Developing a DNA-Based Vaccine for Mycobacterium marinum

Proposed Research Project

Researcher: Nilli Zmora

The study aims to develop an efficient DNA-based vaccine against Mycobacterium marinum to vaccinate striped bass. To do that, two Mycobacterium proteins were identified to serve antigens. These proteins will be produced in the muscles of the 
vaccinated striped bass and trigger an immune response in the form of antibodies. 

Three separate sub-projects are needed to achieve this:

  1. Generate the plasmids expressing the selected protein, which will be the core of the injected vaccine.
  2. Develop specific diagnostic assays to evaluate the immune response of the vaccinated fish and to detect M. marinum in the blood.
  3. Vaccinate fish with different plasmids and combinations and evaluate the immune response using the developed assays.

Expected Outcomes

The project will develop a more potent vaccine to protect fish from mycobacteria infection, and develop a rapid assay to detect immunity and antibody titer.

Best case scenario: The developed treatment will trigger the adaptive immune system. This means that the vaccinated fish immune system will remember the pathogen and will respond quickly to repress the propagation of the mycobacteria immediately upon infection.

Worst case scenario: We believe that some protection will be obtained and the worst-case scenario is that the protection will be partial and temporal.
 

Probable Ancillary Benefits

  • If successful, the vaccine can be used to vaccinate broodstock of striped bass and other fish species to facilitate maternal transfer of the antibodies to fingerlings. The vaccinated fingerlings can be then released from hatcheries to the Chesapeake Bay as part of the restoration efforts, thus contributing to the mitigation of the disease in the Bay (https://dnr.maryland.gov/fisheries/pages/hatcheries/index.aspx).
  • Successful reduction of Mycobacterium infection of fish will also decrease the chances of fishermen and swimmers contracting M. marinum.
  • The approach can be easily adopted to vaccinate other fish species against a variety of diseases in the Bay.

Results

  • Plasmids preparation: The genes of the selected proteins have been synthesized and are now in the process of insertion into the proper plasmids.
  • Diagnostic assay: The two M. marinum proteins were produced, and IgM antibodies were purified from striped bass serum to produce secondary antibodies. These components are essential for the development of the assays.
  • Vaccination trial: 2000 striped bass fingerlings are now raised for us at the DNA facilities. They will be transferred to IMET in about two months. The vaccination trials will begin when the fish are 5-6 months old, when the adaptive immunity is sufficiently developed.
  • Expanding networks: I have been in contact with scientists at the DNR station at Oxford who conduct Mycobacterium surveys in the Chesapeake Bay. These scientists showed interest in the project and in collaborating with us, both for the easy and fast detection of infected fish and for the vaccination.