The cyanobacterial saxitoxin exacerbates neural cell death and brain malformations induced by Zika virus

PLoS Negl Trop Dis. 2020 Mar 12;14(3):e0008060. doi: 10.1371/journal.pntd.0008060. eCollection 2020 Mar.

Abstract

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak took place in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the quantity of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Toxins / analysis
  • Bacterial Toxins / toxicity
  • Brain / pathology
  • Brazil / epidemiology
  • Cell Death / drug effects*
  • Cells, Cultured
  • Cyanobacteria Toxins
  • Disease Models, Animal
  • Disease Outbreaks
  • Female
  • Humans
  • Incidence
  • Marine Toxins / analysis
  • Marine Toxins / toxicity
  • Mice, Inbred C57BL
  • Microcephaly / pathology*
  • Microcystins / analysis
  • Microcystins / toxicity
  • Models, Theoretical
  • Neurotoxins / analysis
  • Neurotoxins / toxicity
  • Poisoning / complications*
  • Poisoning / pathology*
  • Saxitoxin / analysis
  • Saxitoxin / toxicity*
  • Water / chemistry
  • Zika Virus Infection / complications*
  • Zika Virus Infection / pathology*

Substances

  • Bacterial Toxins
  • Cyanobacteria Toxins
  • Marine Toxins
  • Microcystins
  • Neurotoxins
  • Water
  • Saxitoxin

Grants and funding

This work was funded by Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (E-26/201.340/2016), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (88887.116625/2016-01 and 440909/2016-3), Conselho Nacional de Desenvolvimento Científico e Tecnológico (440909/2016-3 and 441096/2016-6), Banco Nacional de Desenvolvimento Econômico e Social (10.2.0051.1), Financiadora de Estudos e Projetos (01.08.0657.00 and 01.12.0161.00) and Departamento de Vigilância em Saúde Ambiental e Saúde do Trabalhador – DSAST (25380.001612/2017-70). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.