Rabies virus (RV) induces encephalomyelitis in humans and animals. However, the pathogenic mechanism of rabies is not fully understood. To investigate the host responses to RV infection, we examined and compared the pathology, particularly the inflammatory responses, and the gene expression profiles in the brains of mice infected with wild-type (wt) virus silver-haired bat RV (SHBRV) or laboratory-adapted virus B2C, using a mouse genomic array (Affymetrix). Extensive inflammatory responses were observed in animals infected with the attenuated RV, but little or no inflammatory responses were found in mice infected with wt RV. Furthermore, attenuated RV induced the expression of the genes involved in the innate immune and antiviral responses, especially those related to the alpha/beta interferon (IFN-␣/␤) signaling pathways and inflammatory chemokines. For the IFN-␣/␤ signaling pathways, many of the interferon regulatory genes, such as the signal transduction activation transducers and interferon regulatory factors, as well as the effector genes, for example, 2-5-oligoadenylate synthetase and myxovirus proteins, are highly induced in mice infected with attenuated RV. However, many of these genes were not up-regulated in mice infected with wt SHBRV. The data obtained by microarray analysis were confirmed by real-time PCR. Together, these data suggest that attenuated RV activates, while pathogenic RV evades, the host innate immune and antiviral responses.Rabies virus (RV) is a nonsegmented negative-stranded RNA virus of the Rhabdoviridae family and induces a fatal neurological disease in humans and animals (15). Although significant advances have been made in rabies prevention and control, the disease remains a major threat to public health and continues to cause numerous human deaths around the world. The dog remains the most important reservoir in Asia, Africa, and Latin America, where most human rabies cases occur (19). In the United States, dog rabies has been largely brought under control through pet vaccination programs, and there have been only a few incidents where large carnivores have transmitted rabies directly to humans (11,26). Most of the human cases in the past decade have been associated with RV found in bats, particularly silver-haired bats (11,18,39,47). Furthermore, most of the cases occurred without a history of exposure (11), suggesting that the silver-haired bat RV (SHBRV) is highly pathogenic and neuroinvasive (18,47).RV invades the nervous system by binding to neural receptors, such as acetylcholine receptor (31), neural cell adhesion molecule (52), or nerve growth factor receptor (NTR75) (53). Then, RV is transported to the central nervous system (CNS) by retrograde transportation, possibly by binding to cytoplasmic dynein (29,46). Despite extensive investigation in the past 100 years, the pathogenic mechanisms by which street (wildtype [wt]) RV infection results in neurological diseases and death in humans are not well understood. This is because there is very little neuronal pathology or d...

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Rabies virus (RABV) is a single-stranded, negative-sense RNA virus that causes a fatal neurological disease in humans and animals. Our previous studies have shown that lab-adapted, but not wild-type (wt), RABV enhances innate immune responses including type I interferon (IFN) and chemokines. To determine if treatment with type I IFN can inhibit RABV infection, mouse neuroblastoma and baby hamster kidney cells were treated with IFN-α before being infected with lab-adapted or wt RABV. It was found that lab-adapted, but not the wt, RABV was able to replicate in IFN-α-pretreated cells. To determine the genes in wt RABV that confer sensitivity to IFN-α treatment, the P and the glycoprotein (G) genes from the wt RABV were used to replace the respective genes in the lab-adapted RABV. The results revealed that it is the P, not the G, gene that is associated with IFN sensitivity. Further studies have identified the regions containing the self-association domain (residues 59-139) and the C-terminal (residue 175-297) region on the P that might be associated with IFN sensitivity. The expression of ISGs, such as ISG15, ISG56, PKR, OAS-1G, was also investigated and found to be greatly increased in wt, but not in lab-adapted RABV-infected cells. It is possible that the P protein from the lab-adapted RABV can interfere with the downstream events in the interferon-signaling cascade.

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