Replication in Cells of Hematopoietic Origin Is Necessary for Dengue Virus Dissemination

Abstract

Dengue virus (DENV) is a mosquito-borne pathogen for which no vaccine or specific therapeutic is available. Although it is well established that dendritic cells and macrophages are primary sites of DENV replication, it remains unclear whether non-hematopoietic cellular compartments serve as virus reservoirs. Here, we exploited hematopoietic-specific microRNA-142 (miR-142) to control virus tropism by inserting tandem target sites into the virus to restrict replication exclusively in this cell population. In vivo use of this virus restricted infection of CD11b ⁺, CD11c ⁺, and CD45 ⁺ cells, resulting in a loss of virus spread, regardless of the route of administration. Furthermore, sequencing of the targeted virus population that persisted at low levels, demonstrated total excision of the inserted miR-142 target sites. The complete conversion of the virus population under these selective conditions suggests that these immune cells are the predominant sources of virus amplification. Taken together, this work highlights the importance of hematopoietic cells for DENV replication and showcases an invaluable tool for the study of virus pathogenesis.

Author Summary

Dengue virus (DENV) is becoming a global threat as anthropogenic factors are increasing the prevalence of vector species capable of transmitting the pathogen. There are currently no vaccines or therapeutics against DENV, and the study of virus pathogenesis and dissemination has been largely limited to artificial mouse models. As DENV is capable of infecting many cell types including dendritic cells (DCs), macrophages, and fibroblasts, it remains unclear which cells permit DENV replication in vivo and are responsible for virus spread. To this end, we inserted microRNA (miRNA) target sites into the virus genome to render it incapable of replicating in DCs and macrophages, while having no direct effect on replication in other cell types. The purpose of this study was to exclude virus growth in a defined cellular population and assess the effects of this restriction on viral dissemination and replication in vivo. With this technology, we demonstrate that restricting replication in hematopoietic cells results in a complete loss of miRNA-targeted virus, indicating that these cells are the predominant reservoirs for virus replication.