Molecular characterization of Coxiella burnetii isolates by infrequent restriction site-PCR and MLVA typing

BACKGROUND: Coxiella burnetii, the causative agent of Q fever, has a wide host range. Few epidemiological tools are available, and they are often expensive or not easily standardized across laboratories. In this work, C. burnetii isolates from livestock and ticks were typed using infrequent restriction site-PCR (IRS-PCR) and multiple loci variable number of tandem repeats (VNTR) analysis (MLVA). RESULTS: By applying IRS-PCR, 14 C. burnetii isolates could be divided into six groups containing up to five different isolates. Clustering as deduced from MLVA typing with 17 markers provided an increased resolution with an excellent agreement to IRS-PCR, and with the plasmid type of each strain. MLVA was then applied to 28 additional C. burnetii isolates of different origin and 36 different genotypes were identified among the 42 isolates investigated. The clustering obtained is in agreement with published Multiple Locus Sequence Typing (MLST) data. Two panels of markers are proposed, panel 1 which can be confidently typed on agarose gel at a lower cost and in any laboratory setting (10 minisatellite markers with a repeat unit larger than 9 bp), and panel 2 which comprises 7 microsatellites and provides a higher discriminatory power. CONCLUSION: Our analyses demonstrate that MLVA is a powerful and promising molecular typing tool with a high resolution and of low costs. The consistency of the results with independent methods suggests that MLVA can be applied for epidemiological studies. The resulting data can be queried on a dedicated MLVA genotyping Web service

Excrétion de Coxiella burnetii dans le lait : suivi d’un troupe bovin

National audienc

Experimental Coxiella burnetii infection in pregnant goats: excretion routes

Q fever is a widespread zoonosis caused by Coxiella burnetii. Infected animals, shedding bacteria by different routes, constitute contamination sources for humans and the environment. To study Coxiella excretion, pregnant goats were inoculated by the subcutaneous route in a site localized just in front of the shoulder at 90 days of gestation with 3 doses of bacteria (10$^{8}$, 10$^{6}$ or 10$^{4}$ I.D.). All the goats aborted whatever the dose used. Coxiella were found by PCR and immunofluorescence tests in all placentas and in several organs of at least one fetus per goat. At abortion, all the goats excreted bacteria in vaginal discharges up to 14 days and in milk samples up to 52 days. A few goats excreted Coxiella in their feces before abortion, and all goats, excreted bacteria in their feces after abortion. Antibody titers against Coxiella increased from 21 days post inoculation to the end of the experiment. For a Q fever diagnostic, detection by PCR and immunofluorescence tests of Coxiella in parturition products and vaginal secretions at abortion should be preferred to serological tests

Fièvre Q : comparaison de l'efficacité de deux vaccins après infection expérimentale

National audienc

Efficacité de vaccins phase I et pahse II contre une infection à Coxiella burnetii de chèvres gestantes

National audienc

Un vaccin phase I contre la fièvre Q réduit considérablement l'excrétion de Coxiella burnetii chez la chèvre lors d'une infection expérimentale

National audienc

Evaluation de deux vaccins contre la fièvre Q dans une infection expérimentale de la chèvre gestante

National audienc

Comparison of the efficacy of Q fever vaccines against Coxiella burnetii experimental challenge in pregnant goats

International audienc

Excretion of Coxiella burnetii during an experimental infection of pregnant goats with an abortive goat strain CbC1

International audienc

Evaluation de deux vaccins contre la fièvre Q dans une infection expérimentale de la chèvre gestante

National audienc