#33: Single-cell RNA sequencing analysis of Zika virus infection in human stem cell-derived neuroprogenitor cells and cerebral organoids

Abstract

Abstract Background The molecular mechanisms underpinning the neurologic and congenital pathologies caused by Zika virus (ZIKV) infection remain poorly understood. It is also unclear why congenital ZIKV disease was not reported prior to the recent epidemics in French Polynesia and the Americas, despite evidence that Zika virus has actively circulated in parts of Africa and Asia since 1947 and 1966, respectively. Methods Due to advances in the stem cell-based technologies, we can now model ZIKV infections of the central nervous system in human stem cell-derived neural progenitor cells and cerebral organoids, which recapitulate complex 3-dimensional neural architecture. We apply Seq-Well — a simple, portable platform for massively parallel single-cell RNA sequencing — to characterize these neural models infected with ZIKV. We detect and quantify host mRNA transcripts and viral RNA with single-cell resolution, thereby defining transcriptional features of both uninfected and infected cells. Results Although flavivirus RNAs lack a poly(A) tail, we present evidence that viral RNAs are specifically primed for reverse transcription at internal runs of adenosines, and that sequencing reads cover the entire non-polyadenylated viral genome. In neural progenitor cells, single cell sequencing reveals that while uninfected bystander cells strongly upregulate interferon pathway genes, these pathways are largely suppressed in cells infected with ZIKV within the same culture dish. Single cell sequencing identifies multiple cell types in our cerebral organoids including neural progenitor cells, intermediate progenitor cells, and neurons of varied maturity. Using this model, we find that neurons, not typically considered targets of ZIKV in the developing brain, contain high copy numbers of ZIKV genomes. It remains uncertain whether neurons are directly infected, or if infected neural progenitor cells differentiate into neurons, carrying virus with them. Notably, the neuronal bystander cell population shows limited interferon gene pathway upregulation compared to neural progenitors. Conclusions Overall, our work provides insight into the pathogenesis of ZIKV associated microcephaly, identifies potential new tropisms of ZIKV in the human brain, and suggests that both virus replication and host response mechanisms underlie the neuropathology of ZIKV infection.