Modification of PCV-2 virulence by substitution of the genogroup motif of the capsid protein

Allemandou, Aude; Grasland, Béatrice; Hernandez-Nignol, Anne-Cécile; Kéranflec'h, André; Cariolet, Roland; Jestin, André

Forty piglets were separated into six groups. Two groups of four piglets (groups 1 and 2) were assigned as controls and housed in the same room but in separate units. The four other groups (groups 3, 4, 5 and 6) were composed of eight piglets each and located in four separate rooms. Piglets of each group received 400 μg of DNA from the parental or mutant DNA clones by intramuscular (IM) route in both sides of the neck. All piglets, except those in group 1, were immunostimulated at 3 days post transfection (dpt) with 1.8 mg of keyhole limpet hemocyanin (KLH) (Sigma Aldrich) and at 8 dpt with 0.9 mg of KLH (Sigma Aldrich) emulsified in incomplete Freund's adjuvant (Sigma Aldrich) in four injections (both sides of the neck and hips) by IM route. Rectal temperatures and clinical signs were recorded daily and weights weekly. Blood samples were taken before DNA inoculation and every week throughout the trial. All the piglets were euthanized in the 5 th week post-transfection by anesthesia followed by exsanguination. Necropsies were performed and tissue samples (tracheobronchial, mesenteric, axillary and inguinal lymph nodes; tonsils, lung, spleen, liver and ileum) were collected and stored at -80°C for laboratory investigations or in formol for histopathology.