Bisgaard, N.P.

Bøtner, Anette

Hansen, Mette Sif

Heegaard, Peter M. H.

Hjulsager, Charlotte Kristiane

Kvisgaard, Lise Kirstine

Larsen, Lars Erik

Nielsen, J.

Rathkjen, P. H.

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 20, 2017Clinical characterization of a type 2 PRRSV causing significant clinical disease in thefield in DenmarkLarsen, Lars Erik; Kvisgaard, Lise Kirstine; Hjulsager, Charlotte Kristiane; Bøtner, Anette; Rathkjen, P.H.; Heegaard, Peter Mikael Helweg; Bisgaard, N.P.; Hansen, Mette Sif; Nielsen, J.Published in:Proceedings of the 23rd IPVS CongressPublication date:2014Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Larsen, L. E., Kvisgaard, L. K., Hjulsager, C. K., Bøtner, A., Rathkjen, P. H., Heegaard, P. M. H., ... Nielsen, J.(2014). Clinical characterization of a type 2 PRRSV causing significant clinical disease in the field in Denmark. InProceedings of the 23rd IPVS Congress185 Proceedings of the 23rd IPVS Congress, Cancun, Mexico – June 8-11, 2014  Log10 TCID50/ml equi val ents   Oral Presentation Virology and Viral Diseases – PRRSV  O.096  Clinical characterization of a type 2 PRRSV causing significant clinical disease in the field in Denmark  LE Larsen1, LK Kvisgaard1, CK Hjulsager1, A Bøtner2, PH Rathkjen3, PMH Heegaard1, NP Bisgaard4, M S. Hansen1, J Nielsen2 1National Veterinary Institute, Technical University of Denmark, Denmark, 2National Veterinary Institute, Technical University of Denmark, Lindholm, Denmark, 3Boehringer Ingelheim Danmark A/S, Copenhagen, Denmark, 4Danvet, Hobro, Denmark,  lael@vet.dtu.dk   Introduction PRRSV is the cause of significant reproductive and respiratory disease in swine worldwide. In Denmark, approximately 50 % of the herds are seropositive for PRRSV of either or both Type 1 or Type 2. In November 2010, a pig herd in the Northern part of Denmark experienced an outbreak with Type 2 PRRSV where the clinical impact appeared to be much more severe than PRRSV was detected by real-time RT-PCR in all pigs inoculated (figure 1). The viremia peaked at DPI 7, and was significantly lower and of much shorter duration in the vaccinated group (group 4) compared to the unvaccinated animals (p= 0.04). Histopathology results are pending and will be presented. usually reported from Danish Type 2 PRRSV affected herds. Due to the clinical observations of reproductive failure (stillborn & mummified) in sows and high mortality in piglets, it was speculated that a new, more pathogenic PRRSV strain had evolved in Denmark. The aim of this study was: 1) to make a clinical characterization of the virus isolated from the herd by comparing the infection dynamics of the virus isolated from the herd with an older Danish Type 2 isolate (DK- 4 Serum Mean ± SD  3  2  1  0 -24  -20  -16  -12   -8    -4     0     4     8    12   16   20   24   28 DPI -1 Control group (Gr.1) DK-1997-19407B (Gr.2)         DK-2010-10-13-1 (Gr. 3) Vaccinated group (Gr.4) 2010-10-13-1) by experimental infection in young pigs and 2) to assess the protective effect of a MLV Type 2 vaccine  against  this  recent  Danish  Type  2  PRRSV isolate.  Materials and Methods Samples from the PRRS clinical case collected in Nov 2010 were obtained and the virus, designated DK-2010- 10-13-1, was isolated in Marc-145 cells using general cell culture procedures and sequenced in full. Twenty- eight 4-week-old pigs from a commercial farm with health status according to the Danish Specific Pathogen Free (SPF) system were randomly divided into one control group N=4 (group 1) and three experimental groups (groups 2-4) (N=8). The groups were housed in separate sections at biosafety 3 facility. Pigs in group 4 were vaccinated (2 ml i.m.) with Ingelvac® PRRS MLV vaccine (Boehringer Ingelheim Animal Health). Four weeks  later,  at  post  inoculation day  (DPI)  0,  pigs  in group 1 were sham- inoculated intranasally (i.n.) with Eagle’s MEM. Pigs in group 2 and group 3 were inoculated i.n. with DK-1997-19407B and DK-2010-10- 13-1 isolates respectively. Pigs in group 4 were challenged with the DK-2010-10-13-1. The study was carried out in accordance with the Danish and EU regulations on the use of laboratory animals for research. Individual daily clinical scoring and individual rectal temps  were  recorded.  Blood  samples  were  collected from all pigs on DPI -28, 0, 3, 7, 10, 14, 21, 28, and 30 for PRRS RT-PCR and serology. Samples were collected from lungs at necropsy for histopathology and virus quantification by RT-PCR. Results All pigs remained healthy throughout the experimental period. At necropsy, only minor lesions were revealed. Figure 1. Viral load in serum quantified by real-time RT-PCR  Conclusions and Discussion PRRSV isolated from a herd experiencing overt clinical signs and significant mortalities, failed to induce comparable signs in this experimental set-up but if the reproductive infection model have been used the signs may have been more like the signs seen in the herd. Full genome  sequencing  of  the  isolate  revealed  that  the isolate was very similar to other Danish Type 2 isolates. Our data suggested that the severity of the disease in the field could be influenced by other factors than the virus and emphasize the need to aim further research for identifying virulence markers of PRRSV. In addition, the results demonstrated that vaccination with Ingelvac® PRRS MLV vaccine (Boehringer Ingelheim Animal Health) reduced viremia and viral excretion, thus being effective of limiting the impact of the DK-2010-10-13-1 case virus and as such would be expected to be effective in  the  control  of  an  outbreak  with  this  and  related viruses.  These  findings  are  in  accordance  with  the finding  that  the  vaccine  was  used  effectively  in  the control of the infected herd.  Acknowledgement The study was supported in part by EU Grant n° 245141 (New tools and approaches to control Porcine Reproductive and Respiratory Syndrome in the EU and Asia (PoRRSCon) coordinated by Prof. H. Nauwynck. 

Clinical characterization of a type 2 PRRSV causing significant clinical disease in the field in Denmark

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Clinical characterization of a type 2 PRRSV causing significant clinical disease in the field in Denmark

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