Caracterización y evolución temporal de la mortalidad por zoonosis bajo declaración obligatoria, entre los años 1997 y 2018 / Characterization and temporal evolution of mortality due to zoonoses under mandatory declaration, between the years 1997 and 2018

INTRODUCCIÓN: Las zoonosis son enfermedades transmitidas desde un hospedador animal al ser humano o viceversa. En Chile, las zoonosis de Notificación Obligatoria (NO) son: brucelosis, carbunco, triquinosis, hidatidosis, leptospirosis, dengue, enfermedad de Chagas, hantavirosis y rabia. OBJETIVO: Evaluar la tendencia y caracterizar la mortalidad por zoonosis de NO en Chile entre 1997-2018. METODOLOGÍA: Estudio ecológico de la mortalidad por zoonosis de NO. Se utilizaron bases de mortalidad y población oficiales. Se describió la mortalidad relativa, general y específica, según variables sociodemográficas. Se calcularon tasas de mortalidad anuales brutas (TMb) y ajustadas (TMa, método directo). Se evaluó la tendencia temporal con modelos de regresión de Prais-Winsten. Resultados: Entre 1997 y 2018 la mortalidad por zoonosis de NO correspondió al 0,12% (2.359 muertes) de la mortalidad total, siendo las principales causas la enfermedad de Chagas (59,8%), hidatidosis (23,9%) y hantavirosis (13,8%). La TMa general disminuyó significativamente (B: -0,017; IC95%: -0,024; -0,009) al igual que hidatidosis (B: -0,011; IC95%: -0,013; -0,008), sólo hantavirosis mostró un aumento (no significativo). CONCLUSIÓN: La mortalidad por zoonosis de NO disminuyó durante el período estudiado; solo la hantavirosis mostró un aumento en su tendencia. Se sugiere enfocar estrategias para prevenir la transmisibilidad y mortalidad por hanta, así como mejorar el acceso a tratamiento para las otras zoonosis.

BACKGROUND: Zoonoses are diseases transmitted from an animal host to humans or vice versa. In Chile, the zoonoses of mandatory notification are brucellosis, anthrax, trichinosis, hydatidosis, leptospirosis, dengue, Chagas disease, hantavirosis and rabies. AIM: To assess the trend and characterize the mortality from zoonoses of mandatory notification in Chile between 1997-2018. METHODS: An official mortality and population data were used. Relative, general and specific mortality rates were described according to sociodemographic variables. Crude and adjusted annual mortality rates (direct method) were calculated. Temporal trend was evaluated with the Prais-Winsten regression model. RESULTS: Between 1997 and 2018, the mortality rate due to zoonosis of mandatory notification corresponded to 0.13% (2152 deaths) of the total mortality, being Chagas disease (59.2%), hydatidosis (24.6%) and hantavirosis (13.5%) the main causes. The general adjusted mortality rate decreased significantly (B: -0.017; IC95%: -0.024; -0.009) as did hydatidosis (B: -0.011; IC95%: -0.013; -0.008), and only hantavirosis showed an increase trend (not significant). CONCLUSION: Mortality due to zoonoses decreased during the period; only hantavirosis showed an increasing trend. It is suggested to focus on strategies to prevent contagion and mortality by hantavirosis, as well as to improve access to treatment for the other zoonoses.

Interferon-Inducible GTPase 1 Impedes the Dimerization of Rabies Virus Phosphoprotein and Restricts Viral Replication.

Rabies, caused by rabies virus (RABV), is an ancient zoonosis and still a major public health problem for humans, especially in developing countries. RABV can be recognized by specific innate recognition receptors, resulting in the production of hundreds of interferon-stimulated genes (ISGs), which can inhibit viral replication at different stages. Interferon-inducible GTPase 1 (IIGP1) is a mouse-specific ISG and belongs to the immunity-related GTPases (IRGs) family. IIGP is reported to constrain intracellular parasite infection by disrupting the parasitophorous vacuole membrane. However, the role of IIGP1 in restricting viral replication has not been reported. In this present study, we found that IIGP1 was upregulated in cells and mouse brains upon RABV infection. Overexpression of IIGP1 limited RABV replication in cell lines and reduced viral pathogenicity in a mouse model. Consistently, deficiency of IIGP1 enhanced RABV replication in different parts of mouse brains. Furthermore, we found that IIGP1 could interact with RABV phosphoprotein (P protein). Mutation and immunoprecipitation analyses revealed that the Y128 site of P protein is critical for its interaction with IIGP1. Further study demonstrated that this interaction impeded the dimerization of P protein and thus suppressed RABV replication. Collectively, our findings for the first reveal a novel role of IIGP1 in restricting a typical neurotropic virus, RABV, which will provide fresh insight into the function of this mouse-specific ISG.IMPORTANCE Interferon and its downstream products, ISGs, are essential in defending against pathogen invasion. One of the ISGs, IIGP1, has been found to constrain intracellular parasite infection by disrupting their vacuole membranes. However, the role of IIGP1 in limiting viral infection is unclear. In this study, we show that infection with a typical neurotropic virus, RABV, can induce upregulation of IIGP1, which, in turn, suppresses RABV by interacting with its phosphoprotein (P protein) and thus blocking the dimerization of P protein. Our study provides the first evidence that IIGP1 functions in limiting viral infection and provides a basis for comprehensive understanding of this important ISG.

A chimpanzee adenoviral vector-based rabies vaccine protects beagle dogs from lethal rabies virus challenge.

Rabies continues to poses serious threats to the public health in many countries. The development of novel inexpensive, safe and effective vaccines has become a high priority for rabies control worldwide. We previously generated a novel recombinant rabies vaccine by cloning rabies virus glycoprotein into a chimpanzee adenoviral vector, termed ChAd68-Gp. The present study evaluated the immune responses and protection afforded by this vaccine in beagle dogs. The results demonstrated that intramuscular immunization with both low-dose and high-dose of ChAd68-Gp induced strong immune responses and provided complete protection in beagles even at low-dose. However, when administered orally, high-dose vaccination was protective while low-dose vaccination was ineffective. Further investigation indicated that the low-pH value of gastric juice in the stomach of beagles might decompose the adenovirus. Therefore, suitable formulation for adenovirus-based oral vaccine should be considered and developed. The chimpanzee adenovirus-vectored rabies vaccine ChAd68-Gp warrants extensive test for clinical application.

Inhibition of MEK-ERK1/2-MAP kinase signalling pathway reduces rabies virus induced pathologies in mouse model.

The extracellular signal-regulated kinase (ERK) pathway has been shown to regulate pathogenesis of many viral infections, but its role during rabies virus (RV) infection in vivo is not clear. In the present study, we investigated the potential role of MEK-ERK1/2 signalling pathway in the pathogenesis of rabies in mouse model and its regulatory effects on pro-inflammatory cytokines and other mediators of immunity, and kinetics of immune cells. Mice were infected with 25 LD50 of challenge virus standard (CVS) strain of RV by intracerebral (i.c.) inoculation and were treated i.c. with U0126 (specific inhibitor of MEK1/2) at 10 µM/mouse at 0, 2, 4 and 6 days post-infection. Treatment with U0126 resulted in delayed disease development and clinical signs, increased survival time with lesser mortality than untreated mice. The better survival of inhibitor-treated and RV infected mice was positively correlated with reduced viral load and reduced viral spread in the brain as quantified by real-time PCR, direct fluorescent antibody test and immunohistochemistry. CVS-infected/mock-treated mice developed severe histopathological lesions with increased Fluoro-Jade B positive degenerating neurons in brain, which were associated with higher levels of serum nitric oxide, iNOS, TNF-α, and CXCL10 mRNA. Also CVS-infected/U0126-treated mice revealed significant decrease in caspase 3 but increase in Bcl-2 mRNA levels and less TUNEL positive apoptotic cells. CVS-infected/U0126-treated group also showed significant increase in CD4+, CD8+ T lymphocytes and NK cells in blood and spleen possibly due to less apoptosis of these cells. In conclusion, these data suggest that MEK-ERK1/2 signalling pathway play critical role in the pathogenesis of RV infection in vivo and opens up new avenues of therapeutics.

Efficient In Vitro and In Vivo Activity of Glyco-Engineered Plant-Produced Rabies Monoclonal Antibodies E559 and 62-71-3.

Rabies is a neglected zoonotic disease that has no effective treatment after onset of illness. However the disease can be prevented effectively by prompt administration of post exposure prophylaxis which includes administration of passive immunizing antibodies (Rabies Immune Globulin, RIG). Currently, human RIG suffers from many restrictions including limited availability, batch-to batch inconsistencies and potential for contamination with blood-borne pathogens. Anti-rabies monoclonal antibodies (mAbs) have been identified as a promising alternative to RIG. Here, we applied a plant-based transient expression system to achieve rapid, high level production and efficacy of the two highly potent anti-rabies mAbs E559 and 62-71-3. Expression levels of up to 490 mg/kg of recombinant mAbs were obtained in Nicotiana benthamiana glycosylation mutants by using a viral based transient expression system. The plant-made E559 and 62-71-3, carrying human-type fucose-free N-glycans, assembled properly and were structurally sound as determined by mass spectrometry and calorimetric density measurements. Both mAbs efficiently neutralised diverse rabies virus variants in vitro. Importantly, E559 and 62-71-3 exhibited enhanced protection against rabies virus compared to human RIG in a hamster model post-exposure challenge trial. Collectively, our results provide the basis for the development of a multi-mAb based alternative to RIG.

Human rabies in India: an audit from a rabies diagnostic laboratory.

OBJECTIVES: Rabies, an acute progressive encephalomyelitis, continues to be a serious public health problem in India and many other countries in Asia and Africa. The low level of commitment to rabies control is partly attributable to challenges in laboratory diagnosis and lack of adequate surveillance to indicate the disease burden. A laboratory audit of human rabies cases was undertaken to disseminate information on the clinical, demographic, prophylactic and most importantly the laboratory diagnostic aspects of rabies. METHODS: A retrospective analysis of all clinically suspected human rabies cases, whose samples were received at a rabies diagnostic laboratory in South India in the last 3 years, was performed. Clinical and demographic details of patients were obtained. The clinical samples included cerebrospinal fluid (CSF), serum, saliva and nuchal skin biopsy collected antemortem, and brain tissue obtained post-mortem. Various laboratory tests were performed for diagnosis. RESULTS: Clinical samples from 128 patients with suspected rabies, from 11 states in India, were received for diagnostic confirmation. About 94% of the victims reported dog-bites, more than a third of them were children and most of the victims did not receive adequate post-exposure prophylaxis. Antemortem confirmation of rabies by a combination of laboratory diagnostic assays (detection of viral RNA in CSF, skin and saliva, and neutralising antibodies in CSF) could be achieved in 40.6% cases. CONCLUSIONS: Increasing awareness about adequate post-exposure prophylaxis, additional rabies diagnostic facilities, and enhanced human and animal rabies surveillance to indicate the true disease burden are essential to control this fatal disease.

Fatal case of imported human rabies in Amadora, Portugal, August 2011.

We report on a case of imported human rabies in Portugal, in July 2011 in a woman who presented initially complaining of back pain, without relating exposure to animal bites. She had travelled from Portugal to Bissau, Guinea-Bissau, in April where she had been bitten by a dog on 1 May. She was diagnosed with rabies on 26 July and died two weeks later in spite of being treated following the Milwaukee protocol.

Intracerebral delivery of small interfering RNAs (siRNAs) using adenoviral vector protects mice against lethal peripheral rabies challenge.

To investigate the potential of RNA interference (RNAi) as antiviral agent against rabies, two small interfering RNAs (siRNAs) targeting rabies virus (RABV) nucleoprotein (N) and polymerase (L) genes were designed and evaluated. Both siRNAs knockdown or silenced the target RABV genes as evaluated in a plasmid based transient expression model. For efficient delivery, adenoviruses expressing the siRNAs were constructed and antiviral potential of the delivered siRNAs was investigated in BHK-21 cells. When cells treated with adenoviruses expressing siRNAs were challenged with RABV, there was 88.35±2.4% and 41.52±9.3% reduction in RABV multiplication in infected cells with siRNAs targeting RABV-N and L genes, respectively. Relative quantification of RABV transcripts using real-time PCR revealed knockdown of both RABV-N and L gene transcripts, however, significant reduction was observed only with adenovirus expressing siRNA against RABV-N. When mice treated intracerebrally with adenoviruses expressing siRNAs were challenged peripherally with lethal RABV by the intramuscular route in masseter muscle, there was 66.6% and 33.3% protection with adenoviruses expressing siRNAs against RABV-N and L genes, respectively. These results demonstrated that adenovirus expressing siRNA against RABV-N efficiently inhibited the RABV multiplication both, in vitro and in vivo and conferred significant protection against lethal RABV challenge. This supported the hypothesis that RNAi, based on siRNA targeting RABV-N gene can prevent RABV infection and holds the potential of RNAi as an approach to prevent rabies infection.

The type I interferon response bridles rabies virus infection and reduces pathogenicity.

Rabies virus (RABV) is a neurotropic virus transmitted by the bite of an infected animal that triggers a fatal encephalomyelitis. During its migration in the nervous system (NS), RABV triggers an innate immune response, including a type I IFN response well known to limit viral infections. We showed that although the neuroinvasive RABV strain CVS-NIV dampens type I IFN signaling by inhibiting IRF3 phosphorylation and STAT2 translocation, an early and transient type I IFN response is still triggered in the infected neuronal cells and NS. This urged us to investigate the role of type I IFN on RABV infection. We showed that primary mouse neurons (DRGs) of type I IFN(α/ß) receptor deficient mice (IFNAR(-/-) mice) were more susceptible to RABV than DRGs of WT mice. In addition, exogenous type I IFN is partially efficient in preventing and slowing down infection in human neuroblastoma cells. Intra-muscular inoculation of type I IFNAR deficient mice [IFNAR(-/-) mice and NesCre ((+/-)) IFNAR ((flox/flox)) mice lacking IFNAR in neural cells of neuroectodermal origin only] with RABV reveals that the type I IFN response limits RABV dissemination in the inoculated muscle, slows down invasion of the spinal cord, and delays mortality. Thus, the type I IFN which is still produced in the NS during RABV infection is efficient enough to reduce neuroinvasiveness and pathogenicity and partially protect the host from fatal infection.

Notificacion evento: rabia en humanos y en perro / Event Notification: rabies in humans and dogs

Una vez realizado el seguimiento y monitoreo epidemiológico del Programa Nacional de Zoonosis hacia los Programas Departamentales de los SEDES, se pudo obtener la siguiente información con relación a la situación epidemiológica y epizoótica en el país hasta la semana epidemiológica 29 de la presente gestión.

Survival after transplantation of corneas from a rabies-infected donor.

PURPOSE: To examine the tissue samples of 2 corneal recipients from a rabies-infected donor for the presence of rabies to explain their survival. METHODS: Interventional case series with a review of the literature. The explanted corneal donor buttons were examined via nested reverse transcriptase polymerase chain reaction. The patients were followed up ophthalmologically and neurologically. Antirabies antibodies were measured in blood samples, and skin biopsies were examined by direct fluorescent antibody staining. RESULTS: Two patients received corneas from the same multiorgan donor. Six weeks after transplantation, 3 of the donor's organ recipients became symptomatic and rabies virus was confirmed in tissue from the donor's central nervous system. Immediately, both the corneal recipients underwent active and passive postexposure treatment. The corneal buttons were replaced. Examination of the explanted donor corneas, skin biopsies, and serum and saliva samples showed no signs of rabies infection. The 2 corneal recipients were followed up at our hospital and, to date, are without symptoms of infection. CONCLUSIONS: Transmission of the potentially deadly rabies virus by corneal transplantation has been described previously. To our knowledge, this is the first report in which no rabies virus transmission occurred without immediate postexposure treatment.

Comportamiento epidemiológico de la rabia humana en el estado Zulia Venezuela: durante el período de vigilancia enero 1993 junio 2009 / Epidemiological Behavior of human rabies in the state of Zulia Venezuela: during the surveillance period january 1993 june 2009

La rabia representa un importante problema de salud pública en el estado Zulia, constituyendo en Venezuela la entidad con mayor incidencia de casos en animales y humanos, registrándose 25 muertes humanas por rabia durante el período enero 1993 - junio 2009. Describir su comportamiento epidemiológico durante este período constituye nuestro objetivo. Estudio epidemiológico realizado: observacional, descriptivo. La muestra incluyó todos los casos confirmados como rabia humana en la entidad durante este lapso (n = 25), con edades entre 2-57 años, de ambos sexos y procedentes de 7 municipios con incidencia. Datos tomados de los informes de casos de rabia de la Dirección Regional de Epidemiología. Los resultados están expresados en porcentajes, promedios, intervalos de confianza, tasa de letalidad y distribuciones según edad, sexo y municipio de ocurrencia. La mayor incidencia ocurrió en varones (68%). El grupo entre 2-10 años resultó mayormente afectado (60%). El 80% casos no efectuó consulta post exposición no recibiendo inmunoprofilaxia oportuna. La Inmunofluorescencia directa fue utilizada para confirmación diagnóstica. El conocimiento sobre las formas de transmisión de rabia es crucial para prevenirla; el tiempo entre la inoculación viral y la invasión neural es quizá el único período para una inmunoprofilaxia efectiva

Rabies represents a major public health problem in the State of Zulia, constituting the entitywith the highest incidence of animal and human cases in Venezuela, registering 25 human deathsby rabies from January, 1993 – June, 2009. The objective of this study is to describe its epidemiologicalbehavior during this period; the epidemiological study was observational and descriptive.The sample included all cases confirmed as human rabies in the entity during this period (n = 25);they were between 2 and 57 years of age, from both sexes and 7 municipalities. Data was takenfrom the reports of rabies cases in the Regional Epidemiology Direction. The results are expressedin percentages, means, confidence intervals, mortality rate and distributions according to age, sexand municipality of occurrence. The highest incidence was in males (68%).The group between2-10 years was principally affected (60%). Eighty per cent of the cases did not seek post-exposureconsultation and did not receive timely prophylaxis. The direct fluorescent antibody test was usedfor diagnostic confirmation. Knowledge about forms of rabies transmission is crucial for its prevention;the time between viral inoculation and neural invasion is perhaps the only period for aneffective prophylaxis

Feline rabies. ABCD guidelines on prevention and management.

OVERVIEW: Rabies virus belongs to the genus Lyssavirus, together with European bat lyssaviruses 1 and 2. In clinical practice, rabies virus is easily inactivated by detergent-based disinfectants. INFECTION: Rabid animals are the only source of infection. Virus is shed in the saliva some days before the onset of clinical signs and transmitted through a bite or a scratch to the skin or mucous membranes. The average incubation period in cats is 2 months, but may vary from 2 weeks to several months, or even years. DISEASE SIGNS: Any unexplained aggressive behaviour or sudden behavioural change in cats must be considered suspicious. Two disease manifestations have been identified in cats: the furious and the dumb form. Death occurs after a clinical course of 1-10 days. DIAGNOSIS: A definitive rabies diagnosis is obtained by post-mortem laboratory investigation. However, serological tests are used for post-vaccinal control, especially in the context of international movements. DISEASE MANAGEMENT: Post-exposure vaccination of cats depends on the national public health regulations, and is forbidden in many countries. VACCINATION RECOMMENDATIONS: A single rabies vaccination induces a long-lasting immunity. Kittens should be vaccinated at 12-16 weeks of age to avoid interference from maternally derived antibodies and revaccinated 1 year later. Although some vaccines protect against virulent rabies virus challenge for 3 years or more, national or local legislation may call for annual boosters.

[Progressive human viral encephalitis associated to a bat bite]. / Encefalitis rábica, consecutiva a mordedura de murciélago.

INTRODUCTION: Human rabies is a rapidly progressive encephalitis that is transmitted by the bites of an infected mammal. METHODS: In June 2004, a male patient was admitted to a hospital emergency department after a 5-days history of progressive right arm pain, paresthesias and muscle weakness. He reported contact with a sick bat 5 weeks before admission. He suffered steady neurologic decline with fever, confusion, disorientation, hydrophobia and aerophobia the following day. The patient died two days later. RESULTS: Postmortem histopathology showed perivascular mononuclear infiltration and extensive neuronolysis. When the fluorescent antibody technique was applied, most residual neurons were infected by the rabies virus. Lyssavirus isolation was achieved in a murine neuroblastoma cell culture. A nested reverse transcription polymerase chain reaction was positive in the patient's cerebrospinal fluid as well as the tissues of the bat Lasionycteris noctivagans. CONCLUSIONS: Clinicians should suspect rabies when unexplained progressive encephalitis is observed.

A single amino acid change in rabies virus glycoprotein increases virus spread and enhances virus pathogenicity.

Several rabies virus (RV) vaccine strains containing an aspartic acid (Asp) or glutamic acid (Glu) instead of an arginine (Arg) at position 333 of the RV glycoprotein (G) are apathogenic for immunocompetent mice even after intracranial inoculation. However, we previously showed that the nonpathogenic phenotype of the highly attenuated RV strain SPBNGA, which contains a Glu at position 333 of G, is unstable when this virus is passaged in newborn mice. While the Glu(333) remained unchanged after five mouse passages, an Asn(194)-->Lys(194) mutation occurred in RV G. This mutation was associated with increased pathogenicity for adult mice. Using site-directed mutagenesis to exchange Asn(194) with Lys(194) in the G protein of SPBNGA, resulting in SPBNGA-K, we show here that this mutation is solely responsible for the increase in pathogenicity and that the Asn(194)-->Lys(194) mutation does not arise when Asn(194) is exchanged with Ser(194) (SPBNGA-S). Our data presented indicate that the increased pathogenicity of SPBNGA-K is due to increased viral spread in vivo and in vitro, faster internalization of the pathogenic virus into cells, and a shift in the pH threshold for membrane fusion. These results are consistent with the notion that the RV G protein is a major contributor to RV pathogenesis and that the more pathogenic RVs escape the host responses by a faster spread than that of less pathogenic RVs.

Region at amino acids 164 to 303 of the rabies virus glycoprotein plays an important role in pathogenicity for adult mice.

The authors have previously reported that the glycoprotein of the pathogenic Nishigahara strain of rabies virus is required to lethality for adult mice. A cluster region of amino acid substitutions exists at the positions 164 to 303 on the glycoprotein between avirulent and virulent strains. In this study, the authors generated a chimeric strain having the region at the positions 164 to 303 of the glycoprotein derived from the pathogenic Nishigahara strain in the genetic background of the avirulent RC-HL strain. The chimeric R(G 164-303) strain restores the lethality for adult mice. This result clearly shows that the region at the position 164 to 303 of glycoprotein plays an important role in the lethality for adult mice. Moreover, the authors observed that the lethality for adult mice correlated well with the viral growth in a brain but not with the pH-dependent fusion activity in vitro.

Management of rabies in humans.

Rabies is a fatal disease in humans, and, to date, the only survivors of the disease have received rabies vaccine before the onset of illness. The approach to management of the rabies normally should be palliative. In unusual circumstances, a decision may be made to use an aggressive approach to therapy for patients who present at an early stage of clinical disease. No single therapeutic agent is likely to be effective, but a combination of specific therapies could be considered, including rabies vaccine, rabies immunoglobulin, monoclonal antibodies, ribavirin, interferon-alpha, and ketamine. Corticosteroids should not be used. As research advances, new agents may become available in the future for the treatment of human rabies.

[Effect of tumor necrosis factor alpha on the efficiency of anti-rabies vaccination]. / Vliianie faktora nekroza opukholi alpha na éffektivnost' vaktsinatsii protiv beshenstva.

Recombinant tumor necrosis factor-alpha (TNF-alpha) improved the survival of random-bred albino mice vaccinated with antirabies vaccine after infection with rabies CVS strain. The agent dose of 0.1 microgram/animal, injected 1 day postvaccination, was the most effective. Improvement of antiviral resistance of non-vaccinated mice under the effect of TNF-alpha suggests that the effect of this factor on nonspecific resistance factors is one of the probable mechanisms of its modulating effect.

Inducible nitric oxide synthase inhibition delays death of rabies virus-infected mice.

A pathophysiological mechanism of cerebral damage and impairment of neuronal function during rabies virus infection was examined. Synthesis of nitric oxide (NO) and expression of the inducible nitric oxide synthase (iNOS) gene are strongly upregulated during rabies virus infection. Treatment of rabies virus-infected mice with a selective inhibitor of iNOS, aminoguanidine (AG), significantly delayed their death. Prolonged survival was not due to suppression of an inflammatory response in the central nervous system. One effect of iNOS inhibition was at the level of viral replication. Treatment with AG delayed rabies virus replication by 2 days. Moreover, iNOS inhibition also suppressed an early phase of expression of an apoptotic gene, Caspase-1, which resulted in slow progression of infected cells into apoptotic death. iNOS inhibition had no effect on expression of the anti-apoptotic gene, bcl-2. In conclusion, iNOS inhibition delayed the death of rabies virus-infected mice by affecting viral replication and apoptotic death of infected cells.