Islam Tanzila, Renz Katrin G, Walkden-Brown Stephen W, Ralapanawe Sithara
Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.
Avian Dis. 2013 Jun;57(2 Suppl):454-63. doi: 10.1637/10341-083112-Reg.1.
Probably the most effective current vaccine against Marek's disease is the live Rispens (CVI988) attenuated serotype 1 Marek's disease virus (MDV). It is unknown whether the currently available Rispens vaccines transmit effectively between chickens. To investigate the kinetics and shedding of three commercially available strains of this virus and the extent of lateral transmission, we measured the shedding rate in dander and the viral load in peripheral blood lymphocytes (PBLs) and feather tips over time. Four identical climate-controlled rooms were stocked with a total of 70 specific-pathogen-free chickens for 56 days. In each of three rooms, 10 chickens were vaccinated with one of the commercial vaccines at day old and left in contact with 10 unvaccinated chickens. The fourth room contained 10 unvaccinated control chickens. As determined by MDV-specific quantitative real-time polymerase chain reaction of weekly room dust and individual PBLs and feather tip samples, the vaccine virus was shed from the vaccinated chickens in dander from day 7 postvaccination and transmitted effectively from vaccinated to in-contact chickens with a lag period of 2-3 wk. Viral load in PBLs and feather tips peaked at days 7 and 14, respectively, and declined thereafter, whereas viral load in dust increased rapidly to day 21 and then increased gradually thereafter. Antibody titer at day 56 was correlated with earlier measures of MDV load in PBLs but not feather tips or dust. These results show that currently available Rispens CVI988 vaccine virus is shed in significant quantities from vaccinated chickens and transmits effectively between chickens.
目前预防马立克氏病最有效的疫苗可能是活的Rispens（CVI988）1型马立克氏病病毒（MDV）减毒株。目前可用的Rispens疫苗在鸡之间能否有效传播尚不清楚。为了研究该病毒三种市售毒株的动力学、排毒情况及横向传播程度，我们测定了皮屑中的排毒率以及外周血淋巴细胞（PBL）和羽毛尖端的病毒载量随时间的变化。四个相同的气候控制房间共饲养70只无特定病原体的鸡，为期56天。在三个房间中，每个房间有10只鸡在一日龄时接种一种市售疫苗，并与10只未接种疫苗的鸡接触。第四个房间饲养10只未接种疫苗的对照鸡。通过对每周房间灰尘以及单个PBL和羽毛尖端样本进行MDV特异性定量实时聚合酶链反应测定，疫苗病毒在接种疫苗的鸡接种后第7天开始从皮屑中排出，并在2至3周的滞后期后从接种疫苗的鸡有效传播至接触鸡。PBL和羽毛尖端的病毒载量分别在第7天和第14天达到峰值，之后下降，而灰尘中的病毒载量在第21天迅速增加，此后逐渐增加。第56天的抗体滴度与PBL中MDV载量的早期测量值相关，但与羽毛尖端或灰尘中的无关。这些结果表明，目前可用的Rispens CVI988疫苗病毒从接种疫苗的鸡中大量排出，并在鸡之间有效传播。
