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PubMed2000

Comparison of amino acid sequences at the amino acid 130-160 region of VP1 polypeptide of Indian field isolates of foot-and-mouth disease virus serotype Asia 1.

The nucleotide and deduced amino acid sequences in the amino acid (aa) 130-160 region of VP1 polypeptide of 65 field isolates of foot- and mouth disease virus (FMDV) serotype Asia 1 were determined and the consensus sequences were deduced. Comparison of amino acid sequences revealed conservation of NGK (130-132), TYG (134-136), RGD (142-144), and LPTSF (156-160) motifs and aa 148 (L) while variation was observed at the rest of the region (variability index (VI) of 2.06 to 16.85). Synonymous and non-synonymous mutations at the nucleotide level were well correlated with those of the corresponding amino acids. Comparison of the aa 130-160 sequence of Asia 1 serotype with those of other serotypes of FMDV revealed conservation of aa 135, 148-149, 157 and 160. Amino acids 133-138 and 148-154 were unique for Asia 1 serotype and are presumably responsible for its distinct antigenic nature. The present study revealed that the FMDV isolates of serotype Asia 1 causing outbreaks in India are very much heterogeneous in the aa 130-160 region of VP1.

Amino Acid Motifs↗
PubMed2003

Curing of foot-and-mouth disease virus from persistently infected cells by ribavirin involves enhanced mutagenesis.

BHK-21 cells persistently infected with foot-and-mouth disease virus (FMDV) can be cured of virus by treatment with the antiviral nucleoside analogue ribavirin. To study whether the process involved an increase in the number of mutations in the mutant spectrum of the viral population, viral genomes were cloned from persistently infected cells treated or untreated with ribavirin. An increase of up to 10-fold in mutation frequencies associated with ribavirin treatment was observed in the viral genomes from the treated cultures as compared with parallel, untreated cultures. To address the possible mechanisms of enhanced mutagenesis, we investigated the mutagenic effects of ribavirin together with guanosine, and mycophenolic acid in the presence or absence of guanosine. Changes in the intracellular nucleotide concentrations were determined for all treatments. The results suggest that the increased mutation frequencies were not dependent on nucleotide pool imbalances or due to selection of preexisting genomes but they were produced by a mutagenic action of ribavirin.

Animals↗
PubMed1997

Evaluation of primers for PCR amplification of RNA polymerase gene sequences of foot-and-mouth disease virus.

Eight oligonucleotide primers in 7 different combinations were used to amplify 3D gene sequences of foot-and-mouth disease virus (FMDV) by reverse transcription-polymerase chain reaction (RT-PCR). Six of the primers were designed at this laboratory. All the primer combinations could specifically amplify 3D gene sequences of FMDV serotypes O, A, and C. The largest fragment amplified was of 1,393 bp and the smallest was of 208 bp in size. The 1,393 bp fragment included sequences from the preceeding P18 region of FMDV genome. The second largest fragment of 734 bp included sequences from the 3'-extracistronic region of viral genome. The remaining fragments were amplified either from the 3'- or 5'-half of the 3D gene. Specific amplification of the entire 3D gene in fragments of different size showed sequence conservation in the 3D genomic region of FMDV and usefulness of the primers reported in detecting inapparent or persistent FMDV infection in susceptible animals by RT-PCR.

Animals↗
PubMed1998

Detection and characterization of foot-and-mouth disease virus in sub-Saharan Africa.

Genomic amplification of the VP1 gene of SAT-type foot-and-mouth disease virus (FMDV) was performed with published and novel oligonucleotide primers. The primer pair with the highest SAT-type recognition (67%) was identified and selected for optimization. Modifications to primers significantly improved SAT-type detection (100%), broadened the recognition range to European (A, O and C) and Asian (Asia-1) serotypes and improved test sensitivity. In addition to being able to confirm the presence of FMDV in a clinical specimen within 6 h of receipt, the PCR product, which is amenable to nucleotide sequencing, enables genetic characterization of viruses into serotype and topotype within 48 h. VP1 gene sequence analysis of isolates from seven African countries and representative of five of the six serotypes occurring on the continent, revealed that SAT-types have the highest levels of intratypic variation. Intratypic variation for the SAT-types ranged from 34-40.4% on nucleotide level, and from 24.1-27.5% on amino acid level. In addition, the methodology presented here was shown to be useful for determining the origin and tracing the course of epizootics in both wild and domestic cloven-hoofed animals.

Africa South of the Sahara↗
PubMed2003

Stable expression of antisense RNAs targeted to the 5' non-coding region confers heterotypic inhibition to foot-and-mouth disease virus infection.

The antiviral potential of transcripts targeted to the non-coding regions (NCRs) of foot-and-mouth disease virus (FMDV) RNA have been studied during transient and constitutive expression in susceptible BHK-21 cells. Transient expression of antisense transcripts corresponding to the 5' and 3'NCRs, alone or in combination, confers specific inhibition of homologous (serotype C) virus infection in BHK-21 cells. Constitutive expression of antisense 5'NCR transcripts (5'AS) exerted higher levels of inhibition to homologous and heterologous (serotypes O, A, Asia, SAT 1, SAT 2 and SAT 3) FMDV infection, as estimated by a 10-fold reduction in virus titre in the supernatants from infected clones and by a plaque reduction assay. These inhibitions were also observed, albeit to a lesser extent, in clones stably expressing antisense 3'NCR transcripts. The antiviral response was specific for FMDV, as the picornavirus encephalomyocarditis virus was not inhibited in any of the transformed cell lines. In all cases, a correlation was found between the level of transcript expression and the extent of virus inhibition. The potential to efficiently inhibit FMDV, including isolates representing the seven serotypes, by expressing interfering 5'AS transcripts opens the possibility of developing transgenic animals with a reduced susceptibility to FMDV.

5' Untranslated Regions↗
PubMed1979

Resolution of block neutralization test curves into components of the foot-and-mouth disease virus system.

Classic neutralization studies by Fazekas de St. Groth and Webster (8) on mixtures of influenza viruses and mixtures of rabbit antisera are reinterpreted in terms of a percentage contaminant in the stock used for the dilution series. A very small amount of a different virus changes the shape of quantal assay curves considerably, but even a large amount of a different antiserum has negligible effect on the shape and merely shifts the curve along the serum dilution axis. These conclusions are the reverse of the authors, who only considered an absolute amount of another component in all dilution tubes. An artificial mixture of 2.7 percent O8 in O1 foot-and-mouth disease virus strains was tested against anti-O1 serum assaying in suckling mice. The small amount of O8 virus greatly altered the shape of the neutralization curve in the direction expected from the reanalysis of the influenza literature data. Results from artificial mixtures are used to explain what were hitherto anomalously broad neutralization curves for some other foot-and-mouth disease strains given by Booth et al. (1) Many of the virus stocks studied can now be postulated as a natural mixture of related virus strains. In fact, the O1 and O8 stocks used might also be of themselves mixtures. These virus strains also exhibit still a further test complication in that the virus-antibody reaction appeared to shift away from complexes on dilution immediately prior to assay.

Antigen-Antibody Reactions↗
PubMed1986

Foot-and-mouth disease virus (FMDV) experimental infection: susceptibility and immune response of adult mice.

Adult mice are susceptible to foot-and-mouth disease virus (FMDV) infection only under some experimental conditions. This paper report the results of pathogenesis studies on 4 different strains of mice (CF1, C3H, NIH-nude, BALB-c/J) infected with the cloned and uncloned 0(1)C strain of FMDV. High virus titers were detected in blood and pancreas 12-24 h after infection (p.i.); these persisted for up to 48 h p.i. in CF1 and BALB-c/J mice and 72 h p.i. in the two other mouse strains. Virus titers observed in other organs were lower than those found in blood. In pancreas, and occasionally in salivary glands, oropharynx, heart and testicles, viral antigen was detected by direct immunofluorescent assay. Circulating neutralizing antibodies appeared in CF1 and C3H mice at 72 and 96 h p.i. respectively, and their titers remained unchanged during the 30-day experimental period. Antibodies against viral infection-associated antigen (VIA) were detected for a shorter period. In animals irradiated with 1 LD 50 (total body irradiation), viremia persisted up to 14 days p.i. and a low antibody response was observed which began at the end of viremia. No differences in the response of mice to cloned or uncloned FMDV were observed.

Animals↗
PubMed2003

Vaccines and companion diagnostic tests for foot-and-mouth disease virus. An overview of the experience in South America.

Vaccination constitutes an important control policy for foot-and-mouth disease (FMD) in affected areas with advanced eradication programmes, as well as in free regions that decide to use immunization as a control measure after a recent introduction of the disease. However, considering that vaccinated animals exposed to FMD virus can establish sub-clinical infection and eventually remain persistently infected, availability of tools to identify sub-clinical infection and its silent transmission within and between herds, regardless of their vaccination state, is of utmost importance. In response to the need for new diagnostic tools to support the eradication campaigns implemented in 1988 in South America, during the past decade we have developed, validated and applied a highly sensitive and specific immuno-enzymatic system for recognition of persistence at a herd level. The system is based on the detection of antibodies against non-capsid proteins required for viral replication. These proteins, in principle, are removed from the viral suspensions destined for production of BEI inactivated vaccines. Within the validation steps, evaluation of potential induction of antibodies to non-capsid proteins caused by traces of these proteins eventually remaining in the vaccines was a major concern. This report presents a review on the experience gathered through the application of the system to various experimental and field immunization conditions. It was concluded that vaccination is not expected to induce antibody responses to non-capsid proteins that could lead to misinterpretation of serological investigations. Progress on the development of approaches towards vaccine certification to guarantee absence of interference will be discussed.

Animals↗
PubMed2001

The early pathogenesis of foot-and-mouth disease in pigs infected by contact: a quantitative time-course study using TaqMan RT-PCR.

Foot-and-mouth disease (FMD) is a highly contagious, economically important virus disease of cloven-hoofed animals. The objective of the present study was to examine the early pathogenesis of FMD in pigs by a quantitative time-course study. Under experimental conditions, recipient pigs were infected by contact with donor pigs affected by FMD. Every 24 h from day 1 to day 4 after exposure, two recipient pigs were selected randomly, killed and necropsied. A range of tissues were analysed by a quantitative TaqMan RT-PCR method and by titration of FMD virus on primary bovine thyroid cells. The titres of virus determined by assay in cell culture and calculated from the quantitative TaqMan data correlated strongly (r>0.9), thereby establishing the validity of the TaqMan calculations. The data indicated that the replication of virus in the lungs contributes only in small part to airborne virus excretion. Sites in the pharynx, trachea and nasal mucosa are probably more important in that regard. The sites of earliest virus infection and possibly replication in recipient pigs appeared to be in the pharynx (soft palate, tonsil and floor of pharynx). The data indicated that FMD virus replication in pigs is rapid and that the majority of virus amplification occurs in the skin. A model for the progression of infection is proposed, indicating initial spread from the pharyngeal region, through regional lymph nodes and via the blood to epithelial cells, resulting in several cycles of virus amplification and spread.

Animals↗
PubMed2004

Characterization of foot-and-mouth disease serotype asial viruses grown in the presence of polyclonal antisera in serology and nucleotide sequence analysis.

Foot-and-mouth disease viruses (FMDV) have a high rate of mutation and spontaneous mutants can be readily. isolated in the laboratory. In this study, plaque purified FMDV Asial vaccine strains (IND 63/72 and IND 491/97) were passaged in-vitro in Baby Hamster Kidney-21 cell monolayers in the presence of sub-neutralizing levels of antiviral polyclonal sera (APS), raised in guinea pigs against the purified and inactivated whole virus particles of IND 63/72, IND 491/97 and IND 13/01. After serial passages under selective immune pressure, the viruses starts growing in the presence of undiluted sera and showed certain characteristics like an increased resistance to neutralization by APS and reduction in plaque counts on titration in plaque assay. Cross-neutralization of these viruses with above-mentioned APS revealed selection of three complete and one partial polyclonal antibody resistant (PAR) viruses based on the 'r' value in micro neutralization test. Alterations were detected at several amino acid residues in the structural protein-coding P1 region. Many of the residues inferred to be positively selected sites in other serotypes of this virus were also prone to substitution under immune selection pressure in Asia1 virus. The present work extends the finding that selection exerted by host antibody also plays a major role in the rapid evolution of FMDV Asia1, as observed in other serotypes.

Amino Acid Sequence↗
PubMed2004

Integrin alphavbeta8 functions as a receptor for foot-and-mouth disease virus: role of the beta-chain cytodomain in integrin-mediated infection.

Field isolates of foot-and-mouth disease virus (FMDV) have been shown to use three alphav integrins, alphavbeta1, alphavbeta3, and alphavbeta6, as cellular receptors. Binding to the integrin is mediated by a highly conserved RGD motif located on a surface-exposed loop of VP1. The RGD tripeptide is recognized by several other members of the integrin family, which therefore have the potential to act as receptors for FMDV. Here we show that SW480 cells are made susceptible to FMDV following transfection with human beta8 cDNA and expression of alphavbeta8 at the cell surface. The involvement of alphavbeta8 in infection was confirmed by showing that virus binding and infection of the transfected cells are inhibited by RGD-containing peptides and by function-blocking monoclonal antibodies specific for either the alphavbeta8 heterodimer or the alphav chain. Similar results were obtained with a chimeric alphavbeta8 including the beta6 cytodomain (alphavbeta8/6), showing that the beta6 cytodomain can substitute efficiently for the corresponding region of beta8. In contrast, virus binding to alphavbeta6 including the beta8 cytodomain (alphavbeta6/8) was lower than that of the wild-type integrin, and this binding did not lead to infection. Further, the alphavbeta6 chimera was recognized poorly by antibodies specific for the ectodomain of alphavbeta6 and displayed a relaxed sequence-binding specificity relative to that of wild-type integrin. These data suggest that the beta6 cytodomain is important for maintaining alphavbeta6 in a conformation required for productive infection by FMDV.

Animals↗
PubMed2004

A global virtual network for foot-and-mouth disease in case of emergency.

The use of emergency vaccination is considered in different contingency national plans as part of a foot-and-mouth disease (FMD) control strategy in countries whether vaccination is practised or not. The development of the inter-governmental and national FMD vaccine and antigen banks and some technical and operational problems that could affect their efficiency are analysed. The possibility of improving and implementing a more rational use of the antigen and vaccine banks through the creation of a Global Virtual Network of Vaccine and Antigen Banks is discussed.

Animals↗
PubMed2005

The foot-and-mouth disease epidemic in Dumfries and Galloway, 2001. 2: Serosurveillance, and efficiency and effectiveness of control procedures after the national ban on animal movements.

After the foot-and-mouth disease (FMD) epidemic in Dumfries and Galloway in south-west Scotland in 2001, serosurveillance of sheep remaining in the 3 km radius Protection Zones around Infected Premises (IPS), and within a 10 km radius of IPS, revealed no evidence of infection. The epidemic was brought under control by a range of traditional techniques: slaughter of all animals on IPS and of veterinary-assessed Dangerous Contacts (DCS), movement restrictions, biosecurity, tracing of potential sources and spread of virus, and surveillance of At-Risk premises. Novel pre-emptive slaughter of FMD-susceptible animals on premises contiguous to IPS, and small ruminants and pigs on premises within 3 km of IPSs, commenced after the epidemic had peaked. Most of the traditional control procedures were undertaken quickly and with appropriate priority. Animals on IPS were usually slaughtered within one day of confirmation, and veterinary-assessed DCS within two days of confirmation of relevant IPS (a median of two days). The pre-emptive contiguous and 3 km culls took somewhat longer (medians of five and 17 days, respectively). IPS were most commonly identified as a result of reporting by farmers or their veterinarians (72 per cent of IPS); veterinary clinical patrols identified 16 per cent, while veterinary assessment of DCS and tracing each identified 5 per cent. No evidence of infection was found on any pre-emptively contiguously culled premises, and IPS were declared only on three 3 km cull premises. The time from estimated first lesion to end of slaughter on an IP was found, by regression analysis, to be a key component in effective control, manifested by a reduction in the estimated dissemination rate (EDR); there was little evidence that the intensity of contiguous culling affected the EDR. Patrols and serological surveillance of residual animals within 10 km of IPS, supported by more extensive evidence from elsewhere in the UK, suggested that cryptic infection in sheep was not widespread. Ultimately, there was insufficient evidence to support the effectiveness of 3 km pre-emptive culling as a control procedure.

Abattoirs↗
PubMed2004

Comparison of immune responses against foot-and-mouth disease virus induced by fusion proteins using the swine IgG heavy chain constant region or beta-galactosidase as a carrier of immunogenic epitopes.

Previously, we demonstrated that a fusion protein (Gal-FMDV) consisting of beta-galactosidase and an immunogenic peptide, amino acids (141-160)-(21-40)-(141-160), of foot-and-mouth disease virus (FMDV) VP1 protein induced protective immune responses in guinea pigs and swine. We now designed a new potential recombinant protein vaccine against FMDV in swine. The immunogenic peptide, amino acids (141-160)-(21-40)-(141-160) from the VP1 protein of serotype O FMDV, was fused to the carboxy terminus of a swine immunoglobulin G single heavy chain constant region and expressed in Escherichia coli. The expressed fusion protein (IgG-FMDV) was purified and emulsified with oil adjuvant. Vaccination twice at an interval of 3 weeks with the emulsified IgG-FMDV fusion protein induced an FMDV-specific spleen proliferative T-cell response in guinea pigs and elicited high levels of neutralizing antibody in guinea pigs and swine. All of the immunized animals were efficiently protected against FMDV challenge. There was no significant difference between IgG-FMDV and Gal-FMDV in eliciting immunity after vaccination twice in swine. However, when evaluating the efficacy of a single inoculation of the fusion proteins, we found that IgG-FMDV could elicit a protective immune response in swine, while Gal-FMDV only elicited a weak neutralizing activity and could not protect the swine against FMDV challenge. Our results suggest that the IgG-FMDV fusion protein is a promising vaccine candidate for FMD in swine.

Animals↗
PubMed2003

The foot-and-mouth disease epidemic of 2001 in the UK: implications for the USA and the ""war on terror".

While there is no evidence to suggest that the recent epidemic of foot-and-mouth disease (Fmd) in the Uk and its subsequent spread to continental Europe were caused by bioterrorism, the extent of the epidemic shows that Fmd could be a very powerful weapon for a bioterrorist wishing to cause widespread disease in livestock and economic disruption for the targeted country. This paper describes the epidemic. It then examines the contentious issues that arose through the use of extensive slaughter to control the epidemic and explores how, in turn, the concerns of society are being translated into a radical change in policy within the European Union with respect to the control of Fmd and other foreign animal diseases. The crisis generated by the Fmd epidemic in Europe in 2001 provides many lessons to be learned for the US and highlights the need for creative thinking in research and teaching within colleges of veterinary medicine to more effectively address the threat of epidemic diseases under the "new world order." There is general agreement that the veterinary profession in the US plays a unique role in protecting the nation against epidemic livestock diseases, whether caused naturally or through bioterrorism. The profession also has a significant role in protecting the public's health, since several epidemic diseases of animals, such as rift valley fever, are zoonotic. However, improved financial support at the federal and state levels is urgently needed to support epidemic-diseases research and teaching in colleges of veterinary medicine.

Animals↗
PubMed2002

Managing compensation for economic losses in areas surrounding foot and mouth disease outbreaks: the response of France.

This article describes the French scheme for providing compensation to stock farmers located in the prevention and surveillance zones in the vicinity of foot and mouth disease (FMD) outbreak sites and for economic losses suffered as a result of restrictions on animal and animal product movement. As early as 1991, the Groupements de Defense Sanitaire (GDS: Animal Health Groups--associations of stock farmers dealing with health issues, recognised under French law) set up a Compensation Fund that was put to use during the FMD episode of 2001. The Fund paid out FRF6,488,000 (Euro989,000) to stockbreeders in the five affected departments (French local administrative divisions). Based on the principle of a national mutual benefit society, the Compensation Fund is the first instance of a system of private compensation, outside of conventional insurance schemes, based on a convention between French stock farmers. With decentralised management and speed of implementation, the Compensation Fund has proved its worth. The Fund now needs to be adjusted on the basis of changes introduced in FMD control policy in France and possibly the European Union.

Animals↗
PubMed1993

Potency control of foot-and-mouth disease vaccine in cattle. Comparison of the 50% protective dose and the protection against generalization.

Potency tests of a total of 658 foot-and-mouth disease (FMD) vaccine batches by bovine protective dose (PD50) showed that 22% of the tests did not follow the expected theoretical model and the results could not be interpreted because of the lack of a dose-response relationship. The protection against generalization (PG) method, using undiluted vaccine, proved to be highly reliable from the analysis of the results of 65 replicate potency tests of three hydroxide-saponin (HS) vaccines and two oil-adjuvanted (OL) vaccines. The PG results were consistent in 64 out of the total of 65 tests. The data obtained indicated that, with regard to direct tests in cattle, the PG test is the preferred method for FMD vaccine potency control. This study also showed that the incorporation of a reference vaccine in routine potency tests is essential to ensure normality of the test system and that good quality HS and OL FMD vaccines may maintain immunogenic stability for at least 27 and 36 months, respectively, when stored at 2-8 degrees C.

Animals↗