Vaccination of European Sea Bass at one of the vaccination trials conducted during Sofie Barsøes PhD studies. Photo: Jacob G. Schmidt, DTU Aqua.

PhD defence about vaccination of European sea bass against viral nervous necrosis

Monday 06 Dec 21


Sofie Barsøe
DTU Aqua


Niels Lorenzen
+45 25 52 07 30

On 16 December, Sofie Barsøe, DTU Aqua, will defend her PhD thesis. It is possible to attend the defence at DTU Aqua in Lyngby and online.

European sea bass (Dicentrarchus labrax) is one of the main cultured fish species in the Mediterranean. Unfortunately, it is affected by the disease viral nervous necrosis (VNN) which can result in great losses compromising both fish welfare and the economy of the production. Nervous necrosis virus (NNV), the cause of the disease, circulates both in farmed and wild fish, making prevention and elimination difficult. 

In her PhD study, Sofie Barsøe, DTU Aqua, has conducted vaccination and challenge experiments of European sea bass to investigate natural immunity against the virus in different lines of fish as well as induced immunity following vaccination. 

Natural immunity was investigated through experimental infection of three different populations of sea bass. The results showed that one of the populations—sea bass originating from the eastern Mediterranean—seemed to have higher natural immunity against the viral disease. This might be due to an evolutionary adaptation of this population limiting the ability of the virus to infect and replicate in the fish, Sofie Barsøe states in her PhD thesis. 

Vaccine-induced protection was investigated in the laboratory through vaccination-challenge experiments where the efficacy of different vaccine doses and formulations were tested. The vaccine was a newly developed virus-like particle (VLP)-based vaccine delivered by injection. It showed very good protective effect against disease following experimental infection for at least 7.5 months.

In her thesis, Sofie Barsøe concludes that the tested vaccine harbor great potential for the prevention of viral nervous necrosis in farmed sea bass. She recommends that future studies should test the vaccine under farming conditions and investigate alternative delivery routes to injection, particularly for small fish. Further, she suggests investigations into the protective effect against other strains of the virus and in other fish species. 

About the PhD defence

Sofie Barsøe will defend her PhD thesis "Vaccination of European Sea Bass (Dicentrarchus labrax) against Viral Nervous Necrosis and Characterization of Protective Immunity" on Thursday 16 December, 1:00 p.m. on Zoom and at DTU, Anker Engelunds Vej 101, 2800 Kgs. Lyngby, building 101 (1st floor), meeting room 1.   


  • Main supervisor: Professor Niels Lorenzen
  • Co-supervisor: Researcher Niccolò Vendramin
  • Co-supervisor: Professor Niels Jørgen Olesen


  • Professor Peter Mikael Helweg Heegaard, Department of Health Technology, DTU (chair)
  • Principal Investigator Kimberly Dawn Thompson, Moredun Research Institute, UK
  • Research Scientist Sonal Patel, Norwegian Veterinary Institute, Norway

Chair at defence

  • Senior Researcher Morten Schiøtt, DTU Aqua 

Learn more
A popular science summary of the thesis can be downloaded here 

A copy of the thesis is available by e-mail on request. Please contact Karin Stubgaard,

Link to Zoom and guidelines for online attendance

It is possible to attend Sofie Barsøe’s defence on Zoom using this link:

Please, enter the meeting 10 minutes prior to the defence proceedings are scheduled to start. All participants are muted per default, but we ask you to double check that your microphone is turned off at all times. There will be instructions regarding the proceedings in the beginning of the defence.