Biomedical subjects

J Kleuskens

Publications and source records attributed to J Kleuskens.

7 recordsLinked to original sources

PubMed2006

Recombinant protein Bd37 protected gerbils against heterologous challenges with isolates of Babesia divergens polymorphic for the bd37 gene.

The Bd37gene encoding for a glycosyl-phosphatidyl-inositol anchored protein of Babesia divergens displays genetic polymorphisms among isolates. Five major polymorphic groups (clades) were shown by PCR-RFLP among different B. divergens isolates. Each group has been characterized according to a reference Bd37 gene (Rouen87, W8843, Y5, 6303E and 1705B). Recombinant (GST fusion) protein (Bd37r) expressed from the Bd37 gene, was used as antigen in a saponin-based formulation and was able to protect gerbils, after 2 injections at low dose vaccine concentration (1 mug per dose), against a virulent challenge with the B. divergens Rouen87 isolate. In spite of polymorphism of Bd37 gene, Bd37r induced complete immunoprotection against challenges with each of the 5 reference isolate groups defined by PCR-RFLP.

Amino Acid Sequence↗

PubMed2004

Association between sequence polymorphism in an epitope of Babesia divergens Bd37 exoantigen and protection induced by passive transfer.

In Europe, Babesia divergens is the major agent responsible for babesiosis in cattle and can occasionally infect splenectomised humans. Recently, we reported the characterisation of a 37 kDa exoantigen (Bd37) anchored in the merozoite membrane of B. divergens by a glycosylphosphatidyl-inositol. After phospholipase hydrolyse of the glycosylphosphatidyl-inositol anchor, the Bd37 antigen could be isolated in the plasma of the infected host and from the in vitro culture supernatants. Immunisation of mice with a gel-filtration protective fraction of B. divergens exoantigens, produced a monoclonal antibody (MAb), called F4.2F8-INT, directed against Bd37. In the present study, we report data on passive protection using MAb F4.2F8-INT. This MAb was able to completely protect against virulent challenges with B. divergens isolates Rouen 1987 (Rouen87) and Weybridge 8843 (W8843) but had no protective effect against another French isolate from Massif Central (6303E). Physical characterisation of the epitope recognised by F4.2F8-INT allowed us to explain the differences observed between these isolates by western blotting and passive protection. These results suggest that the antigen carrying this epitope could be used as a target in the development of a recombinant vaccine against B. divergens babesiosis.

Amino Acid Sequence↗

PubMed1998

Parasite localization and dissemination in the Babesia-infected host.

Babesia bovis infections in cattle and B. canis infections in dogs are characterized by non-haemolytic anaemia and low parasitaemia during the acute phase of the disease. In this phase of the disease, animals suffer from hypotension followed by disturbances of the coagulation system. This review discusses the hypothesis that may explain the process of parasite localization in the host, and the consequences of such localization. It is suggested that hypotension favours the interaction between infected erythrocytes and the endothelial lining, thus facilitating localization of the infection. In addition, activation of the coagulation system by a parasite-derived molecule (one associated with the surface of infected erythrocytes or a soluble antigen) might consolidate this situation by causing cellular plugs to form. The continued proliferation of parasites in such plugs may then result in the occurrence of capillaries that are particularly heavily parasitised. An explanation is also suggested for the protective effect of vaccines against clinical babesiosis, based on the soluble parasite antigens that are released into the medium in cultures of babesial parasites.

Animals↗

PubMed1997

Different Babesia canis isolates, different diseases.

Using surface immunofluorescence isolate-specific antigens were detected on the membrane of erythrocytes infected with Babesia parasites. In addition, the strains reacted differently with Plasmagel in that the European isolate (B.c. canis) could be purified on Plasmagel effectively, whereas infected erythrocytes of the South-African isolate (B.c. rossi) could not. Experimental infection of dogs with Babesia canis isolates from geographically different areas revealed different pathology. The European isolate obtained from France exhibited transient parasitaemia, usually below 1%, associated with low PCV values and congestion of internal organs. Clinical disease was correlated with an effect on the coagulation system, and not with peripheral parasitaemia. Infection of dogs with South-African-derived isolate induced high parasitaemia usually much higher than 1%, which required chemotherapeutic treatment. In these animals clinical disease was correlated with peripheral parasitaemia and not with parameters of the coagulation system. The results show that the etiology of disease caused by these isolates of B.c. canis and B.c. rossi is different. This might have implications for the development of vaccines against these infections.

Animals↗

PubMed1995

Strain variation limits protective activity of vaccines based on soluble Babesia canis antigens.

Groups of five dogs were immunized with vaccines containing soluble parasite antigens (SPA) derived from in vitro culture of Babesis canis parasites, either obtained commercially (Pirodog) or produced at laboratory scale. Both vaccines generated antibodies that reacted with parasitised erythrocytes (PE). Upon challenge infection with homologous parasites, protection was evident from less severe decreases of haematocrit values, and reduced morbidity. Vaccinated animals, however, were not protected against challenge infection with heterologous B. canis parasites. Recovery from challenge infection coincided with the production of antibodies against parasitized erythrocytes. The results suggest that SPA from B. canis carry strain-specific determinants that are crucial for inducing protection in dogs against challenge infection, and explain vaccination failures in the field.

Animals↗

PubMed1992

Vaccination of dogs against Babesia canis infection using parasite antigens from in vitro culture.

Groups of five dogs were vaccinated with different Babesia canis vaccine formulations. It appeared that partial protection against challenge infection was obtained when using parasite antigens from in vitro culture in combination with saponin. Protection was evident as a decrease in parasitaemia after challenge and was associated with the presence of serum antibodies against Babesia parasites. In addition, parasite antigen derived from in vitro culture supernatant exhibited more protective activity than somatic parasite antigen, in that a less marked fall of haematocrit values was found after challenge infection. The fall of haematocrit value observed in the animals immunized with somatic parasite antigen was not different from that observed in the adjuvant control group.

Adjuvants, Immunologic↗

PubMed1991

Identification of plasma membrane proteins involved in the hepatocyte invasion of Plasmodium falciparum sporozoites.

To determine whether surface proteins of hepatocytes might be involved in the sporozoite invasion, plasma membrane proteins were prepared from human livers with CHAPS (3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulphonate) and radiolabelled with 125I (Iodogen; 1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenylglycoluril). The labelled proteins were incubated with Plasmodium falciparum sporozoites and cross-linked with DSP (dithio-bis-succinimidylpropionate). Radiolabelled proteins released by reduction after repeated washing of the sporozoite-complex were separated by SDS-PAGE and autoradiographed. Two human hepatocyte membrane proteins of 20 and 55 kDa were found to be involved in the initial binding of P. falciparum sporozoites. The electrophoretically purified 20- and 55-kDa proteins both inhibited the binding of the corresponding radiolabelled proteins to P. falciparum sporozoites and reduced the invasion of sporozoites in an in vitro assay. We propose that these 20-kDa and 55-kDa proteins represent putative human hepatocyte receptors for P. falciparum sporozoite invasion.

Animals↗