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Biomedical subjects

R C Wardley

Publications and source records attributed to R C Wardley.

At least 37 records · Page 2Linked to original sources
PubMed1985

The differential growth of virulent and avirulent strains of rinderpest virus in bovine lymphocytes and macrophages.

Rinderpest virus (RV) grew readily in cultures of purified bovine peripheral blood lymphocytes and udder macrophages. The growth of three strains of RV was compared and there appeared to be a relationship between increasing virulence and increased ability to infect lymphocytes and macrophages. The proportion of infected cells as determined by the presence of virus antigens was a better indicator of affinity between a strain and cell type than production of new infectious virus. RV grew better in populations of predominantly T lymphocytes than in T-depleted cultures. Although RV could infect 100% of cells in macrophage monolayers, it did not appear to infect more than about 30% of cells in lymphocyte cultures. Virulent RV grew more readily in bovine than caprine or ovine lymphocytes, whereas virulent peste des petits ruminants virus (PPRV) grew better in lymphocytes from sheep and goats. There was no marked difference in the growth of either virus in lymphocytes from uninfected or recently convalescent animals.

Animals↗
PubMed1985

Importance of ovine cytotoxic T cells in protection against bluetongue virus infection.

In sheep, bluetongue virus (BTV) was shown to induce anti-BTV cytotoxic T lymphocytes (CTL) and their effect to be maximal around 14 days post inoculation (p.i.) of virus. Using cellular adoptive transfer techniques in monozygotic sheep, such cells were shown to partially protect animals from BTV challenge. A short-lived cross-protective mechanism was identified involving thoracic duct lymphocytes (TDL) and nonneutralising antibody. These observations suggest that T lymphocytes play an important role in protection against BTV and that current vaccine design based on in vitro serological typing of BTV can be improved.

Animals↗
PubMed1984

Influence of vaccination on Aujeszky's disease virus and disease transmission.

Parenteral vaccination of fattening pigs with either modified live or inactivated Aujeszky's disease virus did not prevent infection with field strain virus or the development of clinical disease. The duration and severity of the clinical syndrome was, however, reduced and vaccinated pigs did not suffer the severe weight loss and high mortality experienced by non-vaccinated pigs in the acute phase of disease. The range of tissues in which challenge virus replication took place was more restricted in vaccinated animals and the concentration of virus in infected tissues was reduced. Vaccination shortened the duration of field virus excretion and carriage in the tonsil. Replication of modified live vaccine virus was restricted to the site of inoculation in the neck and associated lymph nodes for two days after vaccination and it was not excreted by vaccinated pigs. Attempts to infect pigs by feeding them tissues taken from non-vaccinated or vaccinated pigs soon after challenge infection were unsuccessful.

Animals↗
PubMed1984

Development of an enzyme-linked immunosorbent assay (ELISA) for the detection of specific antibodies against an H7N7 and an H3N8 equine influenza virus.

This paper describes a solid-phase microtitre plate enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to equine influenza viruses. Using egg-grown influenza viruses as the antigens attached to the solid phase, cross-reactions were observed between an H7N7 equine virus (designated A1) and an H3N8 equine influenza virus (designated A2) when untreated antisera were tested. Absorption of antisera with egg-grown A/Porcine/Shope/1/33 influenza virus eliminated cross-reactive antibodies so that specific detection of anti-equine influenza A1 or A2 antibodies was possible. Examination of horse sera following vaccination with A1 and/or A2 isolates showed that antibodies were produced against antigen associated with egg allantoic fluid as well as against virus. Such antibodies were eliminated following the absorption of antisera with porcine influenza virus. Results using sera from horses with known vaccination histories confirmed that the ELISA preferentially detected antibodies homologous to the antigen attached to the solid phase and methods to evaluate the current serological state of individual horses by relating the titres of specific antibodies against equine influenza A1 and A2 isolates are shown. This ELISA provides a simple and rapid method of assessing specific antibodies from horse sera and offers advantages over the 'routine' HI and SRH assessments since it gives high precision, is economical of reagents and has the capacity to handle large numbers of serum samples.

Animals↗
PubMed1984

A study of the role of cell-mediated immunity in bluetongue virus infection in sheep, using cellular adoptive transfer techniques.

The transfer of thoracic duct lymphocytes from sheep inoculated 14 days, but not 7 days previously with bluetongue virus into their monozygotic twin resulted in some protection from challenge with bluetongue virus. T cell enrichment of the 14 day thoracic duct lymphocyte population resulted in a similar effect, indicating the T cell basis of the observed protection. Animals recovered from infection with bluetongue virus type 3 and which received thoracic duct lymphocytes from an identical twin recently infected with the same bluetongue virus type were protected from challenge with bluetongue type 4. These observations suggest that T lymphocytes play an important role in protection against bluetongue virus.

Animals↗
PubMed1984

Natural cytotoxicity detected in swine using Aujeszky's disease virus infected targets.

Using percoll gradients and standard B and T cell depletion techniques, porcine lymphocytes were investigated for their ability to show natural killing (NK) of many targets, including Aujeszky's disease virus (AJDV) infected cells. Although it was possible to enrich for NK activity using these techniques it was not possible to define a distinct subpopulation of NK cells. It was noted that porcine NK cells consistently showed a preferential lysis of AJDV infected cells in comparison to uninfected cells. Furthermore, pretreatment of these effector cells with virus or interferon increased their lytic ability but did not alter the degree of preference on the lysis of target cells shown by untreated effectors. Although in vitro results suggested that porcine NK activity might be an efficient mechanism for controlling AJDV infections in the animal, experiments designed to monitor NK levels in vivo were unable to demonstrate this. The possible explanations for this are discussed.

Animals↗
PubMed1984

Cytotoxic lymphocytes induced by African swine fever infection.

The generation of lymphocytes cytotoxic to African swine fever virus infected testis cells during in vivo infection is described. Peripheral blood lymphocytes from 16 pigs developed cytotoxicity seven to eight days after infection but the lysis was not restricted to autologous cells.

African Swine Fever↗
PubMed1984

Clinical and serological outcome following the simultaneous inoculation of three bluetongue virus types into sheep.

The simultaneous inoculation of sheep with three different bluetongue virus types resulted in the replication of only two of the virus types and the formation of neutralising antibodies to only those two types and a failure in the production of heterotypic antibodies. This suggests that the present system of control, using multivalent vaccines in areas in which a number of bluetongue serotypes exist, should be reappraised.

Animals↗
PubMed1984

Role of neutralising antibody in passive immunity to bluetongue infection.

A group of sheep inoculated with serum obtained from sheep which had recovered from bluetongue virus type 3 infection were protected from challenge with the homologous virus type but not from heterologous challenge. Twin lambs which had received colostrum containing virus antibodies were shown to be only partially protected against homologous challenge. A monoclonal antibody directed against the type-determining protein of the virus was also shown to give partial protection against challenge. From this series of experiments it was concluded that antibody has a significant role in protection from bluetongue but that the outcome of challenge will depend on several interacting factors.

Animals↗
PubMed1983

Experimental Aujeszky's disease in pigs: excretion, survival and transmission of the virus.

Airborne Aujeszky's disease virus was recovered from looseboxes containing groups of pigs infected with virus strains from England, Northern Ireland and Denmark from days 1 to 7 after infection. Pigs sampled individually excreted most airborne virus on days 2 and 3 after infection. On a 24 hour basis the maximum amount of airborne virus excreted per pig was log10 5.3 TCID50. Subclinical infection was transmitted from a clinically affected group of pigs to a seronegative group held in separate looseboxes when air was drawn through ducting connecting one box with the other. Tissues taken from pigs killed at varying times after infection showed that the main sites of virus replication were in the head and neck region. Aujeszky's disease virus was detected for up to 40 days in a range of tissues taken from pigs at the acute stage of disease and stored at -20 degrees C.

Air Microbiology↗
PubMed1983

Interactions of porcine alveolar macrophages and bone marrow cells with African swine fever virus and virus-infected cells.

Virus yields from porcine alveolar macrophages (AM) infected with African swine fever virus (ASFV) were greater and were achieved more rapidly, when inoculated at a high multiplicity of infection (MOI) than at low MOI. The difference was related to a lower percentage of cells becoming infected after low MOI inoculation. The reduced yields after low MOI were not caused by prolongation of the culture time, by bacterial endotoxins or by production of inhibitory substances by infected AM. Virus-infected AM were not susceptible to lysis in antibody-dependent cell mediated cytotoxicity (ADCC) assays and this was apparently due to a paucity of viral antigen expressed on the cell surface. Uninfected AM did not act as effectors in ADCC. Porcine bone marrow (PBM) cells were effective in mediation of ADCC and their activity was reduced after ASFV infection. Cells separated into adherent and non-adherent populations, depleted by carbonyl iron treatment or separated by Ficoll-Hypaque centrifugation, all showed effector activity in ADCC. The effector cells were not mature neutrophils or lymphocytes and were probably granulocytic precursors.

African Swine Fever Virus↗
PubMed1983

Serological response of pigs infected with Aujeszky's disease virus.

The temporal development of antibody in four groups of pigs infected with different Aujeszky's disease virus isolates was examined. The enzyme-linked immunosorbent assay detected antibody by five to six days after infection and the antibody-dependent cell-mediated cytotoxicity assay detected antibody seven to nine days after infection. Neutralising antibody was first detected nine to 10 days after infection, whereas assays measuring complement mediated antibody lysis did not detect antibody until 10 days after infection. These results are discussed in terms of their importance to the diagnosis of and recovery from Aujeszky's disease.

Animals↗
PubMed1983

Investigation of porcine natural-killer cell activity with reference to African swine-fever virus infection.

The natural killing of the human myeloid leukaemia cell line by pig mononuclear cells was investigated in an 18 hr assay; the most active natural-killer (NK) effectors were those cells not adhering to nylon-wool columns or rosetting with sheep red blood cells. Mononuclear cells cultured in the presence of African swine-fever virus maintained NK activity. Pigs infected with African swine-fever virus exhibited a suppressed NK activity, possibly due to the sensitivity of NK cells to increased temperatures. The possible role of NK cells in recovery from African swine fever is discussed.

African Swine Fever↗
PubMed1983

Effector mechanisms in the pig. Antibody-dependent cellular cytolysis of African swine fever virus infected cells.

Antibody dependent cellular cytolysis (ADCC) against African swine fever virus infected nucleated cells was investigated in a porcine system. Of the peripheral blood components examined, only neutrophils acted as effectors. Lymph node derived cells displayed no ADCC activity. In vitro yield reduction assays suggested that neutrophil mediated ADCC may play a role in recovery from African swine fever virus infection.

African Swine Fever↗
PubMed1982

The immunological response of pigs and guinea pigs to antigens of African swine fever virus.

Pigs vaccinated with glutaraldehyde-fixed alveolar macrophages (AM) infected with African swine fever virus (ASFV) had an accelerated serological response after subsequent challenge and a slight reduction in levels of viraemia. Vaccination of pigs with detergent-treated infected AM produced no detectable serological response and no protection against homologous challenge. Guinea pigs were vaccinated with glutaraldehyde-fixed ASFV-infected cells, detergent-treated infected cells, detergent-treated infected spleen homogenate, purified ASFV or sonicated infected cells. Antibody was detectable by ELISA after vaccination with all preparations except the detergent-treated infected spleen vaccine. However, vaccination with purified ASFV or sonicated infected cells induced antibodies that were also strongly reactive in antibody-dependent cell-mediated cytotoxicity and complement-mediated lysis assays. If such antibodies are protective, immunization of pigs with purified ASFV or sonicated infected cells may induce a protective immunity.

African Swine Fever↗
PubMed1982

The induction of murine cytotoxic T lymphocytes by bluetongue virus.

After inoculation with live bluetongue virus, mice produced cytotoxic T lymphocytes (CTL) which showed virus and H-2 restriction. Inactivated preparations failed to induce CTLs. On secondary in vitro stimulation, specifically sensitised memory cells also produced high numbers of CTLs. The need for replicating virus to induce primary CTLs, evidence for partial type specificity and the role which cell-mediated immunity might play in the early stages of a bluetongue virus infection are discussed.

Animals↗
PubMed1982

Effect of African swine fever on lymphocyte mitogenesis.

The effect of African swine fever virus replication on T and B lymphocytes was studied by mitogen-driven assays. Live attenuated isolates caused a marked suppressive effect which was dose- and time-dependent. This effect appeared to be mediated through a monokine. Live virulent isolates enhanced lymphocyte mitogenesis in most cases, with increased [3H]-thymidine uptake by T cells and increased Ig secretion by B cells. Killed preparation had no effect. These results are discussed in the light of the allergic response and immunopathological lesions produced by African swine fever virus infections.

African Swine Fever Virus↗