Effect of thimerosal concentration on the efficacy of inactivated Newcastle disease oil-emulsion vaccines.
Different quantities of the preservative thimerosal in inactivated Newcastle disease oil-emulsion vaccines were tested to determine the influence on the hemagglutination-inhibition (HI) response of broilers. The effect of thimerosal was measured in vaccines that had been stored for 1, 21, and 52 weeks; HI serology was conducted at 2, 4, and 6 weeks after vaccination. Mean HI titers 4 weeks after vaccination decreased at a significant rate (P less than or equal to 0.001) with increasing concentrations of thimerosal. HI titers 4 weeks after vaccination with 1-week-old vaccine were significantly (P less than or equal to 0.05) higher than those after vaccination with 52-week-old vaccine at all thimerosal concentrations tested. Titers were also significantly higher (P less than or equal to 0.05) after vaccination with 1-week-old vaccine than after vaccination with 21-week-old vaccine at all thimerosal concentrations below about 8.25 mg/ml of antigen. Thimerosal at the levels recommended in commercial vaccines does not significantly decrease vaccine efficacy.
D000818:Animals; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D004355:Drug Stability; D004655:Emulsions; D005035:Ethylmercury Compounds / Q000627:therapeutic use*; D006385:Hemagglutination Inhibition Tests; D007167:Immunotherapy; D009521:Newcastle Disease / Q000276:immunology*; D009821:Oils; D013849:Thimerosal / Q000008:administration & dosage / Q000627:therapeutic use*; D013997:Time Factors; D014612:Vaccines / Q000008:administration & dosage*
D004655:Emulsions; D005035:Ethylmercury Compounds; D009821:Oils; D014612:Vaccines; D013849:Thimerosal