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PubMed2002

The effects of gamma interferon on replication of foot-and-mouth disease virus in persistently infected bovine cells.

Foot-and-mouth disease virus (FMDV) causes a highly contagious viral disease of cloven-hoofed animals, which has a considerable socio-economic impact on the countries affected. In addition, persistent infection can occur following clinical or sub-clinical disease in either vaccinated or non-vaccinated cattle. The mechanism(s) by which FMDV persistence is established and maintained is not fully understood. To better understand the basic mechanisms controlling the virus infection in cattle, the effects of interferon gamma (IFN-gamma) on the replication of FMDV was evaluated in vitro in persistently infected-epithelial cells isolated from FMDV infected cattle. Initially primary bovine thyroid (BTY) cells were treated with varying doses of bovine recombinant IFN-gamma. The cytokine activity was measured by detection of viral antigen in cell supernatants and viral RNA expression compared with cells without INF-gamma treatment. Pretreatment with IFN-gamma profoundly affected FMDV growth in BTY cells. The replication of FMDV was affected in the presence of more than 2.5 u/ml of IFN-gamma and the effect was both dose-dependent and related to the time of exposure. Analysis of the mechanism of inhibition suggests that IFN-gamma did not inhibit the viral replication through induction of nitric oxide. More interesting is the finding that continuous treatment with IFN-gamma severely restricts FMDV replication or even cures persistently infected bovine epithelial cells, indicating that a cytokine-mediated pathway may be involved in the in vivo clearance of persistent FMDV.

Animals↗
PubMed1999

Protective immune response to 16 kDa immunoreactive recombinant protein encoding the C-terminal VP1 portion of Foot and Mouth Disease Virus type Asia 1.

Recombinant protein of Foot and Mouth Disease Virus (FMDV) type Asia 1 corresponding to the C-terminal half of VP1 was expressed in Escherichia coli. As an alternative to the synthetic peptide, this selected C-terminal region was used as a protein vaccine in guinea pigs in order to study the immune response with various adjuvant formulations: immune stimulatory complexes (ISCOMs), Montanide ISA 206, Freund's incomplete adjuvant (FIA), lipopolysaccharide (LPS) and cytokine mixture. A primary dose of 40 microg/animal followed by a booster of the same dose was injected after a 21-day interval. The sera were collected at intervals of 21, 42 and 63 days after the booster. The humoral response to vaccine was monitored by sandwich enzyme-linked immunosorbent assay (ELISA) and a serum neutralization test (SNT). The guinea pig sera showed high titers both in ELISA and SNT, which could be protective. Further, irrespective of the adjuvant preparation used, the vaccine conferred protection against the challenge virus 105 days post-vaccination in 13 of 15 animals (86%). The results indicated that a combination of recombinant protein ISCOMs and Montanide ISA 206 would be a better choice for achieving early protective titers and longer lasting immunity and that the C-terminal half of the VP1 protein may be tried as a safe vaccine for secondary immunization.

Animals↗
PubMed2005

Dioxins and polychlorinated biphenyls (PCDD/Fs and PCBs) in food from farms close to foot and mouth disease animal pyres.

To control the outbreak of foot and mouth disease, which occurred in the UK in early 2001, a large number of farm animals were slaughtered. Where it was not possible to render or landfill the carcasses, they were destroyed by burning on open pyres, with wood, coal and other materials. Uncontrolled combustion such as this is known to produce small quantities of dioxins and an investigation was made into whether, as a result of the burning, there was an elevation in the concentrations of these compounds in food produced in the areas close to the pyres. With few exceptions, concentrations of PCDD/Fs and PCBs were within the expected ranges as predicted by reference data. No accumulation over time was evident from a repeat milk sampling exercise. Where elevated concentrations of PCDD/Fs and PCBs were found in chickens and eggs, they were in samples not destined for the food chain. Elevated levels in some samples of milk from Dumfries and Galloway were not found in earlier or later samples and may have been found as a result of a temporary feeding regime. Elevated concentrations in lamb from Carmarthenshire were from very young animals which would not have entered the food chain. There was no evidence of any significant increase in dietary exposure to PCDD/Fs and PCBs as a result of the FMD pyres.

Agriculture↗
PubMed2004

The ultrastructure of the developing replication site in foot-and-mouth disease virus-infected BHK-38 cells.

Foot-and-mouth disease virus (FMDV) is the type species of the Aphthovirus genus of the Picornaviridae: Infection by picornaviruses results in a major rearrangement of the host cell membranes to create vesicular structures where virus genome replication takes place. In this report, using fluorescence and electron microscopy, membrane rearrangements in the cytoplasm of FMDV-infected BHK-38 cells are documented. At 1.5-2.0 h post-infection, free ribosomes, fragmented rough endoplasmic reticulum, Golgi and smooth membrane-bound vesicles accumulated on one side of the nucleus. Newly synthesized viral RNA was localized to this region of the cell. The changes seen in FMDV-infected cells distinguish this virus from other members of the Picornaviridae, such as poliovirus. Firstly, the collapse of cellular organelles to one side of the cell has not previously been observed for other picornaviruses. Secondly, the membrane vesicles, induced by FMDV, appear distinct from those induced by other picornaviruses such as poliovirus and echovirus 11 since they are relatively few in number and do not aggregate into densely packed clusters. Additionally, the proportion of vesicles with double membranes is considerably lower in FMDV-infected cells. These differences did not result from the use of BHK-38 cells in this study, as infection of these cells by another picornavirus, bovine enterovirus (a close relative of poliovirus), resulted in morphological changes similar to those reported for poliovirus-infected cells. With conventional fixation, FMDV particles were not seen; however, following high-pressure freezing and freeze-substitution, many clusters of virus-like particles were seen.

Animals↗
PubMed1989

Analysis of neutralizing antigenic sites on the surface of type A12 foot-and-mouth disease virus.

A series of seven neutralizing monoclonal antibodies (nMAbs) directed against type A12 foot-and-mouth disease virus was used to generate neutralization-resistant variants. Both plaque reduction neutralization and microneutralization assays showed that the variants were no longer neutralized by the nMAbs used to generate them, although some of the variants still reacted with the nMAbs at high antibody concentrations. Results of cross-neutralization studies by both plaque reduction neutralization and microneutralization assays suggested the presence of at least one immunodominant antigenic site on the surface of type A12 foot-and-mouth disease virus, along with evidence of a second antigenic site on the viral surface. Two of the variants had reduced virulence in tissue culture as evidenced by their inability to inhibit cellular protein synthesis and a marked reduction in virus-induced cellular morphological alterations. Nucleotide sequencing of the variant genomes placed three epitopes of the major antigenic site on VP1 and the fourth epitope on VP3 and VP1. The one epitope of the minor site appears to reside only on VP1.

Amino Acid Sequence↗
PubMed2002

The foot and mouth disease (FMD) epidemic in the United Kingdom 2001.

The foot and mouth disease epidemic commenced in February 2001 when diseased pigs were identified in an abattoir. The infection had become widespread in sheep in England and Wales before this discovery. It was decided to eradicate the disease by slaughter rather than use vaccine. The virus was a Pan-Asia O strain that caused few lesions in sheep and this made the identification of infected flocks very difficult leading to a long drawn-out epidemic. Over four million animals were slaughtered in 2000 herds and flocks. The last outbreak was in September.

Animals↗
PubMed2002

Serial passage of foot-and-mouth disease virus in sheep reveals declining levels of viraemia over time.

If an infectious agent is to maintain itself within a closed population by means of an unbroken serial chain of infections, it must maintain the level of infectiousness of individuals through time, or termination of the transmission chain is inevitable. One possible cause of diminution in infectiousness along serial chains of transmission may be that individuals are unable to amplify and transmit comparable levels of the infectious agent. Here, the results are reported of a novel experiment designed specifically to assess the effects of serial passage of foot-and-mouth disease virus (FMDV) in experimental groups of sheep. A virus isolate taken from an epidemic of foot-and-mouth disease (FMD) characterized by rapid fade-out of infection was passed serially through four groups of sheep housed in an isolation unit. Although it was not possible to measure individual infectiousness directly, blood virus load from infected individuals was quantified using a real-time PCR assay and used as an underlying indicator of the level of infection. The results of this assay concurred well with those of the traditional tissue-culture assay and were shown to be highly repeatable. The level of peak viraemia was shown to fall significantly with the time of infection and with passage group, both in terms of the group mean and regression analysis of individual values, suggesting that this isolate of FMDV may, under certain conditions, be unable to maintain itself indefinitely in susceptible sheep populations. The results of these experiments are discussed in terms of the epidemiology of FMD in sheep.

Animals↗
PubMed2002

Isolation of foot-and-mouth disease virus from Japanese black cattle in Miyazaki Prefecture, Japan, 2000.

Four outbreaks of foot-and-mouth disease (FMD) occurred from March to May 2000 in Miyazaki and Hokkaido Prefectures, Japan. FMD virus isolation was achieved by sampling probang materials from Japanese Black cattle in the third case found in Miyazaki Prefecture. The probang materials were inoculated to bovine kidney (BK) and bovine thyroid cell cultures. CPE was observed in the BK at two days post-inoculation. Specific amplified DNA segments for FMD virus (FMDV) were detected by reverse transcriptase polymerase chain reaction in the culture fluid. The FMDV was identified as type O by enzyme-linked immunosorbent assay (ELISA) for antigen detection and the nucleotide sequence encoding the VPI was determined. This FMDV is a strain that is widespread in Pan-Asia and was designated as O/JPN/2000 by the World Reference Laboratory of the Pirbright Institute, England. This report marks the first isolation of FMDV in Japan.

Animals↗
PubMed2002

Phylogenetic analysis of serotype A foot-and-mouth disease virus isolated in India between 1977 and 2000.

The genetic diversity among the Indian serotype A Foot-and-mouth disease virus (FMDV) isolates sampled over a period of 24 years (1977-2000) was studied by sequencing the VP1 gene. In the phylogenetic tree, constructed from 83 Indian and 37 other available sequences, the FMDV type A isolates were distributed into 10 major genotypes (designated as I-X). The Indian isolates were distributed in 4 genotypes (I, IV, VI and VII), and co-circulation of at least 2 genotypes (VI and VII) in different states of the country in recent years is evident from the result. The study also revealed differential geographic distribution of genotypes, for example, some (genotypes I and VII) were recovered from large geographical areas, some time even across the continents, suggesting the spread of the viruses beyond continental barriers. Localization of genotypes restricting to a particular country (genotypes III and X) was also observed in the study. The genetic diversity in the field isolates has been discussed in relation to the amino acid substitutions at the known antigenic sites. This work provides valuable insights into the epidemiological situation of type A FMDV in India and necessary information in the selection of suitable vaccine strain(s), if required, for the National FMD control program.

Amino Acid Sequence↗
PubMed2003

Immunogenicity of plasmids encoding T and B cell epitopes of foot-and-mouth disease virus (FMDV) in swine.

In this work, we have investigated the immune response in pigs to two recombinant plasmids containing immunodominant neutralizing antibody epitopes of foot-and-mouth disease virus structural protein (VP1) coexpressed with viral non-structural proteins as a source of T cell epitopes. The plasmid pcDNA3.1/3D15 contained a sequence coding for the 3D polymerase upstream of a sequence coding for peptide FMDV15, a peptide derived from VP1, previously shown to stimulate protective immunity to foot-and-mouth disease virus (FMDV), that consisted of the carboxy terminal peptide [VP1(200-213)] linked by ProProSer to the "loop" peptide [VP1(143-160)] and terminating in CysGly. The plasmid, pcDNA3.1/2B15 contained a sequence coding for the non-structural protein 2B, and the same FMDV15 peptide sequence. Pigs injected with both constructs showed antibody and T cell responses to 3D and 2B, but not to the FMDV15 peptide. Additionally, delayed type hypersensitivity responses were observed in some cases to both 3D or 2B and to FMDV virus. Finally, no protection was seen against FMDV infection in animals immunized with either of the two FMDV DNA constructs. The additional co-immunization of plasmids encoding for GMCSF did not result in any significant change in the immune responses to the plasmids encoding for FMDV. This work gives some optimism for the construction of a DNA vaccine for FMDV in the future.

Animals↗
PubMed2005

Phylogeny, genome evolution, and antigenic variability among endemic foot-and-mouth disease virus type A isolates from India.

The capsid-coding (P1) and 3A regions of foot-and-mouth disease virus (FMDV) type A field isolates including two vaccine strains collected during 1977-2000 were analyzed. In the phylogenies, the isolates were distributed into two previously identified genotypes VI and VII, with multiple sub-genotypes that are temporally clustered. Comparison of the antigenic relationships of field isolates with the two vaccine strains (IND 17/77 and IND 490/97) and the reference strains of the genotypes VI (IND 233/99) and VII (IND 40/00) indicated two broad antigenic groups that correlate with the phylogenetic groupings (genotypes VI and VII), and are highly divergent from the vaccine strains. The maximum likelihood method of selection analysis identified a number of amino acid sites within the P1 region to be under weak positive selection. Some of the positively selected sites were mapped at/near the antigenically critical amino acid sites of the P1 region, indicating host immune pressure as one of the important driving force behind the observed genetic and antigenic diversity in FMDV. A small number of selected sites are located in the heparan sulphate-binding pocket of the virus, suggesting a fitness advantage for cell entry of the virus. No positive selection was detected in the 3A dataset.

Amino Acid Sequence↗
PubMed2002

Unapparent foot and mouth disease infection (sub-clinical infections and carriers): implications for control.

Unlike animals which are carriers of foot and mouth disease (FMD), sub-clinically infected animals may be highly contagious. The implications of sub-clinical infections for the control of FMD are serious because such animals are likely to disseminate the disease when in contact with susceptible livestock. Recent dissemination of FMD virus (FMDV) in Europe shows that sub-clinically infected animals render trade in animals or animal products a potential risk for importing countries. This clearly demonstrates that the paradigm 'free of FMD without vaccination' is not synonymous with 'risk-free'. The risk of introduction of subclinical FMD into FMD-free countries may increase significantly, with the occurrence of large susceptible animal populations, changed agricultural practices, expansion of trade in live animals and animal movements, increased trade in animal products and greater mobility of people. Such changes in circumstances require that national and international authorities remain continuously vigilant to determine any altered risk for importation of FMD. A few historical reports and some recent observations in southern Africa indicate the possibility of dissemination of FMD by bovine carriers into herds of susceptible cattle. These reports have greatly influenced FMD trade policies and thus, FMD control and eradication strategies. However, other field evidence does not support this claim and several controlled experiments were unable to show that carriers are able to initiate disease. When millions of cattle were systematically vaccinated with good quality vaccines, FMD disappeared in spite of a large sentinel population in the form of calves and unvaccinated sheep and pigs. A low number of carriers most likely persisted, but they did not hamper the eradication of the disease. Vaccination policies and trade regulation must be based on risk assessments taking these factors into consideration.

Animals↗
PubMed1994

Genetic variation of foot-and-mouth disease virus during persistent infection in cattle.

Genetic variation of foot-and-mouth disease virus O1 Campos has been analyzed in consecutive isolates recovered over a one- or two-year period from four cattle with experimental persistent infection. Comparisons of RNase T1 two-dimensional maps and nucleotide sequences of the VP1-coding region revealed a continual, although irregular, increase in the fixation of mutations as the infection progressed. Most changes were not conserved in consecutive isolates. These results, together with the substantial rates of genomic variation observed between some pairs of strains recovered at close time periods, suggested the coexistence of heterogeneous populations in which variants evolve independently from each other, and predominate at irregular time intervals. Furthermore, non-related patterns of variation were observed in the four animals. Similarly, genetic diversity of representative strains from major serotype O outbreaks in endemic disease regions of southeastern Brazil and central eastern Argentina which occurred between 1958 and 1983, suggested that outbreak strains are also likely to represent fluctuations of heterogeneous populations which evolve independently from each other. The possible role of persistent infections in the introduction of variant populations in the field is discussed.

Amino Acid Sequence↗
PubMed1991

Enhancement of the immune response elicited with foot-and-mouth disease virus vaccines by an extract of the Mycobacterium sp. wall.

The immunomodulating effect of an extract of the cell wall of Mycobacterium sp. (WSF, Vetrepharm Inc., London, Canada) in foot-and-mouth disease virus inactivated vaccines was tested in a murine model. The duration of immunity, protection, stimulation of immunocompetent cells acting on the long-lasting secondary response and possible tissue damage were examined. The incorporation of 10 micrograms WSF into aqueous and oil vaccines induced a high and long-lasting specific antibody response. The neutralizing titres of these antibodies were significantly higher than those observed in animals immunized with vaccines lacking WSF and conferred protection for at least 7 months. The data collected in repopulation assays indicate that WSF participates in the activation of immune cell populations involved in long-lasting memory. This results in an efficient B-cell secondary response even in the absence of T cells, lasting at least 5 months. No adverse reactions were detected. The enhancement effect of WSF on the immune response to foot and mouth disease vaccines observed in the murine model indicates the possibility of its inclusion in aqueous vaccines to be tested in cattle.

Adjuvants, Immunologic↗
PubMed2006

DNA vaccination against foot-and-mouth disease via electroporation: study of molecular approaches for enhancing VP1 antigenicity.

BACKGROUND: Foot-and-mouth disease virus (FMDV) affects susceptible livestock animals and causes disastrous economic impact. Immunization with plasmid expressing VP1 that contains the major antigenic epitope(s) of FMDV as cytoplasmic protein (cVP1) failed to elicit full protection against FMDV challenge. MATERIALS AND METHODS: In this study, mice were immunized via electroporation with four cDNA expression vectors that were constructed to express VP1 of FMDV, as cytoplasmic (cVP1), secreted (sVP1), membrane-anchored (mVP1) or capsid precursor protein (P1), respectively, to evaluate whether expression of VP1 in specific subcellular compartment(s) would result in better immune responses. RESULTS: Electroporation enhanced immune responses to vectors expressing cVP1 or P1 and expedited the immune responses to vectors expressing sVP1 or mVP1. Immunization of mice via electroporation with mVP1 cDNA was better than sVP1 or cVP1 cDNA in eliciting neutralizing antibodies and viral clearance protection. Vaccination with P1 cDNA, nonetheless, yielded the best immune responses and protection among all four cDNAs that we tested. CONCLUSIONS: These results suggest that the antigenicity of a VP1 DNA vaccine can be significantly enhanced by altering the cellular localization of the VP1 antigen. Electroporation is a useful tool for enhancing the immune responses of vectors expressing VP1 or P1. By mimicking FMDV more closely than that of transgenic VP1 and eliciting immune responses favorably toward Th2, transgenic P1 may induce more neutralizing antibodies and better protection against FMDV challenge.

Animals↗
PubMed1985

Variation in foot-and-mouth disease virus isolates in Kenya: an examination of field isolates by T1 oligonucleotide fingerprinting.

Ribonuclease T1 oligonucleotide maps of strains of 4 of the endemic serotypes of foot-and-mouth disease virus isolated in Kenya between 1964 and 1982 have been compared with data obtained in complement-fixation and neutralization tests. There was a continual change in the oligonucleotide maps obtained for all the serotypes examined. This genetic heterogeneity was generally associated with antigenic variation. Viruses isolated during the 12-month course of an epidemic of the SAT 1 serotype showed few changes in their oligonucleotide fingerprints, and were serologically related. These maps form a data base that will be useful in future epidemiological studies on the maintenance and spread of foot-and-mouth disease virus in this region.

Animals↗
PubMed1986

Comparative studies on growth of foot-and-mouth disease virus types 0 and Asia 1 in BHK-21 Razi cells.

Growth pattern of foot-and-mouth disease virus types 0 and Asia 1 in BHK-21 Razi cells was compared; while type 0 virus grew in high titre, Asia 1 virus was produced in low titre. Inhibition of host protein synthesis in type 0 virus-infected cells was more pronounced than in Asia 1 virus-infected cells. Foot-and-mouth disease virus type 0 infected cells showed higher lactic dehydrogenase activity when compared to Asia 1 virus. A significant decrease in virus yield was observed when Actinomycin D had been added at 50 micrograms/ml to infected cells.

Animals↗
PubMed1998

[Synthesis and immunogenic properties of peptides--fragments of the immunodominant regions of the VP1 protein of the Asia-1 type of foot- and-mouth disease virus].

Potential immunodominant epitopes were predicted on the basis of a theoretical analysis of the antigenic structure of the VP1 protein of the type Asia-1 foot-and-mouth disease virus. Peptides corresponding to the 140-153, 136-153, 132-153, 143-157, 137-157, and 193-208 fragments of the VP1 protein sequence were synthesized by the solid phase method, and the immunogenic properties of the peptides were studied on guinea pigs. The shortest peptide exhibiting the protective effect was found to correspond to the, 140-153 fragment of the VP1 sequence. The Plm-(Gly)3-(140-153)-(Gly)2-Lys(Plm)-Leu and [Ac-(140-153)-(Gly)3]8-(Lys)7-Gly synthetic constructions in combination with adjuvants provided up to 80% protection of immunized animals against infection with the foot-and-mouth disease virus.

Adjuvants, Immunologic↗