Some impressions from the 13th European Association of Fish Pathologists meeting

17 - 20 September 2007
Grado, Italy

Eric Rijke, Intervet International

Around 350 participants attended. The scientific program consisted of 127 oral (parallel sessions) and more than 200 poster presentations.

The conference keynote presentation was given by Prof. P. Smith entitled: Fish vaccines- a short but remarkable journey. Vaccines for fish have only been available from the beginning of the 80’s with only two products registered in 1982 while 25 vaccines were registered in 2004. Some of the vaccines were discussed in particular: a vaccine for tilapia which only afforded a 4% increase in survival but the benefit of vaccination for the farmer was much higher. Similar calculations were presented with a Vibrio product for shrimp. Also vaccines can lead to growth penalties due to adhesions occurring when using oil-adjuvanted vaccines. In the future, fish vaccines will beyond doubt benefit from developments taking place in other vaccine fields like the use of improved growth media, the use of attenuated live vaccines although there might be some regulatory issues to be solved especially when applying recombinant (live) vaccines which are considered to be GMO’s. In addition, oral vaccines, new adjuvants, DNA vaccination, use of VLP’s, the use of RNAi silencing and finally, the use of molecular decoys and molecular sponges might be strategies applied in aquaculture.

Several contributions on infectious pancreatic necrosis (IPN) dealt with the importance of viral virulence markers and diagnostic methods but also good protection studies were presented by Ramstad on the beneficial use of vaccines in high and low IPN sensitive salmon strains.

Pancreas disease (PD) got a lot of attention in various contributions. A new challenge model (Hodneland & Knappskog) was presented which could lead to better vaccines against PD. Furthermore diagnostic techniques as well the selection of cell lines for the optimal growth of the PD virus were shown (Graham, Smail). For the first time, evidence was presented for the existence of 6 subtypes of Salmonid Alpha Virus (SAV) based on sequence data comparison of the E2 and nsP3 proteins of SAV isolates from Norway, Ireland, England, Scotland, France, Italy and Spain during 1999-2007. Subtype 1 was only found in Ireland, subtype 2 (causing Sleeping Disease in trout) was found in Scotland, France, Italy and Spain while subtype 3 was only found in Norway. Remarkably, subtype 2 was recently also found in salmon in Scotland. Subtype 4 was found in Ireland and Scotland while subtype 5 was only observed in Scotland. A single but distinct isolate was found in Ireland and was designated as subtype 6. No clear relationship between mortality and viral strain was observed.

Nodaviruses are known to cause disease problems in different Asian marine species as well as sea bass and bream in the Mediterranean, but recently have become an important cause of disease in cod farming in Norway, Scotland and Canada, not only in small (150-460 g), but also in big (1.5 kg) fish. High sea temperature and early maturation and spawning might play a role (Heilberg). Three new genotypes were identified in wild and farmed cod, while nodavirus has been identified in several wild marine species such as pollack, saithe, mackerel and plaice. Their role as potential carriers for the disease is still unknown.

Koi Herpes Virus (KHV) is still recognized as an important disease as demonstrated during a separate workshop organized by Olga Haenen. She also presented a recent survey on the presence of KHV in 26 countries while another 24 countries seem to be free. Diagnosis is done by PCR although test validation by laboratories is needed. Several contributions dealt with the diagnostic tests for KHV but also that a tk-KHV mutant was still pathogenic for juvenile carp making it not safe enough as a vaccine (Fichtner). 

Heart and Skeletal Muscle inflammation (HSMI) incidence seems to have increased in Norway and is suspected in Scotland (identified by histological analysis). Although the  identity of the agent is not publicly known, infection studies were performed with tissue culture adapted challenge inoculum whereafter several immune parameters  (CD4/CD8, IFNγ, granzyme, IL-10, IL-12) were followed. It seems that the immune response in the heart was mainly of a cytotoxic nature, but that an antibody component is involved as well.

Several contributions dealt with Flavobacterium: it was speculated that different colony types of F. columnare (Kunttu) and F. psychrophilum (Wiklund) might relate to virulence. In addition, farm conditions such as fish density and water temperature seem to have an impact on virulence (Suomalainen).

Francisella sp. was presented as a new disease causing bacteria affecting cod in Norway (Lund, Nordstrøm) but also in Denmark (Dalsgaard). There is a need for an effective vaccine in cod, and preliminary results do indicate this is feasible (Krossøy). In addition Francisella sp. are also causing disease problems in tilapia in Costa Rica. In Chile, a new Vibrio anguillarum serotype O3 has been isolated causing problems in Atlantic salmon (Avendano-Herrera).

Access to winning posters and the book of abstracts can be gained via the following links.

Winning Posters
Book of Abstracts