DETECTION OF HUMAN ANTI-ZIKA VIRUS IgG BY ELISA USING AN ANTIGEN FROM in vitro INFECTED VERO CELLS: PRELIMINARY RESULTS

Abstract

SUMMARYZika 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.

Natural versus Recombinant Viral Antigens in SARS-CoV-2 Serology: Challenges in Optimizing Laboratory Diagnosis of COVID-19

“…A novel and highly transmissible human coronavirus (SARS-CoV-2) was identified as being responsible for severe acute respiratory syndrome: Coronavirus disease 2019 (COVID- 19). The disease was declared by the World Health Organization as a pandemic, and several molecular and serological tools have been developed to identify ongoing viral infections and to evaluate immunity against SARS-CoV-2 (1)(2)(3)(4)6,7).…”

“…In the past, most serological tests for viral diseases such as measles ( 17 ) and rubella ( 18 ), have been performed using natural viral proteins from the infected cell cultures. Although the production of these antigens is laborious because of the need for cell culture and adequate biosafety conditions, the use of WVAs instead of recombinant proteins in serological tests, could result in a better diagnostic accuracy for viral infections ( 19 ). In the present study, we proposed to standardize an in-house ELISA based on comparison of the results of SARS-CoV-2 WVA and SARS-CoV-2 rNP ELISAs to assess whether the association of these different antigens could reduce variability in estimates and enhance the performance of ELISAs for the detection of anti-SARS-CoV-2 IgG in stratified groups of asymptomatic patients, and in individuals with mild or moderate symptoms.…”

Mapping Putative B-Cell Zika Virus NS1 Epitopes Provides Molecular Basis for Anti-NS1 Antibody Discrimination between Zika and Dengue Viruses

“… 8 − 11 At present, there are only a very few commercially available serology kits for ZIKV antibody detection; moreover, the specificity of these kits remains elusive, given the high cross-reactivity already reported among individuals who experienced consecutive flavivirus infections. 12 , 13 On the basis of this, PRNT remains the “gold standard” for antiflavivirus differentiation. 10 PRNT, however, is a high-cost technique that requires highly specialized laboratories and special regulations due to live virus manipulations.…”

Aedes Aegypti E Arboviroses No Brasil

“…Grande parte dos agentes causadores das infecções congênitas possui prevalência alta e baixa morbidade na população em geral, constituindo um problema de saúde quando uma mulher grávida apresenta infecção aguda. Sumita et al (2016), nesse trabalho, procuraram examinar IgG específica em amostras de soro de pacientes ou mães suspeitas para identificar infecção prévia e para testar a especificidade em relação às infecções flavivirais ocorrendo na mesma área. Esta técnica utilizada (ELISA) pode identificar IgG específica em indivíduos infectados pelo Zika vírus, o que pode vir a ser útil no diagnóstico de infecções congênitas após a depuração do RNA de vírus materno ou em estudos epidemiológicos.…”