Abstract
In this study, Marek’s disease(MD) vaccines including herpes virus of turkeys (HVT) vaccine, attenuated serotype 1 Marek’s disease virus (MDV) CVI988/Rispens vaccine and nonpathogenic serotype 2 MDV (SB1 strain) culture were used individually or jointly to immunize 1-day-old specific pathogen free (SPF) chickens at different doses, the immunized chickens were intradermally infected with 2000 plague forming unit (PFU) of duck embryo fibroblast (DEF) passaged SD2012-1, a very virulent Marek's disease virus. All chickens of the experiments and control chickens were observed daily throughout the entire experimental period to assess the vaccines efficacy and immunization dose against MDV SD2012-1 Strain. CVI988, CVI988+HVT and CVI988+SB1+HVT could partially protect immunized chickens against SD2012-1. CVI988+HVT and CVI988+SB1+HVT could provide more efficient protection than CVI988 at normal and high immunization dose. Excessive dilution of these vaccines could result in obvious decrease on protection against SD2012-1. In this study, 450 feather pulp samples collected from the dead or living chickens on Day 150 were detected to be MDV positive by polymerase chain reaction (PCR), and the positive rate of MDV was 100%.
Highlights
Marek's disease virus serotype-1(MDV-1), known as Gallid herpes virus 2 (GaHV-2), was an oncogenic poultry herpes virus, causing lymph proliferative and demyelinating disorder in infected chickens
In the 16 groups of challenged chickens the earliest death appeared on 42-45 days post challenge on chickens with sham vaccine, herpes virus of turkeys (HVT) and HVT+SB1 vaccine
We demonstrated the protective efficacy of Marek's Disease (MD) vaccine in different doses to protect against SD2012-1
Summary
Marek's disease virus serotype-1(MDV-1), known as Gallid herpes virus 2 (GaHV-2), was an oncogenic poultry herpes virus, causing lymph proliferative and demyelinating disorder in infected chickens. There are three kinds of MD vaccine strains including nonpathogenic herpes virus of turkeys (HVT) [6,7], known as Meleagrid herpes virus 1, nonpathogenic serotype 2 MDV (SB1) [8], known as Gallid herpes virus 3, and attenuated serotype 1 MDV (CVI988/Rispens) [9]. These vaccine strains could be used as monovalent vaccines or mixed with each other as multivalent vaccines [10]. Studies had shown that higher vaccine dosages which had more plaque forming unit (PFU) per dose offered higher efficacy of vaccination [11,12]
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