title: Elevated dietary zinc oxide levels do not have a substantial effect on porcine reproductive and respiratory syndrome virus (PPRSV) vaccination and infection.
abstract: BACKGROUND
  Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important infectious agents for the swine industry worldwide. Zinc (Zn) salts, which are widely used as a dietary supplement in swine nutrition, have shown antiviral effects in vitro as well as in vivo. The purpose of this study was to determine the influence of dietary zinc oxide supplementation on vaccination and challenge infection with PRRSV.
  
  
  RESULTS
  The clinical course of PRRS and the success of vaccination with an experimental inactivated vaccine were compared between animals receiving a conventional diet (50 ppm Zn, control group) and diets supplemented with Zn oxide (ZnO) at final Zn concentrations of 150 or 2,500 ppm. Pigs receiving higher dietary Zn levels showed a tendency towards higher neutralizing antibody levels after infection, while dietary Zn levels did not substantially influence the number of antiviral IFN-gamma secreting cells (IFN-gamma-SC) or percentages of blood immune cell subsets after infection. Finally, feeding higher dietary Zn levels reduced neither clinical symptoms nor viral loads.
  
  
  CONCLUSIONS
  Our results suggest that higher levels of dietary ZnO do not have the potential to stimulate or modulate systemic immune responses after vaccination and heterologous PRRSV infection to an extent that could improve the clinical and virological outcome.
authors.forename: Weidong
authors.initials: W
authors.lastname: Chai
authors.forename: Zhenya
authors.initials: Z
authors.lastname: Wang
authors.forename: Pawel
authors.initials: P
authors.lastname: Janczyk
authors.forename: Sven
authors.initials: S
authors.lastname: Twardziok
authors.forename: Ulrike
authors.initials: U
authors.lastname: Blohm
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Osterrieder
authors.affiliation: Institut für Virologie, Freie Universität Berlin, Robert-von-Ostertag-Str, 7-13, 14163 Berlin, Germany. burwinkelm@rki.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Burwinkel
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D001831:Body Temperature; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D008297:Male; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology* / Q000517:prevention & control / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000276:immunology*; D013552:Swine; D014611:Vaccination; D019562:Viral Load; D014765:Viral Vaccines / Q000276:immunology; D015034:Zinc Oxide / Q000008:administration & dosage*
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D014765:Viral Vaccines; D015034:Zinc Oxide
references.citation: Vet J. 2008 Sep;177(3):345-51
references.pmid: 17644436
references.citation: Vaccine. 2009 Jun 8;27(28):3704-18
references.pmid: 19464553
references.citation: Vet Res. 2012 Apr 19;43:30
references.pmid: 22515169
references.citation: Vet Res. 2009 Nov-Dec;40(6):63
references.pmid: 19674539
references.citation: PLoS Pathog. 2010 Nov 04;6(11):e1001176
references.pmid: 21079686
references.citation: Vaccine. 2011 May 23;29(23):4058-66
references.pmid: 21419162
references.citation: Br J Nutr. 2011 Jun;105(11):1592-600
references.pmid: 21477404
references.citation: Vet Microbiol. 2012 Dec 7;160(3-4):468-72
references.pmid: 22818659
references.citation: Virol J. 2012 Feb 16;9:45
references.pmid: 22340040
references.citation: Res Vet Sci. 1998 May-Jun;64(3):225-31
references.pmid: 9690608
references.citation: Vaccine. 2011 Oct 26;29(46):8192-204
references.pmid: 21925560
references.citation: J Vet Diagn Invest. 2005 Mar;17(2):165-70
references.pmid: 15825498
references.citation: PLoS One. 2014 Jan 28;9(1):e87007
references.pmid: 24489827