virology, Aggeu Magalhães Research Center, Fundação Oswaldo Cruz.|Center for Vaccine Research.|Department of Infectious Disease and Microbiology, University of Pittsburgh, Pennsylvania.
authors.forename: Ernesto T A
authors.initials: ET
authors.lastname: Marques
mesh_terms: D000293:Adolescent; D000328:Adult; D057134:Antibodies, Neutralizing / Q000097:blood* / Q000134:cerebrospinal fluid*; D000914:Antibodies, Viral / Q000097:blood* / Q000134:cerebrospinal fluid*; D001769:Blood / Q000276:immunology; D002555:Cerebrospinal Fluid / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood*; D007231:Infant, Newborn; D008297:Male; D009500:Neutralization Tests; D012680:Sensitivity and Specificity; D010948:Viral Plaque Assay; D055815:Young Adult; D000071244:Zika Virus / Q000276:immunology*; D000071243:Zika Virus Infection / Q000151:congenital / Q000175:diagnosis*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D007075:Immunoglobulin M
keywords: ZIKV antibodies; Zika virus; anti-ZIKV IgM; congenital Zika; microcephaly