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Biomedical subjects

F Jongejan

Publications and source records attributed to F Jongejan.

At least 55 records · Page 3Linked to original sources
PubMed1999

Validation of the indirect MAP1-B enzyme-linked immunosorbent assay for diagnosis of experimental Cowdria ruminantium infection in small ruminants.

The major antigenic protein 1 fragment B (MAP1-B) enzyme-linked immunosorbent assay (ELISA) for the diagnosis of Cowdria ruminantium infections was validated to determine cutoff values and evaluate its diagnostic performance with sheep and goat sera. Cowdria-infected populations consisted of 48 sheep and 44 goats, while the noninfected populations consisted of 64 sheep and 107 goats. Cutoff values were determined by two-graph receiver-operating characteristic (TG-ROC) curves. The cutoff value was set at 31 and 26.6% of the positive control reference samples for sheep and goat sera, respectively. The test's diagnostic performance was evaluated with measurements of the area under the concentration-time curve (AUC) of the ROC curves and by the valid range proportion (VRP). The AUCs were 0.978 for sheep sera and 0.989 for goat sera. The VRP for both sheep and goat sera was approximately 1.0. The intermediate range (IR), which defines results that are neither positive nor negative, was 0 for goat sera and 2.81 for sheep sera. In an ideal test, the AUC and VRP would be 1.0 and the IR would be 0. In this study these parameters were close to those of an ideal test. It is concluded that the MAP1-B ELISA is a useful test for the diagnosis of C. ruminantium infection in small ruminants.

Animals↗
PubMed1999

Simultaneous detection of bovine Theileria and Babesia species by reverse line blot hybridization.

A reverse line blot (RLB) assay was developed for the identification of cattle carrying different species of Theileria and Babesia simultaneously. We included Theileria annulata, T. parva, T. mutans, T. taurotragi, and T. velifera in the assay, as well as parasites belonging to the T. sergenti-T. buffeli-T. orientalis group. The Babesia species included were Babesia bovis, B. bigemina, and B. divergens. The assay employs one set of primers for specific amplification of the rRNA gene V4 hypervariable regions of all Theileria and Babesia species. PCR products obtained from blood samples were hybridized to a membrane onto which nine species-specific oligonucleotides were covalently linked. Cross-reactions were not observed between any of the tested species. No DNA sequences from Bos taurus or other hemoparasites (Trypanosoma species, Cowdria ruminantium, Anaplasma marginale, and Ehrlichia species) were amplified. The sensitivity of the assay was determined at 0.000001% parasitemia, enabling detection of the carrier state of most parasites. Mixed DNAs from five different parasites were correctly identified. Moreover, blood samples from cattle experimentally infected with two different parasites reacted only with the corresponding species-specific oligonucleotides. Finally, RLB was used to screen blood samples collected from carrier cattle in two regions of Spain. T. annulata, T. orientalis, and B. bigemina were identified in these samples. In conclusion, the RLB is a versatile technique for simultaneous detection of all bovine tick-borne protozoan parasites. We recommend its use for integrated epidemiological monitoring of tick-borne disease, since RLB can also be used for screening ticks and can easily be expanded to include additional hemoparasite species.

Animals↗
PubMed1999

Identification of Theileria buffeli/orientalis and Babesia bigemina in Apulian cattle using molecular techniques and study of changes in blood parameters.

Recently several cases of theileriosis due to the haemoprotozoan Theileria buffeli/orientalis have been recorded in the Apulian region, Italy. In this area other tick-borne pathogens were usually identified such as Anaplasma marginale and Babesia bigemina. Outbreaks were recorded showing that these pathogens can be observed separately or in mixed infections. Sub-clinical cases and carrier animals were also previously identified. A lack of specific techniques could not rule out the presence of other haemoparasites such as T. annulata, B. divergens, B. bovis, Ehrlichia phagocytophila and E. bovis. Moreover little is known about the tick species involved in the dissemination of these diseases. Therefore more powerful techniques to specifically identify Theileria or Babesia species have been recently developed. A PCR technique and reverse line blotting (RLB) system to specifically identify six Theileria species and three Babesia species were used. T. buffeli/orientalis and B. bigemina were the only pathogens observed in the targeted animals. The authors also present some changes in blood parameters for the animals followed during this study.

Animals↗
PubMed1999

Integrated control of ticks and tick-borne diseases.

Integrated control of ticks and tick-borne diseases (ICTTD) is currently promoted by an international project, supported by the European Union, with the aim to increase livestock productivity through the development of improved strategies for tick control, vaccine delivery and integrated diagnostics for tickborne diseases. This paper gives a brief overview of the ICTTD project activities against the background of recent initiatives to assess the impact of ticks and tick-borne diseases in the Mediterranean region.

Animals↗
PubMed1999

Molecular characterization of ticks and tick-borne pathogens.

Ticks and their vertebrate hosts often carry several pathogens simultaneously, which either belong to different or to the same genera. Conventional methods (such as blood smear examination or tick salivary gland staining) are often unable to discriminate between pathogens. Therefore, molecular methods for the detection and differentiation of tick-borne pathogens are increasingly used. Technical problems still remain to identify pathogens within tick tissues, or within host animals when infection rates are very low. Recently we developed an integrated approach to identify several pathogens with only one molecular test. This approach, the reverse line blot hybridization (RLB) reduces costs of analysis, gives quicker results. and allows standardized inter-laboratory comparisons. Finally, this paper also focuses on the molecular diagnostic techniques currently used in the laboratories of the Mediterranean countries.

Animals↗
PubMed1998

Analysis of cellular responses to native and recombinant proteins of Cowdria ruminantium.

The response of PBMC collected from cattle immunized with killed Cowdria to MAP1, MAP1-B, MAP2 and to a lysate of Cowdria was characterized in vitro. CD4+ T lymphocytes responded strongly to Cowdria lysates while B cells and gamma delta T cells proliferated in response to recombinant proteins. Short-term cell lines derived from PBMC using Cowdria lysates were more than 90% CD4+ and did not respond to any of the recombinant proteins. Restimulation of PBMC with MAP1, MAP1-B, and MAP2 proved difficult, and cultures usually stopped proliferating after 2 to 3 weeks. Only one cell line could be generated using MAP1 and it was composed of 85% gamma delta T cells. This study indicates that in animals immunized with killed Cowdria, proteins other than the serologically immunodominant MAP1 and MAP2 are strongly immunogenic for T lymphocytes.

Animals↗
PubMed1998

Different vaccine strategies used to protect against Theileria annulata.

SPAG-1, a sporozoite surface antigen of T. annulata, has previously been shown to elicit partial protection when used, as an hepatitis B core antigen fusion, to immunize cattle. The objective of this study was to try and improve the protective capacity of this antigen by enlisting different vaccine strategies. Cattle were immunized with SPAG-1, as a fusion protein with a His6 tag, either incorporated into ISCOMs, with or without the merozoite antigens TAMS 1-1 and 1-2, or with RWL as adjuvant three times at monthly intervals. Another group of cattle were immunized with p67, the T. parva sporozoite antigen, in RWL to assess whether any cross-protection could be induced. The animals were then challenged with an estimated LD50 of T. annulata sporozoites, and their ability to resist the infection was investigated. Serum responses and T-cell proliferative responses were analyzed throughout the trial. Post-challenge analyses included lymph node biopsies and blood smears to check for the presence of parasites, routine hematological parameters, and observation for clinical manifestations of the disease. The results of this trial will be discussed.

Animals↗
PubMed1998

Evaluation of the MAP-1B ELISA for cowdriosis with field sera from livestock in Zimbabwe.

The Map 1B (Senegal) antigen-based indirect ELISA was evaluated in Zimbabwe with field sera from heartwater-free and heartwater-endemic areas. Of 205 sheep sera samples from a heartwater-free area, 34 were negative and 171 were positive by immunoblotting. These 171 samples were classified as false positives. Of the same 205 samples, 199 were negative and only 6 were positive by the MAP 1B ELISA. Of 72 cattle samples tested from a similar area, 71 were negative, with only 1 sample positive by MAP 1B ELISA. By immunoblotting, 43 of 72 cattle sera were negative and 29 were positive. Of the 46 goat samples tested from a heartwater-free area, only 2 were positive by the MAP 1B ELISA. Based on these results, the MAP 1B ELISA was more specific for heartwater than the immunoblotting assay. Of 96 and 282 cattle sera analyzed from heartwater-endemic farms in the lowveld and highveld of Zimbabwe, respectively, approximately 33% were positive by the MAP 1B ELISA. Goat sera from the same farms had a higher sero-prevalence (> 90%). The implications of these results for serodiagnosis of heartwater using the MAP 1B ELISA will be discussed.

Animals↗
PubMed1998

Validation and comparison of three enzyme-linked immunosorbent assays for the detection of antibodies to Cowdria ruminantium infection.

Serological tests for Cowdria ruminantium infection have been hampered by low specificity. Here, an indirect ELISA based on purified antigen, a competitive ELISA using a recombinant major antigenic protein (MAP-1) and an indirect ELISA based on the MAP-1B region of the recombinant MAP-1 were compared. The tests were validated using 3000 sera of ruminants from 14 islands of the Lesser Antilles as well as sequential serum samples from 10 cattle, 17 goats and 10 sheep vaccinated with inactivated C. ruminantium in ISA 50 adjuvant and from 14 goats infected with a virulent culture supernatant. All tests detected significantly higher percentages of positives on Antigua, Guadeloupe and Marie-Galante, where C. ruminantium had been isolated before. Overall specificity calculated with sera from the other 11 heartwater-free islands was 98.1%, 98.5%, and 99.4% for the ELISA based on crude antigen, recombinant MAP-1 and MAP-1B, respectively. Sensitivities observed with sequential serum samples were similar for all tests. Tests based on recombinant antigens, especially the MAP-1B, showed improved specificity, suggesting their use for epidemiological studies in regions where the distribution of cowdriosis is unknown. In addition, the competitive ELISA is useful for studies in wildlife for which species-specific conjugates do not exist.

Animals↗
PubMed1998

Ixodes ricinus strains in Europe.

An analysis of cuticular hydrocarbons (CH) of unfed adult Ixodes ricinus ticks collected throughout Europe showed that there are 10 distinct I. ricinus groups. Studies on the seasonal and annual consistency of CH composition and possible effects of host and environmental factors suggested that CHs may be used as a genuine genetic marker for I. ricinus. Preliminary studies compared the vector competence of ticks from three of the most separated I. ricinus groups and the results suggested that there may be significant differences in tick susceptibility to Borrelia afzelii.

Animals↗
PubMed1998

European reservoir hosts of Borrelia burgdorferi sensu lato.

Existing knowledge on reservoir hosts of Borrelia burgdorferi sensu lato was collated and reviewed and several species, particularly birds, were identified as reservoir competent. At the present time, 9 small mammals, 7 medium-sized mammals and 16 bird species, including passerines, sea birds and pheasants, appear to be capable of transmitting spirochaetes to ticks and thus of participating in the natural circulation of B. burgdorferi s.l. in Europe. The house mouse, Mus musculus is strongly suspected of reservoir competence and many other small rodent species, particularly in eastern Europe and Russia, have been implicated. Ungulates are not thought to play a major role as reservoir hosts, though co-feeding transmission may permit some tick infection. The criteria for establishment of reservoir status are outlined and a method for identification of host blood meals of previous instars of unfed ticks, developed in a participant laboratory, is briefly described.

Animals↗
PubMed1998

Detection of Borrelia burgdorferi sensu lato in ticks: immunofluorescence assay versus polymerase chain reaction.

Immunofluorescence (IFA) and polymerase chain reaction (PCR) were examined as methods for detecting Borrelia burgdorferi sensu lato spirochaetes in unfed Ixodes ricinus nymphs. Although similar results were produced in some cases, a great deal of variation occurred. Furthermore, in both the highly controlled initial laboratory study, involving 252 shared samples, and the study on field-collected ticks (n = 460), the IFA tended to detect more infected ticks than the PCR. The basis for these findings are as yet undetermined. The development of a quality assurance scheme is recommended so that laboratories can validate their methods and a preliminary feasibility study suggested that such a scheme is practical.

Animals↗
PubMed1998

Lyme borreliosis habitat assessment.

Tick ecologists throughout Europe provided descriptions of Lyme borreliosis habitats according to a standardised format and data for 105 habitats in 16 countries were received. The data showed that high risk situations, as defined by the presence of large numbers of B. burgdorferi sensu lato-infected nymphal I. ricinus, occur in heterogeneous deciduous woodland, usually with a recreational function and with a diverse fauna, usually including deer. Large numbers of ticks occurred in some other habitats, but infection prevalence was usually low. The situation for adult I. ricinus was similar but less clearly defined. Tick infection rates were found to be lower in western Europe than in the east, and the infection rate in I. persulcatus, the most easterly vector species, was markedly higher than in I. ricinus. In the vast majority of habitats the infection rate in adult I. ricinus was greater than in nymphs. Larvae were rarely found to be infected.

Animals↗
PubMed1998

Lyme borreliosis awareness.

A Lyme borreliosis information leaflet has been produced to promote awareness amongst the general public. It was designed to provide a framework for similar material throughout Europe and complements a questionnaire produced to measure awareness of Lyme borreliosis. This questionnaire can be used to determine the impact of educational campaigns using material such as the leaflet. Feasibility studies showed that the questionnaire successfully highlighted predictable differences between sample groups and also that the leaflet performed well in increasing knowledge in low-awareness groups.

Blood Donors↗
PubMed1998

Characterization of variable immunodominant antigens of Cowdria ruminantium by ELISA and immunoblots.

Cross-immunization experiments have revealed a significant antigenic diversity of the isolate of Cowdria ruminantium which needs to be characterized for the development of vaccines. We identified polymorphic immunodominant antigens by ELISA and immunoblot. Using serum from a goat immune to the Gardel stock of Cowdria (isolated in Guadeloupe) adsorbed on antigen of the Senegal stock of this pathogen, distinct serogroups were revealed by ELISA among six isolates from different geographical origins. Furthermore, a goat serum directed against the Senegal stock and adsorbed on Gardel antigens was shown to be specific for the Senegal stock, thus confirming the existence of serotypes in Cowdria. The Major Antigenic Protein 1 (MAP1) of Cowdria was shown to have variable antigenic determinants. Also in a group of variable proteins ranging from 23 to 29 kDa, one antigen of 26-27 kDa had a determinant specific for the Gardel isolate. These polymorphic antigens may be relevant components of Cowdria ruminantium for a vaccine as the sera revealing these antigens originated from a goal surviving a lethal challenge. However, the presence of T-cell epitopes and the ability of the these antigens to confer protection to ruminants remain to be investigated. The production of a rabbit antiserum against this group of polypeptides will be of great use for their purification and for the screening of expression libraries.

Animals↗