Phylogenetic analysis of segment 10 from African horsesickness virus and cognate genes from other orbiviruses

Utilizing the reverse transcriptase-polymerase chain reaction (RT-PCR) procedure, we have synthesized full-length copies of segment 10 from African horsesickness virus (AHSV) serotypes 1,4 and 8. The genes were cloned, sequenced and compared with the sequence of the cognate gene from AHSV serotypes 3 and 9. Sequences were analyzed to assess evolutionary relationships among serotypes using cladistics. Based on this analysis the data support a close relationship between serotypes 4 and 9 and between serotypes 1 and 8 and a closer relationship of serotype 3 to the 4 and 9 group

Identification of the Active-Site Residues of the 3C Proteinase of Foot-and-Mouth Disease Virus

AbstractTo identify the active-site residues of the 3C proteinase of foot-and-mouth disease virus (FMDV), we introduced mutations into the 3C coding region and examined the activity of mutant enzymes on various substrates. Based on alignment of FMDV 3C with other picornavirus 3C proteinases and with the trypsin family of serine proteinases, mutations were introduced at residues presumed to be part of the catalytic triad, involved in substrate binding, or present in nonconserved regions. Wild-type and mutant 3C proteins were expressed inEscherichia coliand tested for their ability to cleave synthetic substrates corresponding to different portions of the viral genome. Substitutions at His-46 (catalytic triad), Asp-84 (catalytic triad), or His-181 (substrate binding) produced enzymes unable to process P1, P2, or P3 substratesin trans,whereas a change in the conserved Asp-98 had no effect on enzyme activity. Substitution of Ser for Cys-163 (catalytic triad) yielded an enzyme that retained activity on some substrates, while a substitution of Gly at this position resulted in a completely inactive enzyme. The kinetics oftransprocessing of translation products from a transcript encoding the P1 and P2 coding regions and the 2C/3A cleavage site with wild-type 3C or a transcript encoding P1 with 3C mutants revealed that the order of cleavage was VP3-VP1, VP0-VP3, VP1-2A, 2C-3A, and 2B-2C. Mutations in 3C that resulted in a partially active enzyme were individually introduced into full-length FMDV cDNA and RNA transcripts were translated in a cell-free system and used to transfect cells. In all cases the virus that was rescued had reverted to the wild-type 3C codon

Venezuelan Equine Encephalitis Replicon Particles Can Induce Rapid Protection against Foot-and-Mouth Disease Virus

We have previously shown that delivery of the porcine type I interferon gene (poIFN-α/β) with a replication-defective human adenovirus vector (adenovirus 5 [Ad5]) can sterilely protect swine challenged with foot-and-mouth disease virus (FMDV) 1 day later. However, the need of relatively high doses of Ad5 limits the applicability of such a control strategy in the livestock industry. Venezuelan equine encephalitis virus (VEE) empty replicon particles (VRPs) can induce rapid protection of mice against either homologous or, in some cases, heterologous virus challenge. As an alternative approach to induce rapid protection against FMDV, we have examined the ability of VRPs containing either the gene for green fluorescent protein (VRP-GFP) or poIFN-α (VRP-poIFN- α) to block FMDV replication in vitro and in vivo. Pretreatment of swine or bovine cell lines with either VRP significantly inhibited subsequent infection with FMDV as early as 6 h after treatment and for at least 120 h posttreatment. Furthermore, mice pretreated with either 107 or 108 infectious units of VRP-GFP and challenged with a lethal dose of FMDV 24 h later were protected from death. Protection was induced as early as 6 h after treatment and lasted for at least 48 h and correlated with induction of an antiviral response and production of IFN- α. By 6 h after treatment several genes were upregulated, and the number of genes and the level of induction increased at 24 h. Finally, we demonstrated that the chemokine IP-10, which is induced by IFN- α and VRP-GFP, is directly involved in protection against FMDV

The Presence of Alpha Interferon at the Time of Infection Alters the Innate and Adaptive Immune Responses to Porcine Reproductive and Respiratory Syndrome Virus

Porcine reproductive and respiratory syndrome (PRRS) is one of the most devastating and costly diseases to the swine industry worldwide. Overall, the adaptive immune response to PRRS virus (PRRSV) is weak, which results in delayed elimination of virus from the host and inferior vaccine protection. PRRSV has been shown to induce a meager alpha interferon (IFN-α) response, and we hypothesized that elevated IFN-α levels early in infection would shorten the induction time and increase elements of the adaptive immune response. To test this, we measured both antibody and cell-mediated immunity in pigs after the administration of a nonreplicating human adenovirus type 5 vector expressing porcine IFN-α (Ad5–pIFN-α) at the time of PRRSV infection and compared the results to those for pigs infected with PRRSV alone. Viremia was delayed, and there was a decrease in viral load in the sera of pigs administered the Ad5–pIFN-α. Although seroconversion was slightly delayed in pigs receiving Ad5–pIFN-α, probably due to the early reduction in viral replication, little difference in the overall or neutralizing antibody response was seen. However, there was an increase in the number of virus-specific IFN-γ-secreting cells detected in the pigs receiving Ad5–pIFN-α, as well as an altered cytokine profile in the lung at 14 days postinfection, indicating that the presence of IFN-α at the time of infection can alter innate and adaptive immune responses to PRRSV

Foot-and-Mouth Disease

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals. The disease was initially described in the 16th century and was the first animal pathogen identified as a virus. Recent FMD outbreaks in developed countries and their significant economic impact have increased the concern of governments worldwide. This review describes the reemergence of FMD in developed countries that had been disease free for many years and the effect that this has had on disease control strategies. The etiologic agent, FMD virus (FMDV), a member of the Picornaviridae family, is examined in detail at the genetic, structural, and biochemical levels and in terms of its antigenic diversity. The virus replication cycle, including virus-receptor interactions as well as unique aspects of virus translation and shutoff of host macromolecular synthesis, is discussed. This information has been the basis for the development of improved protocols to rapidly identify disease outbreaks, to differentiate vaccinated from infected animals, and to begin to identify and test novel vaccine candidates. Furthermore, this knowledge, coupled with the ability to manipulate FMDV genomes at the molecular level, has provided the framework for examination of disease pathogenesis and the development of a more complete understanding of the virus and host factors involved

Nuevas aproximaciones hacia el control de la fiebre aftosa: antivirales y nuevas vacunas New approaches to control foot-and-mouth disease: antivirals and novel vaccines

La fiebre aftosa es una enfermedad viral altamente contagiosa, que afecta a los animales de pezuña hendida y produce pérdidas económicas importantes, afectando el comercio internacional pecuario de los países que la padecen. En la actualidad las medidas de control para esta enfermedad incluyen la restricción del movimiento de animales susceptibles, el sacrificio de animales infectados y aquellos susceptibles que entran en contacto con los infectados, la desinfección y la posible vacunación con un antígeno viral completo inactivado. No obstante, existen varios problemas con el uso de las vacunas disponibles durante los brotes en países que habían sido considerados previamente libres de la enfermedad. Como resultado de lo anterior, los países que vacunan, enfrentan una demora significativa en obtener nuevamente el estado de “país libre” de fiebre aftosa, a diferencia de aquellos que no vacunan y deciden sacrificar todos sus animales infectados o los susceptibles que se exponen a la infección. Los científicos han estado tratando de desarrollar nuevas vacunas para superar las limitaciones de las actuales vacunas inactivadas, a la vez que se intentan desarrollar nuevos métodos para inducir una respuesta inmune protectora más rápida. En este documento se discuten, nuevas vacunas que son más efectivas para controlar la fiebre aftosa e igualmente, estrategias antivirales novedosas que están actualmente en investigación.Foot and mouth disease (FMD) is a highly contagious viral-induced disease of cloven-hoofed animals that results in serious economic consequences in affected countries that have a significant international livestock trade. Currently disease control measures include inhibition of susceptible animal movement, slaughter of infected and susceptible in-contact animals, disinfection, and possibly vaccination with an inactivated whole virus antigen. However, there are a number of problems with use of the current vaccine in outbreaks in countries which have been previously free of FMD. As a result countries which vaccinate face a longer delay in regaining FMD-free status than countries which do not vaccinate but rather slaughter all infected or susceptible in-contact animals. Researchers have been attempting to develop both new FMD vaccines to overcome the limitations of the current inactivated vaccine as well as methods to more rapidly induce a protective response. In this manuscript I discuss the most effective new FMD vaccines and novel antiviral strategies that are currently being examined

New approaches to control foot-and-mouth disease: antivirals and novel vaccines

Foot and mouth disease (FMD) is a highly contagious viral-induced disease of cloven-hoofed animals that results in serious economic consequences in affected countries that have a significant international livestock trade. Currently disease control measures include inhibition of susceptible animal movement, slaughter of infected and susceptible in-contact animals, disinfection, and possibly vaccination with an inactivated whole virus antigen. However, there are a number of problems with use of the current vaccine in outbreaks in countries which have been previously free of FMD. As a result countries which vaccinate face a longer delay in regaining FMD-free status than countries which do not vaccinate but rather slaughter all infected or susceptible in-contact animals. Researchers have been attempting to develop both new FMD vaccines to overcome the limitations of the current inactivated vaccine as well as methods to more rapidly induce a protective response. In this manuscript I discuss the most effective new FMD vaccines and novel antiviral strategies that are currently being examined