Identification of host factors for Rift Valley fever phlebovirus

Authors: BALARAMAN, VELMURUGAN - Kansas State University; INDRAN, SABARISH - Sanofi, Paris; MEEKINS, DAVID - Kansas State University; JAKKULA, LAXMI - Fabgennix International, Incorporated; LIU, HEIDI - University Of Missouri; HAYS, MICHAEL - Kansas State University; LI, YONGHAI - Kansas State University; SOUZA-NETO, JAYME - Kansas State University; GAUDREAULT, NATASHA - Kansas State University; HARDWIDGE, PHILIP - Kansas State University; Wilson, William - Bill; WEBER, FIEDEMANN - Justus-Liebig University; RICHT, JUERGEN - Kansas State University

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2023
Publication Date: 11/13/2023
Citation: Balaraman, V., Indran, S.V., Meekins, D., Jakkula, L.U., Liu, H., Hays, M.P., Li, Y., Souza-Neto, J.A., Gaudreault, N.N., Hardwidge, P.R., Wilson, W.C., Weber, F., Richt, J.A. 2023. Identification of host factors for Rift Valley fever phlebovirus. Viruses. 15(11). Article 2251. https://doi.org/10.3390/v15112251.
DOI: https://doi.org/10.3390/v15112251

Interpretive Summary: The emerging zoonotic pathogen, Rift Valley fever phlebovirus (RVFV) can cause lethal disease in livestock and humans. There no licensed mitigation tools (therapeutic or vaccines) for humans and only a conditional licensed vaccine for animals in the US. Host factors that affect virus susceptibility are not well understood.In this study we used a genetic screening tool to identitive cellular factors affecting RVFV infection in human cells. From our screen, we found approximately 900 genes putatively involved in host interaction with RVFV infection. Of these, six genes effects on viral replication gene knockdowns studies confirmed two genes that lack of significantly impaired RVFV replication. This effect was also verified with a related virus, La Crosse encephalitis virus (LACV). One was found to play an important role in virus infection with the two related viruses, RVFV and LACV. The mechanism of how this occurs will be investigated in future studies.

Technical Abstract: Rift Valley fever phlebovirus (RVFV) is an emerging zoonotic pathogen that causes Rift Valley fever (RVF) in livestock and humans. Currently, there is no licensed human vaccine or antiviral drug to the control of RVF. Although multiple species of animals and humans are vulnerable to RVFV infection, host factors affecting susceptibility are not well understood. Here, we performed CRISPR-Cas9 knock-out screen in human A549 cells to identify host factors essential for RVFV replication. From our screen, we found approximately 900 genes putatively involved in host interaction with RVFV infection. Further evaluation of the effect of six genes on viral replication using siRNA-mediated knockdowns found that silencing two genes (WDR7 and LRP1) significantly impaired RVFV replication. We focused on WDR7 for further analysis as the role of LRP1 in RVFV replication is well reported. Knock-out A549 cell lines were generated and used to dissect the effect of WRD7 on RVFV and La Crosse encephalitis virus (LACV), another bunyavirus. We observed significant effects of WDR7 knock-out on both intracellular RVFV RNA load and viral titers. At the intracellular RNA level, WRD7 influence on virus replication was observed at a later phase for RVFV (24h) compared to an earlier phase for LACV (12h). Overall, we describe an important role of WDR7 as a host factor for the replication of two relevant bunyaviruses, RVFV and LACV. The mechanism by which WDR7 allows/facilitates arbovirus replication will be investigated in future studies.