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Biomedical subjects

T R Doel

Publications and source records attributed to T R Doel.

At least 37 records · Page 2Linked to original sources
PubMed1990

Isotype responses of infected, virus-vaccinated and peptide-vaccinated cattle to foot-and-mouth disease virus.

An ELISA to measure bovine serum immunoglobulin isotypes (IgG1, IgG2, IgM and IgA) specific for foot-and-mouth disease virus (FMDV) or for synthetic FMDV peptides is described. Sera from cattle infected by FMDV, vaccinated with conventional inactivated virus vaccines or vaccinated with synthetic peptides were examined using this assay. Generally IgG subclasses dominated the antibody responses of all groups after an early IgM response had waned. An exception to this pattern was seen in the case of a group of immature calves given multiple or high doses of synthetic peptide and in which levels of IgM continued to rise until the end of the experimental period. Both infected animals and those vaccinated with inactivated virus mounted antibody responses in which IgG1 titres tended to predominate over those of IgG2. In some infected animals, an early IgG2 response was evident but resolution of lesions and clinical recovery did not occur until IgG1 antibody appeared in the serum some days later. In synthetic-peptide immunized animals the response was more variable but IgG1:IgG2 ratios at 21 days postvaccination were significantly lower than those of virus-vaccinated animals. It is proposed that differences in the isotype profiles induced by conventional FMD vaccines and those resulting from vaccination of cattle with synthetic FMDV peptides may in part account for the lower protective index of peptide-induced antibodies.

Animals↗
PubMed1990

International bank for foot-and-mouth disease vaccine: stability studies with virus concentrates and vaccines prepared from them.

An international bank foot-and-mouth disease (FMD) vaccine has been established at the Pirbright Laboratory of the AFRC Institute for Animal Health. The bank is based on concentrated virus preparations stored in the gaseous phase of liquid nitrogen and is capable of producing up to 0.5 million cattle doses of each of five common strains of the virus (FMDV) for the member nations of the bank. This paper describes the initial and subsequent testing of the virus concentrates and vaccines prepared from them. There was no evidence of deterioration of the virus concentrates during liquid nitrogen storage. High levels of protection of cattle and guinea-pig were achieved when vaccines were used immediately following preparation from the recently thawed virus concentrates. In contrast, storage of vaccines at 4 degrees C for one or more months resulted in loss of potency in guinea-pigs and was attributed, in part to proteolytic enzymes in the virus concentrates.

Animals↗
PubMed1990

Heterotypic recognition of foot-and-mouth disease virus by cattle lymphocytes.

Lymphoproliferation against foot-and-mouth disease (FMD) virus was examined using peripheral blood mononuclear cells from vaccinated cattle. Ten weeks after revaccination the optimum conditions for proliferation were obtained with 1 microgram/ml of purified virus after 5 to 6 days in culture. This contrasted with the response at 20 months post-revaccination, when the response required less antigen and showed a peak response after 3 to 4 days in culture. Proliferation was specific for FMD virus, but was cross-reactive between serotypically distinct strains of the virus. The proliferative response to isolated virus proteins (VP) involved all three major capsid proteins (VP1, -2 and -3), although the proliferation of lymphocytes from heterotypically vaccinated cattle was due to VP3. Furthermore, the response induced by purified virus, chemically fixed virus and subunit virus particles was indistinguishable and thus it is likely that processing was required for the induction of proliferation. Together these data strongly suggest that FMD virus-induced lymphoproliferation is T cell-mediated and that VP3 may contain dominant, cross-reactive sequences.

Animals↗
PubMed1990

Heterotypic protection induced by synthetic peptides corresponding to three serotypes of foot-and-mouth disease virus.

Synthetic peptide vaccines of the general sequence Cys-Cys(200-213)-Pro-Pro-Ser-(141-158)-Pro-Cys-Gly, where the numbered residues refer to VP1 sequences of three different strains of foot-and-mouth disease virus, have been evaluated in cattle and guinea pigs. High levels of serotype-specific (homotypic) antiviral and antipeptide antibody were produced with each peptide. The A- and O-serotype peptides provided complete protection of guinea pigs against their respective virus challenges. The C-serotype peptide appeared to be less effective than the other peptides. In cross-protection studies (heterotypic) in guinea pigs, it was possible to protect A-serotype peptide-vaccinated animals against O-virus challenge and vice versa. Some heterotypic protection was also achieved with the C-serotype peptide. The heterotypic protection observed related more to the presence of cross-reactive antipeptide antibody than to neutralizing antibody.

Amino Acid Sequence↗
PubMed1989

T cell-dependent induction of antibody against foot-and-mouth disease virus in a mouse model.

Nude and normal BALB/c mice were primed by intravenous inoculation of purified, infectious foot-and-mouth disease virus (FMDV) type A24, strain Cruzeiro. Frequency estimation of antigen-specific antibody-secreting cells (ASC) and Thy 1+ T cells in the spleens of immunized mice identified that the IgM response was similar for both nude and normal mice, whereas substantial numbers of both IgG ASC and Thy 1+ cells were present in normal mice only. In contrast, nude and normal mouse sera both contained IgG although the nude mouse serum was deficient in IgG1. Antigen-specific antibody could not be induced in spleen cell cultures from C57BL/6 mice after depletion of T cells with monoclonal antibody plus complement. However, the antibody response could be reconstituted if either a source of exogenous lymphokines or T cells from primed but not unprimed mice were added. Similarly, polyclonal stimulation or unprimed T cells could restore the in vitro response and thus complemented the finding of a low frequency of helper T cells in unprimed mice. Taken together, these data identify that the induction of IgG in FMDV-immunized mice is T cell-dependent and regulated by lymphokines. Furthermore, in nude mice a site other than the spleen must be responsible for the synthesis of the observed serum IgG.

Animals↗
PubMed1988

Immunization against foot-and-mouth disease with synthetic peptides representing the C-terminal region of VP1.

Foot-and-mouth disease virus challenge experiments in guinea-pigs and immunoassays with a range of peptides equivalent to either or both of the sequences 141 to 158 and 200 to 213 of VP1 showed the most effective structure, in terms of protection, to be one in which both 'sites' were present with a minimum of additional amino acids. An 80 residue peptide comprising amino acids 134 to 213 was considerably less effective than 40 or 45 residue peptides. The major site for the induction of protection was deduced to be in the region 141 to 158. Thus, protection with the 40 or 45 residue peptide did not appear to be due to the presence of antibody directed solely to the 200 to 213 sequence. Finally, induction of antibody to the latter site appeared to be dependent on both the size of the peptide and the disposition of 'sites' within it.

Animals↗
PubMed1987

Synthetic peptide vaccines against foot-and-mouth disease. I. Duration of the immune response and priming in guinea-pigs, rabbits and mice.

The immunogenicity of two aphthovirus-specific synthetic peptides was investigated. One peptide copied the sequence of amino acids 141 to 160 from the capsid VP1 of the aphthovirus strains O1 BFS 1860 and O1 Kaufbeuren (O peptide), the other copied the equivalent sequence from aphthovirus strain A24 Cruzeiro (A peptide). Peptide coupled to keyhole limpet haemocyanin (KLH) stimulated a long-lasting immune response in guinea-pigs and rabbits. Significant levels of antibody were detectable at least one year after vaccination, although the reactivity of the antibody depended on the species and the peptide used. In some circumstances the peptides were able to prime the immune system such that a subsequent dose of peptide boosted antibody production. This effect, also, was dependent on the species of experimental animal and on the peptide used, an observation which has important implications for the use of such peptides as vaccines.

Animals↗
PubMed1987

Synthetic peptide vaccines against foot-and-mouth disease. II. Comparison of the response of guinea-pigs, rabbits and mice to various formulations.

The immune response of guinea-pigs to vaccination with either of two aphthovirus-specific synthetic peptides was investigated. One peptide copied the sequence of amino acids 141 to 160 from the VP1 of aphthovirus strains O1BFS 1860 and O1 Kaufbeuren (O peptide), the other copied the equivalent sequence from aphthovirus strain A24 Cruzeiro (A peptide). The immune response was enhanced when the peptides were conjugated to a carried protein, but the choice of carrier protein and cross-linking agent was not critical in obtaining enhancement. The response was greatest when the peptide or peptide-carrier conjugate was adjuvanted in Freund's complete adjuvant (FCA). The O peptide was poorly immunogenic and did not confer protection against challenge with infectious virus, whereas the A peptide had good immunogenicity and did confer protection. This reflected the relative immunogenicity of the parent viruses. Rabbits, three strains of guinea-pigs and seven strains of mice were vaccinated with the O peptide conjugated to keyhole limpet haemocyanin (KLH). Considerable variation was observed between the responses of each strain and it is proposed that this relates to their repertoire of immune response genes.

Animals↗
PubMed1985

Prospects for improved foot and mouth disease vaccines.

Improved foot and mouth disease (FMD) vaccines which have increased efficiency and stability are highly desirable. Work which aims to increase the stability of FMD virus particles for vaccine use is described and the use of these particles and of antigenic fragments of the virus for controlled release vaccine products is considered.

Animals↗
PubMed1985

An international collaborative study on foot and mouth disease virus assay methods. 2. Quantification of 146S particles.

Workers in 11 laboratories in Europe and one in North America participated in a collaborative study to assess the variability of a sucrose gradient procedure used for the quantification of foot and mouth disease virus (FMDV). To this end, a range of standards was distributed from one of the participating laboratories. A series of adenine preparations were used to assess the various spectrophotometers/UV monitors and it showed most to be accurate and linear in their responses. The FMDV and MS2 ribophage standards were used to assess the sucrose gradient procedure and indicated low levels of within laboratory variation whereas between laboratory variation was greater. Recalculation of results from the unprocessed data in the coordinating laboratory permitted the identification and reduction of one source of between laboratory variation. Despite the observed variations, the results indicated that meaningful comparisons could be made between the data of different laboratories provided that a procedure similar to the one described in this report is used.

Adenine↗
PubMed1984

The stability and potency of vaccines prepared from inactivated foot-and-mouth disease virus concentrates.

The stability of 146S particles in concentrates of foot-and-mouth disease virus stored at 4 degrees C was similar to that of 146S particles in a conventional virus preparation. Proteolytic degradation of VPl was not observed in the stored conventional virus preparation or inhibitor-supplemented concentrate but was observed in a supplement-free concentrate. The potencies of vaccines made from the conventional and concentrated preparations and stored in parallel at 4 degrees C appeared to decrease after 16 weeks. The vaccines made from the supplement-free concentrate and the Trasylol supplemented concentrate appeared to be at least as potent as the conventional vaccine and were clearly superior to vaccine made from ox serum supplemented concentrate.

Animals↗
PubMed1984

The evaluation of a physical method for the quantification of inactivated poliovirus particles and its relationship to D-antigenicity and potency testing in rats.

The use of a density gradient procedure for the quantification of intact, inactivated poliovirus particles in vaccine preparations is described. The procedure is both sensitive and highly reproducible and the results correlate with those of potency tests in rats and with D-antigen content as measured by ELISA. Because of the occasional ambiguity observed with D-antigen assays, it is suggested that the density gradient procedure will provide valuable additional information for the in vitro assessment of inactivated poliovirus preparations.

Animals↗
PubMed1984

Induction of antibody to foot-and-mouth disease virus in presensitized mouse spleen cell cultures.

Cultures of spleen cells from immunized mice were stimulated in vitro by soluble preparations of purified foot-and-mouth disease virus. Virus-specific antibody, as detected by an enzyme-linked immunosorbent assay, was produced by immune spleen cells but not by normal, nonimmune cells. The optimal specific response was obtained with 1 microgram of virus per ml of culture; as the virus concentration was increased, the production of specific antibody was reduced. For very low concentrations of virus (less than 0.01 microgram per culture), there was tentative evidence of suppression of the specific antibody response. The levels of specific antibody induced were dependent on the source and number of plastic-adherent cells present in the cultures. We intend to use this model system to study further the basis of immunity to foot-and-mouth disease virus.

Animals↗
PubMed1983

Isolation of capsid proteins of foot-and-mouth disease virus by chromatofocusing.

A method for the isolation of foot-and-mouth disease virus (FMDV) capsid proteins was developed. The FMDV capsid proteins VP1, VP2, VP3 and VP0 were isolated from sucrose gradient purified virus by chromatofocusing in a pH 7.4-4.0 gradient on Polybuffer exchanger PBE 94. Under the conditions used the proteins eluted in the sequence VP1, VP2, VP0 (when present) and VP3. Capsid protein VP4 did not elute and could not be isolated by this method. Protein concentration in the eluate was monitored by the use of a radiolabelled marker and recoveries of approximately 50% of the input marker could be achieved when using up to 15 mg of virus and a 30-ml column. The high capacity and relative simplicity of chromatofocusing make it a useful alternative to other methods of purifying proteins.

Animals↗
PubMed1983

The detection and inhibition of proteolytic enzyme activity in concentrated preparations of inactivated foot-and-mouth disease virus.

Proteolytic enzyme activity was detected in a large number of concentrated preparations of inactivated foot-and-mouth disease virus. Several lines of evidence indicated that at least some of this activity could be attributed to BHK cells, although low levels of microbial contamination in many of our preparations could not be discounted and would certainly enhance the cellular proteolytic activity. From an experiment with different concentrations of trypsin, it was concluded that the proteolytic activities of virus concentrates were sufficient to cause significant degradation of VP1. It was also shown that Trasylol and ox serum were effective inhibitors of proteolytic enzymes in concentrated virus preparations stored at 4 degrees C for 8 months.

Animals↗