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15. University of Valencia

University of Valencia

Department of Microbiology and Ecology

Carmen Amaro

The team of the Department of Microbiology and Ecology of the University of Valencia (Spain) is focused on two main areas one of basic research (lead by me) and the other of applied research to the Aquaculture industry (lead by Belen Fouz).

Basic research: main topic V. vulnificus (Vv)

Vv is an aquatic bacterial species with pathogenic potential for human and fish. The species includes a zoonotic serovar that causes a hemorrhagic septicaemia in fish called warm-water vibriosis. This serovar can sporadically infect humans and cause wound infections or even septicaemia in immunodeficient patients, which is why its presence in fish on sale constitutes a Public Health risk. Interestingly, fish and human vibriosis exhibit similar clinical presentations, where infection can lead to a severe form of the disease associated with high mortality rates, especially among immunocompromised hosts.

The main goal of our research is to identify common and host-specific virulence mechanism in Vv and, at the same time, to understand the emergence of the zoonotic serovar within the species.

To get this objective, we use the following approaches

  1. Comparative genomics and phylogenomic: The genomes of 45 strains isolated worlwide from different types of samples (clinical and environmental) have been sequenced and are being analyzed.
  2. Host-pathogen interactionship studies: We have selected eels and mice for in vivo experiments and eel and human cell lines for in vitro experiments. To determine the genes that are expressed by the eel against Vv, we have sequenced the eel transcriptome from PAMP-immunostimulated eels and we have designed and validated an oligonucleotide microarray (format 4x44K) from selected sequences (e-values<10-5) (Agilent eArray; Agilent Technologies). In parallel, we have also designed and validated a microarray for the pathogen with the same technology and used the microarray technology or RNAseq depending on the experiment. In case of human genes, we have selected a battery of genes for citokines, chemokynes, PRRs… and used RT-qPCR technology. All these experiments are completed with phenotypic assays (ELISA, Western blot, Dot blot, etc.)
  3. Virulence genes and regulation: To find out whether the bacterial genes identified in the host-pathogen interaction studies are virulence genes, we obtain defective mutants by allelic exchange and assess their virulence by using in vivo and in vitro tests. The regulation of bacterial gene expression by iron or nitric oxide is being currently studied by growing the bacterium or its derivatives in different conditions (presence absence of iron/nitric oxide), including in presence of eukaryotic cells, and using RNAseq.

Applied research: main topic infectious diseases of fish (including fish vibriosis)

The group carries out research projects in close collaboration with authorities and national and international companies linked to the aquaculture sector with the objective to elucidate and prevent infectious pathologies, including vibriosis, in different cultivated fish species like eels, see bass, gilthead, turbot, sole or trout. Large-scale experiments are performed at the Pilot Plant of Experimental Aquaria (PPEA) located at the Scientific Park of the University. This plant occupies 500 m2 and is designed in three contiguous areas, containing each different types of tanks and a modular system for water treatment. The whole facility possesses sources of hot and cold water, seawater, chlorine-free freshwater and deionised water, a centralized water-recycling circuit, and a system for treatment, filtering and sterilization of sewage. Close to the plant, there is a microbiology and a necropsy laboratory with a climatic chamber to perform experiments with larvae or little fishes (see http://www.uv.es/uvweb/central-service-for-experimental-research/en/scsie/sections/aquariums-floor/equipment-1285876856670.html).

The applied research work focused on Vv could be summarized in the design and validation of

  1. molecular methods for fish vibriosis diagnosis and for the detection of Vvpathogenic in healthy carriers or potential reservoirs (mainly seafood).
  2. a vaccine (Vulnivaccine) and a vaccination protocol applicable to intensive eel farming industry.