Lethal Nipah Virus Infection Induces Rapid Overexpression of CXCL10

Mathieu, Cyrille; Guillaume, Vanessa; Sabine, Amélie; Ong, Kien Chai; Wong, Kum Thong; Legras-Lachuer, Catherine; Horvat, Branka

To better understand virus-host interaction, we have analysed the effect of NiV infection at the level of gene expression in HUVECs, using Codelink microarray (see Materials and Methods). Cells were infected with either NiV or treated with mock preparation and RNA was taken 8 h p.i., to obtain the information about the early changes in NiV-induced gene expression in HUVEC in the conditions when cell viability was still preserved. Among 55.000 analyzed genes, pair-wise comparisons between infected and uninfected samples revealed 807 deregulated genes (fold change cut-off = 1.3). NiV infection down-regulated galectin 3 gene expression, a member of the lectin family, involved in cell adhesion, cell activation and chemoatraction [16] , but most of the other down-regulated genes were not found associated with any known function (table 1) . The 538 up-regulated genes were classified according to their Gene Ontology (GO) biological processes and molecular functions. This analysis revealed that NiV-infection up-regulated 34 genes implicated in the immune response, particularly those associated with the interferon pathway, including MxA, RIGI, MDA, 2959-OAS 1 and 2 ( Fig. 2) . Interestingly, among the top ten up-regulated genes was CXCL10 (interferon gamma-induced protein 10, IP10), an important chemokine secreted by endothelial cells (table 1). These results have been further confirmed by RT-qPCR at 8 and 24 h post-infection for several genes linked to interferon pathway, including MXA, OAS1, IFN beta and CXCL10 (Fig. 3A ). In addition to stimulation of CXCL10, which was observed at different MOI of infection, MOI of 1 as well as 3, the induction of the closely related chemokine CXCL11 (Interferon-inducible Tcell alpha chemoattractant, I-TAC or IP-9), being at 19 th position among up-regulated genes, was also confirmed by RT-qPCR (Fig. 3A) . However, the production of the third closely related chemokine CXCL9 (MIG), which shares the same receptor CXCR3 with CXCL10 and CXCL11, was not detected. Finally,