2023-10-19 06:00:07
Polymicrobial diseases, which involve infections with multiple pathogens, are difficult to control. Scientists analyzed the interactions within the polymicrobial consortium that kills young oysters during Pacific Oyster Mortality Syndrome (POMS). caused by the virus OsHV-1 and various bacterial genera. They identified cooperative and cheating bacteria.
Cooperating bacteria impair the oysters’ cellular immunity and accelerate disease progression. They also share metabolites that allow cheaters to colonize oysters. Targeting these cooperation mechanisms or countering their effects are avenues to explore for disease control.
A number of polymicrobial diseases affect human and animal species. These are diseases resulting from infections by multiple pathogens, which complicates the control of epidemics and treatments. Within these microbial consortia, microbes interact and accelerate disease progression. Such polymicrobial synergies are sometimes observed between viruses and bacteria. In humans (A man is an adult male individual of the species called modern man (Homo…), this is particularly the case for the influenza virus (Influenza (or influenza) is a disease common and contagious infectious disease caused by…) A or human immunodeficiency virus (HIV). Polymicrobial consortia exhibit cooperative capabilities at the cellular level that include the production of common goods (e.g., shared metabolites), the division (Division is a law of composition which associates the product of the first with two numbers…) of work, transport (Transport is the act of carrying something, or someone, from one place to another, the most…) of resources, as well as the creation and maintenance of the extracellular environment. However, these complex diseases are rarely studied in natural pathosystems.
Recently, researchers from the IHPE laboratory and their collaborators showed that Pacific oyster mortality syndrome (POMS), which devastates farms of young oysters of the species Crassostrea gigas on a global scale, is caused by Ostreid Herpesvirus 1 (OsHV-1) and pathogenic bacteria, particularly from the Vibrionaceae family. POMS thus constitutes an excellent natural pathosystem for characterizing the interactions at work in polymicrobial assemblages and identifying those which play a key role in the progression of the disease.
In a study published in PNAS, researchers found that two species of Vibrio, called Vibrio harveyi and Vibrio rotiferianus, were predominant in the tissues of pond oysters. stagnant, shallow, surface water, etc.) of Thau infected with OsHV-1. The authors used controlled laboratory infections to explore the interactions between these two species of bacteria and the virus in C. gigas.
Crassostrea gigas oysters in the Thau pond.
Credit: Delphine Destoumieux-GarzĂłn.
The results indicate that V. harveyi and OsHV-1 promote their reciprocal growth, which accelerates oyster mortality. The authors also characterized the underlying mechanisms. They notably showed that V. harveyi favored the colonization of microbes by altering the cellular defenses of the oyster (The term oyster (or oyster) covers a certain number of groups of marine molluscs…) thanks to a secretion system of type III, a behavior previously observed but mediated by other effectors in Vibrio species that infect oysters during POMS in the Atlantic.
On the other hand, V. rotiferianus benefits opportunistically from the metabolites produced by V. harveyi without itself actively participating in the disease, which constitutes an example of cheating behavior (Cheating is the fact of not respecting rules to benefit from advantages. We can…). The control of cooperative behavior thus appears to be an area of ​​research to be explored to mitigate the polymicrobial synergy between the virus and bacteria which leads to death. oysters.
Reference
Proceedings of the National Academy of Sciences of the United States of America, published on 26/09/2
Oyanedel , D. , Lagorce , A. , Bruto , M. , Haffner , P. , Morot , A. , Labreuche , Y. , Dorant , Y. , De La Forest Divonne , S. , Delavat , F. , Inguimbert , N. , Montagnani , C. , Morga , B. , Toulza , E. , Chaparro , C. , Escoubas , J. , Gueguen , Y. , Vidal-Dupiol , J. , De Lorgeril , J. , Petton , B. , Destoumieux-Garzon , D. ( 2010 ).
Cooperation and cheating orchestrate vibrio assemblages and polymicrobial synergy in oysters infected with OSHV-1 virus.
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