An Acute Stress Model in New Zealand White Rabbits Exhibits Altered Immune Response to Infection with West Nile Virus

Abstract

The immune competence of an individual is a major determinant of morbidity in West Nile virus (WNV)-infection. Previously, we showed that immunocompetent New Zealand White rabbits (NZWRs; Oryctolagus cuniculus) are phenotypically resistant to WNV-induced disease, thus presenting a suitable model for study of virus-control mechanisms. The current study used corticosteroid-treated NZWRs to model acute “stress”-related immunosuppression. Maximal effects on immune parameters were observed on day 3 post dexamethasone-treatment (pdt). However, contrary to our hypothesis, intradermal WNV challenge at this time pdt produced significantly lower viremia 1 day post-infection (dpi) compared to untreated controls, suggestive of changes to antiviral control mechanisms. To examine this further, RNAseq was performed on RNA extracted from draining lymph node—the first site of virus replication and immune detection. Unaffected by dexamethasone-treatment, an early antiviral response, primarily via interferon (IFN)-I, and induction of a range of known and novel IFN-stimulated genes, was observed. However, treatment was associated with expression of a different repertoire of IFN-α-21-like and IFN-ω-1-like subtypes on 1 dpi, which may have driven the different chemokine response on 3 dpi. Ongoing expression of Toll-like receptor-3 and transmembrane protein-173/STING likely contributed to signaling of the treatment-independent IFN-I response. Two novel genes (putative HERC6 and IFIT1B genes), and the SLC16A5 gene were also highlighted as important component of the transcriptomic response. Therefore, the current study shows that rabbits are capable of restricting WNV replication and dissemination by known and novel robust antiviral mechanisms despite environmental challenges such as stress.