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Biomedical subjects

R M Gaskell

Publications and source records attributed to R M Gaskell.

At least 91 records · Page 5Linked to original sources
PubMed1987

Antibody and complement mediated lysis of felid herpesvirus 1 infected cells in vitro.

The lysis of cells infected by felid herpesvirus 1 (FHV) by feline anti-FHV antibody and complement was demonstrated. Lytic activity was sensitive to dilution of both antibody and, especially, complement. It was first detected within 10 to 20 minutes, increased rapidly during the next 30 minutes of incubation and then rose more slowly in a linear manner. Using standard antibody and complement concentrations and assay duration, it was shown that FHV infected cells underwent significant (P less than 0.05) lysis from eight hours after infection in a system in which FHV-specific membrane antigen was first detected at three hours after infection and spread of FHV by the intracellular route began eight to nine hours after infection. The ability of antibody and complement to reduce FHV spread in this system was demonstrated by a significant (P less than 0.05) reduction in FHV plaque numbers, although the restriction of spread was not absolute. Chelation of divalent cations and heat inactivation of complement factor B revealed that the lytic system was dependent on factor B and Mg2+ but not Ca2+, suggesting involvement of the alternative pathway of complement activation.

Animals↗
PubMed1987

Demonstration in live chickens of the carrier state in infectious laryngotracheitis.

Two separate groups of nine-week-old specific pathogen free cockerels maintained in isolation were infected with a field strain of infectious laryngotracheitis (ILT) virus, either by intratracheal or combined intranasal and supraconjunctival inoculation. Birds were monitored for virus shedding from five sites on alternate days during the acute phase and three times weekly until week 17. They were then treated with cyclophosphamide on three consecutive days and thereafter swabbed daily. During the acute phase clinical signs were observed and virus was recovered from ocular and nasal sites for up to six to eight days. Initially after the acute phase no virus could be detected. However, from the seventh week after infection intermittent, apparently spontaneous shedding was detected in four of five birds in each group. There was no clear effect of cyclophosphamide treatment on re-excretion patterns, possibly because of the high levels of virus shedding already occurring. Thus, a carrier state for ILT virus has been demonstrated experimentally in live clinically recovered birds.

Acute Disease↗
PubMed1986

Assay of prolyl 4-hydroxylase by the chromatographic determination of [14C]succinic acid on ion-exchange minicolumns.

An assay for prolyl 4-hydroxylase (EC 1.14.11.2) is described which measures succinic acid produced during the decarboxylation of 2-oxoglutaric acid in the presence of poly(L-Pro-Gly-L-Pro). [1-14C]Succinic acid was separated from its precursor 2-oxo[5-14C]glutaric acid by using ion-exchange minicolumns. The contamination of succinic acid by 2-oxoglutaric acid was approx. 1%, and the recovery of succinic acid was 100%. Kinetic parameters of prolyl 4-hydroxylase measured by the assay showed good agreement with published values. Our experience indicates that the measurement of prolyl 4-hydroxylase by the production of succinic acid is especially suited to investigations involving large numbers of assays.

Carbon Radioisotopes↗
PubMed1986

Ecology of orthopoxviruses and use of recombinant vaccinia vaccines.

Little is known of the ways in which orthopoxviruses are maintained in nature, and the role of wild-life reservoirs requires further investigation. This lack of information is important in view of proposals to use as vaccines recombinant vaccinia viruses which carry genes for other immunising antigens. The possibility that such strains may become established in nature, as vaccinia may have in Indian buffaloes, and/or undergo genetic hybridisation with existing orthopoxviruses should be considered.

Animals↗
PubMed1986

Poxvirus infection in the domestic cat: some clinical and epidemiological observations.

The clinical findings from 30 cases of feline poxvirus infection in the UK are reviewed and some epidemiological observations described and discussed. In most cases the clinical signs consisted of skin lesions only, although systemic signs were also occasionally seen. Over half the cats had a history of a single recent lesion, assumed to be primary, on the head, neck or a forelimb. Twenty-nine of 30 cats developed more widespread secondary skin lesions. Cat-to-cat transmission was apparently rare. More cases were recognised in the autumn than at other times of the year. The possibility of a wild mammal reservoir of infection is discussed.

Animals↗
PubMed1986

Responses of cats to nasal vaccination with a live, modified feline herpesvirus type 1.

Intranasal vaccination with a cold-adapted strain of feline herpesvirus type 1 (FHV-1) two days before challenge gave partial protection, and four days before challenge gave complete protection, against feline viral rhinotracheitis. Protection at this time appeared to be specific since vaccination with FHV-1 did not affect the disease caused by the unrelated feline calicivirus. The time course of onset of protection also confirmed that the protective mechanism was likely to be specific. However, six days after vaccination only low levels of FHV-specific IgA and IgM antibody and of interferon were found in serum and nasal washings. In lymphocyte transformation assays neither peripheral blood lymphocytes nor tonsil lymphocytes gave a significant proliferative response in the presence of FHV antigen. Pathogenesis experiments demonstrated that the tonsil and nasal turbinates were the most important sites of virulent FHV-1 replication. Vaccination significantly reduced levels of infectious virus found in both sites. The results provide evidence that no one mechanism is responsible for protection following vaccination but local specific responses are more likely to be involved.

Administration, Intranasal↗
PubMed1985

Isolation of felid herpesvirus I from the trigeminal ganglia of latently infected cats.

Felid herpesvirus I (FHV I) is a respiratory pathogen of cats. Recovered animals remain latently infected but episodes of virus shedding may occur, particularly after stress. Previous attempts to identify the site(s) of latency of FHV I using co-culture, explant or tissue homogenization methods have been unsuccessful. Using a tissue fragment culture technique, however, FHV I was isolated from the trigeminal ganglia of three of 17 cats latently infected with field virus. No virus was found in four cats previously infected with a cold-adapted vaccine strain of FHV I, or in four cats given vaccine strain and field virus. The three trigeminal ganglion isolates had similar plaque size and morphology to the vaccine strain, the plaques being significantly smaller (P less than 0.001) than those of the field viruses.

Animals↗
PubMed1984

Cowpox in cats.

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Animals↗
PubMed1983

Natural and experimental pox virus infection in the domestic cat.

Three naturally occurring cases of cowpox virus infection in the domestic cat are described. Isolate L97 was identified as cowpox virus on the basis of morphology, serology and characteristic cytopathic effect in tissue culture and on the chorioallantoic membrane of embryonated eggs. All three cases showed multiple skin lesions, slight conjunctivitis or purulent ocular discharge but there were no respiratory signs. Two animals recovered, the third was put down as a stray. The disease was reproduced in experimental cats. Isolate L97 was inoculated into two cats intravenously and two cats by skin scarification. All four developed skin lesions at the site or sites of inoculation, and in one cat multiple lesions developed. The two intravenously inoculated animals also developed severe oedema of the neck and brisket around the site of inoculation into the jugular vein, and one cat died. Serological and pathological findings on both the natural and experimental infections are described. Serum neutralising antibody titres in both natural and experimental early convalescent cases were significantly enhanced by the addition of complement.

Animals↗
PubMed1982

Transmission of feline viral rhinotracheitis.

The transmission of feline viral rhinotracheitis (FVR) virus was investigated. Virus could be successfully transmitted between shedding carrier cats and unrelated susceptible kittens, but only if there was intimate contact between them. Studies on the transmission of FVR virus from carrier queens to their kittens showed that although four of 10 queens shed virus in the post partum period, a total of only four kittens from three litters developed a contact infection. All four kittens remained asymptomatic. Two shed for one day only and did not become carriers (as evidenced by corticosteroid treatment) and two shed for 15 days and 25 days and were subsequently shown to have become carriers. None of the remaining kittens tested shed virus. There was no evidence of in utero transmission between FVR-recovered queens and kittens. Passive antibody titres in kittens born to FVR-recovered queens declined to less than 1 in 4 in individual animals by two to 10 weeks of age. Mean titres calculated from a linear regression equation reached less than 1 in 4 and less than 1 in 2 by six and nine weeks of age, respectively. Experiments using a multistage liquid impinger demonstrated that FVR virus was unlikely to be transmitted between cats by aerosol and this was confirmed by the ability of a sentinel cat to withstand virus shedding from carriers over a six month period, although housed in the same air space.

Aerosols↗
PubMed1982

Efficacy of an inactivated feline calicivirus (FCV) vaccine against challenge with United Kingdom field strains and its interaction with the FCV carrier state.

The efficacy of an inactivated vaccine derived from feline calicivirus (FCV) strain FS2 was assessed against challenge with three UK field strains of FCV. The mean clinical score, calculated on the number of signs recorded per day over 21 days after challenge, was lower for vaccinated cats when compared to unvaccinated animals though the difference was not statistically significant. All cats excreted FCV throughout the three weeks following challenge and there was no difference in the number of days of virus shedding during this period between vaccinated and unvaccinated animals. The development of FCV serum neutralising antibody titres following vaccination and challenge was recorded. In the second part of the study the ability of vaccinated and challenged cats to become FCV carriers and then infect susceptible in-contact animals was demonstrated.

Animals↗
PubMed1980

Interaction of an intranasal combined feline viral rhinotracheitis, feline calicivirus vaccine and the FVR carrier state.

Eight cats were vaccinated intranasally with a combined feline calicivirus/feline viral rhinotracheitis (FVR) virus commercial vaccine. Following intranasal challenge with a field strain of FVR virus and subsequent treatment with corticosteroid, no virus was recovered from any of the eight cats, while FVR virus was recovered following corticosteroid treatment from two of four unvaccinated and challenged controls. No evidence was found for the development of an FVR virus carrier state with the intranasal vaccine virus.

Animals↗