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Biomedical subjects

R M Gaskell

Publications and source records attributed to R M Gaskell.

At least 55 records · Page 3Linked to original sources
PubMed1994

Effect of 3'azido-2',3'-deoxythymidine (AZT) on experimental feline immunodeficiency virus infection in domestic cats.

The compound 3'azido-2',3'-deoxythymidine (AZT) inhibits the replication of feline immunodeficiency virus (FIV) in cell culture, and treatment with the compound has been reported to induce some clinical improvement in some cases of feline FIV infection. In order to determine the effect of prophylactic treatment with AZT on experimental FIV infection, cats were treated with the compound at 0.2, 1.0, 5, 25 or 50 mg kg-1 day-1 for 29 days. One day after the treatment was started, they were inoculated with 150 cat infectious doses of FIV. All the cats became viraemic, seroconverted and developed lymphadenopathy, although the onset of each was delayed in the cats given higher doses of AZT. Anaemia developed in the cats given high doses of AZT. Virus re-isolated from the cats given 50 mg kg-1 day-1 was as susceptible to AZT in cell culture as the inoculated virus. Thus AZT is much less effective in cats than might have been expected from the results of in vitro studies.

Animals↗
PubMed1994

Acute arthritis of cats associated with feline calicivirus infection.

Twelve specific pathogen-free cats were infected either by intra-articular inoculation or by contact exposure to one of two strains of feline calicivirus (FCV), either F65, a field strain originating from an outbreak of lameness in a group of cats, or a vaccine strain. Following either route of exposure, both strains induced signs typical of FCV infection including oral and nasal ulceration, conjunctivitis and ocular discharge. These signs were of equal severity for both virus strains, but overall, following either route of infection, F65 induced more severe disease than the vaccine strain, with marked pyrexia, lethargy and lameness. Vaccine virus only induced a relatively mild lameness following intra-articular inoculation. Gross pathological and histopathological lesions were seen in some of the joints, but again changes were more severe in the F65-exposed cats. Virus was isolated from both normal and affected joints from both groups of F65-exposed cats, and from a joint from each cat inoculated intra-articularly with vaccine virus. Mild transient lameness was also seen in one of two control cats inoculated intra-articularly, but no pathological changes were seen or virus isolated from joints. A cDNA probe used in RNA dot blot hybridisation experiments was found to be specific and more sensitive than virus isolation in detecting FCV in selected tissues. This may be useful in future studies on the pathogenesis of FCV disease and in studies on viral persistence in FCV carriers.

Acute Disease↗
PubMed1994

Studies on the survival of canine coronavirus under different environmental conditions.

Canine coronavirus (CCV) is a common faecal agent which is difficult to isolate. This study shows CCV to survive well at temperatures below -20 degrees C but not at temperatures above 4 degrees C. The presence of faecal material markedly reduced CCV survival times at temperatures ranging from 20 degrees C to -70 degrees C. Thus, it is suggested that diagnostic faecal material should be diluted 1:10 (w/v) with growth medium and examined at the earliest opportunity.

Animals↗
PubMed1994

Susceptibility in cell culture of feline immunodeficiency virus to eighteen antiviral agents.

The in-vitro susceptibilities of two strains of feline immunodeficiency virus to 18 antiviral agents were determined in two cell lines. In terms of inhibiting p24 antigen production, the nucleoside-analogue reverse transcriptase inhibitors were the most effective compounds. Inhibition was also observed with aurintricarboxylic acid, phosphonoformate and butyldeoxynorjirimycin, but not with the other agents tested.

Animals↗
PubMed1993

Typing of feline calicivirus isolates from different clinical groups by virus neutralisation tests.

One hundred and thirteen isolates of feline calicivirus originating from seven different clinical groups were typed by virus neutralisation tests using eight different cat antisera. The clinical groups comprised 'healthy' cats, cases of acute oral/respiratory disease, chronic stomatitis, acute febrile lameness syndrome, vaccine reactions (clinical disease seen within 21 days of vaccination) and vaccine breakdowns (clinical disease seen more than 21 days after but within one year of vaccination). Isolates from the vaccine reaction cases were grouped into those associated with acute oral/respiratory disease alone and those associated with the lameness syndrome, and the latter group was further subdivided according to the vaccine used. Two groups appeared significantly different from others with some of the antisera. Thus the lameness vaccine reaction isolates associated with vaccine B were significantly different from the isolates from all the other clinical groups, including other lameness isolates, with a number of the antisera. In addition, the chronic stomatitis isolates were significantly different from those from the 'healthy' and the acute oral/respiratory disease groups with one or two of the antisera. Eighty-five to 88 per cent of the isolates were neutralised by antisera raised against F9 or F9-like vaccine strains at a dilution of 1 in 2. Twenty antibody units of such antisera neutralised 42 to 80 per cent of the isolates. A bivalent antiserum raised against a vaccine F9 strain and field strain LS015 neutralised 96 per cent of the isolates at a dilution of 1 in 2, and 20 antibody units neutralised 68 per cent of isolates. Antisera to field strain F65 neutralised all the remaining isolates at a dilution of 1 in 2 and 44 per cent of the remaining isolates at a dilution of 20 antibody units. Therefore, strains LS015 and F65 may be of use in the production of a polyvalent feline calicivirus vaccine, together with the widely used strain F9.

Animals↗
PubMed1993

Investigation of vaccine reactions and breakdowns after feline calicivirus vaccination.

The clinical and epidemiological features of feline calicivirus associated vaccine reactions and breakdowns were investigated. Twenty per cent of 123 vaccine reactions were associated with acute oral/respiratory disease alone, and 80 per cent were associated with lameness either alone or in association with other clinical signs. Feline calicivirus was isolated from oropharyngeal swabs from 69 per cent of the vaccine reaction cases. Twenty-four of 31 vaccine breakdowns were associated with acute oral/respiratory disease and only seven with lameness; the virus was isolated from 28 of the 31 breakdowns. Some of the viruses isolated from the vaccine reactions were compared with the appropriate vaccine virus in virus neutralisation tests; the majority appeared to be different from the vaccine virus and were presumably field viruses. However, some appeared more similar to the vaccine virus and the majority of these were associated with lameness after the first vaccination.

Animals↗
PubMed1993

Studies on the epizootiology of canine coronavirus.

The seroprevalence and, or, incidence of canine coronavirus infection was determined in several dog populations in the UK. Seroprevalence ranged from 76 per cent for a rescue kennel to 100 per cent in a commercial breeding colony. In the rescue kennel there was no difference in seroprevalence of the virus between dogs less than or more than four months of age. In the breeding colony, subclinical seroconversion occurred between six and 10 weeks of age. The virus was isolated from faecal samples from 45 of 100 dogs in the rescue kennel; it was isolated from 73 per cent of the dogs with diarrhoea and from 43 per cent of those which did not have diarrhoea. In field cases of acute, mainly haemorrhagic diarrhoea in pet dogs, eight of 32 were positive for canine coronavirus. No canine coronavirus was isolated from either clinically healthy pet dogs in a boarding kennel or from non-diarrhoeic pet dogs examined at the University of Liverpool Small Animal Hospital. It would appear that although canine coronavirus is widespread, the role of the virus in canine enteritis is still equivocal.

Animals↗
PubMed1992

Characterization of orthopoxviruses isolated from feline infections in Britain.

The biological properties and genomes of orthopoxviruses isolated from cats in Britain were compared with strains of cowpox virus isolated from cows and their handlers. All the isolates tested produced haemorrhagic pocks and A-type inclusions on the CAM, but did not produce pocks above 40 degrees C. Thus the feline isolates behaved as typical strains of cowpox virus. Differences were found in the heat resistance of the virions and in the character of the A-type inclusion which did not correlate with the host from which the viruses were isolated. Analysis of the genomes with a variety of restriction endonucleases showed very close relationship between all the isolates and also failed to separate feline isolates from cowpox virus. However again minor differences, which may prove to be of epidemiological value were detected. We conclude that the orthopoxvirus currently isolated from domestic cats in Britain is cowpox virus and that there is no evidence that a feline variant or subspecies circulates in Britain.

Animals↗
PubMed1992

Identification and sequence determination of the capsid protein gene of feline calicivirus.

We have determined 4380 bases of the sequence from a cDNA clone containing the 3' end of feline calicivirus strain F9. We find four candidate open reading frames of which three are complete and comprise 245, 317 and 2012 nucleotides. The fourth continues toward the 5' end. We have expressed the largest complete open reading frame in E. coli. Sera raised to this antigen react specifically with the capsid protein and its intracellular precursor molecule. N-terminal sequence analysis of purified, mature capsid protein confirms this assignment and has identified the position at which precursor is cleaved.

Amino Acid Sequence↗
PubMed1992

The complete nucleotide sequence of a feline calicivirus.

We have determined the complete sequence of a feline calicivirus. The virus genome is 7690 bases long and contains two large open reading frames. Proteins specified by these have similarity to those encoded in the corresponding regions of a candidate calicivirus rabbit hemorrhagic disease virus, but are distinctly different from those specified by another such virus, hepatitis E virus. A third, small open reading frame at the 3' end of the genome is present in both feline and rabbit viruses but is absent from hepatitis E. These findings suggest that the calicivirus family, which consists of a single genus, may require subdivision.

Amino Acid Sequence↗
PubMed1992

Demonstration of sites of latency of infectious laryngotracheitis virus using the polymerase chain reaction.

Mature laying chickens were inoculated intratracheally with a field strain of infectious laryngotracheitis (ILT) virus. Tracheal swabs were collected regularly from all birds for virus culture. At various times post-inoculation, pairs of birds were killed and tissues removed for detection of virus products using conventional tissue homogenization and culture, organ culture, indirect immunofluorescence (IF) and also the polymerase chain reaction (PCR). The latter was used to detect a DNA sequence from the ILT virus thymidine kinase gene. Following inoculation the birds developed mild respiratory disease with clinical signs characteristic of ILT from 3 to 10 days post-inoculation. Trachea and turbinate tissues were virus-positive as determined by virus isolation, organ culture, IF and PCR on day 4 post-inoculation. After recovery from the acute phase, virus shedding initially ceased, then intermittent, low level shedding was recorded for five of the six remaining birds. In an attempt to locate sites of latency, pairs of birds were sampled at 31, 46 and 61 days post-inoculation. Virus was not detected in upper respiratory tract or ocular tissues by conventional techniques, or in the trigeminal, proximal and distal ganglia. All tissues were also negative by PCR, except for the trigeminal ganglia of five of the six birds. All PCR-positive birds had previously shed ILT virus intermittently between days 19 and 59 post-inoculation. As we did not detect viral DNA in any of the other tissues sampled from clinically recovered birds, we conclude that the trigeminal ganglion is the main site of latency of ILT virus.

Animals↗
PubMed1992

Induction and enhancement of feline infectious peritonitis by canine coronavirus.

Preexisting antibody to feline infectious peritonitis virus (FIPV) causes acceleration and enhancement of disease on subsequent infection of cats with FIPV. Other workers have shown that canine coronavirus (CCV) can infect cats subclinically, but have found no evidence of enhancement of, or protection against, subsequent FIPV infection. With various isolates of CCV, we determined that 1 strain of CCV can induce transient mild diarrhea in cats and, furthermore, that previous infection with CCV causes acceleration and enhancement of subsequent infection with FIPV. In addition, sequential inoculation of cats with another strain of CCV caused lesions indistinguishable from those of FIP, without exposure at any time to FIPV.

Animals↗
PubMed1991

Survey of field outbreaks of avian infectious laryngotracheitis in England and Wales.

Field outbreaks of infectious laryngotracheitis in commercial chicken flocks in England and Wales between 1985 and 1988 were investigated. Material from 49 outbreaks was submitted to Liverpool University, and virus was isolated from 17 of them. The results of a questionnaire on each outbreak are described. Generally, the disease was of moderate severity, and mainly affected laying flocks; it occurred in birds of a wide age range but most of the outbreaks were in birds between 10 and 20 weeks of age. The disease was not seen more frequently at any particular time of the year, and there was no evidence of a common source of infection. Three of the affected flocks had recently been moved and were beginning to lay; these stresses may have caused the re-excretion of latent virus.

Age Factors↗