Identification of Novel Host Cell Binding Partners of Oas1b, the Protein Conferring Resistance to Flavivirus-Induced Disease in Mice

Abstract

Oas1b was previously identified as the product of the Flv r allele that confers flavivirus-specific resistance to virus-induced disease in mice by an uncharacterized, RNase L-independent mechanism. To gain insights about the mechanism by which Oas1b specifically reduces the efficiency of flavivirus replication, cellular protein interaction partners were identified and their involvement in the Oas1b-mediated flavivirus resistance mechanism was analyzed. Initial difficulties in getting the two-hybrid assay to work with full-length Oas1b led to the discovery that this Oas protein uniquely has a C-terminal transmembrane domain that targets it to the endoplasmic reticulum (ER). Two peptides matching to oxysterol binding protein-related protein 1L (ORP1L) and ATP binding cassette protein 3, subfamily F (ABCF3), were identified as Oas1b interaction partners in yeast two-hybrid assays, and both in vitro-transcribed/translated peptides and full-length proteins in mammalian cell lysates coimmunoprecipitated with T he genus Flavivirus, in the family Flaviviridae, consists of ϳ70 viruses and includes human pathogens such as dengue virus, yellow fever virus, tick-borne encephalitis virus, Japanese encephalitis virus, and West Nile virus (WNV) (20). WNV was first isolated in Uganda in 1937 and was previously reported to be endemic in Africa, Australia, and southern Asia (3); it has recently emerged in the Americas, with over 23,000 human infections reported in the United States as of late 2006 (2, 39). WNV is arthropod borne, with a natural transmission cycle typically between Culex mosquito species and birds, with occasional virus transmission by mosquitoes to horses and humans (3). Usually, WNV infections in humans are asymptomatic or cause mild flu-like symptoms. However, some infections cause more severe disease with symptoms such as meningitis, encephalitis, or paralysis, which can be fatal (3).The 2=-5= oligoadenylate synthetase (OAS) pathway functions as an innate host defense response against viral infections. OAS gene expression is upregulated by the signaling of interferons produced by cells in response to a viral infection (34). Viral doublestranded RNA (dsRNA) binds to and activates OAS, causing it to polymerize ATP into short 2=-5=-linked oligomers (2-5A) (14). These 2-5A oligomers bind to and activate latent endoribonuclease L (RNase L,) which is constitutively expressed in cells. Activated RNase L cleaves viral and cellular single-stranded RNAs.Data from numerous studies indicate that both host factors and virus virulence factors determine the outcome of a virus infection. Genetically controlled resistance to flavivirus-induced central nervous system (CNS) disease in mice was first discovered in the 1920s and rediscovered several times in the 1930s because it was not appreciated that all of the viruses being tested belonged to the same virus genus and family (4). Breeding studies with mice displaying differential susceptibility to flavivirus-induced disease showed that the alleles of a single gene, Flv, control...

A Mouse Model of Chronic West Nile Virus Disease

“…apparent by histopathology (Fig 2 and S1 Fig). Of note, differences in susceptibility to and disease outcome following WNV between CC-RIX lines was not due solely to Oas1b haplotype, which has previously been shown to be a susceptibility allele for WNV and other flaviviruses in mice [19,20]; one of the RIX lines with no disease has two copies of the wild-derived “functional” Oas1b allele (F/F), whereas two of them are heterozygous (N/F), one of the RIX lines with disease has two copies of the non-functional (truncated) allele present in classic inbred strains (N/N), whereas two of the RIX lines are heterozygous, and the chronic RIX is also homozygous for the non-functional classic inbred allele (Fig 2A). These data, and the fact that the B6 model, which also has 2 copies of the classic inbred allele, does not show chronic disease outcomes, lead us to conclude that differences in disease outcome across CC-RIX lines and the mechanism leading to chronic infection are not due solely to Oas1b status.…”

Adenovirus Modulates Toll-Like Receptor 4 Signaling by Reprogramming ORP1L-VAP Protein Contacts for Cholesterol Transport from Endosomes to the Endoplasmic Reticulum

“…Our results suggest that RID␣ is necessary and sufficient to recruit ORP1L to endocytic vesicles that are not traditionally classified as early or late endosomes. ORP1L was recently shown to interact with Oas1b, an interferon-inducible ER membrane protein that confers resistance to infection with flavivirus West Nile virus as well as several other types of RNA viruses in mice (75). Although the exact mechanism is incompletely understood, the interaction between ORP1L and Oas1b apparently blocks late endosome transport/fusion processes required for viral replication by interfering with normal function of RILP/Rab7/ ORP1L complexes (76).…”

An updated review of avian-origin Tembusu virus: a newly emerging avian Flavivirus

“…Our previous study demonstrated that stimulation of goose PBMCs with duck TMUV significantly increased goOASL transcription levels in vitro [56]. The mammalian OAS protein exhibits good antiviral activity against flavivirus infection [57], and hOAS1, OAS3 and OASL can block replication of type 2 DENV via the OAS/RNase L pathway in human cells [58]. In addition, mouse OAS1b and chicken OAS*A show antiviral activity against WNV in mouse cells [59,60].…”