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Biomedical subjects

C G Bridges

Publications and source records attributed to C G Bridges.

14 recordsLinked to original sources
PubMed1992

Latent equid herpesviruses 1 and 4: detection and distinction using the polymerase chain reaction and co-cultivation from lymphoid tissues.

The polymerase chain reaction (PCR) and co-cultivation were used to identify the lymphoreticular system as the site of latency of equid herpesvirus I (EHV-1). Primers for PCR were designed from aligned nucleotide sequences of the glycoprotein gB genes to amplify the same region of both the EHV-1 and EHV-4 genomes. Subsequent restriction digests using specific enzymes distinguished the amplified fragments of the EHV-1 genome from those of the EHV-4 genome. Ten weeks following an experimental infection of five ponies with EHV-1, latent virus was detected by PCR and recovered by co-cultivation, predominantly from lymphoid tissues draining the respiratory tract. Significantly, latent EHV-1 also persisted in peripheral blood leukocytes (PBL). Latent EHV-4, presumably from a preceding natural infection, was also detected in some tissues, including PBL, from all animals. Of additional interest was the recovery of EHV-1 and -4 only in the presence of the ubiquitous EHV-2.

Acute Disease↗
PubMed1990

One way protection between equid herpesvirus 1 and 4 in vivo.

Two groups each of six sibling ponies were exposed to sequential infections with equid herpesvirus 1 or 4 (EHV-1 or EHV-4) at four or five month intervals. Two exposures to EHV-4 did not significantly reduce virus shedding or pyrexia when the ponies were subsequently exposed to EHV-1. However, two sequential infections with EHV-1 completely protected against challenge with EHV-4. Virus neutralising antibody in each group did not increase until 21 days after primary exposure and was subtype specific. However, complement fixing antibody rose within seven days after inoculation with EHV-1, and 14 days after inoculation with EHV-4, and while the latter was subtype specific the former was directed against both EHV-1 and EHV-4. Interpretation of these findings in relation to vaccination is discussed.

Animals↗
PubMed1990

Olga--oligonucleotide primer design program for the Atari ST.

A program to facilitate the design of oligonucleotide primers has been devised. Olga is written in draft ANSI standard 'C' and makes use of the implementation of Digital Research GEM (Graphics Environment Manager) on the Atari ST. Olga is specifically suited to the polymerase chain reaction (PCR) allowing simultaneous analysis of two primer sequences. The advantage of Olga is that it provides in one program analyses for direct repeats, secondary structures and primer dimerization as well as several useful 'finishing' tools for workers engaged in PCR optimization and oligonucleotide syntheses.

Drug Design↗
PubMed1989

Further investigations of equine interferons in vitro.

Following a published procedure, preparations of equine interferon (EqIFN) were prepared. Equine mononuclear leukocytes were induced with equine influenza virus to yield a preparation designated EqIFN-alpha, or with phytohemagglutinin to yield a preparation designated EqIFN-gamma. A preparation designated EqIFN-beta was obtained from equine embryo kidney cells treated with poly(rI):poly(rC) and DEAE Dextran. The pH and heat stability of these preparations were studied, and also their activity on various equine and ovine cells challenged with difference viruses. Unexpectedly, the EqIFN-gamma preparation was found to be stable at pH 2 and to heat at 60 degrees C for 2 h, whereas the EqIFN-beta preparation was labile under these conditions.

Animals↗
PubMed1989

Equine interferons following exposure to equid herpesvirus-1 or -4.

When 23 ponies were infected with equid herpesvirus-1 or -4 (EHV-1 or EHV-4), nasal shedding of interferon (IFN) correlated closely with the duration of viral excretion. Equine interferon (EqIFN) was detected in the serum only from animals infected with the EHV-1 virus, and here high levels correlated with clinical symptoms of locomotor disorder and indicated a poor prognosis. Low levels of IFN were detected in explanted mononuclear cells from ponies infected with either virus.

Animals↗
PubMed1988

The characterization of equine herpes virus-1-infected cell polypeptides recognized by equine lymphocytes.

Ponies, without evidence of previous exposure to Equine herpes virus-1 (EHV-1), were experimentally infected with EHV-1 subtype 2 and investigated for lymphocyte transformation to virus-infected cell polypeptides, as shown by separation with gel electrophoresis. Animals made significant responses to Western blot fractions that corresponded to molecular weights of approximately 30,000, 40,000-45,000, 60,000-65,000, 80,000-95,000 and 100,000-140,000 MW. These molecular weight ranges correlated with the positions of major EHV-1 subtype 2 glycoproteins that were found at migration distances approximating to 137,000, 111,000, 90,000, 65,000 and 47,000 MW. Responses were also made to a subset of similar points on the subtype 1 profile. Hyperimmune equine serum precipitated numerous infected-cell proteins of both subtypes; in particular the recognition of polypeptides with MW of 142,000, 132,000, 114,000, and 46,000 was in agreement with the mitogenic responses. Labelling with 125I indicated that immunoprecipitated greater than 250,000, 182,000, 142,000, 132,000, 75,000, 46,000 and 32,000/34,000 MW products were exposed on the surface of infected cells.

Animals↗
PubMed1987

Rapid diagnosis and characterization of equid herpesvirus 1 using monoclonal antibodies.

Twelve monoclonal antibodies (Mabs) were produced against the attenuated RACH subtype 1 strain of Equid herpesvirus 1. Nine were subtype specific by immunofluorescence or immunoperoxidase, while the other three were against epitopes common to both subtypes. Use of these Mabs allowed isolates to be rapidly and easily subtyped. Immunoblotting indicated that the subtype common Mabs were against viral proteins of MW 140 K and 90 K (VP 9 and 14), while the subtype-specific Mabs were against the glycosylated VP 2 (MW greater than 240 K), and also against VP 12 (MW 110 K) and VP 15 (MW 88 K). Membrane, cytoplasmic, or particulate nuclear patterns of fluorescence were characteristic for each of these proteins. None of the Mabs had neutralising activity but those directed against VP 2 restricted plaque size.

Animals↗
PubMed1987

Genetic restriction of cytolysis during equid herpesvirus 1 subtype 2 infection.

Six Welsh Mountain pony foals were experimentally infected with a subtype 2 isolate of Equid Herpesvirus 1 (EHV-1) and subsequently examined for T cell mediated cytotoxicity against both subtypes. Cytotoxicity was not observed at 3 or 7 days after primary exposure but virus-specific, and genetically restricted, cytotoxicity of EHV-1-labelled autologous skin fibroblasts could be demonstrated 7 and 21 days after the animals were given a second exposure to live virus. Killing of subtype 2 antigen-labelled targets was more efficient than subtype 1 coated cells. This finding was paralleled by the observation that virus-neutralizing and complement-fixing antibody levels were subtype specific after the primary infection but after secondary exposure were directed against both subtypes. During primary infection the lymphocyte proliferative response to EHV-1 subtype 2 was not evident at 7 days post infection (dpi) but by 18 dpi was present in all animals. The second exposure produced an earlier (3 dpi) and larger proliferative response which was specific to the infecting isolate. The non-specific proliferative response to Concanavalin A mitogen indicated that virus infection induced a state of activation in circulating lymphocytes.

Animals↗
PubMed1987

The proteins of equid herpesvirus 1 (EHV 1) recognised by equine antisera and their ability to promote antibody-dependent cell-mediated cytotoxicity.

Equine sera were used to immunoprecipitate radiolabelled virus-infected cell proteins; subsequent resolution with polyacrylamide gel electrophoresis identified the EHV-1 polypeptides VP 2, 10a, 11, 13, 14, 15, 16, 20, 21 and 23a. The humoral support of ADCC by these sera was examined in vitro. Cytotoxicity could be demonstrated against both subtypes irrespective of the immunising isolate. The implications of these results are discussed.

Animals↗
PubMed1986

Endothelial cell infection and thrombosis in paralysis caused by equid herpesvirus-1: equine stroke.

Eight mares were infected with equid herpesvirus-1 subtype 1 isolated from a case of equine paresis. In two mares killed at 4 d.p.i. immunofluorescence showed endothelial cell infection together with thrombosis in the rete arteriosus of the nasal mucosa and also in the spinal cord of one of these mares. Circulating platelet counts in the other six mares fell as early as 2 d.p.i. and remained depressed for seven days. Circulating immune complexes started to appear at 2 d.p.i., reached maximum levels at 10 d.p.i., but were undetectable at 28 d.p.i. Three of the six remaining mares developed varying degrees of inco-ordination at 8 and 9 d.p.i. In the two inco-ordinate mares that were killed at 9 and 10 d.p.i. the haemorrhages in the spinal cord and brain were associated with extensive endothelial cell fluorescence and thrombus formation. Clinical paresis coincided with an increase in circulating complement fixing and neutralising antibodies which in all six mares were higher against the subtype 2 isolate than subtype 1. In five yearlings infected with a subtype 2 isolate of EHV-1 platelet counts remained normal and neither immune complexes nor viraemia, nor inco-ordination were detected.

Animals↗
PubMed1986

Innate immunity during Equid herpesvirus 1 (EHV-1) infection.

Intrinsic phagocytosis and killing of C. albicans by equine monocytes and polymorphonuclear leucocytes (PMN) was examined during Equid Herpesvirus 1 (EHV-1) (subtypes 1 or 2) and Adenovirus infections. Monocyte function increased during EHV-1 subtype 2 and Adenovirus infection. Conversely, there was an impairment of monocyte ingestion during EHV-1 subtype 1 infection which was ascribed to virus replication in peripheral blood mononuclear cells. PMN phagocytosis was not decreased in any of the infections studied. The raised levels of haemolytic complement in animals which subsequently developed EHV-1 subtype 1 induced paresis suggested an abnormality of complement turnover. Increased levels of interferon were evident in the nasal secretions of both subtype 1 and subtype 2 infected animals but only subtype 1 virus induced measurable levels of serum interferon. No intrinsic abnormality of interferon production by monocytes or lymphocytes was found.

Adenoviridae Infections↗
PubMed1985

Further evidence for the procidin function of C3.

It was found that heat-inactivated serum supported phagocytosis, but did not promote oxygen consumption or killing of Candida, by human polymorphonuclear leucocytes (PMNs). It was also established that C3 is required for activation of the PMN candidacidal related mechanisms of superoxide anion generation and iodination. Addition of purified C3 to C3 deficient serum restored phagocytic killing. Further evidence for C3 involvement in Candida killing was obtained from studies of PMN ingestion and killing in the presence of trypan blue or heparin. Trypan blue, which antagonises C3 receptors, prevented efficient killing, as did heparin, which affects C3 conversion in normal serum. From these results it is evident that phagocytic killing is not an obligatory consequence of ingestion. The findings also indicate that killing by PMNs is dependent upon the interaction of humoral factors, termed procidins, with receptors responsible for initiation of microbicidal mechanisms. Activation products of C3 may stimulate phagocytic killing by engagement of their counterpart receptors on PMNs.

Candida albicans↗
PubMed1985

Experimental reactivation of equid herpesvirus 1 (EHV 1) following the administration of corticosteroids.

Eight ponies were experimentally infected with equid herpesvirus 1 (EHV 1) (subtype 1). All animals showed clinical and serological evidence of infection and virus was isolated from nasal swabs and leucocytes. These ponies were kept in isolation for a further three months during which time complement fixing antibody decreased at least four-fold. Following immunosuppression with dexamethasone and prednisolone subtype 1 virus was recovered from six of the eight animals within 14 days. Five of these six ponies were viraemic and three of them shed virus in nasal secretions; only four displayed significant rises in complement fixing antibody and only two in neutralising antibody. Clinical abnormalities were not detected during reactivation.

Animals↗