PubMed Health⌕ Search

Biomedical subjects

D A Harbour

Publications and source records attributed to D A Harbour.

At least 19 recordsLinked to original sources
PubMed1996

Parasite prevalence in free-ranging farm cats, Felis silvestris catus.

No animals tested were positive for feline leukemia virus antigen and Chlamydia psittaci antibodies, but all were positive for antibodies to feline calicivirus (FCV), feline herpesvirus 1 (FHV1) and rotavirus. They had antibodies to feline parvovirus (96%), feline coronavirus (84% and cowpox virus (2%). Antibody to feline immunodeficiency virus (FIV) was found in 53% of animals, which were less likely to be infected with Haemobartonella felis, and had higher FHV antibody titres than cats without FIV. FCV was isolated from 51% cats and FHV1 and feline reovirus each from 4%. H. felis was present in 42% of animals, and antibody to Toxoplasma gondii in 62%. Clinical abnormality had a significant association with FIV and feline calicivirus infections, but sex, age, social status and feeding group had no significant association with prevalence of any parasites. Toxocara cati and Toxascaris leonina eggs were found, respectively, in 91% and 82% of animals tested.

Animals↗
PubMed1996

An abattoir-based study of the prevalence of subclinical Johne's disease in adult cattle in south west England.

The prevalance of subclinical Johne's disease was estimated in adult cattle slaughtered at three major abattoirs in south west England. A polymerase chain reaction (PCR) based on IS900 was used to detect Mycobacterium paratuberculosis in intestinal lymph nodes of 1553 cattle. Culture was also carried out on all PCR positive and inconclusive samples. The prevalence of subclinical disease in adult cattle was 3.5% (95% confidence intervals (CI) 2.6-4.7) by PCR and 2.6% (CI 1.8-3.6) by culture. The proportion of the disease in each month ranged from 1.6% (CI 0.2-5.5) in April to 4.6% (CI 2.8-6.9) in November, but the difference was not significant (P > 0.05). The proportion of PCR positive lymph nodes in each abattoir ranged from 2.8% (CI 1.6-4.6) to 4.9% (CI 2.9-7.6), this difference was not significant either (P > 0.05). The prevalence in young cattle was 2.0% (CI 0.6-4.5). The difference between age groups was not statistically significant (P > 0.05).

Abattoirs↗
PubMed1994

Clinical aspects of Chlamydia psittaci infection in cats infected with feline immunodeficiency virus.

Two groups of six cats were established, one a control group and one infected with feline immunodeficiency virus (FIV) 18 months previously. The cats in both groups were inoculated with Chlamydia psittaci and the clinical progression of the infection was monitored by means of a clinical scoring system for 10 months. Haematological, serological and viral and chlamydial isolation studies were also made. The response of the FIV infected group to treatment with oxytetracycline was monitored in the 11th and 12th months. The FIV infection prolonged the duration of the clinical signs resulting from the infection with C psittaci and led to the development of chronic conjunctivitis. The haematological and antibody responses to C psittaci were comparable in the two groups. However, it was possible to isolate C psittaci from the FIV-infected cats up to day 270, when the treatment began, but only up to day 70 in the control group. In addition, it appeared that the infection with a secondary pathogen may have accelerated the clinical progression of the FIV infection.

Animals↗
PubMed1993

Chronic gingivitis in a colony of cats infected with feline immunodeficiency virus and feline calicivirus.

The inadvertent introduction of feline calicivirus into a colony of 19 experimental cats, 13 of which were infected with feline immunodeficiency virus, resulted in the development of chronic gingivitis in nine animals. Of these, six were infected with both viruses, one with the immunodeficiency virus alone and two with the calicivirus alone. The gingivitis was generally more severe in the cats infected with both viruses, suggesting that feline immunodeficiency virus may make cats infected with calicivirus more susceptible to chronic gingivitis.

Animals↗
PubMed1993

Polymerase chain reaction and partial sequencing of a British isolate (T637) of feline immunodeficiency virus.

We have used the polymerase chain reaction (PCR) and direct sequencing of the amplified products to obtain information of the molecular nature of an FIV isolate, T637. Cats experimentally infected with T637 have progressed to clinical immunodeficiency disease. The 5' long terminal repeat (LTR), most of the genes coding for internal proteins (GAG) and surface proteins (ENV), and part of the polymerase (POL) gene have been sequenced. The LTR of T637 has 92% nucleic acid identity with the prototype strain, FIV-Petaluma and the Glasgow isolate, FIV-14, 89% with a Swiss isolate, FIVZ2, and 95% with the PPR isolate. Both GAG and POL genes of T637 share extensive homology with Petaluma and PPR. In the ENV gene, T637 has 91% nucleic acid homology with Petaluma and 86% with PPR, and an overall amino acid homology of between 81-87%. For the surface (SU) region of the ENV gene product, T637 has 89% amino acid homology with Petaluma and FIVZ2 and 86% with PPR.

Amino Acid Sequence↗
PubMed1993

Programmed cell death (apoptosis) as a mechanism of cell death in peripheral blood mononuclear cells from cats infected with feline immunodeficiency virus (FIV).

FIV is a lentivirus infection of cats which induces an immunodeficiency syndrome associated with early qualitative defects in antigen-specific T cell function and with late quantitative defects in CD4+ T lymphocytes. We have observed that peripheral blood mononuclear cells (PBMC) from FIV-infected cats have impaired survival in culture. The mechanism of this in vitro dysfunction and depletion is not known. We have proposed that inappropriate induction of programmed cell death (apoptosis) could account for these in vitro defects. Here, we report that PBMC from FIV-infected cats, with impaired T cell blastogenesis and impaired survival in vitro, undergo an active cell death upon culture, which has the morphological and biochemical characteristics of programmed cell death (PCD). Apoptosis occurred in all six asymptomatic FIV-infected cats, and in none of the nine uninfected cats, which were studied. Changes in cell morphology under both light and electron microscopy, and fragmentation of genomic DNA were characteristic for apoptosing cells. Cell death was spontaneous and occurred in the absence of any stimuli, and culture with the T cell mitogen, concanavalin A (Con A), did not significantly enhance cell death. Activation-induced cell death was inhibited, in a dose-dependent manner, by addition to the incubation medium of zinc, which has been shown to inhibit the action of endonuclease responsible for the characteristic fragmentation of DNA. Since apoptosis has recently been implicated in AIDS pathogenesis, FIV infection may prove useful to study this aspect of retroviral, in particular HIV, infection.

Animals↗
PubMed1992

Comparison of antibody and cell-mediated immune responses in horses following feeding of a novel dietary antigen, ovalbumin, and rotavirus.

Adult ponies which were fed ovalbumin (OVA) daily for 2 weeks had significantly greater serum anti-OVA IgG (P = 0.001) and antigen specific lymphocyte responses (P = 0.031) after intramuscular injection with OVA given with saponin than control ponies which had not been fed the antigen. This suggests that, despite the lack of evidence of B- or T-cell activation in peripheral blood during the period of OVA feeding, the animals were primed for an active secondary immune response. Adult ponies were challenged with equine rotavirus, strain H-2, but no statistically significant differences were found in serum IgG-associated antibody responses or antigen-specific lymphocyte responses between the rotavirus-challenged group and the control group, either following rotavirus challenge or intramuscular injection of rotavirus antigen given with saponin. Our findings, that feeding the non-replicating protein antigen OVA appeared to prime for an increased immune response rather than inducing oral tolerance, may be of relevance to future studies on the way the equine gastrointestinal tract handles usually harmless antigens.

Animals↗
PubMed1992

Reovirus type 2 in domestic cats: isolation and experimental transmission.

Five reovirus isolates were recovered in MA104 cell cultures from the faeces of three cats with nictitating membrane protrusion and diarrhoea, one cat with diarrhoea only and from one healthy cat. Four of these isolates were characterised as reovirus type 2 and one as reovirus type 3 by haemagglutination-inhibition and serum neutralization tests. Reovirus type 2 has not been reported previously in cats. Mild clinical signs of diarrhoea were noted in kittens infected experimentally with one of the feline reovirus type 2 isolates.

Animals↗
PubMed1992

Impaired T-cell priming and proliferation in cats infected with feline immunodeficiency virus.

OBJECTIVE: Cats naturally infected with feline immunodeficiency virus (FIV) are particularly susceptible to infection with opportunistic pathogens, suggesting that these animals are unable to develop an effective immune response against the pathogen. Previous studies have used CD4+:CD8+ lymphocyte ratios and mitogen blastogenesis to identify immunological abnormalities in FIV-infected cats. However, these studies provide limited information for understanding the nature of the cellular dysfunction in FIV-infected cats, particularly defects in antigen-specific immune responses. DESIGN: To investigate whether cats infected with FIV are less able to mount an immune response to previously unencountered antigens, we compared the development of antigen-specific cellular immunity at the stage of T-cell priming in uninfected and FIV-infected cats. INTERVENTIONS: The general immune status of cats was assessed by peripheral blood CD4+:CD8+ lymphocyte ratios (flow cytometry), and by lymphocyte blastogenesis response to T- and B-cell mitogens. In addition, we describe the development of an autologous culture system to measure specific priming of naive feline T-cells to soluble antigen in vitro. This assay was used to compare T-cell priming in uninfected cats and cats which had been infected with FIV for 6-27 months. RESULTS: As in HIV infection, CD4+:CD8+ lymphocyte ratios in FIV-infected cats were found to be inverted, due to a reduction in the percentage of CD4+ cells. In addition, lymphocyte blastogenesis to both T- and B-cell mitogens was significantly impaired in FIV-infected cats. Priming to keyhole limpet haemocyanin (KLH) elicited a late proliferative response resulting from the expansion of CD4+ (T-helper cells). T-cell growth factor secretion correlated with cell proliferation. Restimulation of cells with fresh antigen-presenting cells and antigen showed that antigen-specific T-cell priming had occurred in the initial culture. When primary proliferation responses in FIV-infected cats were examined, it was observed that naive CD4+ T-cells from FIV-infected cats were significantly impaired (P less than 0.001) in their ability to be primed to KLH when compared with uninfected controls. CONCLUSIONS: Impaired priming of naive CD4+ T-helper cells to antigen in FIV-infected cats may explain the increased susceptibility of these animals to infection by opportunistic pathogens. The poor ability of human patients with AIDS to develop humoral immunity following vaccination may also be caused by such a defect in T-cell priming.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Differential in vitro inhibition of feline enteric coronavirus and feline infectious peritonitis virus by actinomycin D.

The growth of feline enteric coronavirus strain 79-1683 in whole feline embryo cells was inhibited by the presence of 1 microgram/ml of actinomycin D in the culture fluid. No virus-specific mRNAs could be detected in such cultures and yields of infectious virus were depressed by > 99%. By contrast, the antigenically related feline infectious peritonitis virus strain 79-1146 was unaffected by the presence of actinomycin D, indicating a fundamental difference between the two feline coronavirus strains in their requirements for host-encoded function(s).

Animals↗
PubMed1992

An early defect in primary and secondary T cell responses in asymptomatic cats during acute feline immunodeficiency virus (FIV) infection.

As in HIV infection of humans, cats infected with FIV are particularly susceptible to secondary infection by opportunistic pathogens, suggesting an impaired ability to elicit an effective immune response against foreign antigens. In order to investigate the development of immunity in FIV-infected cats, we have used an autologous culture system to directly measure priming of naive CD4+ T cells to soluble protein antigen, in vitro. Using this assay, we showed previously that cats infected with FIV for several months had significantly reduced primary proliferative responses. We have now examined cats before infection, and at varying times after infection with FIV, to determine how soon after infection this defect in T cell priming was evident, compared with other quantitative and qualitative measurements of lymphocyte function. Our results showed a progressive decline in immune function in asymptomatic cats during the acute stage of infection with FIV. Primary T cell responses were most sensitive and a significant reduction in proliferation of naive T cells to foreign antigen occurred 5 weeks after infection, despite normal blastogenesis to T cell mitogens and normal CD4+/CD8+ ratios at these times. Whilst lymphocyte proliferation to T cell mitogens was unaffected throughout, a significant reduction in proliferation to a B cell mitogen occurred from week 8 onwards. CD4+/CD8+ ratios fell significantly from week 13 onwards, and proliferation of the memory T cell population to a recall antigen was significantly impaired later, from week 19 onwards. The defect in the priming of naive T cells to foreign antigen early after infection may be important in determining susceptibility to secondary infections.

Animals↗
PubMed1991

Feline infectious peritonitis: a review of clinicopathological changes in 65 cases, and a critical assessment of their diagnostic value.

In 65 natural cases of feline infectious peritonitis (FIP) the common clinicopathological changes included lymphopenia (77 per cent), neutrophilia (45 per cent), anaemia (37 per cent), hyperproteinaemia (39 per cent) and hyperglobulinaemia (39 per cent). There was no difference in the frequency of these abnormalities between the 38 cases of effusive disease and the 27 cases of non-effusive disease. The most consistent changes shown by serum protein electrophoresis were increases in alpha 2- and gamma-globulins. The protein content of the effusions ranged from 39 to 98 g/litre with the globulins comprising 50 to 82 per cent. Coronavirus serology showed a wide variation in antibody titres (0 to 2560) with 320 the modal titre. The diagnostic value of this information was evaluated by comparing it with data from 65 cats in which FIP was considered as a differential diagnosis, but another disease was diagnosed. None of the laboratory tests, including coronavirus serology, had good sensitivity and specificity for the diagnosis of the disease. The presence of multiple abnormalities compatible with the disease increased the specificity but decreased the sensitivity of the diagnosis.

Anemia↗
PubMed1991

Isolation of feline calicivirus and feline herpesvirus from domestic cats 1980 to 1989.

Isolation rates of feline herpesvirus (FHV) and feline calicivirus (FCV) from oropharyngeal swabs, taken from 6866 cats in 1980 to 1989 were studied retrospectively. FCV was isolated from 1364 (19.9 per cent) and FHV from 285 (4.2 per cent). The ratio of FCV:FHV isolations varied from 1.3:1 to 15:1 in individual years with an overall ratio of 4.8:1. Isolation of both viruses was fairly uniform for each year and there was no breed or sex disposition to either virus. Of 872 cats shedding FCV and 213 cats shedding FHV, of known age, 447 (51.3 per cent) with FCV and 140 (65.7 per cent) with FHV were under one year old, compared to only 35.3 per cent of the whole population sampled. For the years 1985 to 1989, more information was obtained about the cases. Of 4626 cats tested, 1180 (25.5 per cent) had acute upper respiratory tract disease (URTD) of which 348 (29.5 per cent) were shedding FCV and 162 (13.7 per cent) FHV. A further 597 had chronic URTD and of these, 102 (17.1 per cent) were shedding FCV and 18 (3 per cent) FHV. In 120 cases of suspected vaccine reaction/breakdown, FCV was isolated from 34 (28.3 per cent) and FHV from only two (1.7 per cent). FHV was not isolated from any of 412 cases presenting with chronic gingivitis/stomatitis alone; 181 (43.9 per cent) were shedding FCV and when cats with other signs in addition to chronic gingivitis were included, this proportion increased to 70.4 per cent.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Restriction endonuclease mapping of the genome of feline herpesvirus type 1.

Restriction endonuclease mapping was used to determine the molecular structure of feline herpesvirus type 1 (FHV-1) strain B 927. FHV-1 DNA purified from infected cells by pulsed field gel electrophoresis was partially restricted with Sau 3A to generate a series of overlapping fragments of 10-20 kb. EMBL 4 DNA was digested with Bam HI and Sal I and viral DNA was inserted into the "stuffer" region. Recombinant phage were selected on E. coli strain Q359. Single and double digestions with the enzymes Eco RI, Bam HI, Sal I, Sst I and Xho I enabled construction of physical maps of the genome. The FHV-1 genome is approximately 126 kbp in length and is composed of a long unique region of 99 kbp and a short region of 27 kbp comprising an unique sequence of 8-9 kbp flanked by inverted repeats of 7-8.5 kbp.

Animals↗