Persistence of commercial modified live reovirus vaccines in chicks.
Four modified live reovirus vaccines were compared with a field isolate (81-176) of reovirus for safety in 1-day-old and 1-wk-old specific-pathogen-free chicks. At 1, 3, 5, and 7 wks after vaccination, blood, cloacal swabs, and hock tendon samples were collected and assayed for residual virus. Tendon samples were also examined microscopically and scored for histological changes. Vaccine efficacy was monitored by challenging chicks 7 wks postvaccination via the footpad with the 81-176 isolate. Serum samples were collected throughout the trials and assayed for reovirus antibodies using an enzyme-linked immunosorbent assay. In chicks vaccinated at 1 day of age, three of the four vaccine viruses were consistently recovered from the hock tendon tissues. Post-challenge virus recoveries were similarly positive for the same vaccine viruses. Histological lesion scores of the tendons paralleled the degree of virus recovery. In the chicks vaccinated at 1 wk old, none of the vaccine viruses were recovered, nor were tendon lesion scores substantially elevated. Following challenge, however, virus was recovered from all vaccinated groups.
Montgomery
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RD
College of Veterinary Medicine, Mississippi State, Mississippi 39762.
Maslin
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WR
D000367:Age Factors; D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis; D002645:Chickens / Q000382:microbiology*; D004797:Enzyme-Linked Immunosorbent Assay; D012087:Reoviridae / Q000276:immunology* / Q000302:isolation & purification; D013047:Specific Pathogen-Free Organisms; D013710:Tendons / Q000382:microbiology; D014611:Vaccination / Q000662:veterinary; D014613:Vaccines, Attenuated / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines