Feather tip monitoring of Marek’s disease virus in experimental and commercial settings

Date
2010
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University of Delaware
Abstract
Marek’s disease (MD) is a lymphoproliferative disorder in chickens caused by an alphaherpesvirus, Marek’s disease virus (MDV). MD has been controlled successfully for a half-century by vaccination with various non-oncogenic related viruses, but outbreaks still occur. Field monitoring of MDV vaccine and challenge strains has potential utility for both commercial producers and researchers. Feather tip sampling offers the possibility of measuring virus loads in field settings in a non-invasive manner. To assess the potential of feather tip monitoring, end-point and qPCR were used to evaluate the presence of vaccine and challenge viruses under both experimental and commercial settings. Using a controlled experimental environment, levels of vaccine and challenge virus were determined in chickens that were vaccinated with herpesvirus of turkeys (HVT; monovalent), HVT + SB-1 (bivalent), or HVT + SB-1 + CVI988 (trivalent). Half of the vaccinated chickens were challenged with the T. King very virulent plus (vv+) strain of MDV, and the other half were left unchallenged. In general, differences in virus loads were observed early in life; i.e., during the first three weeks, but were not evident later when all viruses were present in feather tips and infections became more complex. Also, in general, qPCR confirmed end-point PCR results in almost every instance, indicating that end-point PCR is adequate for feather tip monitoring.
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