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Biomedical subjects

A I Donaldson

Publications and source records attributed to A I Donaldson.

At least 55 records · Page 3Linked to original sources
PubMed1988

An enzyme-linked immunosorbent assay for the detection of vesicular stomatitis virus antigen.

An indirect, sandwich enzyme-linked immunosorbent assay (ELISA) has been developed for the laboratory diagnosis of vesicular stomatitis (VS). The assay which uses rabbit and guinea-pig antisera to the purified glycoprotein antigens of Serotypes New Jersey (VSV-NJ) and Indiana (VSV-IND-1), has both high sensitivity and specificity, but has lower reactivity for the two other Indiana subtypes VSV-IND-2 and VSV-IND-3.

Animals↗
PubMed1988

Detection of foot-and-mouth disease antigen in bovine epithelial samples: comparison of sites of sample collection by an enzyme linked immunosorbent assay (ELISA) and complement fixation test.

Serially collected epithelial samples from lesions in the mouth and on the feet of calves experimentally infected with foot-and-mouth disease (FMD) type O1 BFS 1860 were assayed for the presence of FMD viral antigen using a double antibody sandwich enzyme-linked immunosorbent assay (ELISA) and a complement fixation (CF) test. The amount of infectious virus in each sample was also determined. FMD viral antigen was detected by ELISA in 70 per cent of the mouth samples and 92 per cent of samples from the feet. The CF test was less sensitive; it detected antigen in 44 per cent of mouth and 85 per cent of foot samples. In mouth samples the amount of antigen decreased rapidly becoming undetectable by the fourth day of sampling whereas in foot samples the quantity of antigen declined more slowly, and could be detected until the seventh day of sampling. Therefore it was concluded that the age of lesion and the site from which epithelial samples are collected are both important determinants in the laboratory diagnosis of FMD. In cattle, foot lesions are more likely than mouth lesions to yield antigen and to remain positive for a longer period.

Animals↗
PubMed1987

Enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against foot-and-mouth disease virus. III. Evaluation of antibodies after infection and vaccination.

Investigations using a liquid-phase blocking sandwich enzyme-linked immunosorbent assay (ELISA) for the measurement of antibodies against foot-and-mouth disease virus (FMDV) in sera from sheep and from cattle are reported, and results compared with those obtained by virus neutralization (VN) tests. Serum antibody titres in sheep after primary vaccination and in cattle challenged with a natural aerosol after vaccination were similar by ELISA and VN. However, the antibody levels detected in sera of cattle during early infection and of vaccinated cattle after intradermolingual challenge were clearly greater by ELISA than by VN. The ELISA titres in cattle sera following synthetic peptide vaccination indicated some relationship to protection and were clearly different from those recorded by VN. On the other hand, the antibody levels following conventional vaccination showed that ELISA and VN titres in cattle sera were related to protection. Although there was a good agreement between the ELISA antibody titre and protection for the four vaccines used, by VN the titre which afforded protection varied depending on the vaccine used. The ELISA was considered therefore to be more reliable than the VN and may prove useful for evaluating the immunological response of animals following infection and following vaccination.

Animals↗
PubMed1987

Infection of cattle by airborne foot-and-mouth disease virus: minimal doses with O1 and SAT 2 strains.

Equipment has been constructed and methods developed for exposing individual cattle to two strains of foot-and-mouth disease (FMD) virus in aerosols to determine the minimal infective dose by the respiratory route. The aerosols used were produced either artificially by a spinning-top aerosol generator, in which case they were of homogeneous small particle size (less than 3 micron in diameter) or else they were derived naturally from infected pigs, in which case the particles were heterogeneous in size. Two strains of FMD virus were used: an O1 strain of UK origin and a SAT 2 strain from South Africa. The lowest doses which initiated infection were 12.5 TCID50 of O1 BFS virus and 25 TCID50 of SAT 2 virus, infectivity having been assayed in primary bovine thyroid cell cultures. Following exposure to low doses of virus (range 12 to 316 TCID50) 33 per cent of the cattle exposed to O1 BFS virus and 27 per cent exposed to SAT 2 virus were infected but did not develop detectable vesicular lesions.

Aerosols↗
PubMed1986

Exposure of sheep to natural aerosols of foot-and-mouth disease virus.

Sheep taken individually and allowed to inhale air being drawn along a duct from a cabinet containing pigs acutely infected with foot-and-mouth disease virus for 10 or 15 minute periods were infected by doses as low as 10 TCID50 of virus. The most consistent and reliable indicators of infection were viraemia and seroconversion. The mean times from exposure to onset of viraemia, pyrexia and the appearance of vesicular lesions were 2.5, 3.8 and 4.7 days, respectively. Neither the time from exposure to first detectable viraemia nor vesication correlated with dose. Around 27 per cent of sheep which were known to have been infected did not develop vesicles.

Air Microbiology↗
PubMed1986

Functional antibody responses in pigs vaccinated with live and inactivated Aujeszky's disease virus.

Functional antibody tests, including virus neutralising activity of serum, antibody dependent cellular cytotoxicity and complement mediated lysis, were used to measure the response of pigs given either live or inactivated Aujeszky's disease virus vaccines. Pigs were then challenged with virulent Aujeszky's disease virus and antibody responses were analysed and found not to correlate with protection. Reasons for this lack of correlation are discussed and it is suggested that these results indicate that more emphasis should be placed on measuring the local immune response.

Animals↗
PubMed1984

Experimental foot-and-mouth disease in fattening pigs, sows and piglets in relation to outbreaks in the field.

The progression of foot-and-mouth disease in sows and their litters of piglets following exposure to O1 Lausanne virus has been investigated. The majority of piglets died with acute myocarditis but without developing vesicles. Deaths occurred before and also when sows began showing early evidence of vesicle formation. This clinical picture parallels that seen at the beginning of both the Normandy 1979 and Britanny 1981 epidemics in France and points to the necessity of including foot-and-mouth disease in the differential diagnosis of acute death among cloven-hoofed livestock and furthermore the importance of extending clinical inspections to adult animals on premises when such events take place. In investigations in which the susceptibility of fattening pigs to infection with O1 Lausanne virus given by the intramuscular route was examined it was found that the 50 per cent infective dose was log (10)4.8 TCID50. This finding suggests that large amounts of virus are required for successful initiation of disease. This is more likely to come from animals already infected than by inoculation with contaminated material.

Acute Disease↗
PubMed1984

Influence of vaccination on Aujeszky's disease virus and disease transmission.

Parenteral vaccination of fattening pigs with either modified live or inactivated Aujeszky's disease virus did not prevent infection with field strain virus or the development of clinical disease. The duration and severity of the clinical syndrome was, however, reduced and vaccinated pigs did not suffer the severe weight loss and high mortality experienced by non-vaccinated pigs in the acute phase of disease. The range of tissues in which challenge virus replication took place was more restricted in vaccinated animals and the concentration of virus in infected tissues was reduced. Vaccination shortened the duration of field virus excretion and carriage in the tonsil. Replication of modified live vaccine virus was restricted to the site of inoculation in the neck and associated lymph nodes for two days after vaccination and it was not excreted by vaccinated pigs. Attempts to infect pigs by feeding them tissues taken from non-vaccinated or vaccinated pigs soon after challenge infection were unsuccessful.

Animals↗
PubMed1984

Analysis of a series of outbreaks of Aujeszky's disease in Yorkshire in 1981-82: the possibility of airborne disease spread.

A series of outbreaks of Aujeszky's disease occurred in Yorkshire during 1981-82. These were investigated from epidemiological and meteorological viewpoints to determine if airborne disease spread could have occurred between any of the premises. The results suggest that seven out of the 11 outbreaks investigated could have resulted from airborne virus.

Air Microbiology↗
PubMed1984

Response of sheep vaccinated with large doses of vaccine to challenge by airborne foot and mouth disease virus.

Administration of three-fold or six-fold larger doses of conventional monovalent type O foot and mouth disease (FMD) vaccine to sheep prevented viraemic distribution of virus after exposure to airborne virus one week later. However, virus replication in the respiratory tract or excretion in oesophageal-pharyngeal fluids and breath was not prevented. The implication of these findings for the use of vaccine as an adjunct to a 'stamping out' policy for countries which are free from FMD and which do not practice mass annual vaccination are discussed.

Animals↗
PubMed1983

Experimental Aujeszky's disease in pigs: excretion, survival and transmission of the virus.

Airborne Aujeszky's disease virus was recovered from looseboxes containing groups of pigs infected with virus strains from England, Northern Ireland and Denmark from days 1 to 7 after infection. Pigs sampled individually excreted most airborne virus on days 2 and 3 after infection. On a 24 hour basis the maximum amount of airborne virus excreted per pig was log10 5.3 TCID50. Subclinical infection was transmitted from a clinically affected group of pigs to a seronegative group held in separate looseboxes when air was drawn through ducting connecting one box with the other. Tissues taken from pigs killed at varying times after infection showed that the main sites of virus replication were in the head and neck region. Aujeszky's disease virus was detected for up to 40 days in a range of tissues taken from pigs at the acute stage of disease and stored at -20 degrees C.

Air Microbiology↗
PubMed1983

The influence of normal guinea-pig serum and tissue culture assay system on foot-and-mouth disease virus neutralisation.

The inclusion of normal guinea-pig serum in neutralisation reactions involving foot-and-mouth disease virus (FMDV) increased the neutralisation titre and rate of neutralisation by guinea-pig antiserum derived from animals convalescent from FMDV. Such inclusion had little or no effect on neutralisation involving guinea-pig antiserum collected early in infection or early or convalescent bovine antisera. Higher neutralisation titres and more rapid neutralisation were found from assay in bovine thyroid cells than in IB-RS-2 cells. Not all the increase in neutralising activity was removed by heating at 56 degrees C, indicating that other factors in addition to complement were responsible. In some tests a virus fraction resisting neutralisation was found and, when rabbit anti-guinea-pig gamma-globulin was added, an increase in neutralisation resulted, suggesting that most of the persistent virus fraction was due to the presence of infective virus-antibody complexes.

Animals↗
PubMed1983

Serological response of pigs infected with Aujeszky's disease virus.

The temporal development of antibody in four groups of pigs infected with different Aujeszky's disease virus isolates was examined. The enzyme-linked immunosorbent assay detected antibody by five to six days after infection and the antibody-dependent cell-mediated cytotoxicity assay detected antibody seven to nine days after infection. Neutralising antibody was first detected nine to 10 days after infection, whereas assays measuring complement mediated antibody lysis did not detect antibody until 10 days after infection. These results are discussed in terms of their importance to the diagnosis of and recovery from Aujeszky's disease.

Animals↗
PubMed1983

Comparative studies of United Kingdom isolates of swine vesicular disease virus.

The characteristics of four United Kingdom isolates of swine vesicular disease (SVD) virus from 1981 to 1982 have been compared with those of an isolate obtained from the first outbreak of swine vesicular disease diagnosed in the United Kingdom in 1972. When the virus structural proteins were examined by polyacrylamide gel electrophoresis the four isolates from 1981-82 all had the same polypeptide pattern, which was different from that of the 1972 isolate. Immunodiffusion tests with the 1972 isolate and one 1982 isolate did not reveal any antigenic difference between the viruses but minor antigenic differences were shown by cross-neutralisation tests between the 1972 isolate and the four isolates from 1981-82. In experimentally infected pigs the 1972 isolate produced typical SVD lesions whereas the four more recent SVD viruses produced only very mild clinical disease. Clinical lesions scored numerically were four- to 10- and five- to 11-fold higher at seven and 14 days after infection for pigs infected with the 1972 isolate than with the four isolates from 1981-82. The serum of pigs infected with the 1972 isolate contained significantly higher levels of neutralising antibody than those of pigs infected with more recent isolates. The antibody titres of pigs with only primary lesions ranged from log10 1.9 to 2.8 and one clinically normal pig had a titre of log10 2.4 at 14 days after infection. Attention is drawn to the implication of these findings for SVD control policies based only on the recognition and reporting of clinical disease.

Animals↗
PubMed1982

Long distance transport of foot-and-mouth disease virus over the sea.

The conditions required for the transport of foot-and-mouth disease (FMD) virus in the atmosphere over long distances and in sufficient concentrations to cause infection in exposed animals are described. Using these factors a series of 23 outbreaks of FMD in Europe, where the original outbreaks were separated from later outbreaks by sea passage, have been investigated. The findings obtained support the hypothesis that under certain conditions the airborne transmission of FMD over a long sea passage is possible.

Air Microbiology↗
PubMed1982

Use of prediction models to forecast and analyse airborne spread during the foot-and-mouth disease outbreaks in Brittany, Jersey and the Isle of Wight in 1981.

Between March 4 and 26, 1981 the French veterinary authorities reported a series of 14 outbreaks of disease due to type O foot-and-mouth (FMD) virus, 13 in Brittany and one in Normandy. The United Kingdom reported FMD type O in Jersey on March 19 and in the Isle of Wight on March 22. The field and laboratory investigations on the farm in the Isle of Wight are outlined. The way in which short and long range numerical models were used to forecast the airborne spread of FMD from Brittany to the UK and then to assess the risk of further airborne spread within the UK is described.

Air Microbiology↗
PubMed1982

Air sampling of pigs infected with foot-and-mouth disease virus: comparison of Litton and cyclone samplers.

The air in looseboxes containing groups of pigs in the acute stage of foot-and-mouth disease was sampled simultaneously with two air-sampling devices: a large volume sampler (Litton) and a cyclone sampler. Although the cyclone sampler was slightly less efficient at trapping airborne virus it was easier to operate. When pigs were sampled individually within a 610 litre cabinet using the cyclone sampler, the mean recovery of virus over a 24 hour period was log10 8 X 6 TCID50 per animal. This figure is four times higher than the maximum amount estimated in previous studies in which groups of pigs held in looseboxes were sampled with a Litton apparatus.

Air Microbiology↗