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

为预防马立克氏病病毒（MDV）引起的鸡马立克氏病（MD），火鸡疱疹病毒（HSV）单价疫苗已被广泛应用于鸡的免疫。然而，最近在接种疫苗的鸡中观察到由MDV极强毒力（vvMDV）引起的MD。本研究的最终目的是开发MD疫苗，如重组疫苗、多价疫苗或组分疫苗，以控制由vvMDV引起的MD暴发流行。1）构建了表达MDV A抗原的重组杆状病毒（rBV-A）。rBV-A感染草地贪夜蛾（Spodoptera frugiperda，Sf）细胞后，A抗原（A Ag）表达定位于细胞表面。用<35>抗A-Ag单克隆抗体免疫沉淀法，在rBV-A感染的细胞中检测到大量的A-Ag（58- 68 kDa），而在感染细胞的培养上清中检测到少量的A-Ag（46- 54 kDa）。重组A Ag与MDV感染鸡血清呈阳性反应。2）在MDV基因组上发现了编码单纯疱疹病毒糖蛋白B同源物（gB homolog）的基因。重组杆状病毒（rBV-B）感染Sf细胞后，用鸡或兔抗B血清和抗B抗原单克隆抗体进行免疫荧光检测，发现rBV-B在细胞质和细胞表面均有表达。表达的蛋白具有88/100、64和54 kDa三种分子大小。3）用抗鸡CD 4或CD 8单克隆抗体感染vvMDV。CD 8-耗竭的鸡同时发生神经增大和内脏肿瘤，而CD 4-耗竭的鸡仅显示神经增大。

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.