Microscale tracking of coral-vibrio interactions

Abstract

To improve our understanding of coral infection and disease, it is important to study host-pathogen interactions at relevant spatio-temporal scales. Here, we provide a dynamic microscopic view of the interaction between a coral pathogen, Vibrio coralliilyticus and its coral host Pocillopora damicornis. This was achieved using a microfluidics-based system facilitating control over flow, light and temperature conditions. Combined with time-resolved biochemical and microbial analyses of the system exudates, this approach provides novel insights into the early phases of a coral infection at unprecedented spatio-temporal resolution. We provide evidence that infection may occur through ingestion of the pathogen by the coral polyps, or following pathogen colonization of small tissue lesions on the coral surface. Pathogen ingestion invariably induced the release of pathogen-laden mucus from the gastrovascular cavity. Despite the high bacterial load used in our experiments, approximately one-third of coral fragments tested did not develop further symptoms. In the remaining two-thirds, mucus spewing was followed by the severing of calicoblastic connective tissues (coenosarc) and subsequently necrosis of most polyps. Despite extensive damage to symptomatic colonies, we frequently observed survival of individual polyps, often accompanied by polyp bail-out. Biochemical and microbial analyses of exudates over the course of symptomatic infections revealed that severing of the coenosarc was followed by an increase in matrix metaloprotease activity, and subsequent increase in both pathogen and total bacterial counts. Combined, these observations provide a detailed description of a coral infection, bringing us a step closer to elucidating the complex interactions underlying coral disease.

Use and Evaluation of a pES213-Derived Plasmid for the Constitutive Expression of gfp Protein in Pathogenic Vibrios: a Tagging Tool for In Vitro Studies

“…Several subsequent studies have successfully employed pES213-derived donor plasmids for the creation of stable GFP tags in A. fischeri ( 33 ) and the Vibrio spp. V. harveyi ( 18 , 34 ), V. parahaemolyticus ( 35 , 36 ), V. coralliilyticus ( 37 ), V. aestuarianus ( 22 ), and V. tapetis ( 38 ). However, a formal side-by-side comparison of conjugation methods and the acquired plasmid retention is needed to standardize these methods across different vibrios.…”

The community profiles of symbiotic bacteria at the different life stages of coral Dipsastraea favus

“…Coral holobionts harbor a complex consortium of microorganisms, including zooxanthellae, bacteria, archaea, fungi, viruses, and protists (Knowlton and Rohwer, 2003). Coral microbial flora has been attracting attention for their potentials to protect corals from environmental stresses and their relevance with coral hosts, such as defense against pathogens, promotion of coral health, development, nutrition-based symbioses, and environmental adaption (Krediet et al, 2013;Soffer et al, 2015;Lema et al, 2016;Yang et al, 2016;Zhou et al, 2017;Bernasconi et al, 2019;Babbin et al, 2021;Gavish et al, 2021;Kitamura et al, 2021). For example, the confirmation of anaerobic nitrogen metabolism in coral microorganisms sheds new light on coral and reef productivity (Babbin et al, 2021).…”

Coral disease and ingestion: investigating the role of heterotrophy in the transmission of pathogenicVibriospp. using a sea anemone (Exaiptasia pallida) model system

“…Certner et al (2017) demonstrated that white-band disease (WBD) transmission can be facilitated through zooplankton ingestion following incubation in tissue homogenate from diseased corals. In a similar vein, Gavish et al (2021) utilized a microscale visualization system to observe colonization of Pocillopora damicornis by Vibrio coralliilyticus from ambient sea water, suggesting that ingestion may be a primary route of entry for the pathogen. Corals support their carbon and nutrient needs through the mutualistic relationship with their algal symbionts and through direct feeding.…”

“…Heterotrophy provides up to 35% of a healthy coral’s daily metabolic needs and up to 100% in bleached corals, largely by nighttime feeding on zooplankton (Houlbrèque & Ferrier-Pagès, 2009; Ferrier-Pagès et al, 2010). While Gavish et al (2021) demonstrates the viability of pathogen acquisition via direct ingestion of bacteria, preferential grazing of zooplankton, which are known to be colonized by bacteria (and Vibrio in particular [Erken et al, 2015]), may represent an important exploitable pathway for pathogenic microbes to gain entry to a coral host. We hypothesize that pathogen-colonized zooplankton may serve as a foodborne vector for disease transmission in uninjured corals.…”