Serologic response of roosters to gradient dosage levels of a commercially available live F strain-derived Mycoplasma gallisepticum vaccine over time.
Spray application is a commonly used, time- and labor-efficient means to deliver live Mycoplasma gallisepticum (MG) vaccine to laying hens in commercial production facilities. The dosage of vaccine received by spray-vaccinated birds can vary due to variation in the spray plume and the vaccine suspension droplet trajectory. In this study, a total of 48 Hy-Line W-36 males were placed individually in isolation units following eye-drop application of gradient levels (1 x, 10(-1) x, 10(-2) x, 10(-3) x, 10(-4) x, 10(-5) x, 10(-6) x, and unvaccinated control) of the MG vaccine. The determined titer associated with a 1 x dose was 2 x 10(6) colony-forming units/dose. Serologic response was assessed weekly following vaccination via serum plate agglutination (SPA) for weeks one through seven postvaccination (p.v.). In addition, immunologic response was assessed at 5, 6, and 7 wk p.v. via MG enzyme-linked immunosorbent assay (ELISA). As indicated by SPA analyses, a 1 x dose of vaccine resulted in 100% seroconversion, and dose levels of 10(-1) x and 10(-2) x resulted in 75% and 37.5% seroconversion, respectively, at 6 wk p.v. The MG ELISA results at 6 wk p.v. demonstrated immunologic responses in 100%, 57.1%, and 28.6% of the 1 x, 10(-1) x, and 10(-2) x dosed birds, respectively. The lower dosage levels of 10(-3) x, 10(-4) x, 10(-5) x, and 10(-6) x did not elicit a response from any bird at 6 wk p.v. Utilizing the SPA data, a logistic regression model was used to determine the relationship between dosage level and seroconversion rate (R2 = 0.999 with a standard error of prediction of 1.6%). The model predicted a required effective dosage of 0.26 x for 90% seroconversion at 6 wk p.v. under test conditions.
USDA-ARS Poultry Research Unit, P.O. Box 5367, Mississippi State, MS 39762, USA. joseph.purswell@ars.usda.gov
J L
JL
Purswell
J D
JD
Evans
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SL
Branton
D000336:Aerosols / Q000008:administration & dosage; D000372:Agglutination Tests / Q000662:veterinary; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D002645:Chickens; D004306:Dose-Response Relationship, Immunologic; D004333:Drug Administration Routes; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D008297:Male; D009175:Mycoplasma Infections / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D045686:Mycoplasma gallisepticum / Q000276:immunology*; D011201:Poultry Diseases / Q000382:microbiology / Q000517:prevention & control*
D000336:Aerosols; D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines