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Biomedical subjects

R M Gaskell

Publications and source records attributed to R M Gaskell.

97 records · Page 6Linked to original sources
PubMed1978

Interaction of a combined feline viral rhinotracheitis-feline calicivirus vaccine and the FVR carrier state.

The effect of field feline viral rhinotracheitis (FVR) virus challenge on cats previously vaccinated with a combined FVR/feline calicivirus intramuscular vaccine was studied in relation to the development of an FVR carrier state. There was no virus shedding of either of the two vaccine viruses following vaccination. Treatment with corticosteroid 60 days after vaccination and before challenge with FVR virus did not induce virus re-excretion in vaccinates or controls; neither did similar treatment induce shedding 63 days after challenge of both vaccinates and controls with virulent field virus. After a further 55 days however, FVR virus shedding was elicited in one of four previously vaccinated and challenged cats compared with two of four unvaccinated and challenged controls. Two sentinel cats remained virologically and serologically free of FVR throughout. The vaccine was shown to be effective in controlling the disease; 12 weeks after initial vaccination no clinical signs were seen in three of four cats following intranasal challenge with 10(5)CCID50 of virulent field FVR virus, and a mild transient unilateral ocular and nasal discharge was seen in the remaining cat for one day only. Severe clinical signs of approximately 10 days' duration were seen in all four unvaccinated challenged controls. The virological and serological responses of the cats were also recorded.

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PubMed1977

Experimental induction of feline viral rhinotracheitis virus re-excretion in FVR-recovered cats.

The re-excretion of feline viral rhinotracheitis (FVR) virus (feline herpesvirus I) by FVR-recovered cats is recorded both spontaneously and following a variety of stimuli, namely, corticosteroid administration, change of housing, and parturition and lactation. At least 27 of 33 (82%) FVR-recovered cats studied were shown to be viral carriers. The carrier state was characterised by periods of viral latency interspersed with episodes of viral shedding. Administration of 0-75 mg dexamethasone trimethylacetate and 2-25 mg prednisolone on days 0,2 and 4 resulted in re-excretion after a mean lag period of 7-2 days in 22 of 32 (69%) FVR-recovered cats on a total of 31 of 57 (54%) occasions. Rehousing resulted in virus re-excretion after a mean lag period of 7-2 days in four of 22 (18%) cats tested on a total of six of 40 (15%) occasions. Apparently spontaneous shedding occurred on a total of 10 occasions in nine of 31 (29%) cats during a mean observation period of 8-8 months. Four of six FVR-recovered queens in a total of four of 10 litters (40%) shed virus within two to 10 weeks of parturition. Serum neutralising antibody titres were generally boosted at the time of first re-infection but afterwards remained essentially constant. Although 82% of cats in these studies were shown to be viral carriers, only 45% of cats shed virus spontaneously or as a result of the natural stress situations and it is postulted that these naturally excreting cats are of most significance epidemiologically.

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PubMedDate not supplied

The use of sequence analysis of a feline calicivirus (FCV) hypervariable region in the epidemiological investigation of FCV related disease and vaccine failures.

A reverse transcriptase polymerase chain reaction (PCR) was used to amplify a 235 bp hypervariable region of the feline calicivirus (FCV) genome which encodes part of the capsid protein. Sequence from this region was used to compare viruses used in three attenuated vaccines to viruses isolated from vaccinated cats with clinical signs of FCV-infection (vaccine failures). All three vaccine viruses contained sequence similar to that published for FCV strain F9 (Carter et al. 1992, Virology 190, 443-448). However, two of the three vaccines contained a separate sequence which was 20.67% distant (number of nucleotide substitutions per 100 bases) from F9. The sequences derived from isolates obtained from vaccine failures fell into two categories. Most were distinct (21.33-38.00% distant) from vaccine sequence. However, in some cases, sequences were sufficiently similar to the vaccines' (0.00-5.33% distant) to suggest that the isolate may have originated from the vaccine. In addition, comparison of sequence determined for isolates from the same disease outbreak showed them to be closely related (0.00-1.33% distant), whereas epidemiologically unrelated isolates were 20.67-38.00% distant.

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PubMedDate not supplied

Restriction endonuclease patterns of some European and American isolates of avian infectious laryngotracheitis virus.

Eleven isolates of infectious laryngotracheitis virus (nine European and two American) were compared by restriction endonuclease analysis of their DNA after radiolabeling with 32P. Digestion with KpnI gave identical cleavage patterns for all the European isolates, but the two American viruses (one field and one vaccine) showed some differences from them and from each other. In the case of the American vaccine strain, however, these differences were only minor. After BamHI digestion, only the American field isolate appeared to be different, whereas with HindIII, all 11 isolates were identical.

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