Les campagnes de Touraine au XVIIIe siècle

Maillard, Brigitte

doi:10.4000/books.pur.17117

Cited by 16 publications

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“…Hope (Maillard and Maillard, 1998). It is therefore possible that the Gardel genotype did not come from West Africa, as has long been assumed, but from western central Africa (Angola, the Congo or Gabon).…”

Section: Discussionmentioning

confidence: 95%

“…It is not surprising, then, that the core genes of Gardel are unique, and since they have only been separated from their African orthologs for about 300 years (Maillard and Maillard, 1998) this argues that the original Gardel stock taken to Guadeloupe was different from western, eastern and southern genotypes. This fits with the phylogenetic analysis, which places Gardel near the root of the tree and in neither of the main clades (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Extensive genetic recombination occurs in the field between different genotypes of Ehrlichia ruminantium

Allsopp

2007

Veterinary Microbiology

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The intracellular bacterium Ehrlichia ruminantium is the causative agent of heartwater throughout sub-Saharan Africa, Madagascar, and some islands of the Caribbean. The disease is tick-borne and causes substantial livestock losses, threatening food security and productivity in both the commercial and small-scale farming sectors in endemic areas.Immunization by infection and treatment is currently practised in South Africa, and it is known that a variety of immunotypes of the organism occur in the field, and that crossprotection between them varies widely from total to minimal. Future vaccines may therefore need to incorporate components from different genotypes so it is essential to have information on the extent of genetic variation among isolates. To obtain this information we amplified and sequenced a panel of eight core function genes from 12 different cultured stocks originally isolated in different areas of Africa and the Caribbean.Phylogenetic trees inferred from the sequences yielded different branching orders for different genes, and the reason for this inconsistency appears to be that extensive recombination takes place between different genotypes in the field. It is possible that recombination occurs during the period when the organisms are extracellular within the tick, immediately after feeding and before intracellular infection is established, although detection of more than one genotype in DNA from single ticks is encountered infrequently. The results of the analysis show that the phylogenetic variation is greatest openUP

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Extensive genetic recombination occurs in the field between different genotypes of Ehrlichia ruminantium

Allsopp

2007

Veterinary Microbiology

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“…Heartwater is a major obstacle to domestic livestock productivity in areas where it is endemic (Mukhebi et al, 1999), and is particularly serious when susceptible animals are moved from heartwater-free to heartwater-infected areas (Simpson et al, 1987). Amblyomma variegatum, the most widespread African vector of heartwater, was introduced, together with the disease, on to some Caribbean islands during the 18th or 19th centuries (Maillard and Maillard, 1998).…”

Section: Introductionmentioning

confidence: 99%

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

Allsopp

Strijp

Faber

et al. 2007

Veterinary Microbiology

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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 openUP when a blood stabilate was sub-passaged in a clean sheep, preventing the subsequent establishment of any of the organisms in culture.

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Pierre de Saint Jacob (1905–1960)

Collins

2010

French Historians 1900–2000

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Les campagnes de Touraine au XVIIIe siècle

Cited by 16 publications

References 0 publications

Extensive genetic recombination occurs in the field between different genotypes of Ehrlichia ruminantium

Extensive genetic recombination occurs in the field between different genotypes of Ehrlichia ruminantium

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

Pierre de Saint Jacob (1905–1960)

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