Comparison of the complement fixation test and competitive ELISA for serodiagnosis of Anaplasma marginale infection in experimentally infected steers

OBJECTIVE: To compare sensitivity of a complement fixation (CF) test and competitive ELISA (cELISA) for detection of Anaplasma marginale in experimentally infected steers. ANIMALS: 40 crossbred (Angus-Simmental) steers. PROCEDURES: Steers were inoculated with 2.6 x 10(9) A marginale-infected erythrocytes (day 0). Blood samples were collected on days 9, 13, 20, 28, 34, 41, 61, 96, 126, and 156 days after inoculation. The percentage of parasitized erythrocytes (PPE) was determined by microscopic examination of stained blood films, and sera were evaluated with the CF test and cELISA by use of USDA-approved methods. Sensitivity and agreement (kappa statistic) between the 2 methods were determined. Persistent infections were confirmed by inoculation of blood obtained from infected steers into susceptible, splenectomized calves. RESULTS: 9 days after inoculation, sensitivity of the cELISA was 47.5%, whereas the CF test failed to identify seropositive steers. After day 13, sensitivity of the cELISA and CF test was 100% and 20%, respectively. During peak parasitemia (day 20), sensitivity of the cELISA and CF test was 100%. Thereafter, sensitivity of the CF test fluctuated between 7.5% and 37.5%, whereas sensitivity of the cELISA remained at 100%. Overall sensitivity of the cELISA and CF test was 94.8% and 26.5%, respectively (kappa statistic, 0.039). CONCLUSIONS AND CLINICAL RELEVANCE: The cELISA had superior sensitivity for serologic detection of A marginale.The CF test and cELISA each had a high percentage of false-negative results during the prepatent period. These findings are relevant for export certification and anaplasmosis prevention or eradication programs.     

Shiga toxin-producing Escherichia coli and their bacteriophages as a model for the analysis of virulence and stress response of a food-borne pathogen

Enterohemorrhagic Escherichia coli (EHEC) are a subgroup of Shiga toxin-producing Escherichia coli (STEC) that are able to cause serious food-borne intestinal diseases which can be followed in 5 to 15% by extraintestinal sequelae such as the hemolytic-uremic syndrome (HUS). One of the major pathogenicity factors of EHEC is the production of one or more Shiga toxins (Stx), which act as inhibitors of protein biosynthesis and have profound effects on the signal transduction and immunological response in eukaryotic cells. The stx genes are located in the genome of heterogeneous, lambdoid, functional or cryptic bacteriophages and are expressed during the phage life cycle. Due to the linkage between the phage life cycle and stx expression, STEC and their bacteriophages are useful as a model for the analysis of stress response and virulence of this food-borne pathogen.     

Contrasting edge and pasture matrix effects on ant diversity from fragmented landscapes across multiple spatial scales

Landscape Ecology - Harmful effects of habitat loss and fragmentation can be detected across multiple spatial scales, yet most studies that aim to characterize these effects take place at a single...     

Disturbance‐induced responses of VHF and satellite tagged harbour seals

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Cover crop and plant density in seed production of white clover (Trifolium repens L.)

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Assessment of EST- and genomic microsatellite markers for variety discrimination and genetic diversity studies in wheat

It is likely that in the near future sequence information from sequencing programmes and EST libraries will generate an abundance of genic microsatellite markers. This study is focused on the assessment of their likely impact and performance vis-à-vis their genomic counterparts. Microsatellites from two sources were used to assess the genetic diversity in 56 old and new varieties of bread wheat on the UK Recommended List. A set of 12 microsatellite markers generated from genomic libraries and 20 expressed sequence tag (EST)-derived microsatellites were used in the study, and the performance of both marker sets assessed. The EST-derived or genic microsatellites delivered fingerprints of superior quality, amplifying clear products with few stutter bands. Diversity levels as revealed bygenic microsatellites are similar to the few published results. The PIC values for the genic markers were generally lower than those calculated for the genomic microsatellites, though advantages of both marker classes for variety identification applications are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Land-use history has a stronger impact on soil microbial community composition than aboveground vegetation and soil properties

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