GENOMIC DIVERSITY OF LISTERIA MONOCYTOGENES STRAINS THROUGHOUT THE AGRI-FOOD CHAIN : A CONTRIBUTION TO CONTAMINATION CONTROL
Résumé
Listeria monocytogenes (Lm) is a zoonotic foodborne pathogen. Wildlife and soil are pivotal reservoirs for its introduction in agricultural production. The strain clonal complex (CC) has become the common language for Lm typing, linked to virulence for human. The CC identification was recently made accessible by real-time PCR for 30 major clones.
Three CC distribution studies were conducted from farm to retail including 452 and 687 strains in dairy and pork sector in France and, a third study on 1484 strains, balanced between animals, environment and food products, in 21 European countries.
These studies showed four different distributions profiles of the major CCs. Five clones are observed from farm environment to food products in all sectors and frequent in ruminant clinic cases: CC1, CC4, CC6, CC7 hypervirulent (HV) and CC37 of intermediate virulence (IV). Three clones present a similar distribution but rare in ruminant clinical cases: CC2 (HV), CC5 and CC8 (IV). Seven clones are rare at animal and environment level but frequent in food: CC87, CC101 (HV), CC3, CC155 (IV) and CC9, CC31, CC121 less virulent clones. Finally, CC18, CC20, CC29 (IV) are rare in food but frequent at animal and environment level.
From these results, the hypothesis put forward is that certain strains have a better genetic fitness for food production environment while other are outdoor adapted. (i) Nine CCs are rare at animals and environment level but frequent in food (CC3, CC8, CC9, CC31, CC87, CC101, CC121 and CC155). (ii) Conversely, 12 CCs present the inverted distribution (CC1, CC4, CC11-ST11, CC18, CC20, CC21, CC29, ST124, ST191, CC315, CC388, CC224). Genome wide association study of these strains enabled to identify 25 new genetic factors that may explain their distribution. They include osmoregulation and metabolic stress resistance pathways, that may lead to improved solution for Lm control.
Domaines
Sciences du Vivant [q-bio]Origine | Fichiers produits par l'(les) auteur(s) |
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