Ehrlichia ruminantium variants which do not cause heartwater found in South Africa

In 1994 a batch of apparently healthy goats was selected for intended export to the USA from a heartwater-free and vector tick-free region of South Africa. The animals were tested serologically for heartwater, using either or both an IFA and an ELISA test, and 52% were found to be serologically positive. A PCR assay based on Ehrlichia ruminantium 16S gene sequences gave positive results for 54% of the animals, suggesting that apparently non-pathogenic E. ruminantium variants existed in this heartwater-free area. To identify and characterise the agents responsible for the positive serological and PCR results, ticks and animal blood samples were collected from two of the three farms involved in the original survey during two successive seasons of expected peak tick activity. Ticks were kept alive for a minimum of 3 weeks to allow digestion of any blood meal before being processed. Over the two seasons, 28% of the livestock and 15% of the ticks sampled were found to be carrying E. ruminantium. E. ruminantium 16S and pCS20 sequences were detected in all of the four tick species collected from the livestock (Rhipicephalus evertsi evertsi, Rhipicephalus evertsi mimeticus, Hyalomma truncatum, Hyalomma marginatum rufipes), suggesting that some of the species may act as vectors. Animals generally carried multiple E. ruminantium 16S genotypes, whereas ticks rarely carried more than one. Infection levels in both animals and ticks were too low to generate a marked response when a blood stabilate was sub-passaged in a clean sheep, preventing the subsequent establishment of any of the organisms in culture.This research was funded by the Red Meat Research and Development Trust (RMRDT) of South Africa. We thank Prof. Ivan Horak for advice and critical reading of the manuscript

Identification of Ehrlichia ruminantium proteins that activate cellular immune responses using a reverse vaccinology strategy

Ehrlichia ruminantium is an obligate intracellular bacterial pathogen which causes heartwater, a serious tick-borne disease of ruminants throughout sub-Saharan Africa. The development of promising recombinant vaccines has been reported previously, but none has been as effective as immunisation with live organisms. In this study we have used reverse vaccinology to identify proteins that elicit an in vitro cellular immune response similar to that induced by intact E. ruminantium. The experimental strategy involved four successive steps: (i) in silico selection of the most likely vaccine candidate genes from the annotated genome; (ii) cloning and expression of the selected genes; (iii) in vitro screening of the expressed proteins for their ability to induce interferon-gamma (IFN-ᵧ) production in E. ruminantium–immune lymphocytes; and (iv) further examination of the cytokine response profiles of those lymphocytes which tested positive for IFN-ᵧ induction. Based on their overall cytokine induction profiles the recombinant proteins were divided into four distinct groups. Eleven recombinant proteins induced a cytokine profile that was similar to the recall immune response induced by immune peripheral blood mononuclear cells (PBMC) stimulated with intact E. ruminantium. This response comprised the upregulation of cytokines associated with adaptive cellular immune responses as well as innate immunity. A successful vaccine may therefore need to contain a combination of recombinant proteins which induce both immune pathways to ensure protection against heartwater.The South African Department of Agriculture OV9/23/C167 grant and the FP6 EU INCO-DEV EPIGENEVAC FP6-003713 grant.http://www.elsevier.com/locate/vetimmab201

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Comparison of the CollaboRATE and SDM-Q-9 questionnaires to appreciate the patient-reported level of shared decision-making

OBJECTIVE: To compare CollaboRATE and SDM-Q-9 questionnaires when appreciating patient-perceived level of shared decision-making (SDM) in doctor-patient consultations. METHODS: Data were harvested from five separate studies on SDM, conducted in three university and one large community hospital in the Netherlands, using Dutch versions of both questionnaires. CollaboRATE and SDM-Q-9 scores were expressed as percentages. Correlation was assessed using Spearman's Rho coefficient. Bland&Altman analysis was used to assess the degree of agreement. Top scores were calculated to assess possible ceiling effects. RESULTS: The five studies included 442 patients. Median CollaboRATE scores (88.9%, IQR 81.5-100%) were significantly higher (p < 0.001) than SDM-Q-9 scores (80.0%, IQR 64.4-100%). Correlation was moderate (Rho=0.53, p < 0.001). A systematic, 12.5-point higher score was found across the range of scores when using CollaboRATE. Top scores for CollaboRATE and SDM-Q-9 were present in 37.5% and 17% of questionnaires, respectively. CONCLUSIONS: Overall, CollaboRATE and SDM-Q-9 questionnaires showed a high level of patient-perceived SDM. However, CollaboRATE only moderately correlated with SDM-Q-9 and had a stronger ceiling effect. PRACTICE IMPLICATIONS: When choosing a SDM-measurement tool, its benefits and limitations should be weighed. These metrics should be combined with objective scores of SDM, as these may differ from the patients' subjective interpretation

Identification of Ehrlichia ruminantium proteins that activate cellular immune responses using a reverse vaccinology strategy

Ehrlichia ruminantium is an obligate intracellular bacterial pathogen which causes heartwater, a serious tick-borne disease of ruminants throughout sub-Saharan Africa. The development of promising recombinant vaccines has been reported previously, but none has been as effective as immunisation with live organisms. In this study we have used reverse vaccinology to identify proteins that elicit an in vitro cellular immune response similar to that induced by intact E. ruminantium. The experimental strategy involved four successive steps: (i) in silico selection of the most likely vaccine candidate genes from the annotated genome; (ii) cloning and expression of the selected genes; (iii) in vitro screening of the expressed proteins for their ability to induce interferon-gamma (IFN-ᵧ) production in E. ruminantium–immune lymphocytes; and (iv) further examination of the cytokine response profiles of those lymphocytes which tested positive for IFN-ᵧ induction. Based on their overall cytokine induction profiles the recombinant proteins were divided into four distinct groups. Eleven recombinant proteins induced a cytokine profile that was similar to the recall immune response induced by immune peripheral blood mononuclear cells (PBMC) stimulated with intact E. ruminantium. This response comprised the upregulation of cytokines associated with adaptive cellular immune responses as well as innate immunity. A successful vaccine may therefore need to contain a combination of recombinant proteins which induce both immune pathways to ensure protection against heartwater.The South African Department of Agriculture OV9/23/C167 grant and the FP6 EU INCO-DEV EPIGENEVAC FP6-003713 grant.http://www.elsevier.com/locate/vetimmab201