Epidemiology and genetic diversity of Anaplasma ovis in goats in Corsica, France.

BACKGROUND: Anaplasma ovis is a major cause of small ruminant anaplasmosis, a tick-borne disease mainly affecting small ruminants in tropical and subtropical regions of the world. Due to health and production problems in dairy goat flocks in Corsica, France, and the demonstration of A. ovis infection in some animals, an extensive survey was conducted in the island in spring 2016. The aim of the survey was to determine the prevalence and geographical distribution of A. ovis infections in goats and ticks as well as possible relationships with anaemia and other health indicators. In addition, the genetic diversity of A. ovis was evaluated. METHODS: Blood and faecal samples were collected in 55 clinically healthy flocks (10 goats per flock) for A. ovis qPCR, haematocrit determination, paratuberculosis ELISA seropositivity and gastrointestinal nematode egg excretion quantification. Ticks were collected, identified and processed for A. ovis DNA detection. RESULTS: A high prevalence of A. ovis DNA detection was found at the individual (52.0%) and flock levels (83.6%) with a within-flock prevalence ranging between 0-100%. Rhipicephalus bursa was the only tick species collected on goats (n = 355) and the detection rate of A. ovis DNA in ticks was 20.3%. Anaplasma ovis DNA prevalence was higher in flocks located at an altitude above 168 m, in goats of Corsican/crossbred breed and in goats > 3 years-old. No relationship was found between A. ovis DNA detection at the individual or flock level and haematocrit, paratuberculosis seropositivity or gastrointestinal parasites. Positive A. ovis goat samples were used for amplification of gltA and msp4 genes for species confirmation and strain identification, respectively. Sequence and phylogenetic analysis of these genes confirmed the detection of A. ovis and allowed identification of six different strains of this pathogen (named Corsica 1-6 (COR1-6). While the msp4 sequence of strain COR1 had 100% identity with strains previously reported, COR2 to 6 were found to be novel strains. The strain COR1 was the most represented, corresponding to 94.6% of the msp4 sequences obtained. CONCLUSIONS: The results showed a relatively high genetic diversity of A. ovis associated with high bacterial prevalence in goats.

Genetic isolates in Corsica (France): linkage disequilibrium extension analysis on the Xq13 region.

Genetic isolates with a history of a small founder population, long-lasting isolation and population bottlenecks represent exceptional resources in the identification of genes involved in the pathogenesis of multifactorial diseases. In these populations, the disease allele reveals linkage disequilibrium (LD) with markers over significant genetic intervals, therefore facilitating disease locus identification. This study has been designed to examine the background LD extension in some subpopulations of Corsica. Our interest in the island of Corsica is due to its geographical and genetic proximity to the other Mediterranean island of Sardinia. Sardinian isolates in which the extension of the background LD is particularly high have been recently identified and are now the object of studies aimed at the mapping of genes involved in complex diseases. Recent evidence has highlighted that the genetic proximity between the populations of Corsica and Sardinia is particularly true for the internal conservative populations. Given these considerations, Sardinia and Corsica may represent a unique system to carry out parallel association studies whose results could be validated by comparison. In the present study, we have analyzed the LD extension on the Xq13 genomic region in three subpopulations of Corsica: Corte, Niolo and Bozio, all located in the mountainous north-center of the island. Our results show a strong degree of LD over long distance for the population of Bozio and to a less extent for the population of Niolo. Their LD extent is comparable to or higher than that reported for other isolates.

Population variability in some genes involving the haemostatic system: data on the general population of Corsica (France), Sardinia and Sicily (Italy)

Three different population samples from Corsica (France), Sardinia and Sicily (Italy) were studied using nine genetic markers. For the first time, allele distributions of FGA TaqI, FGB Bcl I, FGB Hind III, PAI-1 Hind III, PLAT TPA-25, GPIIIa Taq I, GPIIb I/D 9bp, FVII HVR4 and FVII -323 10 bp markers, which are thought to be associated with cardiovascular disease risk, were studied in the general population of the three islands. The frequencies of the markers analysed in the present work show some peculiarities: the locus FVII HVR4 is characterized by the presence of a rare allele (H5), found in Corsicans and in Sardinians; the locus FBG BcII shows a low frequency of the B1 allele and the absence of the B1B1 genotype. The frequencies of some alleles have a distribution that is in agreement with the low risk for cardiovascular diseases in south European countries. The results highlight a genetic differentiation between the three Mediterranean islands and the other European populations.

A pentanucleotide repeat polymorphism (TTTTA) in the apolipoprotein (a) gene--its distribution and its association with the risk of cardiovascular disease.

Apolipoprotein (a) is a component of lipoprotein (a). Several studies have shown the association between risk of coronary heart diseases and the size of apo(a) isoforms, although this issue is still controversial. Recent researches focused the attention on the pentanucleotide (TTTTA), highlighting a statistical correlation between low Lp(a) levels and high repeat numbers. In the present paper we studied the distribution of the apo(a) pentanucleotide polymorphism among populations from Corsica, and we then compared it with other populations from Europe, Africa and Asia. The results stressed out the usefulness of these markers in population genetics analysis. We later investigated the possible association of the apo(a) pentanucleotide polymorphism with serum lipid levels in two samples from Corsica (France): one comprises patients or individuals with high risk of future coronary heart disease and the other is a control sample. No significant differences between the two groups have been found, but the analysis of variance showed a significant association between different genotypes and cholesterol and LDL serum levels.

Beta-globin gene cluster haplotypes in the Corsican and Sardinian populations.

The distribution of beta-globin cluster haplotypes has been studied in the populations of Corsica (France) and Sardinia (Italy). The analysis was carried out using five restriction fragment length polymorphism markers on chromosome 11 inside the beta-globin cluster using the restriction enzymes HincII and HindIII. The results show a remarkable heterogeneity within the two islands. However, the presence of rare haplotypes common to the most conservative areas (Nuoro and Corte) of the two islands is particularly interesting. These data support the hypothesis of a common origin of the populations of Sardinia and Corsica during the middle and upper Paleolithic periods and could be interpreted as a founder effect.