The Influence of Psychological Stress on HPV Infection Manifestations and Carcinogenesis.

Psychological stress is an important factor involved in disease manifestations of human papillomavirus (HPV) infection, and it can participate in HPV-associated carcinogenesis. The impact or effect which stress can have (exert) depends on a person's genetic pool, experiences and behaviors. Due to inconsistencies in some study results, this issue remains a subject of research. Concerning the course of HPV manifestations, it has been observed that a higher number of life stressors in at least the previous 6 months, the absence of social support and the types of personal coping mechanisms employed, all influence HPV progression. In women with cervical dysplasia, a connection between greater stress experiences and dysregulation of specific immune responses has been observed. Once HPV enters a cell via the α6 integrin there are three possible sequences: latent infection, subclinical infection, and clinically manifest disease. HPV proliferation in differentiated epithelial cells induces morphologically cytopathic changes (koilocytosis, epidermal thickening, hyperplasia, hyperkeratosis). Oncogenic transformation requires the integration of the virus genome into the host genome. In doing so, DNA in the E1 region of E2 breaks down, leading to transcription disorders of E6 and E7. For the formation of irreversible malignancy, the following sequence is necessary: initial expression of E6 and E7 genes followed by suppression of apoptosis and the stabile expression of E6 and E7 proteins that protect transformed cells from apoptosis. A successful immune response is characterized by a strong, local cell-mediated immune response. Several factors are important for the regression of HPV manifestation/infection, among which is psychological stress which can prolong the duration and severity of HPV disease. Stress hormones may reactivate latent tumor viruses, stimulate viral oncogene expression, and inhibit antiviral host responses. In the regression of HPV infection, increased activity of Th1 cells was observed. However, during psychosocial stress, a decrease in the Th1 type of immune response is seen, and there is a shift towards a Th2 response. Understanding perceived stress and biological changes in stress, as well as the evaluation of immune parameters, gives researchers a better picture of how stress influences HPV infections and how to improve disease management and outcomes.

Neuropathogenic human coronaviruses: A review.

Human Coronaviruses (HCoVs) have long been known as respiratory viruses. However, there are reports of neurological findings in HCoV infections, particularly in patients infected with the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) amid Coronavirus disease 2019 (COVID-19) pandemic. Therefore, it is essential to interpret the interaction of HCoVs and the nervous system and apply this understanding to the COVID-19 pandemic. This review of the literature analyses how HCoVs, in general, and SARS-CoV-2, in particular, affect the nervous system, highlights the various underlying mechanisms, addresses the associated neurological and psychiatric manifestations, and identifies the neurological risk factors involved. This review of literature shows the magnitude of neurological conditions associated with HCoV infections, including SARS-CoV-2. This review emphasises, that, during HCoV outbreaks, such as COVID-19, a focus on early detection of neurotropism, alertness for the resulting neurological complications, and the recognition of neurological risk factors are crucial to reduce the workload on hospitals, particularly intensive-care units and neurological departments.

Determinants of neurological syndromes caused by varicella zoster virus (VZV).

Varicella zoster virus (VZV) is a pathogenic human herpes virus which causes varicella as a primary infection, following which it becomes latent in peripheral autonomic, sensory, and cranial nerve ganglionic neurons from where it may reactivate after decades to cause herpes zoster. VZV reactivation may also cause a wide spectrum of neurological syndromes, in particular, acute encephalitis and vasculopathy. While there is potentially a large number of coding viral mutations that might predispose certain individuals to VZV infections, in practice, a variety of host factors are the main determinants of VZV infection, both disseminated and specifically affecting the nervous system. Host factors include increasing age with diminished cell-mediated immunity to VZV, several primary immunodeficiency syndromes, secondary immunodeficiency syndromes, and drug-induced immunosuppression. In some cases, the molecular immunological basis underlying the increased risk of VZV infections has been defined, in particular, the role of POL III mutations, but in other cases, the mechanisms have yet to be determined. The role of immunization in immunosuppressed individuals as well as its possible efficacy in preventing both generalized and CNS-specific infections will require further investigation to clarify in such patients.

COVID-19 and the nervous system.

A pandemic due to novel coronavirus arose in mid-December 2019 in Wuhan, China, and in 3 months' time swept the world. The disease has been referred to as COVID-19, and the causative agent has been labelled SARS-CoV-2 due to its genetic similarities to the virus (SARS-CoV-1) responsible for the severe acute respiratory syndrome (SARS) epidemic nearly 20 years earlier. The spike proteins of both viruses dictate tissue tropism using the angiotensin-converting enzyme type 2 (ACE-2) receptor to bind to cells. The ACE-2 receptor can be found in nervous system tissue and endothelial cells among the tissues of many other organs.Neurological complications have been observed with COVID-19. Myalgia and headache are relatively common, but serious neurological disease appears to be rare. No part of the neuraxis is spared. The neurological disorders occurring with COVID-19 may have many pathophysiological underpinnings. Some appear to be the consequence of direct viral invasion of the nervous system tissue, others arise as a postviral autoimmune process, and still others are the result of metabolic and systemic complications due to the associated critical illness. This review addresses the preliminary observations regarding the neurological disorders reported with COVID-19 to date and describes some of the disorders that are anticipated from prior experience with similar coronaviruses.

Unpuzzling COVID-19: tissue-related signaling pathways associated with SARS-CoV-2 infection and transmission.

The highly infective coronavirus disease 19 (COVID-19) is caused by a novel strain of coronaviruses - the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) - discovered in December 2019 in the city of Wuhan (Hubei Province, China). Remarkably, COVID-19 has rapidly spread across all continents and turned into a public health emergency, which was ultimately declared as a pandemic by the World Health Organization (WHO) in early 2020. SARS-CoV-2 presents similar aspects to other members of the coronavirus family, mainly regarding its genome, protein structure and intracellular mechanisms, that may translate into mild (or even asymptomatic) to severe infectious conditions. Although the mechanistic features underlying the COVID-19 progression have not been fully clarified, current evidence have suggested that SARS-CoV-2 may primarily behave as other ß-coronavirus members. To better understand the development and transmission of COVID-19, unveiling the signaling pathways that may be impacted by SARS-CoV-2 infection, at the molecular and cellular levels, is of crucial importance. In this review, we present the main aspects related to the origin, classification, etiology and clinical impact of SARS-CoV-2. Specifically, here we describe the potential mechanisms of cellular interaction and signaling pathways, elicited by functional receptors, in major targeted tissues/organs from the respiratory, gastrointestinal (GI), cardiovascular, renal, and nervous systems. Furthermore, the potential involvement of these signaling pathways in evoking the onset and progression of COVID-19 symptoms in these organ systems are presently discussed. A brief description of future perspectives related to potential COVID-19 treatments is also highlighted.

Systemic Complications of COVID-19.

Coronavirus disease-2019 (COVID-19) creates severe respiratory distress and often a cascade of other systemic complications impacting several organ systems. The immune response includes a cytokine storm that creates many life-threatening problems including coagulopathies, arrhythmias, and secondary infections. This article discusses the multisystem responses to the physical insults created by this corona virus.

[Effects of Enterovirus 71 on Mitochondrial Dynamics in Human Glioma U251 Cells].

OBJECTIVE: To investigate the effects of enterovirus 71 (EV71) on mitochondrial dynamics in human Glioma U251 cells. METHODS: The EV71 was replicated in Vero cells and the 50% tissue culture infective dose (TCID 50) was calculated based on the Reed-Muench formula. After the U251 cells were infected with EV71, the cellular morphology was assessed through the light microscope. The mitochondrial morphology was detected by MitoTracker Deep Red staining under laser confocal microscopy and the mitochondrial ultrastructure was visualized by transmission electron microscopy. The expressions of mitochondrial fission proteins Drp1, p-Drp1 and fusion protein Opa1 were examined by Western blot. The level of ATP was measured by a commercial ATP assay kit. The generation of mitochondrial superoxide was detected by MitoSOX staining. RESULTS: The TCID 50 of EV71 was 10 －5.4/0.1 mL. Twenty-four or 48 h after EV71 infection, the U251 cells appeared shrunken, round and dead. The laser confocal microscopy and transmission electron microscopy images showed that the EV71 infection induced mitochondrial elongation and cristae damage. Moreover, Western blot analysis demonstrated that the protein expressions of Drp1 and Opa1 were downregulated at both 24 and 48 h after EV71 infection in U251 cells, companied with a significant increase in Drp1 phosphorylation at 48 h after infection ( P<0.05). In addition, a decreased ATP level and elevated mitochondrial superoxide generation were observed in the EV71 infected group, as compared to the control group. CONCLUSION: Our study demonstrated that infection with EV71 led to changes of mitochondrial morphology and dynamics in U251 cells, which may impair mitochondrial function and contribute to nervous system dysfunction.

[Neurological aspects of the COVID-19 pandemic caused by the SARS-CoV-2 coronavirus]. / A SARS-CoV-2 koronavírus által okozott COVID-19-járvány neurológiai vonatkozásai.

By the spring of 2020 the COVID-19 outbreak caused by the new SARS-CoV-2 coronavirus has become a pandemic, requiring fast and efficient reaction from societies and health care systems all over the world. Fever, coughing and dyspnea are considered the major signs of COVID-19. In addition to the involvement of the respiratory system, the infection may result in other symptoms and signs as well. Based on reports to date, neurological signs or symptoms appear in 30-50% of hospitalized COVID-19 patients, with higher incidence in those with more severe disease. Classical acute neurological syndromes have also been reported to associate with COVID-19. A drop in the volume of services for other acute diseases has been described in countries with healthcare systems focusing on COVID-19. During the COVID-19 epidemic it is also important to provide appropriate continuous care for those with chronic neurological disorders. It will be the task of the future to estimate the collateral damage caused by the COVID-19 epidemic on the outcome of other neurological disorders, and to screen for the possible late neurological complications of the SARS-CoV-2 coronavirus infection.

A proposal for a tailored protocol for focal suppurative infection of the central nervous system: analysis of an institutional experience in pediatric patients.

OBJECTIVE: The incidence of focal suppurative infections (FSIs) of the brain has significantly decreased owing to the better health and fundamental conditions of the population on the one hand and earlier detection and the availability of more potent antibiotics on the other. Interestingly, the antibiotic protocols have not been well defined in terms of duration despite a prompter diagnosis, definitive management of the etiology, and the advent of various higher-generation antibiotics. In this study, the authors evaluated the current treatment protocol. Their aim was to optimize management protocols for FSIs of the central nervous system based on clinical parameters. METHODS: The study was a retrospective analysis of all children who had undergone surgical management for an FSI at the Division of Paediatric Neurosurgery, Amrita Institute of Medical Sciences and Research Centre, Kochi, Kerala, in the period from January 2001 to February 2018. In addition to demographic characteristics, the details of culture reports and antibiotic regimens were collected. The response to treatment was compared to changes in the infective profile (C-reactive protein) and imaging. Instances of reaspiration were compared with clinical signs, imaging findings, and infective profiles. Treatment response was separated into two groups: responders within or at 2 weeks and responders beyond 2 weeks. The clinical characteristics of these two groups were compared. RESULTS: Forty-eight children were treated in the study period. Nineteen patients benefited from the 2-week (short-term) protocol of intravenous antibiotics. Twenty-nine patients required more than 2 weeks (approximately 4 weeks; long-term protocol) for resolution. Of those requiring more than 2 weeks, 69% had cardiogenic etiology. All patients were followed up with a minimum of 3 weeks of oral antibiotics. In a comparative analysis between short-term and long-term responders, only etiology was significantly different. None of the patients who had the short-term protocol had a recurrence. CONCLUSIONS: A shorter antibiotic protocol can be used successfully in carefully selected patients who are surgically treated and followed up. It is clear that the 2-week intravenous antibiotic protocol is more suitable for immunocompetent patients who have a noncardiogenic etiology.

Herpesvirus transport to the nervous system and back again.

Herpes simplex virus, varicella zoster virus, and pseudorabies virus are neurotropic pathogens of the Alphaherpesvirinae subfamily of the Herpesviridae. These viruses efficiently invade the peripheral nervous system and establish lifelong latency in neurons resident in peripheral ganglia. Primary and recurrent infections cycle virus particles between neurons and the peripheral tissues they innervate. This remarkable cycle of infection is the topic of this review. In addition, some of the distinguishing hallmarks of the infections caused by these viruses are evaluated in terms of their underlying similarities.

End-point disease investigation for virus strains of intermediate virulence as illustrated by flavivirus infections.

Viruses of intermediate virulence are defined as isolates causing an intermediate morbidity/mortality rate in a specific animal model system, involving specific host and inoculation parameters (e.g. dose and route). Therefore, variable disease phenotype may exist between animals that develop severe disease or die and those that are asymptomatic or survive after infection with these isolates. There may also be variability amongst animals within each of these subsets. Such potential variability may confound the use of time-point sacrifice experiments to investigate pathogenesis of this subset of virus strains, as uniformity in disease outcome is a fundamental assumption for time-course sacrifice experiments. In the current study, we examined the disease phenotype, neuropathology, neural infection and glial cell activity in moribund/dead and surviving Swiss white (CD-1) mice after intraperitoneal infection with various Australian flaviviruses, including West Nile virus (WNV) strains of intermediate virulence (WNVNSW2011 and WNVNSW2012), and highly virulent Murray Valley encephalitis virus (MVEV) isolates. We identified notable intragroup variation in the end-point disease in mice infected with either WNVNSW strain, but to a lesser extent in mice infected with MVEV strains. The variable outcomes associated with WNVNSW infection suggest that pathogenesis investigations using time-point sacrifice of WNVNSW-infected mice may not be the best approach, as the assumption of uniformity in outcomes is violated. Our study has therefore highlighted a previously unacknowledged challenge to investigating pathogenesis of virus isolates of intermediate virulence. We have also set a precedent for routine examination of the disease phenotype in moribund/dead and surviving mice during survival challenge experiments.

Neurotropism of Saffold virus in a mouse model.

Saffold virus (SAFV) is a highly seroprevalent human Cardiovirus discovered recently. No clear association between SAFV infection and human disease has been established. Rare infection cases, however, correlated with neurological symptoms. To gain insight into the pathogenesis potential of the virus, we performed experimental mouse infection with SAFV strains of genotypes 2 and 3 (SAFV-2 and SAFV-3). After intraperitoneal infection, both strains exhibited a typical Cardiovirus tropism. Viral load was most prominent in the pancreas. Heart, spleen, brain and spinal cord were also infected. In IFN-receptor 1 deficient (IFNAR-KO) mice, SAFV-3 caused a severe encephalitis. The virus was detected by immunohistochemistry in many parts of the brain and spinal cord, both in neurons and astrocytes, but astrocyte infection was more extensive. In vitro, SAFV-3 also infected astrocytes better than neurons in mixed primary cultures. Astrocytes were, however, very efficiently protected by IFN-α/ß treatment.

A molecularly cloned, live-attenuated japanese encephalitis vaccine SA14-14-2 virus: a conserved single amino acid in the ij Hairpin of the Viral E glycoprotein determines neurovirulence in mice.

Japanese encephalitis virus (JEV), a mosquito-borne flavivirus that causes fatal neurological disease in humans, is one of the most important emerging pathogens of public health significance. JEV represents the JE serogroup, which also includes West Nile, Murray Valley encephalitis, and St. Louis encephalitis viruses. Within this serogroup, JEV is a vaccine-preventable pathogen, but the molecular basis of its neurovirulence remains unknown. Here, we constructed an infectious cDNA of the most widely used live-attenuated JE vaccine, SA14-14-2, and rescued from the cDNA a molecularly cloned virus, SA14-14-2MCV, which displayed in vitro growth properties and in vivo attenuation phenotypes identical to those of its parent, SA14-14-2. To elucidate the molecular mechanism of neurovirulence, we selected three independent, highly neurovirulent variants (LD50, <1.5 PFU) from SA14-14-2MCV (LD50, >1.5×105 PFU) by serial intracerebral passage in mice. Complete genome sequence comparison revealed a total of eight point mutations, with a common single G1708→A substitution replacing a Gly with Glu at position 244 of the viral E glycoprotein. Using our infectious SA14-14-2 cDNA technology, we showed that this single Gly-to-Glu change at E-244 is sufficient to confer lethal neurovirulence in mice, including rapid development of viral spread and tissue inflammation in the central nervous system. Comprehensive site-directed mutagenesis of E-244, coupled with homology-based structure modeling, demonstrated a novel essential regulatory role in JEV neurovirulence for E-244, within the ij hairpin of the E dimerization domain. In both mouse and human neuronal cells, we further showed that the E-244 mutation altered JEV infectivity in vitro, in direct correlation with the level of neurovirulence in vivo, but had no significant impact on viral RNA replication. Our results provide a crucial step toward developing novel therapeutic and preventive strategies against JEV and possibly other encephalitic flaviviruses.

Xpr1 is an atypical G-protein-coupled receptor that mediates xenotropic and polytropic murine retrovirus neurotoxicity.

Xenotropic murine leukemia virus-related virus (XMRV) was first identified in human prostate cancer tissue and was later found in a high percentage of humans with chronic fatigue syndrome (CFS). While exploring potential disease mechanisms, we found that XMRV infection induced apoptosis in SY5Y human neuroblastoma cells, suggesting a mechanism for the neuromuscular pathology seen in CFS. Several lines of evidence show that the cell entry receptor for XMRV, Xpr1, mediates this effect, and chemical cross-linking studies show that Xpr1 is associated with the Gß subunit of the G-protein heterotrimer. The activation of adenylate cyclase rescued the cells from XMRV toxicity, indicating that toxicity resulted from reduced G-protein-mediated cyclic AMP (cAMP) signaling. Some proteins with similarity to Xpr1 are involved in phosphate uptake into cells, but we found no role of Xpr1 in phosphate uptake or its regulation. Our results indicate that Xpr1 is a novel, atypical G-protein-coupled receptor (GPCR) and that xenotropic or polytropic retrovirus binding can disrupt the cAMP-mediated signaling function of Xpr1, leading to the apoptosis of infected cells. We show that this pathway is also responsible for the classic toxicity of the polytropic mink cell focus-forming (MCF) retrovirus in mink cells. Although it now seems clear that the detection of XMRV in humans was the result of sample contamination with a recombinant mouse virus, our findings may have relevance to neurologic disease induced by MCF retroviruses in mice.

Differential impact of interferon regulatory factor 7 in initiation of the type I interferon response in the lymphocytic choriomeningitis virus-infected central nervous system versus the periphery.

Interferon (IFN) regulatory factors (IRFs) are a family of transcription factors involved in regulating type I IFN genes and other genes participating in the early antiviral host response. To better understand the mechanisms involved in virus-induced central nervous system (CNS) inflammation, we studied the influence of IRF1, -3, -7, and -9 on the transcriptional activity of key genes encoding antiviral host factors in the CNS of mice infected with lymphocytic choriomeningitis virus (LCMV). A key finding is that neither IRF3 nor IRF7 is absolutely required for induction of a type I IFN response in the LCMV-infected CNS, whereas concurrent elimination of both factors markedly reduces the virus-induced host response. This is unlike the situation in the periphery, where deficiency of IRF7 almost eliminates the LCMV-induced production of the type I IFNs. This difference is seemingly related to the local environment, as peripheral production of type I IFNs is severely reduced in intracerebrally (i.c.) infected IRF7-deficient mice, which undergo a combined infection of the CNS and peripheral organs, such as spleen and lymph nodes. Interestingly, despite the redundancy of IRF7 in initiating the type I IFN response in the CNS, the response is not abolished in IFN-ß-deficient mice, as might have been expected. Collectively, these data demonstrate that the early type I IFN response to LCMV infection in the CNS is controlled by a concerted action of IRF3 and -7. Consequently this work provides strong evidence for differential regulation of the type I IFN response in the CNS versus the periphery during viral infection.

Describing the silent human virome with an emphasis on giant viruses.

Viruses are the most abundant obligate intracellular entities in our body. Until recently, they were only considered to be pathogens that caused a broad array of pathologies, ranging from mild disease to deaths in the most severe cases. However, recent advances in unbiased mass sequencing techniques as well as increasing epidemiological evidence have indicated that the human body is home to diverse viral species under non-pathological conditions. Despite these studies, the description of the presumably healthy viral flora, i.e. the normal human virome, is still in its infancy regarding viral composition and dynamics. This review summarizes our current knowledge of the human virome under non-pathological conditions.

Ocular and neural distribution of feline herpesvirus-1 during active and latent experimental infection in cats.

BACKGROUND: Herpes simplex virus 1 (HSV-1) and varicella zoster virus (VZV) cause extensive intra-ocular and neural infections in humans and are closely related to Felid herpes virus 1 (FeHV-1). We report the extent of intra-ocular replication and the extent and morphological aspects of neural replication during the acute and latent phases of FeHV-1 infection. Juvenile, SPF cats were inoculated with FeHV-1. Additional cats were used as negative controls. Cats were euthanized on days 6, 10, and 30 post-inoculation. RESULTS: FeHV-1 was isolated from the conjunctiva, cornea, uveal tract, retina, optic nerve, ciliary ganglion (CG), pterygopalatine ganglion (PTPG), trigeminal ganglion (TG), brainstem, visual cortex, cerebellum, and olfactory bulb of infected cats during the acute phase, but not the cranial cervical ganglion (CCG) and optic chiasm. Viral DNA was detected in all tissues during acute infection by a real-time quantitative PCR assay. On day 30, viral DNA was detected in all TG, all CCG, and 2 PTPG. Histologically mild inflammation and ganglion cell loss were noted within the TG during acute, but not latent infection. Using linear regression, a strong correlation existed between clinical score and day 30 viral DNA copy number within the TG. CONCLUSIONS: The correlation between clinical score and day 30 viral DNA copy number suggests the severity of the acute clinical infection is related to the quantity of latent viral DNA. The histologic response was similar to that seen during HSV-1 or VZV infection. To the author's knowledge this is the first report of FeHV-1 infection involving intraocular structures and autonomic ganglia.

Identification of a neurovirulence factor from Marek's disease virus.

In addition to tumors, Marek's disease (MD) virus (MDV) can induce a variety of syndromes linked to the central nervous system. In fact, early descriptions of MD suggested that it was a condition affecting mainly the nervous system. Cytokines and other immune-related genes have been suggested to play a crucial role in MDV-mediated neuropathology, but the mechanisms behind the viral-induced neurologic dysfunction are still poorly understood. In the present study we have used reverse genetic strategies to show that pp14 is not involved in the oncogenic phenotype of MDV1 and is not required for viral replication; however, we provide evidence indicating that the absence of pp14 expression is correlated with increased survival of MDV1-infected chickens, and that its expression is associated with enhanced viral neurovirulence. Our data identify for the first time pp14 as a neurovirulence factor from MDV1 and open the possibility to investigate the molecular mechanisms by which pp14 mediates the damage to the avian nervous system.

Alphavirus-induced encephalomyelitis: antibody-secreting cells and viral clearance from the nervous system.

Sindbis virus (SINV) infection of the central nervous system (CNS) provides a model for understanding the role of the immune response in recovery from alphavirus infection of neurons. Virus clearance occurred in three phases: clearance of infectious virus (days 3 to 7), clearance of viral RNA (days 8 to 60), and maintenance of low levels of viral RNA (>day 60). The antiviral immune response was initiated in the cervical lymph nodes with rapid extrafollicular production of plasmablasts secreting IgM, followed by germinal center production of IgG-secreting and memory B cells. The earliest inflammatory cells to enter the brain were CD8(+) T cells, followed by CD4(+) T cells and CD19(+) B cells. During the clearance of infectious virus, effector lymphocytes in the CNS were primarily CD8(+) T cells and IgM antibody-secreting cells (ASCs). During the clearance of viral RNA, there were more CD4(+) than CD8(+) T cells, and B cells included IgG and IgA ASCs. At late times after infection, ASCs in the CNS were primarily CD19(+) CD38(+) CD138(-) Blimp-1(+) plasmablasts, with few fully differentiated CD38(-) CD138(+) Blimp-1(+) plasma cells. CD19(+) CD38(+) surface Ig(+) memory B cells were also present. The level of antibody to SINV increased in the brain over time, and the proportion of SINV-specific ASCs increased from 15% of total ASCs at day 14 to 90% at 4 to 6 months, suggesting specific retention in the CNS during viral RNA persistence. B cells in the CNS continued to differentiate, as evidenced by accumulation of IgA ASCs not present in peripheral lymphoid tissue and downregulation of major histocompatibility complex (MHC) class II expression on plasmablasts. However, there was no evidence of germinal center activity or IgG avidity maturation within the CNS.

Developments in rabies vaccines.

The development of vaccines that prevent rabies has a long and distinguished history, with the earliest preceding modern understanding of viruses and the mechanisms of immune protection against disease. The correct application of inactivated tissue culture-derived vaccines is highly effective at preventing the development of rabies, and very few failures are recorded. Furthermore, oral and parenteral vaccination is possible for wildlife, companion animals and livestock, again using inactivated tissue culture-derived virus. However, rabies remains endemic in many regions of the world and causes thousands of human deaths annually. There also remain no means of prophylaxis for rabies once the virus enters the central nervous system (CNS). One reason for this is the poor immune response within the CNS to infection with rabies virus (RABV). New approaches to vaccination using modified rabies viruses that express components of the innate immune system are being applied to this problem. Preliminary reports suggest that direct inoculation of such viruses could trigger an effective anti-viral response and prevent a fatal outcome from RABV infection.