Biomedical subjects

F Jongejan

Publications and source records attributed to F Jongejan.

At least 37 records · Page 2Linked to original sources

PubMed1995

Simultaneous detection and genotyping of three genomic groups of Borrelia burgdorferi sensu lato in Dutch Ixodes ricinus ticks by characterization of the amplified intergenic spacer region between 5S and 23S rRNA genes.

We developed a rapid and reliable method for the identification Borrelia burgdorferi sensu lato species in ticks. We used the DNA sequence polymorphism of the spacer region between 5S and 23S rRNA genes, which has been shown to be able to discriminate between eight genomic groups of B. burgdorferi sensu lato (D. Postic, M. Assous, P. A. D. Grimont, and G. Baranton, Int. J. Syst. Bacteriol. 44:743-752, 1994). Spacer DNA was amplified by PCR and was then hybridized to five membrane-bound oligonucleotides. The oligonucleotides were specific for B. burgdorferi sensu stricto, Borrelia garinii, Borrelia afzelii, and group VS116. A probe which reacted with all genomic groups of B. burgdorferi sensu lato was also used. Ninety-six ticks collected in the field were destructed by bead beating, and the supernatant was used directly in a PCR. B. burgdorferi sensu lato DNA was detected in 6 of 57 adult ticks (11%) and 9 of 39 nymphs (23%). B. garinii was found in three nymphs and four adults, three nymphs carried B. afzelii, and one adult and one nymph carried group VS116. Double infections with B. afzelii and group VS116 were found in two nymphs and one adult. Thus, our method can simultaneously identify three genomic groups of B. burgdorferi sensu lato in ticks collected in the field. This technique provides new ways to study the association of genomic groups present in ticks and the risk of Lyme borreliosis.

Animals↗

PubMed1995

Use of a specific immunogenic region on the Cowdria ruminantium MAP1 protein in a serological assay.

Currently available serological tests for cowdriosis (Cowdria ruminantium infection) in domestic ruminants are hampered by their low specificities because of cross-reactivity with Ehrlichia spp. The use of recombinant major antigenic protein (MAP1) of C. ruminantium for serodiagnosis was investigated. Overlapping fragments of the MAP1 protein were expressed in Escherichia coli and were reacted with sera from sheep infected with either C. ruminantium or Ehrlichia ovina. Two immunogenic regions on the MAP1 protein, designated MAP1-A and MAP1-B, were identified. MAP1-A was reactive with C. ruminantium antisera, E. ovina antisera, and three MAP1-specific monoclonal antibodies, whereas MAP1-B reacted only with C. ruminantium antisera. An indirect enzyme-linked immunosorbent assay (ELISA) based on MAP1-B was further developed and validated with sera from animals experimentally infected with C. ruminantium or several Ehrlichia spp. Antibodies raised in sheep, cattle, and goats against nine isolates of C. ruminantium reacted with MAP1-B. Cross-reactivity with MAP1-B was limited to Ehrlichia canis and Ehrlichia chaffeensis, two rickettsias which do not infect ruminants. Antibodies to Ehrlichia spp. which do infect ruminants (E. bovis, E. ovina, and E. phagocytophila) did not react with MAP1-B. Antibody titers to C. ruminantium in sera from experimentally infected cattle, goats, and sheep were detectable for 50 to 200 days postinfection. Further validation of the recombinant MAP1-B-based ELISA was done with sera obtained from sheep raised in heartwater-free areas in Zimbabwe and from several Caribbean islands. A total of 159 of 169 samples which were considered to be false positive by immunoblotting or indirect ELISA did not react with MAP1-B. In conclusion, recombinant MAP1-B may be a suitable antigen for a sensitive serological test for cowdriosis, with dramatically improved specificity.

Animals↗

PubMed1995

Detection of Cowdria ruminantium in blood and bone marrow samples from clinically normal, free-ranging Zimbabwean wild ungulates.

Cowdria ruminantium causes severe, often fatal disease in domestic ruminants, whereas wildlife species usually are not affected. Blood and bone marrow samples from healthy, free-ranging Zimbabwean ungulates were taken during translocation from areas harboring Amblyomma ticks and tested for the presence of C. ruminantium, using a PCR assay based on the C. ruminantium map1 gene. Positive reactions were obtained in tsessebe (Damaliscus lunatus), waterbuck (Kobus ellipsiprymnus), and impala (Aepyceros melampus). Wildlife species may therefore be a reservoir for C. ruminantium thus contributing to the spread of cowdriosis.

Animals↗

PubMed1994

Infection rates of Borrelia burgdorferi in different instars of Ixodes ricinus ticks from the Dutch North Sea Island of Ameland.

Between 1988 and 1993, a total of 7173 I. ricinus ticks, predominantly, were collected from the vegetation on the Dutch North Sea Island of Ameland. A proportion of the ticks (n = 547) was screened for the presence of Borrelia by immunofluorescence. Infection rates of Borrelia varied, in nymphs (n = 347) from 13% to 46% and in adults, (n = 122) from 20% to 43%. The infection rate in larvae (n = 84) collected in 1993 was 21%, showing that transovarial transmission of B. burgdorferi occurs in the I. ricinus population on Ameland. Two tick-naive sheep seroconverted for B. burgdorferi after field-collected adult or nymphal I. ricinus were allowed to feed on them. Larval progeny (n = 168) of 15 female adult ticks fed on one of these sheep were free from B. burgdorferi. B. burgdorferi was isolated in culture from field-collected adult ticks. Serotyping using monoclonal antibodies against outer surface proteins A and C indicated that both isolated belonged to genospecies B. garinii, and this was confirmed by DraI restriction analysis of the variable DNA sequence between the 5S and 23S rRNA genes.

Animals↗

PubMed1994

Molecular cloning of a gene encoding the immunogenic 21 kDa protein of Cowdria ruminantium.

Major immunogenic polypeptides (21, 32, 40, 46, 58, 85 and 160 kDa) of Cowdria ruminantium were identified by immunoprecipitation and immunoblotting. A pUC13 library of C. ruminantium genomic DNA was screened with hyperimmune sheep serum to identify Escherichia coli colonies which expressed genes encoding these immunogenic proteins. A recombinant E. coli colony, F5.2, was identified containing plasmid insert DNA of 2773 bp. The cloned DNA insert contained two long open reading frames (ORFs) of 627 bp (complete) and 831 bp (incomplete), both potentially encoding proteins containing an N-terminal signal peptide. Deletion experiments suggested that the hyperimmune sheep serum recognized a protein that was encoded by the 627 bp ORF. The 627 bp ORF was amplified by polymerase chain reaction (PCR), subcloned and expressed to a high level in E. coli. A sheep antiserum made to the expressed recombinant fusion protein recognized a 21 kDa protein of all strains of C. ruminantium tested, confirming that the 627 bp ORF encodes a native 21 kDa protein in C. ruminantium. Similarly, the recombinant protein was recognized by all sera tested from heartwater-infected animals. The antigenic conservation of the 21 kDa protein and its immunogenic nature are reasons for further testing of this recombinant protein in subunit diagnostic tests.

Amino Acid Sequence↗

PubMed1994

Size variation of the major immunodominant protein of Cowdria ruminantium.

An immunodominant response is made to a polypeptide of approximately 32 kDa in animals infected with the rickettsial pathogen Cowdria ruminantium. We show here using cultured strains of the rickettsia from different geographical areas that the apparent size of this polypeptide varies with strain origin. Changes in the primary structure between strains should be considered in the design of vaccines and diagnostic tests based on this antigen.

Animals↗

PubMed1994

Molecular cloning, sequence analysis, and expression of the gene encoding the immunodominant 32-kilodalton protein of Cowdria ruminantium.

Cowdria ruminatium, the causative agent of heartwater disease, expresses an immunodominant and conserved 32-kilodalton protein (MAP1; formerly called Cr32), which is currently in use for serodiagnosis of the disease. The gene encoding this protein, designated map1, was detected, cloned, and characterized. The gene is conserved between four different stocks of C. ruminantium originating from Senegal, Sudan, South Africa, and Zimbabwe. Homology searches revealed MAP1 to be homologous to the Anaplasma marginale surface protein MSP4, a potential protective antigen. The MAP1 protein, expressed in Escherichia coli fused with glutathione S-transferase, is specifically recognized by sera from animals infected with seven different stocks of C. ruminantium.

Amino Acid Sequence↗

PubMed1994

Production of alpha interferon in Cowdria ruminantium-infected cattle and its effect on infected endothelial cell cultures.

Cattle that resisted experimental heartwater infection caused by the rickettsia Cowdria ruminantium produced significant levels of circulating alpha interferon (IFN-alpha), whereas animals that died from heartwater did not. In vitro, recombinant bovine IFN-alpha was found to significantly reduce the yield of Cowdria organisms in bovine endothelial cells, but even at a high concentration (1,000 U/ml), IFN-alpha did not completely prevent the growth of Cowdria organisms in these cells. This limited inhibitory effect of IFN-alpha is in agreement with the in vivo situation where an infectious process has to take place to induce a protective immune response. Our results suggest that IFN-alpha produced in vivo in response to Cowdria infection may represent an efficient way to slow down the infection and allow the animal to mount a protective immune response. IFN-alpha is the first endogenously produced factor shown to have anti-Cowdria activity.

Animals↗

PubMed1994

Ticks and control methods.

Ticks are the most important ectoparasites of livestock in tropical and sub-tropical areas, and are responsible for severe economic losses both through the direct effects of blood sucking and indirectly as vectors of pathogens and toxins. Feeding by large numbers of ticks causes reduction in live weight gain and anaemia among domestic animals, while tick bites also reduce the quality of hides. However, the major losses caused by ticks are due to the ability to transmit protozoan, rickettsial and viral diseases of livestock, which are of great economic importance world-wide. The authors review general aspects of tick biology, the taxonomy, pathogenic effects and vector role of these species, and methods for the control of ticks. The distribution of ticks is continuously changing, as illustrated by the spread of the African tick Amblyomma variegatum in the Caribbean, where a large-scale eradication campaign is now under way.

Animals↗

PubMed1994

[Borrelia burgdorferi infection of ticks in some regions of Poland].

Ixodes ricinus and Dermacentor reticulatus ticks were collected by flagging from the vegetation at five different locations in Poland in May 1994. I. ricinus (n191) and D. reticulatus (n48), as well as 24 Argas reflexus collected from Katowice, Kornie, Szcyglice, Urwitałt and Zwierzyniec, were examined for the presence of Borrelia spirochetes by the indirect immunofluorescent antibody test (IFA). Borrelia were found in adult I. ricinus ticks at all 5 collection sites. Nine out of 39 I. ricinus males (23%) and 16 out of 72 I. ricinus females (22.2%) were infected. In addition, 2 out of 72 I. ricinus larvae (2.7%) were heavily infected, whereas none of the D. reticulatus and A. reflexus contained Borrelia. These results show that I. ricinus is also in Poland the main vector of Lyme disease-causing spirochetes. The finding that some larvae are also infected merits further investigations into the relative role of transovarial transmission of Borrelia in field populations of I. ricinus ticks.

Animals↗

PubMed1994

[Field trial of an attenuated vaccine against heartwater disease].

The results are given of a field trial using a Senegalese stock of Cowdria ruminantium which had been attenuated by passage in cell culture. Thirty vaccinated and thirty control sheep were exposed in the Niayes region of Senegal and were monitored daily. In the control group, 22 animals died of heartwater, associated in one case with anaplasmosis. In the vaccinated group, 13 animals died; Cowdria was found only in two sheep which had previously suffered from ehrlichiosis or anaplasmosis; three other cases of ehrlichiosis and two of anaplasmosis were also observed among these 13 animals. The resistance of the two vaccinated animals which showed Cowdria in their cerebral cortex was apparently lowered by the intercurrent infections. The other animals of the vaccinated group showed no evidence of Cowdria infection.

Animals↗

PubMed1993

[Equine granulocytic ehrlichiosis (EGE), a review].

Equine granulocytic ehrlichiosis (EGE) has been observed in the U.S.A., Brazil, Germany, Sweden, Switzerland and possibly in Great Britain. The causative agent is rickettsia Ehrlichia equi, identified for the first time in 1969. The clinical features of the disease are anorexia, fever, depression, (limb) oedema, icterus, ataxia, petechiae and orchitis. Hematologic changes are leukopenia, thrombocytopenia, anemia and cytoplasmic inclusion bodies in the neutrophils and eosinophils. Vasculitis may be observed at autopsy. Following a positive hematological diagnosis (Giemsa stained blood smear) of EGE, treatment with oxytetracycline can be initiated.

Animals↗

PubMed1993

Ticks (Acari: Ixodidae) infesting the Arabian camel (Camelus dromedarius) in the Sinai, Egypt with a note on the acaricidal efficacy of ivermectin.

In this study, tick burdens on camels (Camelus dromedarius) were determined in the vicinity of the St. Catherine monastery, Sinai, Egypt. In total 2,545 ticks (1,491 adults and 1,054 nymphs) were collected and identified. Mean tick burdens were relatively heavy and the range in number of ticks per camel was very broad (6-173). Hyalomma dromedarii was the predominant tick species and accounted for 95.6% of the adult ticks. Other ticks found were H. marginatum subspp. and H. anatolicum excavatum. All nymphs collected were Hyalomma spp. In addition, the effect of ivermectin (Ivomec MSD AGVET) on tick burdens, when given subcutaneously at 0.2 mg/kg-1, was evaluated in nine camels in the date-palm plantation of Kibbutz Yahel in the Arava valley, Israel. Initial tick burdens on these camels (half-body tick counts) ranged from 20-105 ticks per camel. Seven camels from the same herd with half-body tick counts ranging from 40-107 ticks per camel were not treated and served as a control group. Ivermectin was not effective against Hyalomma tick infestation in camels under these conditions.

Animals↗

PubMed1993

Correlation between antibodies to Cowdria ruminantium (rickettsiales) in cattle and the distribution of Amblyomma vector ticks in Zimbabwe.

Cowdriosis, caused by Cowdria ruminantium, is transmitted by Amblyomma ticks, which are widely distributed in Zimbabwe. To assess the distribution of this disease in Zimbabwe, cattle either exposed to Amblyomma ticks or maintained in areas free from these ticks were tested for antibodies to Cowdria. A total of 324 sera were tested using competitive ELISA and the indirect fluorescent antibody test (IFAT). At diptanks in Amblyomma-infested areas 52% (n = 95) and 26% (n = 47) of sera were positive by cELISA and IFAT, respectively. At diptanks in Amblyomma-free areas 11% (n = 125) and 10% (n = 134) of sera were positive by cELISA and IFAT, respectively. The results were significantly different between Amblyomma-infested and tick-free areas (chi 2 = 24.73, P < or = 0.005 for IFAT and chi 2 = 57.53, P < or = 0.005 for cELISA). High background readings in field sera, possibly due to cross-reactive antibodies to Ehrlichia spp., complicated the determination of a realistic cut-off point, especially in cELISA. On the basis of the distribution of Amblyomma ticks, currently a large part of Zimbabwe can be considered endemic for the disease.

Animals↗

PubMed1993

Detection of the protozoan parasite Theileria annulata in Hyalomma ticks by the polymerase chain reaction.

Adult Hyalomma ticks were examined for the presence of Theileria annulata infection using the Polymerase Chain Reaction (PCR). A 372 bp DNA fragment derived from the small ribosomal RNA gene of T. annulata was amplified from 45 out of 50 (90%) H. dromedarii ticks and from 36 out of 50 (72%) H. marginatum marginatum ticks. No product was amplified from non-infected control ticks. Restriction enzyme digestion with Sac II confirmed that the product was derived from the targeted T. annulata gene. As a further confirmation it was shown that both species of Hyalomma ticks were able to transmit T. annulata to experimental calves. PCR detection of Theileria parasites in ticks was compared with conventional staining of dissected salivary glands using methyl green pyronin and its comparative advantages are discussed.

Animals↗

PubMed1993

Antibodies to Cowdria ruminantium in Mozambican goats and cattle detected by immunofluorescence using endothelial cell culture antigen.

Endothelial cell cultures, established from bovine umbilical cord arteries and subsequently infected with Cowdria ruminantium, were used as antigen in the indirect fluorescent antibody test. Bovine sera (374) and caprine sera (388) collected in 6 provinces of Mozambique were tested. Overall, 30.4% of goat sera had antibodies to Cowdria, and 43% of sera collected from cattle. North of the River Save, where the tick Amblyomma variegatum is highly prevalent, overall percentages of positive sera were low, 10% in goats and 20% in cattle. However, south of the river where the tick Amblyomma hebraeum is abundant percentages were much higher, 63.5% in goats and 59.4% in cattle. These results are discussed in relation to field observations that clinical disease is rare or absent in the north with enzootic instability in goats and Friesian calves in the south.

Animals↗

PubMed1993

Detection of antibodies to Cowdria ruminantium in the serum of domestic ruminants by indirect ELISA.

A solid phase enzyme immunoassay for the detection of antibodies to Cowdria ruminantium in the serum of domestic ruminants was developed by using microorganisms cultivated on bovine umbilical endothelial cells as antigen. When the culture showed 90% lysis, the supernatant was centrifuged, sonicated and coated on polystyrene microtiter plates. Antibodies were detected as early as 9 days after experimental immunization of goats. The sensitivity of the ELISA calculated with 73 ruminant sera ranged between 97.3% and 98.6%. The overall specificity of the test was 97% (N = 2925). However, the specificity was far lower for sheep (94.4%, N = 881) than for goats (98.6%, N = 651) and cattle (97.8%, N = 1393). Crossreactivity which could explain some of the false positive reactions, was found between Cowdria antigen and sera raised against Ehrlichia bovis (1 bovine positive out of 2 inoculated) or E. ovina (2 sheep out of 2 inoculated became positive) but not with E. phagocytophila. The intra-assay and inter-assay variability were 7.5% and 7.8% respectively, indicating a good reproducibility of the ELISA.

Animals↗

PubMed1993

The sero-diagnosis of heartwater: a comparison of five tests.

Five serological tests, the indirect and competitive ELISA, the indirect fluorescent antibody (IFA) test with 2 different antigens and the Western blot technique were compared and applied to sera that were known to be either negative or positive against Cowdria ruminantium or that were collected from animals in heartwater-free regions. No false positive reactions were recorded with any of the tests against the known negative sera. Except for minor variations in the sensitivity of the 5 tests, there was good correlation between them. Their specificity, however, remains in dispute since in all 5 tests extensive cross-reactions were recorded with antibodies in response to an as yet unidentified agent, probably Ehrlichia.

Animals↗