title: Impact of maternally derived immunity on piglets' immune response and protection against porcine circovirus type 2 (PCV2) after vaccination against PCV2 at different age.
abstract: BACKGROUND
  This study was aimed at evaluating the clinical protection, the level of Porcine circovirus type 2 (PCV2) viremia and the immune response (antibodies and IFN-γ secreting cells (SC)) in piglets derived from PCV2 vaccinated sows and themselves vaccinated against PCV2 at different age, namely at 4, 6 and 8 weeks. The cohort study has been carried out over three subsequent production cycles (replicates). At the start/enrolment, 46 gilts were considered at first mating, bled and vaccinated. At the first, second and third farrowing, dams were bled and re-vaccinated at the subsequent mating after weaning piglets. Overall 400 piglets at each farrowing (first, second and third) were randomly allocated in three different groups (100 piglets/group) based on the timing of vaccination (4, 6 or 8 weeks of age). A fourth group was kept non-vaccinated (controls). Piglets were vaccinated intramuscularly with one dose (2 mL) of a commercial PCV2a-based subunit vaccine (Porcilis® PCV). Twenty animals per group were bled at weaning and from vaccination to slaughter every 4 weeks for the detection of PCV2 viremia, humoral and cell-mediated immune responses. Clinical signs and individual treatments (morbidity), mortality, and body weight of all piglets were recorded.
  
  
  RESULTS
  All vaccination schemes (4, 6 and 8 weeks of age) were able to induce an antibody response and IFN-γ SC. The highest clinical and virological protection sustained by immune reactivity was observed in pigs vaccinated at 6 weeks of age. Overall, repeated PCV2 vaccination in sows at mating and the subsequent higher levels of maternally derived antibodies did not significantly interfere with the induction of both humoral and cell-mediated immunity in their piglets after vaccination.
  
  
  CONCLUSIONS
  The combination of vaccination in sows at mating and in piglets at 6 weeks of age was more effective for controlling PCV2 natural infection, than other vaccination schemas, thus sustaining that some interference of MDA with the induction of an efficient immune response could be considered. In conclusion, optimal vaccination strategy needs to balance the levels of passive immunity, the management practices and timing of infection.
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy. paolo.martelli@unipr.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Martelli
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Saleri
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Ferrarini
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: De Angelis
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Cavalli
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Benetti
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Ferrari
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Canelli
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna (IZSLER), Via Pitagora, 2-42100, Reggio, Emilia, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Bonilauri
authors.affiliation: Veterinary Practitioner, 46100, Mantua, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Arioli
authors.affiliation: Veterinary Practitioner, 46100, Mantua, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Caleffi
authors.affiliation: Swine Clinic, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, CH-3012, Bern, Switzerland.
authors.forename: Heiko
authors.initials: H
authors.lastname: Nathues
authors.affiliation: Department of Veterinary Science, University of Parma, Via del Taglio, 10 - 43126, Parma, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Borghetti
mesh_terms: D000375:Aging / Q000276:immunology; D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis / Q000276:immunology; D001835:Body Weight; D018173:Circoviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D017925:Circovirus / Q000276:immunology*; D004311:Double-Blind Method; D005260:Female; D007111:Immunity, Cellular; D007112:Immunity, Maternally-Acquired; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D013552:Swine; D013553:Swine Diseases / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D014765:Viral Vaccines; D007371:Interferon-gamma
keywords: Immune response; Porcine circovirus type 2 (PCV2); Protection; Vaccine efficacy