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Biomedical subjects

D A Harbour

Publications and source records attributed to D A Harbour.

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

Mucosal infection and vaccination against feline immunodeficiency virus.

Feline immunodeficiency virus (FIV) infection is a naturally occurring lentiviral infection of cats which progresses to immunodeficiency in a manner strikingly similar to that observed in HIV infection in man. The rectal and cervico-vaginal mucosae are common routes of transmission of HIV and it has been shown that the gastrointestinal tract is an important site of HIV infection and primary pathology. Although biting is the principle mode of transmission for FIV, we have shown that it is possible to reliably infect cats via both the rectal and vaginal routes. Using a biotin-streptavidin linked immunoperoxidase technique we have detected FIV core and envelope proteins in the colonic follicle associated epithelial cells, cells within the lymphoid follice and occasional cells in the lamina propria. Further, in the intestine we have detected FIV RNA and proviral DNA in epithelial cells, colonic lymphoid aggregates and isolated lamina propria cells. We have studied a group of asymptotic cats which have been rectally infected with FIV for 1 year or longer and shown an increase in the number of lamina propria CD8+ cells and greater levels of IL-2, IL-6, IL-10 and gamma-IFN mRNA. Since these cats remained clinically healthy these results might suggest that both local antibody and class I restricted cytotoxic lymphocytes (CTLs) may play a role in control of viral replication. We have investigated a range of vaccination regimes for their ability to generate responses which would protect from rectal challenge with virulent virus. Cats have been immunized with whole virus (FIV-pet, FIV-GLA-8), V3, V3MAP or C2 with cholera toxin (CT), or Quil A based adjuvants via rectal, intra-nasal, parenteral or targeted lymph node routes, and challenged rectally with ten mucosal cat infectious doses (MCID) of FIV-GLA-8. We have shown that the adjuvant effects of cholera toxin and Quil A are not influenced by the route of delivery (intraperitoneal (i.p.) versus rectal) with CT more effective in stimulating humoral and Quil A more effective in stimulating cellular responses to FIV antigens. However we have shown that, quantitatively, CT is more effective when used as an adjuvant via the intra-nasal than the rectal route. Recently, we have begun to investigate if the promising results obtained with targeted lymph node (TLN) vaccination in monkeys could be reproduced in the cat. We have shown that TLN was more effective than rectal immunisation in stimulating both humoral and proliferative responses. In a preliminary study we have also been able to detect FIV specific CTLs and have observed protection from rectal challenge in four out of four cats.

Animals↗
PubMed1999

Immune-mediated haemolytic anaemia in two sibling cats associated with multicentric lymphoblastic infiltration.

Immune-mediated haemolytic anaemia associated with multicentric lymphoblastic infiltration is reported in two sibling cats. Both cats presented at under 16 months of age with clinical signs of acute anaemia. In each case there was autoagglutination, a positive Coombs' test and the anaemia was regenerative. At presentation, both cats were negative for FeLV antigen. In each case, the disease proved fatal within 2 months of the initial diagnosis. In both cases, T-lymphoblastic infiltration of bone marrow, liver and spleen was found at post-mortem examination.

Anemia, Hemolytic, Autoimmune↗
PubMed1999

Cytokine mRNA expression in lesions in cats with chronic gingivostomatitis.

Semiquantitative reverse transcription-PCR assays were developed to measure feline interleukin-2 (IL-2), IL-4, IL-5, IL-6, IL-10, and IL-12 (p35 & p40); gamma interferon (IFN-gamma); and glyceraldehyde-3-phosphate dehydrogenase mRNA concentrations in biopsies of feline oral mucosa. Biopsies were collected from 30 cats with chronic gingivostomatitis (diseased) prior to each cat receiving one of four treatments. In 23 cases replicate biopsies were collected 3 months after treatment commenced. Biopsies were also analyzed from 11 cats without clinical disease (nondiseased). Expression of IL-2, IL-10, IL-12 (p35 and p40), and IFN-gamma was detected in most nondiseased biopsies, while IL-6 was detected in a minority, and IL-4 and IL-5 were both undetectable. Compared to nondiseased cats, the diseased population showed a significant increase in the relative mRNA expression of IL-2, IL-4, IL-6, IL-10, IL-12 (p35 and p40), and IFN-gamma. In contrast, IL-5 mRNA expression was unchanged and was only detected in one case. No significant relationship was demonstrable between the change in relative expression of specific cytokine mRNA and the change in clinical severity of the local mucosal lesions over the treatment period. The results demonstrate that the normal feline oral mucosa is biased towards a predominantly (Th) type 1 profile of cytokine expression and that during the development of lesions seen in feline chronic gingivostomatitis there is a shift in the cytokine profile from a type 1 to a mixed type 1 and type 2 response.

Animals↗
PubMed1998

Natural Borna disease virus infection in cats in the United Kingdom.

Borna disease virus (BDV) is a novel RNA virus that has only recently been characterised and classified in a new virus family, Bornaviridae. The virus was detected in buffy coat cells from four of five cats with neurological disease and in the brains of five of 15 cats with nervous signs and of one of three cats with non-neurological disease. In a serosurvey of 111 cats the incidence of antibody to BDV in cats with neurological disease was higher than in cats with other types of disease, suggesting that the virus may play a role in nervous diseases of cats in the UK.

Animals↗
PubMed1998

Antibody and cytokine responses in kittens during the development of feline infectious peritonitis (FIP).

Two recombinant FIPV spike proteins were assessed for their immunogenic properties in 8-week-old kittens, which were then challenged intranasally with FIPV 79-1146. Humoral responses were assessed by ELISA and serum neutralisation test. Changes in PBMC cytokine mRNA levels were detected by a reverse transcription, semiquantitative polymerase chain reaction assay (RT-sqPCR), assessing IL-2, IL-4, IL-6, IL-10, IL-12 and IFNgamma. All of the kittens developed clinical signs typical of FIP, which were confirmed on gross post mortem examination. The recombinant proteins induced little or no specific antibody response prior to challenge, and failed to alter the course of disease compared to controls. One week after virus challenge, the stimulated PBMCs showed small increases in the expression of IL-6 and IFNgamma mRNA, which correlated with a transient pyrexia. After this time expression of IL-6 mRNA remained unaltered but, as FIP developed, mRNA levels of IL-2, IL-4, IL-10, IL-12 and IFNgamma became markedly depressed.

Animals↗
PubMed1998

Detection of feline coronaviruses by culture and reverse transcriptase-polymerase chain reaction of blood samples from healthy cats and cats with clinical feline infectious peritonitis.

A reverse transcriptase-polymerase chain reaction (RT-PCR) assay for the detection of the feline coronavirus (FCoV) genome and a co-cultivation method for the isolation of field strains of FCoV are described. Using the RT-PCR assay to assess blood samples from cats with feline infectious peritonitis (FIP) (n = 47) and healthy cats from households with endemic FCoV (n = 69) it was shown that approximately 80% of the cats were viraemic, irrespective of their health status. It was also shown that, over a 12-month period, a similar percentage of healthy cats remained viraemic, and that the presence of viraemia did not appear to predispose the cats to the development of FIP. The co-cultivation system proved to be a suitable method for the culture of field strains of FCoV from blood samples, so long as the cultures were maintained for at least 4 weeks. Using this system, followed by the RT-PCR, viraemia was detected as frequently as by RT-PCR on RNA extracted directly from peripheral blood mononuclear cells.

Animals↗
PubMed1998

Assessment of intestinal function in cats with chronic diarrhea after infection with feline immunodeficiency virus.

OBJECTIVE: To identify consistent relevant mechanisms of small intestinal dysfunction in cats with experimentally induced feline immunodeficiency virus infection (FIV) that developed chronic diarrhea during the time they were being used in studies of pathogenicity and transmission of FIV. ANIMALS: 10 cats. PROCEDURE: The following investigative tests and techniques were performed on each of the cats: routine hematologic and serum biochemical analyses; urinalysis; fecal parasitologic and microbiologic examinations; breath hydrogen lactulose (BH2LT) and xylose (BH2XT) tests; intestinal permeability test; endoscopic examination of the intestinal mucosa; bacteriologic culture of endoscopically collected small intestinal juice; and histologic examination of endoscopically obtained intestinal biopsy specimens. RESULTS: Neutrophilia was evident in 3 cats, and lymphopenia was detected in 2 cats. Serum biochemical abnormalities were not observed. Urinalysis results were unremarkable. Fecal bacteriologic and parasitologic results were normal, except for isolation of Campylobacter sp from 1 cat. Abnormal BH2XT values suggestive of D-xylose malabsorption were identified in 2 cats, and BH2LT values indicated evidence of small intestinal bacterial overgrowth in 1 cat. Finally, permeability test results, quantitation of bacterial flora from the proximal part of the small intestine and histologic examination of biopsy specimens did not reveal any abnormalities. CONCLUSIONS: Enteric pathogens did not account for the development of diarrhea in cats with experimentally induced FIV infection, and consistent relevant mechanisms of small intestinal dysfunction were not identified.

Animals↗
PubMed1997

Comparison of the complete sequence of feline spumavirus with those of the primate spumaviruses reveals a shorter gag gene.

The complete nucleotide sequence of the provirus of feline foamy virus (FeFV), strain F-17, was determined, and compared to the available data for human and simian spumaviruses. In addition to the usual retroviral gag, pol and env genes, two open reading frames are present between the env gene and the 3'-LTR, as in the simian spumaviruses, the first being the putative transactivator. The gag gene is predicted to encode a precursor protein of only 53 kDa compared to 70 kDa for simian spumaviruses and a doublet of 70/74 kDa for human spumavirus. The gag gene contains conserved splice acceptor and donor sites suggesting that, like human foamy virus, FeFV expresses its pol gene using a spliced mRNA. The poland envgenes showed greater sequence similarity to their counterparts in the primate spumaviruses than the gag gene and additional open reading frames.

Amino Acid Sequence↗
PubMed1996

Vaginal and rectal infection of cats with feline immunodeficiency virus.

The objective of this study was to examine the potential of vaginal and rectal mucosal routes for feline immunodeficiency virus (FIV) uptake and infection, as a model of mucosal HIV infection, and to determine the fate of virus at these mucosal sites following transmission of infection. SPF cats were exposed to FIV isolates (PET, GL-8, T637), administered as either cell-associated or cell-free inocula, via the rectum or vagina. Establishment of infection was confirmed by isolation of infectious FIV from peripheral blood mononuclear cells (PBMC), and by presence of FIV proviral DNA in PBMC using a nested polymerase chain reaction. Fate of virus in tissue taken at necropsy from cats infected for 6-48 weeks was assessed by localizing FIV core and envelope proteins, p24 and gp41, using a biotin-streptavidin linked immunoperoxidase (IP) technique. Cells susceptible to infection were identified by an in situ hybridization technique for FIV viral DNA and RNA. Cell-free, as well as cell-associated, virus was infectious across intact vaginal and rectal mucosal surfaces. Transmission was most successful using cell-associated inocula, and via the rectal route. Cells infected with FIV were detected by IP staining in the colon of 6/9 rectally challenged cats and 1/5 vaginally challenged cats. Virus was predominantly localized within the epithelium at the base of the colonic crypts associated with lymphoid aggregates (follicle associated epithelium; FAE), and within the lymphoid follicle itself. Occasional infected cells were also noted within the lamina propria. The distribution of FIV DNA positive cells in the colon was similar to that for FIV antigen whilst FIV RNA positive cells were found more extensively, including within the lamina propria and lymphoid follicle. FIV infected cells were not detected within the vagina, or colonic and ileac lymph nodes. Similar patterns of infected cells were seen in all of the positive cats, indicating that colonic tissues remain persistently actively infected with FIV. We conclude that the FIV/cat model of rectal and vaginal mucosal infection should prove useful for characterizing the mechanism by which HIV infects mucosal surfaces and as a challenge system for the design of vaccines effective at preventing HIV infection via rectal and vaginal routes.

Animals↗
PubMed1996

Vaccination with fixed feline immunodeficiency virus (FIV) infected cells: protection, breakthrough and specificity of response.

Infection of cats with feline immunodeficiency virus (FIV), a naturally occurring lentivirus infection of cats which causes an AIDS-like disease, has generated considerable interest as an animal model for HIV vaccination. This paper reports on experiments performed to examine the potential of a fixed infected cell vaccine to confer protection against intraperitoneal challenge with cell-free FIV. The cell vaccine was highly immunogenic and elicited antibody responses to virus core antigen, p24, high virus neutralizing (VN) antibody titres, and antibodies which recognized cellular components of the vaccine. Whilst protection, assessed by the inability to detect infectious virus by virus isolation or polymerase chain reaction, against homologous but not heterologous FIV isolates was apparent up to week 12 post-challenge, when cats were monitored longer up to week 50 post-challenge a breakthrough in vaccine protection against homologous virus was observed. Protection could not be correlated with levels of antibody to p24 or VN antibody titres. In contrast with simian immunodeficiency virus vaccine studies in macaques there was no clear evidence that antibodies recognizing cellular components of the vaccine, including MHC class I and II antigens, conferred any protective effect following challenge. These results indicate that long-term post-challenge monitoring for infection is essential in lentivirus vaccine trials.

Animals↗
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↗
PubMed1996

Encephalitis associated with giant cells in a cat with naturally occurring feline immunodeficiency virus infection demonstrated by in situ hybridization.

This report describes the clinical, pathological, immunocytochemical, and in situ hybridization characteristics of encephalitis associated with feline immunodeficiency virus (FIV) infection in a 4-year-old domestic cat. Lesions were identified throughout the brain, affecting the cerebrum, medulla, and cervical spinal cord. Perivascular lymphocytic cuffing, gliosis, and white matter vacuolation were most severe in the cerebrum, affecting the white matter and the deep laminae of the grey matter. Gemistocytes were prominent, and many bizarre cells with large, sometimes multinucleate, hyperchromatic nuclei were evident. Immunostaining with antibody specific for FIV p24 nucleocapsid protein produced staining in the gemistocytes and glial cells of the white matter. In situ hybridization with a 327-base pair fragment of the FIV gag gene produced staining that was most intense in the white matter and gemistocytes of the deep laminae of the grey matter. These findings indicated localization of FIV infection within the cerebrum, and the detection of FIV RNA by in situ hybridization confirms the infection as active.

Animals↗
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↗