Preventive measures of Mark's desease (MD) vaccine break caused by very virulent MD virus.

为预防由马立克氏病病毒(MDV)引起的马立克氏病(MD)，火鸡疱疹病毒单价疫苗已在田间鸡群中广泛应用。然而，最近在接种疫苗的雏鸡中发现了由超强毒力MDV(VvMDV)引起的MD。本研究的最终目的是发展MD疫苗，如重组疫苗、多价疫苗或成分疫苗，以控制vvMDV引起的MD暴发。1)构建了表达MDV A抗原的重组杆状病毒(RBV-A)。在感染RBV-A的果蝇细胞中，A抗原(A-Ag)表达定位于细胞表面。用抗A-Ag的单抗免疫沉淀S标记的A-Ag，在感染细胞中检测到大量的A-Ag(58-68 kDa)，但在感染细胞的培养上清液中发现少量的A-Ag(46-54 kDa)。残留的A抗原与MDV感染鸡的血清发生反应。在A抗原免疫的鸡血清中，发现了与MDV感染细胞发生反应的MDV特异性抗体。2)在MDV基因组上发现了编码单纯疱疹病毒B糖蛋白同源基因。用鸡和兔的抗B抗体和B抗原的单抗进行免疫荧光试验，检测到编码MDV B基因同源物(RBV-B)的重组杆状病毒在感染RBV-B的SF细胞的胞浆和表面表达该蛋白。表达的蛋白分子大小分别为88/100、和54 kDa。3)免疫鸡胸腺后注射抗鸡CD8CD_4单抗感染vvMDV。CD8缺失的雏鸡同时出现神经增大和内脏肿瘤，而CD8缺失的雏鸡只表现出神经增大。

For prevention of Marek's disease (MD) caused by Marek's disease virus (MDV), monovalent vaccine of herpesvirus of turkey has been widely used for chickens in the field. Recently, however, MD caused by very virulent MDV (vvMDV) was observed in vaccinated chicknes. The final aim of the present study is to develop MD vaccine such as recombiant, polyvalent or component vaccine for controlling the outbreak of MD due to vvMDV. The following results were obtained.1) Arecombinant baculovirus expressing the A antigen (rBV-A) of MDV was constructed. In Spodoptera frugiperda (Sf) cells infectedwith the rBV-A, A antigen (A Ag) expression was localized to the cell surface. By immunoprecipitation of ^<35>S labelled A Ag with a monoclonal antibody to A Ag, a large amount of the A Ag(58-68kDa) was dtected of the rBV-A infected cells but a small amount of the antigen (46-54kDa) was found in the culture supenatant of infected cells. The reconminant A Ag was shown to be reactive with sera of MDV-infected chickens. In sera of chickens immunized with the A Ag, MDV-specific antibody reactive with MDV-infected cells was found.2) A gene encoding a homolog of glycoprotein B of herpes simplex virus (gB homolog) has been identified on the MDV genome. The recombinant baculovirus encoding the gB homolog (rBV-B) of MDV expressed the protein in the cytoplasm and on the surface of Sf cells infected with the rBV-B, when examined by immunofluorescent assay using anti-B sera from chickens or rabbits, and monoclonal antibody against B antigen. The expressed protein had three molecular sized (88/100, 64 and 54kDa).3) Chicks thymectomized and injected with either monoclonal antibody to chicken CD4 of CD8 were infected with vvMDV. The CD8-depleed chcks developed both nerve enlargement and visceral tumor, whereas the CD4-depleted chicks showed only nerve enlargement.