A/Professor Andy Barnes
Host-microbial interactions in aquatic animals
Marine and aquatic animals exist directly immersed in an environment that supports abundant and diverse microbiota. This provides both unique opportunities and challenges for aquatic animals that are not experienced by their terrestrial counterparts. My research explores the interactions of marine fish and invertebrates with predominantly bacterial associates, both beneficial and pathogenic, focusing on aquatic animal health. Much of my research is applied, having strong collaborations with the aquaculture and veterinary industry both in Australia and overseas.
At the molecular and cellular level, the first point of contact between aquatic animals and environmental microbes is their immune system. We have explored the immune systems of invertebrates such as corals, prawns and oysters, as well as commercially and ecologically important marine fish at both the molecular and functional level. We have identified roles in pathogen exclusion and symbiont selection. At the applied level we have exploited this to develop commercial vaccines for barramundi, improve vaccine adjuvants for fish and to develop tools for marker-assisted selection of disease resistant oysters. At the fundamental level we have identified the first functional immune proteins in reef-building corals and determined their roles in microbial community control and selection of the symbiotic dinoflagellate.
Ultimately, most bacterial invaders are eliminated by macrophages. Therefore, understanding how pathogens circumvent these phagocytic cells is critical in development of vaccine targets. We investigate interactions of pathogenic bacteria with primary leucocyte cultures derived from commercially and ecologically important marine fish species with a view to developing improved vaccines, or explaining why particular epizootics have arisen. Current work focuses on evolution of the capsular operon of S. iniae in response to on-farm vaccination, and on tracing origin and explaining pathogenesis of group B Streptococcus in wild Queensland grouper using genomics and functional assays.
Aquatic animals have complex microbial communities that strongly influence health and growth. The complexity of the communities is confounded further by extremely high variability amongst individuals. We investigate microbial communities with sufficient replication to provide data that can be used predictively or to solve particular issues. In highly replicated studies we have shown strong host –specific selection of bacterial associates in reef-building corals. We have also shown what happens to the metabolically active gut microbiota of Atlantic salmon during the stress of warm summer water temperatures in Tasmania, enabling formulation of novel more sustainable feeds to improve stability of the gut microbiome and improve fish performance during the summer months.
Kvennefors ECE, Leggat W, Hoegh-Guldberg H, Degnan BM, and Barnes AC. (2008) An ancient and variable mannose binding lectin from the coral Acropora millepora binds both pathogens and symbionts. Developmental and Comparative Immunology 32, 1582-1592
Baiano JCF and Barnes AC (2009) Towards the Control of Streptococcus iniae. Emerg. Infect. Dis. 15, 1891-1896.
Nawawi RA, Baiano, JCF, Kvennefors ECE and Barnes AC (2009). Host-directed evolution of a novel lactate oxidase in Streptococcus iniae from farmed barramundi. Appl. Environ. Microbiol. 75, 2908-2919.
Kvennefors ECE, Sampayo E, Kerr C, Vieira G, Roff G, Barnes AC (2011) Regulation of Bacterial Communities Through Antimicrobial Activity by the Coral Holobiont. Microbial Ecology (Online First 7th October 2011)
Kvennefors ECE, Sampayo E, Ridgway T, Barnes AC, and Hoegh-Guldberg O (2010) Bacterial Communities of Two Ubiquitous Great Barrier Reef Corals Reveals Both Site- and Species-Specificity of Common Bacterial Associates. PLoS One 5 e10401
American Society for Microbiology
European Association of Fish Pathologists
World Aquaculture Society