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Biomedical subjects

A I Donaldson

Publications and source records attributed to A I Donaldson.

At least 73 records · Page 4Linked to original sources
PubMed1980

The influence of various chemical additives on the survival of vesicular exanthema virus in aerosols.

The influence of relative humidity (r.h.) on the survival of vesicular exanthema virus (VEV) in aerosols at I s and during the next 5 min when generated from phosphate buffer solution containing polyhydroxy compounds, dimethyl sulphoxide, salt or protein has been examined. VEV was sensitive to r.h. in the range of 40 to 60% in the presence of bovine serum albumin, glucose, inositol or phosphate buffer. Addition of sodium chloride stabilized the virus in aerosols at mid-range r.h. both immediately after generation and after a period of storage for 5 min. In the presence of dimethyl sulphoxide or glycerol, virus survival was reduced at 20% r.h. at I s and at all r.h. during the first 5 min. Pre-humidification did not produce any significant difference in virus recovery.

Aerosols↗
PubMed1980

Sites of release of airborne foot-and-mouth disease virus from infected pigs.

Pigs infected with foot-and-mouth disease virus by different routes of exposure were air-sampled individually, first as 'intact' (I-) pigs and then as 'intubated' (T-) pigs, using an endotracheal tube. Irrespective of the route of infection it was found that during the early stages of disease more virus was recovered from I-pigs than from T-pigs. Most of the virus from I-pigs during incubation and early disease was associated with large and medium sized particles. T-pigs infected by direct or indirect contact excreted a range of particle sizes at this time but T-pigs infected by inoculation only excreted small particles. During advanced disease all sizes of particle were excreted by I- and T-pigs. Greater amount of airborne virus were recovered at this time from I-pigs than T-pigs infected by indirect contact but I-pigs infected by intravenous or intradermal inoculation excreted less infectivity than T-pigs. The results show that the respiratory tract is involved during the early stages of foot-and-mouth disease in pigs infected by either natural or experimental routes of exposure and suggest that upper respiratory infection precedes lower.

Aerosols↗
PubMed1975

The survival of foot-and-mouth disease virus in open air conditions.

The influence of the Open Air Factor (OAF) and daylight on the survival of foot-and-mouth disease (FMD) virus held as captured aerosols on spider microthreads has been investigated. Virus inactivation due to OAF was slight. Similarly, the effect of daylight on the survival of virus was not marked. The results are discussed in relation to the airborne spread of FMD virus in nature.

Aerosols↗
PubMed1970

Further investigations on the airborne excretion of foot-and-mouth disease virus.

Calf thyroid tissue cultures were found to be the most sensitive system in detecting virus collected in a large volume air sampler from boxes, where cattle, sheep and pigs infected with A and C strains of foot-and-mouth disease (FMD) virus were housed. It was confirmed with all strains of FMD virus tested that pigs excreted the most virus followed by cattle and sheep, but there was variation between strains, the highest virus recoveries being obtained from animals infected with O(1) and C Noville viruses. The results are discussed in relation to outbreaks of foot-and-mouth disease in Great Britain since 1954.

Air Microbiology↗
PubMed1970

Ihalation, persistence and dispersal f foot-and-mouth disease virus by man.

Sampling of human subjects, who had been in contact with animals infected with foot-and-mouth disease (FMD) virus, showed that virus could be recovered from the nose, throat, saliva and from air expelled during coughing, sneezing, talking and breathing. The amounts of virus recovered paralleled those collected with a large-volume sampler and multistage impinger and these findings confirmed that the highest recovery of airborne virus was from infected pigs followed by cattle and sheep. More virus was found in the noses of those examining infected animals than in those operating the samplers, but there was variation between the subjects. In the majority there was a 1.8 log fall in titre by 3.5 hr., but virus persisted in the nose of one subject for 28 hr. Nose blowing or washing the nostrils did not remove virus completely, nor were cloth or industrial masks completely effective in preventing inhalation of virus. It was possible to transmit virus from infected subjects to others on one occasion. No clinical cases of FMD in man resulted from exposure, nor was there any rise in antibody. Use was made of these findings in determining sites of aerosol excretion in animals, and the results are discussed in relation to FMD in man and to the spread of respiratory viruses by the airborne route.

Air Microbiology↗
PubMedDate not supplied

Use of pre-coated immunoplates and freeze-dried reagents for the diagnosis of foot-and-mouth disease and swine vesicular disease by enzyme-linked immunosorbent assay (ELISA).

An indirect sandwich ELISA is used by the World Reference Laboratory for Foot-and-Mouth Disease for the diagnosis of foot-and-mouth disease virus and swine vesicular disease virus. The potential for supplying ELISA 'kits' for diagnosis to other laboratories has been assessed by evaluating the reactivity of (a) immunoplates pre-coated with rabbit antisera to FMDV and SVDV and (b) freeze-dried diluted reference antisera. Immunoplates pre-coated using a sodium carbonate/hydrogen carbonate buffer retained 100% sensitivity at temperatures of 4 degrees C and -20 degrees C over the experimental storage period of 140 days but elevated storage temperatures, 18-24 degrees C and 37 degrees C, produced declining reactivity. There was a marked improvement in retention of reactivity upon storage at 37 degrees C when employing an alternative coating buffer, ammonium hydrogen carbonate. The reactivity of the rabbit antisera diluted in sodium carbonate/hydrogen carbonate solution and freeze-dried was high, as was the freeze-dried guinea pig antisera which had been diluted in each of the test solutions investigated. ELISA 'kits' for diagnosis, therefore, could be supplied using pre-coated immunoplates, with freeze-dried antiserum reagents or a combination of the two.

Animals↗