Aquatic Pathobiology

CPHMVS Biomedicine Aquatic Pathobiology

Aquatic Pathobiology

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Crustacean disease research - Virology

Viruses are the major antagonist to the culture of crustaceans. As it is impossible to vaccinate crustacea, novel ways of combating them have to be found. Our group is particularly interested in interfering Ribonucleic acid (RNA) and many of our projects have this a an end point of our investigations so that we can limit the effects of viruses in crustacean aquaculture.

Current projects  

  • Investigation of Macrobrachium rosenbergii nodavirus (white tail disease) Australian isolate.
    This study aims to develop an animal model for white tail disease in order to use interfering ribonucleic acid to control the disease in the future. Also the sequencing of Macrobrachium rosenbergii nodavirus will study to characterise the virus and compare to other isolates.    
  • Suppression subtractive hybridization for genes expressed in redclaw crayfish Cherax quadricarinatus with an idiopathic lesion.
    This study is conducted to characterise possible viral genomes and differentially expressed genes from the gills of two populations of the crayfish suppression subtractive hybridisation (SSH). The identification of viral genomes and differential transcripts of genes in particular immune-related genes in the redclaw crayfish is important in understanding host-virus interaction at the molecular level and it may contribute to developing immuno-interventionstrategies control infectious diseases in crustacean aquaculture.    
  • Investigation of hepatopancreatic parvovirus in Penaeus esculentus and Penaeus merguiensis/indicus
    The project aims to sequence the hepatopancreatic parvovirus (HPV) strain, which will be isolated from Penaeus esculentus, P. merguiensis/indicus purchased from Western Australia (WA). Samples from archived blocks stored at Department of Agriculture and Food (AGRIC) in WA will also be sequenced for Hepatopancreatic Parvovirus (HPV), from which Brian Jones described previously in a Fisheries Report.    

Fish disease research - Bacteriology  

Streptococcus iniae (S.iniae) is a Gram positive bacterium that causes disease and mortality in over 30 species of cultured and wild fish in marine, brackish and freshwater environments. Fish mortality due to S. iniae can be severe, frequently exceeding over half of the infected population and  heading  to  heavy  economic  losses estimated to be over $150 million worldwide.        

Prevention and treatment of S. iniae in aquaculture remains difficult, particularly with the industry seeking safer alternatives to antibiotics and vaccines. Chemical-free “green solutions” appear to be the next era of therapeutics for preventing bacterial epizootics in fish.        

Current projects  

  • The potential of Asparagopsis taxiformis as a green treatment for streptococcosis in fish mariculture.
    The marine algae Asparagopsis taxiformis was tested in vitro against a collection of Streptococcus iniae isolates to study its potential as a treatment tool against the bacteria. The algae itself and extracts the algae inhibited growth of all isolates of S. iniae tested to some degree. The MIC of these extracts against the bacteria were found, and the extracts were tested in vivo with barramundi experimentally infected with S. iniae.    
  • Characterisation of BacL49, a lactococcal bacteriocin with activity against the fish pathogen Streptococcus iniae
    The study aims to characterise a bacteriocin, BacL49, with activity against S. iniae that is produced by a Lactococcus lactis ssp. lactis strain isolated from freshwater sleepy cod (Oxyeleotris lineolatus). BacL49 has a bactericidal mode of action and exhibits a broad activity spectrum for S. iniae, antagonising 93.75% of S. iniae isolates in the JCU collection. This lactococcal bacteriocin is significant because of its heat and pH stability, implicating it as potential new therapeutic against S. iniae. Current research is investigating whether BacL49 is under plasmid regulation.

Turtle health in North Queensland

We are studying a disease in green turtles. It affects mostly the juveniles and it can look quite dramatic with cancerous growths on their skin which sometimes also affect their eyes and organs. The disease has been described from many other parts of the world and is called fibropapillomatosis. We do  know  that it is strongly with a herpesvirus, but the herpesvirus alone is not enough. Usually some cofactor is required for the disease to manifest. Chances are that this herpesvirus needs something else to lower the immune defence of the turtles and it is this something we are looking for.

The area we focus on provides us with a unique opportunity to study what those cofactors could be, because in the middle of a large healthy population of green turtles there is a very small area, where many juveniles are sick.

One big bonus for this project is that we have such great interest and cooperation from the local traditional owners, who can tell us that this disease was not here previously. And it is so spectacular that if it was here before, then they would surely have noticed.

Group Head

Acting/Professor Ellen Ariel