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Biomedical subjects

H W Reid

Publications and source records attributed to H W Reid.

At least 109 records · Page 6Linked to original sources
PubMed1981

Immunosuppression in toxoplasmosis: studies in sheep with vaccines for chlamydial abortion and louping-ill virus.

Toxoplasma gondii infection was established in sheep seven days (acute infection) or 28 days (chronic infection) before they were given enzootic abortion (EAE) vaccine alone or simultaneously with louping-ill (LI) vaccine. Uninfected controls received the same vaccination schedule. The serological response of acute toxoplasma-infected sheep to initial LI vaccination was significantly depressed but after revaccination four weeks later these sheep demonstrated a response equal to that of the revaccinated controls. Infected sheep also gave a significantly poorer response to EAE vaccine than control animals, the effect being more marked in those with chronic infection. Revaccination evoked no clear response in any group but on three of five sampling days antibody titres of controls were significantly higher than those of infected sheep.

Animals↗
PubMed1981

Immune responses of sheep to louping-ill virus vaccine.

The immune responses of sheep to single and double doses of commercially available louping-ill virus vaccine were examined. The susceptibility to challenge of sheep which had been vaccinated but showed a poor response was also investigated. Two injections of vaccine were required to provoke an adequate antibody response and maximum titres were obtained when there was an interval of two to eight weeks between injections. After challenge, viraemia could not be detected in animals with an antibody titre of 20 although increase in the concentration of humoral antibodies indicated that infection had occurred. Vaccinated but seronegative sheep and vaccinated animals with an antibody titre of 10 were also clinically resistant to the challenge, although circulation of virus was demonstrated. That vaccination had sensitised those animals to viral antigen was evident from the reduced viraemias, the early rise in humoral antibody titres and subsequent protection afforded compared to unvaccinated control animals. Thus, animals with minimal antibody titres after vaccination are protected, but it is recommended that vaccines eliciting the highest possible antibody responses will be the most useful under field conditions.

Animals↗
PubMed1981

Experimental louping-ill virus infection of cattle.

The response of six calves to subcutaneous inoculation with louping-ill virus was studied. All developed viraemia of low intensity which lasted two to four days followed by the appearance of haemagglutination inhibiting serum antibody. IgM was the predominant class of antibody until day 14. Only one calf developed clinical signs; following a brief period of incoordination on day 7 it became recumbent and was killed on day 12. Severe meningoencephalitis was detected in this calf and mild changes were observed in one of the five survivors which were killed on day 14 or 20. These findings are discussed in relation to the epidemiology of louping-ill and the diagnosis of the disease in cattle.

Animals↗
PubMed1981

Orbiviruses and bunyaviruses from a seabird colony in Scotland.

Viruses isolated from ticks (Ixodes uriae) and a kittiwake (Rissa tridactyla) from a seabird colony at St. Abb's Head, Scotland, were shown by complement fixation tests (CFT) to be antigenically related to the Uukuniemi and Kemerovo serogroups. Electron microscopic examination of cell cultures infected with the Kemerovo group viruses revealed particles characteristic of orbiviruses, 72 +/- 3 nm in diam., with an inner core 37 +/- 3 nm in diam., in association with intracytoplasmic, densely staining granular areas, and with fibrillar and tubular structures. Cell cultures infected with the Uukuniemi group viruses revealed characteristic bunyavirus particles, 94 +/- 7 nm in diam., with a closely adherent envelope. Both orbi- and bunyaviruses were isolated from two tick pools and the kittiwake. A third tick pool contained an orbivirus which cross-reacted with the other isolates in CFT and fluorescent antibody tests, but was distinguished from them by neutralization tests.

Animals↗
PubMed1980

Transmission of malignant catarrhal fever to rabbits.

A farmed red deer in contact with a flock of lambing ewes developed malignant catarrhal fever (MCF). Tissues from this deer were homogenised and inoculated into two rabbits one of which developed a febrile response on the 11th day. This rabbit was killed on the following day after developing conjunctivitis and hyperaemia of the nostrils. The condition was transmitted from this rabbit through a further three rabbit passes. Of 21 rabbits inoculated 15 reacted after three to 29 days. The clinical and pathological disease that developed was indistinguishable from the response of rabbits to infection with the virus of MCF of wildebeest origin. Infectivity was retained in homogenised tissues stored at -80 degrees C in 10% dimethyl sulphoxide but could not be detected in supernatant fluid of a lightly centrifuged tissue homogenate, which suggests that the agent is cell associated.

Animals↗
PubMed1980

Virus infections in cattle and sheep in Scotland 1975-1978.

Over the four-year period 1975-78 attempts were made to identify virus in samples from 1231 outbreaks of disease in cattle, and 682 outbreaks of disease in sheep. A virus identification was possible in 26 per cent of these disease outbreaks. The nature and significance of these virus infections is discussed.

Animals↗
PubMed1980

Immunosuppression in toxoplasmosis: further studies on mice infected with louping-ill virus.

Mice were infected with an avirulent cyst-producing strain of Toxoplasma gondii and given injections of louping-ill virus 7 days later; control mice were given virus but not Toxoplasma. Test and control mice were then killed, in groups, 2, 4, 6, 8 and 10 days later. In the dually infected mice viraemia was later, greater and more prolonged; titres of virus recovered from brain and spleen were greater; production and haemagglutinating antibody to louping-ill virus was later and less, and inflammation in the brain was more severe, than in mice given virus alone. We suggest that T. gondii suppressed the immunity of mice, making them more susceptible to the virus, and that a significant proportion of the increased number of inflammatory cells observed in the brain could have been toxoplasma specific and not virus-specific and hence contributed to the increased susceptibility of the dually infected mice to louping-ill virus.

Animals↗
PubMed1979

An outbreak of malignant catarrhal fever in red deer (Cervus elephus).

Nine of 15 housed red deer developed an acute disease. Six died and three were killed when severely affected. The clinical and post mortem changes suggested a diagnosis of malignant catarrhal fever (MCF) which was consistent with the pantropic lymphoproliferative histopathological lesions observed. Attempts to isolate an agent or transmit the condition to cattle failed. The relation of the vasculitis to the pathogenesis of the disease and the susceptibility of red deer are discussed.

Animals↗
PubMed1979

Effect of chronic Trypanosoma brucei infection on the course of louping ill virus infection in mice.

The course of louping-ill virus infection in mice chronically infected with Trypanosoma brucei was investigated. The mean survival time of mice infected with virus alone was 10.2 days, compared to 12.8 days in mice infected with T. brucei 14 days before virus challenge, and the cumulative mortality in the two groups was 62.5 and 90%, respectively. Virus was only inconsistently detected in the blood of mice given virus alone but was regularly present at high titers for up to 12 days in the blood of mice previously infected with T. brucei. Titers of virus in brains were also higher in dually infected mice, and encephalitis was of greater severity. These results indicate that the immunosuppressive effect of chronic trypanosomiasis may markedly increase susceptibility to acute virus infection. In addition, it is concluded that vector-vertebrate relationships of arthropod-transmitted viruses may be altered by concurrent trypanosome infection.

Animals↗
PubMed1979

Immunosuppression in bovine trypanosomiasis: studies with louping-ill vaccine.

The antibody response to louping-ill virus vaccine was examined in mice infected with Trypanosoma brucei and T congolense, and in Ethiopian cattle experimentally infected with T brucei, T congolense and T vivax. In mice the antibody response was completely suppressed, while in cattle infected with T congolense and T vivax the antibody response to the vaccine was only 10 per cent that of uninfected animals. In contrast, the response of cattle infected with T brucei was not significantly reduced, and this was attributed to their relatively light and transient parasitaemias. Trypanocidal chemotherapy (diminazine aceturate) administered on the same day as vaccination largely restored the competence of the immune response of both mice and cattle infected with T congolense. The use of such drugs should be considered when cattle are vaccinated in trypanosome endemic areas.

Animals↗
PubMed1978

Studies of louping-ill virus (Flavivirus group) in wild red grouse (Lagopus lagopus scoticus).

Studies were made to find evidence of louping-ill virus infection in free-living red grouse and relate this to their breeding success. In areas where ticks were abundant 61 (84%) adult grouse had antibody to the virus compared with 1 (10%) in areas where ticks were relatively scarce. Of 162 chicks tested 25 were shown to be viraemic. Infected chicks were of significantly less weight than comparably aged uninfected birds and the probability that they died was much greater than that of uninfected birds. It is concluded that the relatively poor breeding success in areas of high tick numbers was principally due to infection with louping-ill virus. The susceptibility of the red grouse to infection is discussed.

Animal Population Groups↗