Over the past decade, a significant increase in the circulation of infectious agents was observed. With the spread and emergence of epizootics, zoonoses, and epidemics, the risks of pandemics became more and more critical. Human and animal health has also been threatened by antimicrobial resistance, environmental pollution, and the development of multifactorial and chronic diseases. This highlighted the increasing globalization of health risks and the importance of the human–animal–ecosystem interface in the evolution and emergence of pathogens. A better knowledge of causes and consequences of certain human activities, lifestyles, and behaviors in ecosystems is crucial for a rigorous interpretation of disease dynamics and to drive public policies. As a global good, health security must be understood on a global scale and from a global and crosscutting perspective, integrating human health, animal health, plant health, ecosystems health, and biodiversity. In this study, we discuss how crucial it is to consider ecological, evolutionary, and environmental sciences in understanding the emergence and re-emergence of infectious diseases and in facing the challenges of antimicrobial resistance. We also discuss the application of the “One Health” concept to non-communicable chronic diseases linked to exposure to multiple stresses, including toxic stress, and new lifestyles. Finally, we draw up a list of barriers that need removing and the ambitions that we must nurture for the effective application of the “One Health” concept. We conclude that the success of this One Health concept now requires breaking down the interdisciplinary barriers that still separate human and veterinary medicine from ecological, evolutionary, and environmental sciences. The development of integrative approaches should be promoted by linking the study of factors underlying stress responses to their consequences on ecosystem functioning and evolution. This knowledge is required for the development of novel control strategies inspired by environmental mechanisms leading to desired equilibrium and dynamics in healthy ecosystems and must provide in the near future a framework for more integrated operational initiatives.

Vibrio splendidus is a dominant culturable Vibrio in seawater, and strains related to this species are also associated with mortality in a variety of marine animals. The determinants encoding the pathogenic properties of these strains are still poorly understood; however, the recent sequencing of the genome of V. splendidus LGP32, an oyster pathogen, provides an opportunity to decipher the basis of the virulence properties by disruption of candidate genes. We developed a novel suicide vector based on the pir-dependent R6K replicative origin, which potentially can be transferred by RP4-based conjugation to any Vibrio strain and which also carries the plasmid F toxin ccdB gene under control of the P BAD promoter. We demonstrated that this genetic system allows efficient counterselection of integrated plasmids in the presence of arabinose in both V. splendidus and Vibrio cholerae and thus permits efficient markerless allelic replacement in these species. We used this technique to construct several mutants of V. splendidus LGP32, including a derivative with a secreted metalloprotease gene, vsm, deleted. We found that this gene is essential for LGP32 extracellular product toxicity when the extracellular products are injected into oysters but is not necessary for virulence of bacteria in the oyster infection model when bacteria are injected.Vibrio splendidus is a dominant culturable Vibrio in coastal marine sediments, seawater, and bivalves, including oysters (23). This organism has long been considered to be an environmental organism without any pathogenic significance. However, over the last few years, different strains phenotypically related to this species have been associated with mortality mainly in mollusks, shrimps, gorgonians, and fish (for a review, see reference 35). Compared to human pathogen species, little is known about Vibrio pathogenesis in marine animals, and despite descriptions of invasiveness and extracellular product (ECP) toxicity, no data are available for a group related to V. splendidus (26,37,48,56).The different types of enzymatic activities that have been shown to play a role in the virulence of a variety of pathogenic bacteria include extracellular proteases; for example, such proteases have been described for Vibrio cholerae (7), Vibrio vulnificus (33), and Vibrio anguillarum (42), although a direct role of these proteases in virulence has not been demonstrated. For example, it has been shown that the V. cholerae metalloprotease cleavage activity is essential for activating the A subunit of the cholera enterotoxin (12), as well as for degrading intestinal mucin and facilitating the action of cholera toxin (7). In the case of V. vulnificus infection, a metalloprotease has been shown to cause a hemorrhagic reaction by degrading type IV collagen in basement membranes (44). Finally, the empA-encoded metalloprotease of V. anguillarum has been shown to be involved in the invasive mechanism of this fish pathogen (49).We recently completed sequencing of the genome of V.splendidus strain LGP32 in...

In animals and plants, social structure can reduce conflict within populations and bias aggression toward competing populations; however, for bacteria in the wild it remains unknown whether such population-level organization exists. Here, we show that environmental bacteria are organized into socially cohesive units in which antagonism occurs between rather than within ecologically defined populations. By screening approximately 35,000 possible mutual interactions among Vibrionaceae isolates from the ocean, we show that genotypic clusters known to have cohesive habitat association also act as units in terms of antibiotic production and resistance. Genetic analyses show that within populations, broad-range antibiotics are produced by few genotypes, whereas all others are resistant, suggesting cooperation between conspecifics. Natural antibiotics may thus mediate competition between populations rather than solely increase the success of individuals.