Rainbow trout. Photo: DTU Aqua.

PhD defence about virulence markers of VHS virus in rainbow trout

Monday 07 Dec 20


Anna Luiza Farias Alencar
PhD Student


Niels Jørgen Olesen
DTU Aqua
+45 35 88 68 31

On 17 December 2020, Anna Luiza Farias Alencar will defend her PhD thesis. The defence can be watched online.

Viral haemorrhagic septicaemia virus (VHSV) is the cause of a very serious and notifiable disease affecting rainbow trout in aquaculture. The virus is not dangerous to humans, but causes a systemic infection in fish with variable mortality rates. 

VHSV is primarily affecting farmed rainbow trout but has been isolated from more than 100 other species of fish, including many marine species, which can be infected and carry the virus without clinical symptoms. It is known that VHSV isolates from marine species cause low to no mortality in rainbow trout.

To find out more about these variations in the virulence of VHS viruses, PhD student Anna Luiza Farias Alencar, DTU Aqua, and her colleagues have performed experimental infection trials with rainbow trout and have conducted genetic studies of various isolates of the virus. The results are presented in Anna Alencar’s PhD thesis "Study of virulence markers in Viral Haemorrhagic Septicaemia Virus".

The infection trials were performed with VHSV isolates from DTU Aqua's VHSV repository in the Institute’s high containment tank facilities designed for research into infectious diseases in fish and shellfish.

A large number of VHSV isolates with varied virulence were subjected to full genome sequencing with Next Generation Sequencing and analyzed together in hope for identifying genetic markers that determine the virulence to rainbow trout. The results corroborate the recent hypothesis that the most prominent virulence markers are located in the nucleoprotein gene of the virus.

In order to further investigate this hypothesis, Anna Alencar also generated recombinant viruses where specific changes had been made in the nucleoprotein and carried out infection experiments with rainbow trout to assess the virulence of these changed viruses. The results obtained from this study support the hypothesis that the nucleoprotein is a contributing factor to the virulence of VHSV in rainbow trout, but also show that this is not the whole explanation and that more research into this subject is still necessary. 

About the PhD defence

Anna Luiza Farias Alencar will defend her PhD thesis "Study of virulence markers in Viral Haemorrhagic Septicaemia Virus (VHSV)” on Thursday 17 December 2020 at 16:00 (CEST) via Zoom. Find link to Zoom in the box below.


  • Principal supervisor: Professor Niels Jørgen Olesen, DTU Aqua
  • Co-supervisor: Senior Researcher Thomas Bruun Rasmussen, Statens Serum Institut, Denmark
  • Co-supervisor: Research Director Michel Brémont, National Research Institute for Agriculture, France
  • Co-supervisor: Researcher Argelia Cuenca, DTU Aqua


  • Professor Niels Lorenzen, DTU Aqua
  • Dr. Gael Kurath, Western Fisheries Research Center, U.S. Geological Survey, Seattle, USA
  • Dr. Katja Einer-Jensen, Qiagen, Denmark

Chairperson at defence

  • Senior Advisor Tine Moesgaard Iburg, 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, stub@aqua.dtu.dk

Link to Zoom and guidelines for attending the defence

It is possible to attend Anna Alencar’s defence on Zoom using this link: https://dtudk.zoom.us/j/66313281792

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 both camera and microphone are turned off at all times. 

There will be instructions regarding the proceedings in the beginning of the defence. After the members of the assessment committee have had time to raise their questions to the candidate, questions from the audience will be addressed if the remaining time allows for it.