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Biomedical subjects

I G Wright

Publications and source records attributed to I G Wright.

At least 37 records · Page 2Linked to original sources
PubMed1992

Bovine babesiosis: failure to induce interferon gamma production in response to Babesia bovis antigens in cattle.

The immune response to Babesia bovis infection or vaccination was evaluated by measuring antibody and interferon gamma (IFN-gamma) production to protective recombinant and crude native B. bovis antigens. Cells from vaccinated or infected cattle failed to produce detectable IFN-gamma when stimulated with B. bovis antigens in vitro. In contrast, antibody was induced by protective recombinant B. bovis antigens. These findings are consistent with the argument that immunity to B. bovis infection is correlated most strongly with humoral rather than cell-mediated immune responses.

Animals↗
PubMed1992

Successful vaccination against Boophilus microplus and Babesia bovis using recombinant antigens.

Current methods for the control of the cattle tick Boophilus microplus and the agent of bovine babesiosis, Babesia bovis are unsatisfactory. Effective immunological control of both parasites would have great advantages. However, naturally acquired immunity to the tick is generally unable to prevent serious production losses. A vaccine against the tick, based on a novel form of immunization, is being developed. A protective antigen has been isolated from the tick, characterized and produced as an effective, recombinant protein. A vaccine incorporating this antigen is currently undergoing field trials. In the Australian situation, improved tick control will probably increase endemic instability with respect to B. bovis. Fortunately, a trivalent, recombinant B. bovis vaccine has also been developed. This too is now undergoing pre-registration field trials.

Animals↗
PubMed1991

Babesia bovis host cell recognition proteins.

Babesia bovis enters host erythrocytes by invagination but nothing is known of the proteins involved. By means of metabolic labelling, differential centrifugation in oil and salt elution, a number of babesial proteins have been shown to bind to bovine erythrocytes. Strong binding is evidenced only by a 38/19 kDa pair. Preliminary experiments indicate that these two proteins also bind to human erythrocytes, although apparently to a lesser extent.

Animals↗
PubMed1991

An ELISA for the diagnosis of Babesia ovis infection utilizing a synthetic, Babesia bovis-derived antigen.

The development of an enzyme-linked immunosorbent assay (ELISA) for the detection of Babesia ovis antibodies is described. In an initial study, a crude Babesia bovis antigen and a synthetic B. bovis-derived antigen (designated 11C5) were used to screen 46 B. ovis-positive and 55 negative sheep sera. A 95% correlation between the two antigenic preparations was found with the positive sera; no negative sera gave positive reactions. The synthetic antigen was then used in the screening of 1466 sera collected from sheep from 18 regions of Turkey. A high incidence of B. ovis-positive reactions was found from all regions (60-80%) in sheep over 1 year old, while from two smaller samples the incidence in young sheep was much less (28 and 52%). This test is superior to existing ones because the synthetic antigen can be produced in a highly reproducible state, is specific and is stable over extended periods of time.

Animals↗
PubMed1991

The effect of immune serum and complement on the in vitro phagocytosis of Babesia rodhaini.

The effect of immune serum and complement on the in vitro phagocytosis of Babesia rodhaini was investigated. Infected erythrocytes and parasites released from erythrocytes by lysis were phagocytosed by mouse peritoneal macrophages in vitro when the infected erythrocytes or parasites were exposed to hyperimmune B. rodhaini serum. Complement, in the presence of immune serum, did not reproducibly enhance phagocytosis of infected erythrocytes or parasites alone. When adjusted for its effect on normal erythrocytes and normal serum, complement generally inhibited rather than enhanced phagocytosis. When coupled with other published data, our data suggest that the activation of the immune system in vivo against this species of Babesia involves a series of mechanisms of which phagocytosis is but one.

Animals↗
PubMed1990

An improved ELISA for the detection of antibodies against Babesia bovis using either a native or a recombinant B. bovis antigen.

Two new enzyme-linked immunosorbent assays (ELISA) for the diagnosis of Babesia bovis in cattle are described. The ELISA using a native antigen is more sensitive and less laborious than the assays described previously, because it does not require adsorption of sera with bovine erythrocytes. The second ELISA, using a recombinant B. bovis antigen expressed in Escherichia coli, was both sensitive and specific. It is suitable to replace the native antigen, thus avoiding large batch-to-batch variations in antigen preparations and the need to sacrifice experimental cattle.

Adsorption↗
PubMed1990

In vitro adherence of erythrocytes infected with Babesia bigemina and Babesia rodhaini to thrombospondin.

The adherence of erythrocytes infected with Babesia bigemina and Babesia rodhaini to thrombospondin (TSP) in vitro is demonstrated. Blood with a range of parasitaemias was used and counts of cells which bound to TSP on plastic were significantly different from the controls with both Babesia species. These studies indicated that TSP receptors are present on the surface of red blood cells infected with the two Babesia species, although these parasites do not alter the membranes of infected erythrocytes obviously and do not cause cerebral symptoms in their hosts. Erythrocytes infected with either B. bigemina or B. rodhaini do not adhere to other erythrocytes in vivo, probably because these parasites induce mild infections in their hosts, but they can adhere to TSP in vitro.

Animals↗
PubMed1990

Babesia bovis: immunity induced by vaccination with a lipid enriched fraction.

A chloroform extract from Babesia bovis-infected erythrocytes was used to vaccinate a group of five naive cattle. Following vaccination, the vaccinates, along with a group of control cattle, were challenged with a virulent heterologous strain of B. bovis. The vaccinates, comparative to the controls, showed delayed as well as decreased parasitaemias. The serological and initial biochemical studies suggested that the immune response was elicited by lipid of babesial origin.

Animals↗
PubMed1990

Babesia bovis--effects of phospholipid translocation and adenosine tri-phosphate consumption.

The adenosine tri-phosphate concentration of Babesia bovis-infected erythrocytes was significantly (P less than 0.001) less than that of pre-infection erythrocytes. In addition, phosphatidyl serine was detected on the plasmatic surface of the infected erythrocyte. These two related findings could play important roles in the microvascular stasis characteristic of acute B. bovis infection.

Adenosine Triphosphate↗
PubMed1990

Immunodiagnosis of and immunoprophylaxis against the haemoparasites Babesia sp. and Anaplasma sp. in domestic animals.

The haemoparasites Babesia bovis and Anaplasma marginale are extremely important pathogens of cattle, affecting more than 300 million animals worldwide. Species of less importance affect cattle, dogs, horses and sheep. No vaccine is available for widespread usage. This review summarises existing immunodiagnostic and immunoprophylactic methods currently available for these diseases and reports on future immunoprophylactic methods.

Anaplasma↗
PubMed1989

In vitro adherence of bovine erythrocytes infected with Babesia bovis to thrombospondin and laminin.

This study was undertaken to examine how eight putative adhesive agents bound to plastic surfaces affected the capacity of bovine erythrocytes, infected with either virulent or avirulent strains of Babesia bovis, to adhere in vitro. Thrombospondin (TSP) induced B. bovis-infected bovine erythrocytes to adhere and adherence was augmented when the infected blood was cultured for 24 h before the assay. Moreover, TSP also caused erythrocytes infected with avirulent strains of B. bovis to adhere to plastic in vitro. Laminin promoted the adherence of infected, and to a lesser extent, of uninfected erythrocytes.

Animals↗
PubMed1989

Immunopathophysiology of babesial infections.

Humans infected with Plasmodium falciparum and bovines infected with Babesia bovis display severe haemolysis, alterations in red cell deformability and rigidity, and endothelial cell damage leading to pulmonary oedema and cerebral dysfunction. Much of the pathology associated with these infections is not easily attributable to the relatively small numbers of parasites present. This paper considers the possible roles of soluble mediators released from macrophages, and chemical and physical changes in the infected red cell membrane, in the pathogenesis of babesial infections, and also discusses the effects of prior immunization with various immunogens.

Animals↗
PubMed1989

Detection of Babesia bigemina in cattle by a radioimmunoassay incorporating specifically depleted antigen.

It was observed that mild acidification (pH less than 4.0) together with solvent extraction of the soluble sonicate of a crude preparation of Babesia bigemina infected cattle erythrocytes caused a quantitative loss of B. bigemina-specific antigen. Cross-reacting antigen activities with Babesia bovis remained intact. These properties were utilized in an assay system wherein antibody response to the specifically depleted antigen preparation was subtracted from the response to the initial crude preparation leaving the net B. bigemina response. The radioimmunoassay based on this antigen system was verified using sera from known negative cattle and from cattle previously infected with B. bigemina, B. bovis or Anaplasma marginale. The following discrimination values were obtained: B. bigemina-positive sera less than 2% false negatives; negative sera, 2% false positives; B. bovis-positive sera, 4% false positives; A. marginale-positive sera, 0% false positives. Levels of cross-reactivity in the false positive results were in the "suspect" rather than positive class and in the case of B. bovis-positive sera, may have been due to non-specific antibodies induced by blood inoculation. In animals naturally infected with B. bovis only, there were no false positive reactions. B. bigemina antibodies were readily detectable in field sera for at least 10 months post-infection following infection by the cattle tick Boophilus microplus. This assay overcomes the problems of currently used tests for B. bigemina infection as it is both sensitive and specific and is able to discriminate between both field and laboratory infections of B. bigemina and B. bovis.

Animals↗
PubMed1988

Immunopathophysiology of Babesia bovis and Plasmodium falciparum infections.

Babesia bovis and Plasmodium falciparum are both vector-borne parasites primarily infecting the erythrocytes of their respective hosts. They have obvious differences, yet the diseases caused by these parasites share many common features. Both have generated a considerable body of research but, perhaps because of the classical distinction between veterinary and medical parasitology, many of the similarities between the two have been neglected. As this review shows however, many of the pathophysiological changes in B. bovis infections are poorly described for P. falciparum - and vice versa. Examples are the roles of lipid peroxidation, neutrophil adhesion and production of tumour necrosis factor (TNF) in malaria, which have been largely unstudied in babesiosis, or conversely the roles of fibronectin, immune complexes, cryofibrinogen and the complement cascade in babesiosis, which have been little studied (partly for ethical reasons) in human malaria. To clarify such questions, it may be that each of these diseases may serve as a partial model for the other.

Journal Article↗
PubMed1988

A sensitive ELISA technique for the diagnosis of Anaplasma marginale infections.

A sensitive enzyme-linked immunosorbent assay (ELISA) technique using a horse radish peroxidase conjugate is described for measuring Anaplasma marginale antibodies in bovine serum. This technique utilizes two antigen preparations, a 'negative' antigen derived from an animal prior to infection and a 'positive' antigen derived from A. marginale-infected red cells from the same animal following infection. This markedly reduces cross-reactions which are a result of isoantigens. Absorbance values obtained using the 'negative' antigen are subtracted from those obtained using the 'positive' antigen to give a net figure. Of 100 A. marginale-positive sera tested no false negative results were obtained. All 11 animals maintained tick-free after initial diagnosis of naturally transmitted anaplasmosis were positive 3 years later, 15 A. marginale-infected animals maintained with ticks were positive 27 months after initial infection and a further 26 animals infected with A. marginale by blood inoculation were positive 3 months later. Three per cent of negative sera, 2% of B. bovis and 4% of B. bigemina-positive sera gave positive reactions.

Anaplasma↗