马立克氏病双价苗的研究Ⅲ.双价苗与单价苗免疫效应的比较病理学研究

Studies of a Bivalent Vaccine against Marek's Disease——Ⅲ. Comparative Pathological Studies on the Efficacy of the Bivalent Vaccine and Monovalent Vaccine against Marek's Disease

选用SPF种蛋孵化的京白鸡60只,随机分为三组,即马立克氏病单价苗组(2000PFU HVT)、双价苗组(2000 PFU HVT+1200 PFU SB—1)以及攻毒对照组.应用组织学和透射电镜等手段对两种疫苗的免疫保护效应进行了比较病理学研究.结果证明,双价苗免疫鸡,MD发病数显著减少,发病时间推迟,病变程度明显减轻,法氏囊有大量具有分泌活性的浆细胞;单价苗免疫鸡发病数较对照组略有减少,但对延缓或减轻MD肿瘤的发生无明显作用,在法氏囊网状细胞胞浆中、核碎片附近和细胞间隙中存在大量无囊膜的马立克氏病病毒粒子,残存的细胞发生变性、坏死.由此认为,双价苗对实验性鸡马立克氏病的免疫效果明显优于HVT单价苗.

The studies were conducted on 60 Beijing White chickens hatched from SPF fer-tilized eggs. They were randomly divided into three groups of 20 each: monovalent vaccine group(2000 PFU HVT), bivalent vaccine group (2000 PFU HVT+1200 PFU SB-1) and controlgroup. The incidence of MD in the chickens vaccinated with bivalent vaccine has dropped consid-erably. Its onset was postponed and the severity of histopathological lesions alleviated distinctly.A lot of plasmacytes with secretory activity were noticed in bursae, which showed that the im-mune response has been activated. Although the incidence of MD in the monovalent vaccinegroup decreased somewhat slightly in comparison with the control, but this vaccine could notpostpone or alleviate the occurence of MD tumor significantly. Under electron microscope, agreat number of nonenveloped virions were found in the cytoplasm and nearby nucleous frag-ments of reticulocytes and in the intercellular spaces in bursae. There were degeneration andnecrosis in the surviving cells. All these mentioned above implied that the monovalent vaccinefailed to produce sufficient immunity against MD.