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Biomedical subjects

D Hannant

Publications and source records attributed to D Hannant.

At least 55 records · Page 3Linked to original sources
PubMed1993

Responses of ponies to equid herpesvirus-1 ISCOM vaccination and challenge with virus of the homologous strain.

An experimental (ISCOM) vaccine previously shown to protect hamsters from lethal challenge with equid herpesvirus-1 (EHV-1), was tested in horses. Vaccination with EHV-1 ISCOMs induced serum antibodies to the major virus glycoproteins gp10, 13, 14, 17, 18 and 21/22a, whereas antibody responses to gp2 were weak or absent. High levels of virus neutralising antibody of long duration were induced, but did not prevent challenge infection with virus of the homologous strain. However, in the vaccinated ponies there was a significant reduction in clinical signs, nasal virus excretion and cell associated viraemia compared with age-matched unvaccinated controls. There was a strong correlation between pre-challenge levels of serum virus neutralising antibody and the duration and total amount of virus excreted from the nasopharynx.

Animals↗
PubMed1993

An immunohistological study of the uterus of mares following experimental infection by equid herpesvirus 1.

Twelve Welsh Mountain pony mares in late gestation were infected intranasally with EHV-1 (AB4 isolate) at dose rates from 10(3) to 10(7.3) TCID50. This resulted in 3 cases of paresis, at Days 9, 10 and 12 after inoculation, and 5 abortions, at Days 6, 9, 18, 19 and 20. Euthanasia was performed between Days 6 and 21, with collection of uterine specimens for histopathology, virus isolation and immunoperoxidase staining from the pregnant horn, non-pregnant horn and body. EHV-1 replication in endometrial vessels was detected as early as Day 6 and was maximal at Days 9-11, when widespread thromboischaemic damage was present. By Days 15-19 in mares remaining pregnant, EHV-1 antigen expression in the endometrium was sparse, despite residual lesions but little associated thrombosis. Endometrial vascular pathology varied considerably in degree and extent, and no consistent predilection sites for replication within the uterus were apparent.

Abortion, Veterinary↗
PubMed1992

Natural killer cells in normal horses and specific-pathogen-free foals infected with equine herpesvirus.

Peripheral blood mononuclear cells (PBMC) from an adult horse and from foals demonstrated natural killer (NK)-type cytotoxicity against a range of xenogeneic and allogeneic cell targets. The human tumour cell line, Chang liver was consistently the most susceptible. Chang liver, rabbit kidney (RK-13), equine sarcoid (ES) and embryonic equine kidney (EEK) cells were more susceptible when presented to horse PBMC than monolayer cultures. Embryonic equine lung (EEL) and murine YAC-1 cells conversely, were more susceptible in a trypsinized state. Horse PBMC demonstrated higher levels of NK-type activity against EEK, EEL and RK-13 cells infected with equine herpesvirus 1 (EHV-1) compared with uninfected cells. Similarly, EEK and EEL cells infected with Semliki forest virus (SFV) were more susceptible. Cytotoxicity against EHV-1-infected EEK cells developed faster, between 4 and 8 h of incubation and reaching a maximum at 24 h. By contrast, cytotoxicity against uninfected fibroblasts was not significant until approximately 16 h of incubation with maximum cytotoxicity observed between 32 h and 48 h. Specific pathogen-free (SPF) foals were inoculated with live EHV-1. PBMC isolated from these foals at different days after inoculation did not display appreciably reduced or elevated NK cytotoxicities against Chang liver cells and EHV-1-infected EEK targets, when compared with that of a PBMC reference from a healthy adult horse.

Aging↗
PubMed1992

The production of equine monoclonal immunoglobulins by horse-mouse heterohybridomas.

Studies were carried out to determine the optimum conditions for the production of equine monoclonal antibodies (MAbs). Lymphocytes from ponies immunised with influenza A equine 2 virus, isolate A/Equine/Newmarket/79 (H3N8) were fused with mouse myeloma (NSO) cells and with horse-mouse heterohybridomas made aminopterin-sensitive by selective growth in 8-azaguanine. Although all fusions initially resulted in heterohybridoma colonies that secreted equine immunoglobulin, many of these were unable to maintain secretion for longer than a few weeks. Increasing the time between immunisation and the booster injection of Newmarket/79 virus, the inclusion of Freund's incomplete adjuvant and the use of an aminopterin-sensitive primary heterohybridoma as the fusion partner, improved the production of HIg-secreting heterohybridomas. After two clonings eight cell lines were established which maintained anti-Newmarket/79 antibody secretion for over a year. FACS analysis of the cell lines provided a useful means of predicting breakdown of MAb secretion by the cell lines, thus enabling re-cloning to be carried out in time.

Animals↗
PubMed1992

Serological responses of specific pathogen-free foals to equine herpesvirus-1: primary and secondary infection, and reactivation.

Serum antibody (virus neutralisation, complement fixation, IgM and IgG) responses to equine herpesvirus-1 (EHV-1) infection were measured in six foals which were initially free from EHV-1 and EHV-4 infection and maternally-derived antibodies. Following primary infection, high titres of virus neutralisation and complement fixation antibodies were detectable against EHV-1, however, corresponding antibody levels against EHV-4 were low or inapparent, although the two viruses share a number of cross-reactive epitopes. In addition, following the primary infection with EHV-1, IgM levels increased before those of IgG, virus neutralisation and complement fixation antibodies, peaked sooner and thereafter declined. Stimulation of IgM levels was observed on secondary infection with EHV-1 given 61 days later. In contrast, IgG, virus neutralisation and complement fixation antibodies following primary infection were more sustained and no increase in their levels was observed on secondary infection. No consistent changes in IgM or IgG levels were seen after administration of dexamethasone to reactivate latent virus.

Animals↗
PubMed1992

Abortion of virologically negative foetuses following experimental challenge of pregnant pony mares with equid herpesvirus 1.

From 1988 to 1991, 51 pregnant pony mares were challenged intranasally or by aerosol with an isolate of EHV-1 (AB4) originally recovered from a quadriplegic mare. This resulted in 32 abortions, occurring from 9 to 29 days after infection. In 14 of the early abortions (Days 9-14), EHV-1 was not demonstrated in the foetal tissues by virus isolation or immunostaining despite no other non-viral cause for the abortion being evident. Application of the polymerase chain reaction to foetal tissues from 9 of these cases also proved negative. One of the 14 mares was destroyed immediately after abortion, and post-mortem examination revealed severe and widespread vasculitis, thrombosis and secondary ischaemic damage in the endometrium with replication of EHV-1 in endothelial cells. These findings suggest that EHV-1 abortion can occur due to endometrial damage without the establishment of a foetal infection.

Abortion, Veterinary↗
PubMed1990

Experimental infection of ponies with equine influenza (H3N8) viruses by intranasal inoculation or exposure to aerosols.

Infection of seronegative Welsh mountain ponies was established by intranasal instillation or exposure to nebulised aerosol of egg grown H3N8 viruses. Pyrexia and coughing were noted following intranasal instillation and high titres of virus were recovered from the nasopharynx. Exposure to aerosol resulted in more severe clinical signs characterised by high temperatures, dyspnoea, anorexia and coughing; lower levels of virus were recovered from the nasopharynx. The severity of clinical signs and the kinetics of virus shedding were dose-related with the minimal infectious dose being 10(2)EID50/ml when ponies were exposed to aerosols produced by nebulisation of 20ml allantoic fluid. Full clinical signs only developed when ponies were exposed to a dose of 10(6)EID50/ml. It was concluded that exposure to nebulised aerosols of egg grown H3N8 viruses was a more reliable method of inducing clinical influenza than intranasal inoculation and would be more suitable for challenge studies.

Administration, Intranasal↗
PubMed1989

Cell mediated immune responses in ponies following infection with equine influenza virus (H3N8): the influence of induction culture conditions on the properties of cytotoxic effector cells.

Cytotoxic cell precursors and/or cytotoxic memory cells were demonstrated in the peripheral blood of ponies after aerosol infection with influenza A/equine/Newmarket/79 (H3N8). In order to reveal their cytotoxic potential, peripheral blood mononuclear cells required a secondary antigenic stimulation. In vitro induced cytotoxic cells showed activity against influenza infected target cells in a 3-4 h 51Cr-release assay. The reactivity of cytotoxic cells was markedly influenced by the conditions of the secondary induction culture. If high concentrations of exogenous crude equine IL-2 were used, virus infected target cells were susceptible to lysis by autologous or allogeneic effector cells. However, if IL-2 concentration was reduced, cytotoxic cells were generated which showed features consistent with cytotoxic T cells in that target-cell killing was genetically restricted.

Animals↗
PubMed1989

Antibody isotype responses in the serum and respiratory tract to primary and secondary infections with equine influenza virus (H3N8).

Serum antibody (IgGab, IgM and IgA) responses to primary and secondary infection with influenza A/equine/Newmarket/79 (H3N8) by nebulised aerosol were compared with local (nasopharyngeal and tracheal) antibody responses in ponies. Circulating IgGab antibody was of long duration after primary infection, whereas IgM responses were short-lived after both primary and secondary infections. The antigenic stimulation of secondary infection with equine influenza was sufficient to induce elevations of serum IgM and IgA in the presence of high levels of circulating IgGab. These results support the potential of virus-specific IgM measurement for the detection of recent exposure to virus in horses which have high levels of circulating IgGab. Unlike serum IgGab, nasal and tracheal wash antibody of this isotype did not show long duration after primary infection, but local antibody memory was demonstrated by anamnestic responses on rechallenge. Nasopharyngeal IgA developed later than IgGab and IgM, and was more durable.

Aerosols↗
PubMed1988

Oil-seed rape.

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Animals↗
PubMed1988

Duration of circulating antibody and immunity following infection with equine influenza virus.

The duration of immunity as measured by virological, serological and clinical responses following infection with influenza A/equine/Newmarket/79 (H3N8) was assessed in repeated challenge experiments in which ponies were infected by exposure to aerosols of infectious virus. Previous infection stimulated complete clinical protection which persisted for at least 32 weeks as demonstrated by the absence of febrile responses and coughing in two groups of ponies infected 16 weeks or 32 weeks after the first infection. Partial clinical protection persisted for over a year as demonstrated by the absence of coughing and a reduction in the number of febrile responses in a group of ponies infected 62 weeks after their first infection. These results contrasted with those observed in immunologically naive control ponies which developed pyrexia, dyspnoea and nasal discharge and coughing. The kinetics of virus specific antibody production in primary and secondary infections with equine influenza were studied by the single radial haemolysis test and a radioisotopic antiglobulin binding assay which measured virus specific IgGab antibody isotype. Antibody to the haemagglutinin, as measured by the single radial haemolysis test, declined rapidly after primary infection whereas the IgGab responses to whole virus antigens persisted for longer. The single radial haemolysis test was therefore particularly useful for the detection of antibody responses in multiple infections or exposures to influenza antigens. The radioisotopic antiglobulin binding assay was more sensitive for identifying infections which had occurred more than six months previously, as evidenced by anamnestic IgGab responses in ponies with low levels of antibody before rechallenge.

Animals↗
PubMed1985

Increased release of hydrogen peroxide and superoxide anion from asbestos-primed macrophages. Effect of hydrogen peroxide on the functional activity of alpha 1-protease inhibitor.

The ability of asbestos-elicited murine peritoneal macrophages to release superoxide anion and hydrogen peroxide, following in vitro triggering, has been investigated. The asbestos-elicited macrophages produced increased levels of superoxide and hydrogen peroxide compared to control macrophages and similar levels to those produced by Corynebacterium parvum elicited macrophages. The supernatants from asbestos-elicited macrophages which had been triggered in vitro were capable of impairing the ability of alpha 1-protease inhibitor to inhibit elastase function. The catalase sensitivity of this effect showed it to be due to hydrogen peroxide.

Animals↗
PubMed1985

Immunomodulatory effects of mineral dust. I. Effects of intraperitoneal dust inoculation on splenic lymphocyte function and humoral immune responses in vivo.

Syngeneic PVG rats and C57BL6 mice were inoculated with liquid suspensions of UICC chrysotile A asbestos, DQ12 quartz or the inert particulate TiO2. Rats received 10 mg and mice received 2.5 mg dust intraperitoneally on day 0. Injection of the pathogenic dusts asbestos and quartz was associated with a significant reduction in mitogenic response to PHA and Con A detected in splenocytes removed from animals 14 days after inoculation. Injection of TiO2 had no significant effect on splenocyte mitogenesis. Pretreatment of C57BL6 mice with asbestos intraperitoneally also impaired subsequent production of antibody to the protein antigen KLH. These data show that intraperitoneal injection of chrysotile A asbestos and DQ12 quartz had a marked effect on generalized T lymphocyte function. An additional immunomodulatory effect of asbestos injection was shown in C57BL6 mice where in vivo humoral immune responses were suppressed.

Animals↗
PubMed1982

Cellular interactions modulating host resistance to tumours.

Active specific immunotherapy of carcinogen-induced rat tumours can be effected using vaccines containing tumour cells admixed with bacterial vaccines such as BCG and C. parvum. The nature of the tumour antigen preparation is important, the most effective immunogen being viable tumour cells whose growth is controlled by responses generated by the bacterial agent in the vaccine. Soluble tumour antigen preparations are usually ineffective due to the preferential induction of suppressor lymphocyte responses in normal hosts. In comparison, removal of suppressor precursors by cyclophosphamide treatment of animals leads to the development of tumour immunity following immunization with soluble antigen preparations. One component of the immune rejection response involves the generation of non-specific effector cells. This type of response can also be induced by administering chemical hypersensitizing agents so as to localize tumour deposits. This approach has proved highly effective in treating the guinea pig line 10 hepatoma by intralesional injection of alkylcatechols. These compounds are highly potent hypersensitizers, being the active constituents of the poison ivy/oak (urushiol oil), and localize in tumour cell membranes.

Adjuvants, Immunologic↗
PubMed1981

Characteristics of two anti-tumour monoclonal antibody preparations.

Monoclonal antibodies directed against one spontaneously arising rat mammary carcinoma and a human osteogenic sarcoma have been prepared following the fusion of spleen cells from appropriately immunised donors with mouse myeloma cells. The characteristics of these antibodies have been analysed and methods for their purification have been developed using immunoadsorption chromatography or by utilising their affinity for Sepharose-linked Protein A. The use of these antibodies for the identification, characterisation and isolation of their target tumour antigenic structures is described.

Animals↗