Generation and Characterization of Closely Related Epizootic and Enzootic Infectious cDNA Clones for Studying Interferon Sensitivity and Emergence Mechanisms of Venezuelan Equine Encephalitis Virus

The host innate immune response provides a critical first line of defense against invading pathogens, inducing an antiviral state to impede the spread of infection. While numerous studies have documented antiviral responses within actively infected tissues, few have described the earliest innate response induced systemically by infection. Here, utilizing Venezuelan equine encephalitis virus (VEE) replicon particles (VRP) to limit infection to the initially infected cells in vivo, a rapid activation of the antiviral response was demonstrated not only within the murine draining lymph node, where replication was confined, but also within distal tissues. In the liver and brain, expression of interferon-stimulated genes was detected by 1 to 3 h following VRP footpad inoculation, reaching peak expression of >100-fold over that in mock-infected animals. Moreover, mice receiving a VRP footpad inoculation 6, 12, or 24 h prior to an otherwise lethal VEE footpad challenge were completely protected from death, including a drastic reduction in challenge virus titers. VRP pretreatment also provided protection from intranasal VEE challenge and extended the average survival time following intracranial challenge. Signaling through the interferon receptor was necessary for antiviral gene induction and protection from VEE challenge. However, VRP pretreatment failed to protect mice from a heterologous, lethal challenge with vesicular stomatitis virus, yet conferred protection following challenge with influenza virus. Collectively, these results document a rapid modulation of the host innate response within hours of infection, capable of rapidly alerting the entire animal to pathogen invasion and leading to protection from viral disease.

Section: Discussionmentioning

confidence: 99%

Acute Infection with Venezuelan Equine Encephalitis Virus Replicon Particles Catalyzes a Systemic Antiviral State and Protects from Lethal Virus Challenge

Konopka

Thompson

Whitmore

et al. 2009

“…The SIN/ZPC virus induced noticeably higher titers of Ab neut , and the boost immunization additionally increased Ab neut levels. This difference might be explained by the ability of ZPC738 to replicate efficiently in wild rodents, which is a distinguishing characteristic of enzootic viruses (55), and the fact that glycoprotein-coding genes were derived from the genome of this virus after a minimal number of passages in the cell culture (2).…”

Section: Recombinant Virusesmentioning

confidence: 99%

Replication and Clearance of Venezuelan Equine Encephalitis Virus from the Brains of Animals Vaccinated with Chimeric SIN/VEE Viruses

Paessler

Petrakova

et al. 2006

Self Cite

100

Venezuelan equine encephalitis virus (VEEV) is an important, naturally emerging zoonotic pathogen. Recent outbreaks in Venezuela and Colombia in 1995, involving an estimated 100,000 human cases, indicate that VEEV still poses a serious public health threat. To develop a safe, efficient vaccine that protects against disease resulting from VEEV infection, we generated chimeric Sindbis (SIN) viruses expressing structural proteins of different strains of VEEV and analyzed their replication in vitro and in vivo, as well as the characteristics of the induced immune responses. None of the chimeric SIN/VEE viruses caused any detectable disease in adult mice after either intracerebral (i.c.) or subcutaneous (s.c.) inoculation, and all chimeras were more attenuated than the vaccine strain, VEEV TC83, in 6-day-old mice after i.c. infection. All vaccinated mice were protected against lethal encephalitis following i.c., s.c., or intranasal (i.n.) challenge with the virulent VEEV ZPC738 strain (ZPC738). In spite of the absence of clinical encephalitis in vaccinated mice challenged with ZPC738 via i.n. or i.c. route, we regularly detected high levels of infectious challenge virus in the central nervous system (CNS). However, infectious virus was undetectable in the brains of all immunized animals at 28 days after challenge. Hamsters vaccinated with chimeric SIN/VEE viruses were also protected against s.c. challenge with ZPC738. Taken together, our findings suggest that these chimeric SIN/VEE viruses are safe and efficacious in adult mice and hamsters and are potentially useful as VEEV vaccines. In addition, immunized animals provide a useful model for studying the mechanisms of the anti-VEEV neuroinflammatory response, leading to the reduction of viral titers in the CNS and survival of animals.Venezuelan equine encephalitis virus (VEEV) is an enveloped virus with a nonsegmented, positive-sense RNA genome of approximately 11.4 kb and belongs to the Alphavirus genus in the Togaviridae family. The 5Ј two-thirds of the genome contains four nonstructural proteins (nsP1 to nsP4) that form an enzyme complex required for viral replication (46-48). After release of the viral genome into the cytoplasm, a nonstructural polyprotein is translated directly from this RNA and utilized in the production of a full-length, negative-sense replicative RNA intermediate (45). The full-length RNA then serves as a template for the synthesis of positive-sense genomic RNA and for transcription of a subgenomic 26S RNA (46). The approximately 4-kb-long, subgenomic RNA corresponds to the 3Ј onethird of the viral genome and is translated into a structural polyprotein that is proteolytically cleaved into the capsid and the envelope glycoproteins E2 and E1 (34). Two hundred forty copies of the capsid protein enclose the genomic viral RNA to form an icosahedral nucleocapsid that buds from the plasma membrane, acquiring a lipid envelope with embedded protein spikes formed by E1/E2 heterodimers (41, 48).Venezuelan equine encephalitis virus is a zoonotic pathogen...

“…In vitro transcription was performed as previously described (4), using the T7 RNA polymerase promoter and the m 7 G(5Ј)ppp(5Ј)G RNA cap structure analog (New England Biolabs, Beverly, MA). The RNAs were transfected into baby hamster kidney (BHK)-21 cells by electroporation, as described previously (4,42), and virus was harvested 18 to 24 h later when cytopathic effects were evident.…”

Section: Vol 82 2008 Determinants Of Eee Virus Virulence 4921 Acatcmentioning

confidence: 99%

Structural and Nonstructural Protein Genome Regions of Eastern Equine Encephalitis Virus Are Determinants of Interferon Sensitivity and Murine Virulence

Aguilar¹,

Adams

Wang

et al. 2008

Self Cite

Eastern equine encephalitis virus (EEEV) causes sporadic epidemics of human and equine disease in NorthAmerica, but South American strains have seldom been associated with human neurologic disease or mortality, despite serological evidence of infection. In mice, most North American and South American strains of EEEV produce neurologic disease that resembles that associated with human and equine infections. We identified a South American strain that is unable to replicate efficiently in the brain or cause fatal disease in mice yet produces 10-fold higher viremia than virulent EEEV strains. The avirulent South American strain was also sensitive to human interferon (