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R M Gaskell

Publications and source records attributed to R M Gaskell.

At least 37 records · Page 2Linked to original sources
PubMed1999

Nucleotide sequence of UK and Australian isolates of feline calicivirus (FCV) and phylogenetic analysis of FCVs.

We have determined the first complete genome sequence and capsid gene sequences of feline calicivirus (FCV) isolates from the UK and Australia. These were compared with other previously published sequences. The viruses used in the comparisons were isolated between 1957 and 1995 from various geographical locations and obtained from cats showing a range of clinical signs. Despite these diverse origins, comparisons between all strains showed a similar degree of sequence variation within both ORF1 (non-structural polyprotein) and ORF2 (major capsid protein) (amino acid distances of 7.7-13.0% and 8.8-18.6%, respectively). In contrast, ORF3 (putative minor structural protein) sequences indicated a more heterogenous distribution of FCV relatedness (amino acid distances of 1.9-17.9%). Phylogenetic analysis suggested that, unlike some other caliciviruses, FCV isolates within the current data set fall into one diverse genogroup. Within this group, there was an overall lack of geographic or temporal clustering which may be related to the epidemiology of FCV infection in cats. Analysis of regions of variability in the genome has shown that, as well as the previously identified variable regions in ORF2, similar domains exist within ORFs 1 and 3 also, although to a lesser extent. In ORF1, these variable domains largely fall between the putative non-structural protein functional domains.

Amino Acid Sequence↗
PubMed1999

Prevalence and risk factors for feline Bordetella bronchiseptica infection.

A cross-sectional survey of a convenience-sample of 740 cats was undertaken to obtain an estimate of the prevalence of Bordetella bronchiseptica infection, and to identify risk factors that might predispose them to the infection. Data on individual cats and household variables, including disease status and animal contacts were obtained by questionnaire. B bronchiseptica was isolated from 82 (11 per cent) of the cats sampled. The prevalence of B bronchiseptica varied with the type of household sampled, being 19.5 per cent in rescue catteries, 9 per cent in breeding catteries, 13.5 per cent in research colonies, and 0 per cent in household pets. On the basis of a univariable analysis, 19 of 29 predictor variables were found to be significantly associated with the isolation of B bronchiseptica, including an association with cats in rescue catteries, and with cats from premises with larger numbers of animals. Separate analysis of the rescue cattery subpopulation showed a highly significant association on multivariable analysis with current respiratory disease, suggesting that different risk factors may operate in this type of environment. In the whole sample there was also strong association with cats from households containing a dog with recent respiratory tract disease. The clinical signs observed in the B bronchiseptica-positive cats included sneezing, ocular and nasal discharges and coughing, although only the association with sneezing was statistically significant. There was no significant association between the isolation of B bronchiseptica and the isolation of respiratory viruses, suggesting that in some circumstances B bronchiseptica may be able to cause disease independently.

Analysis of Variance↗
PubMed1999

Bordetella bronchiseptica infection in the cat.

Feline Bordetella bronchiseptica infection had received little consideration until recent years when it has been increasingly documented in association with respiratory disease. This article reviews current knowledge on the organism; its epidemiology, pathogenesis, and clinical, diagnostic and therapeutic features.

Animals↗
PubMed1999

The capsid gene of feline calicivirus contains linear B-cell epitopes in both variable and conserved regions.

In order to map linear B-cell (LBC) epitopes in the major capsid protein of feline calicivirus (FCV), an expression library containing random, short (100- to 200-bp) fragments of the FCV F9 capsid gene was constructed. Analysis of this library showed it to be representative of the region of the capsid gene that encodes the mature capsid protein. The library was screened by using polyclonal antisera from a cat that had been challenged experimentally with F9 to identify immunoreactive clones containing LBC epitopes. Twenty-six clones that reacted positively to feline antisera in immunoblots were identified. FCV-derived sequence from these clones mapped to a region of the capsid that spanned 126 amino acids and included variable regions C and E. An overlapping set of biotinylated peptides corresponding to this region was used to further map LBC epitopes by using F9 antisera. Four principal regions of reactivity were identified. Two fell within the hypervariable region at the 5' end of region E (amino acids [aa] 445 to 451 [antigenic site (ags) 2] and aa 451 to 457 [ags 3]). However, the other two were in conserved regions (aa 415 to 421 [ags 1; region D] and aa 475 to 479 [ags 4; central region E]). The reactivity of the peptide set with antisera from 11 other cats infected with a range of FCV isolates was also determined. Ten of 11 antisera reacted to conserved ags 4, suggesting that this region may be useful for future recombinant vaccine design.

Amino Acid Sequence↗
PubMed1998

The use of pulsed-field gel electrophoresis to examine the epidemiology of Bordetella bronchiseptica isolated from cats and other species.

A collection (164) of isolates of Bordetella bronchiseptica made predominantly from cats (132) but also from dogs (15), pigs (12) and other species was examined by pulsed field gel electrophoresis following macrorestriction digestion with XbaI. Each isolate was analysed twice and the patterns were entirely reproducible. The isolates fell into 17 different strains (> 3 bands different) and within strains there were numerous subtypes. Feline isolates fell into 12 of the 17 strains. In general, cats housed together had similar or identical strains and subtypes of B. bronchiseptica. There was no difference in the PFGE patterns of isolates made from carrier cats and those from cats with respiratory disease. Isolates from pigs and dogs were in general similar to the feline isolates and there was no great evidence for species specificity. The PFGE pattern of feline and canine isolates were more related to whether the animals were housed together rather than whether they came from dogs or cats.

Animals↗
PubMed1998

Quasispecies evolution of a hypervariable region of the feline calicivirus capsid gene in cell culture and in persistently infected cats.

Feline calicivirus (FCV) is a respiratory pathogen of cats that is capable of causing persistent infections. This study examined the evolution of a hypervariable region of the FCV capsid gene both during 90 passages in cell culture and during replication in persistently infected cats. This region of the capsid protein is known to contain neutralization epitopes and may be a target for immune evasion during virus persistence in the host. Sequence analysis showed that FCV exists as a quasispecies which evolved both in cell culture and in persistently infected cats. Changes involved both loss of sequence present in the infecting isolate and a gain of both synonymous and non-synonymous nucleotide substitutions to generate sequences not detected within earlier isolates. Overall, these changes led to a reduction in population heterogeneity over time. Where virus populations were highly homogeneous allowing a consensus sequence to be determined, evolution rates for the consensus sequence ranged from 0.10-1.07 substitutions per nucleotide per year. Marked changes in virus neutralization profiles were seen in isolates obtained sequentially from a persistently infected cat. This was not the case with cell culture passaged virus, suggesting that the individual amino acid changes found only in virus from persistently infected cats may significantly alter the antigenic profile of FCV, and may be the result of immune selection.

Amino Acid Sequence↗
PubMed1997

Cowpox in British voles and mice.

Serosurveys indicate that bank voles, field voles and woodmice are probably reservoir hosts of cowpox virus in western Europe, although virus has not yet been isolated from these species. In this study, bank voles, field voles, woodmice and laboratory mice were shown to be susceptible to combined intradermal and subcutaneous inoculation with 3-20 plaque-forming units (pfu) of cowpox virus. Bank and field voles, but not laboratory mice, were also susceptible to combined oral and nasal inoculation with 50 pfu. Few clinical signs were seen and virus was generally recovered only from inoculation sites. Bank voles were not susceptible to injection of ectromelia virus (5000 pfu) into the skin (as described above). These results provide information on which further pathogenesis and transmission studies can be based, and support the view that the orthopoxvirus antibody detected in British wild voles and woodmice indicates infection with cowpox virus. However, further investigation of the pathogenesis of cowpox in these species is needed to understand better the epidemiology of the disease.

Administration, Intranasal↗
PubMed1997

Antimicrobial susceptibility of Bordetella bronchiseptica isolates from cats and a comparison of the agar dilution and E-test methods.

One hundred and fifty-two predominantly feline isolates of Bordetella bronchiseptica were tested for their susceptibility to seven antimicrobial agents using an agar dilution method. The majority of isolates tested by the agar dilution method were resistant to trimethoprim (MIC90 500 micrograms/ml) and ampicillin (MIC90 > 32 micrograms/ml) but sensitive to tetracycline, doxycycline and enrofloxacin (MIC90 2 micrograms/ml for all three agents). The isolates showed a spectrum of susceptibility to sulphadiazine and clavulanate potentiated amoxycillin. The MIC's of twenty-nine of the 152 isolates were then compared for five of the antimicrobial agents using the E-test (AB Biodisk, Sweden), a recently introduced method for measuring the MIC's of antimicrobial agents based on the diffusion of a pre-defined antibiotic gradient from a plastic strip. Comparisons with the E-test demonstrated an overall agreement (+/- 1 log2 dilution) with the agar dilution method of 79.4% and an agreement within +/- 2 log2 dilutions of 96.2%.

Agar↗
PubMed1997

Dexamethasone inhibits virus production and the secretory IgA response in oesophageal-pharyngeal fluid in cattle persistently infected with foot-and-mouth disease virus.

Cattle persistently infected with foot-and-mouth disease virus were treated with dexamethasone to suppress the immune system in an attempt to influence the level of virus recovery from oesophageal pharyngeal (probang) samples. Twelve carrier cattle were assigned to one of three groups: control; 0.1 mg/kg dexamethasone; and 0.5 mg/kg dexamethasone. Groups 2 and 3 were injected intramuscularly three times weekly for 3 weeks with dexamethasone between days 33 and 56 post-infection with foot-and-mouth disease virus (FMDV). Cattle in both groups developed a leucocytosis, neutrophilia and lymphopenia. The secretory IgA response to FMDV infection was inhibited following, but not during, dexamethasone treatment between days 70 and 98 post-infection (P < 0.05). FMDV recovery from probang samples was reduced between days 40 and 64 post-infection (P < 0.05) during treatment with either 0.1 or 0.5 mg/kg dexamethasone. Following cessation of dosing with dexamethasone virus recovery returned to control levels. These observations suggest dexamethasone inhibits shedding of FMDV in a reversible manner which may be related to its immunosuppressive, anti-inflammatory or physiological actions.

Animals↗
PubMed1997

Sequences of the ribonucleotide reductase-encoding genes of felid herpesvirus 1 and molecular phylogenetic analysis.

The felid herpesvirus 1 (FHV-1) genes encoding the two ribonucleotide reductase (RR) subunits (RR1, large subunit and RR2, small subunit) were cloned and their nucleotide (nt) sequence determined. The RR1 open reading frame (ORF) is 2358 nts long and is predicted to encode a protein of 786 amino acids (aa). In common with herpesviruses in the Varicellovirus genus of the alphaherpesvirus subfamily, FHV-1 RR1 lacks the N-terminal serine threonine protein kinase region present in herpes simplex virus (HSV)-1 and -2. FHV-1 RR1 has a predicted aa identity of 47-64% with other alphaherpesvirus RR1 peptides, falling to 26-29% for gammaherpesviruses. The RR2 ORF is 996 nts long, predicted to encode a protein of 332 aa and has aa identities of 64-70% with alphaherpesviruses and 38-39% with gammaherpesviruses. Molecular phylogenetic analysis groups FHV-1 with equid herpesviruses 1 and 4 (EHV 1 and 4), pseudorabies virus (PRV) and bovid herpesvirus 1 (BHV 1) within the genus Varicellovirus.

Alphaherpesvirinae↗
PubMed1997

Characterization of antibiotic resistance plasmids from Bordetella bronchiseptica.

Of 52 antibiotic-resistant Bordetella bronchiseptica isolates from cats, ten carried plasmids. Only two of these plasmids, pLV1400 and pLV1401, were self-transmissible to Escherichia coli K12; both plasmids encoded resistance to ampicillin, tetracycline, sulphonamides, streptomycin and mercuric chloride, and were of incompatibility group P (IncP). Transferable tetracycline resistance has not been reported in B. bronchiseptica previously. The plasmids were identical in size (c.51 kb), restriction endonuclease digestion pattern and gene sequences (trfA and korA) within the IncP replicon. The trfA and korA sequences differed from those of the archetypal IncP plasmids RP4 and R751. Although the two B. bronchiseptica isolates were from epidemiologically and geographically separated cats, pulsed-field gel electrophoresis of their XbaI- or DraI-digested chromosomal DNA indicated that they were genotypically identical. The plasmid-encoded ampicillin resistance was mediated by a penicillinase of molecular weight 49,000, and pI 8.45 which was inhibited by clavulanate (IC50 = 0.1 mg/L) and tazobactam (IC50 = 0.42 mg/L) but not by parachloromercuribenzoate or EDTA. The high-level tetracycline resistance was mediated by a class C efflux mechanism that has not been described previously in this genus. The presence of transferable multi-drug resistance on a promiscuous plasmid may limit options for therapy of respiratory tract infection in companion and farm animals.

Animals↗
PubMed1996

Serological survey for orthopoxvirus infection of wild mammals in areas where a recombinant rabies virus is used to vaccinate foxes.

Several fox vaccination campaigns against rabies have been undertaken in Belgium by using a vaccinia-rabies recombinant virus distributed in baits in the field. However, foxes and other wild animals that may ingest the baits could be infected at the same time by another orthopoxvirus, such as cowpox virus, which circulates in wildlife. Recombination between the two viruses could therefore occur. A serological survey for antibodies to orthopoxvirus, and particularly to cowpox virus, was undertaken in foxes and in several other wild species. Antibodies were detected only in two rodent species, in 16 of 25 bank voles (64 per cent) and in two of 29 woodmice (7 per cent). The risk of virus recombination in wildlife can therefore be considered to be extremely low.

Animals↗
PubMed1996

Studies on natural transmission of Bordetella bronchiseptica in cats.

Two pregnant specific-pathogen-free (SPF) cats, from a colony endemically infected with Bordetella bronchiseptica, were housed under barrier conditions in the latter stages of pregnancy in order to study the possible transmission of the organism to their kittens. Both queens had antibody titres to Bordetella bronchiseptica of 1 in 320 at the start of the experiment but did not shed Bordetella bronchiseptica until 9 days and 6 weeks after parturition, respectively. Five of the nine kittens had detectable maternally-derived-antibody to Bordetella bronchiseptica which declined to < or = 1 in 40 by two weeks of age. Kittens were weaned at 12 weeks of age. No Bordetella bronchiseptica was isolated from any of the kittens and none seroconverted over this time. At 15 1/2 weeks of age, half of each litter were housed separately and inoculated intra-nasally with 10(8) colony-forming-units B. bronchiseptica. Mild signs of upper respiratory tract disease were seen and the organism was isolated for 19 weeks following inoculation when the experiment ended. Seroconversion occurred at 4 weeks postinoculation. Oral treatment of two clinically-recovered kittens with doxycycline once a day did not eliminate shedding.

Animals↗
PubMed1996

Feline calicivirus strain differentiation using monoclonal antibody analysis in an enzyme-linked immuno-flow-assay.

Six monoclonal antibodies raised against feline calicivirus (FCV) strain F9 were used in an enzyme-linked immuno-flow-assay (ELIFA) to analyse 55 isolates of FCV. Forty seven field isolates were obtained from cats with acute oral/respiratory disease, chronic oral lesions, and from cats showing vaccine reactions, i.e. clinical signs of FCV infection shortly after vaccination. Eight reference strains including F9 and three vaccine strains based on F9 were also examined. All of the strains of F9, derived from various sources, reacted with all six of the monoclonal antibodies, whereas some of the field isolates did not react with any. In general, the field isolates showed a spectrum of reactivities and selected isolates could be distinguished. However, there were no clear cut differences between the clinical groups. Overall, the oral/respiratory group showed less reactivity with the monoclonals, suggesting they were less related to F9. Although the other groups appeared to be more closely related to F9, none of the isolates tested reacted with all six monoclonal antibodies.

Animals↗
PubMed1995

Comparison of the susceptibility of the red fox (Vulpes vulpes) to a vaccinia-rabies recombinant virus and to cowpox virus.

Sylvatic rabies can be efficiently controlled by vaccination of foxes with a vaccinia-rabies recombinant virus. However, the risk of recombination between the engineered vaccine virus and other orthopoxviruses endemic in wildlife, such as cowpox virus, still needs to be investigated. In this study, foxes inoculated orally and intradermally with cowpox virus were found to be not very susceptible to cowpox virus, which was isolated from only the oropharynx and tonsils, at low titre and for only five days after inoculation. Thus the risk of recombination between these viruses in foxes is very low.

Animals↗
PubMed1995

Serological evidence for the reservoir hosts of cowpox virus in British wildlife.

The reservoir host of cowpox virus in Western Europe is not known, but epidemiological evidence from human and feline infections indicates that the virus is probably endemic in small wild rodents. Therefore, serum and tissue samples were collected from a variety of wild British mammals and some birds, and tested for evidence of Orthopoxvirus infection. Antibody reacting with cowpox virus was detected in 9/44 (20%) bank voles (Clethrionomys glareolus), 8/24 (33%) field voles (Microtus agrestis), 17/86 (20%) wood mice (Apodemus sylvaticus) and 1/44 house mice (Mus musculus), but in no other animal species tested. Although virus was not isolated from any animal, this serological survey, together with other evidence, suggests that bank and field voles and wood mice are the main reservoir hosts of cowpox virus in Great Britain.

Animals↗