Studies on the mechanisms of persistent infection and reactivation of animal viruses.

在持续感染中，病毒可以隐藏在体内，逃脱免疫压力，尽管存在免疫。然而，病毒有时会被重新激活，在宿主体内产生疾病。1.利用人T淋巴细胞系(MOLT-4)建立了猫免疫缺陷病毒(FIV)持续感染的体外模型。在感染的MOLT-4细胞中未检测到FIV特异性RNA的表达，表明病毒复制在病毒生命周期的早期阶段被阻断。此外，用佛波酯(TPA)处理感染的MOLT-4细胞可以拯救感染性病毒。2.实验观察了3只感染FIV A亚型(Petala株)和B亚型(TM1和TM2株)的无特定病原体的猫8年以上。感染FIVA亚型的猫在感染后8年零8个月(P.I.)死亡，而感染FIVB亚型的猫则为st…超过9年的P.I.临床健康状况更差在鸡马立克氏病病毒持续感染过程中，不同亚型间的致病性差异和动物所处的环境是导致艾滋病的重要因素。马立克氏病病毒在血清学和遗传学上可分为3个血清型，均可引起鸡的持续感染。MDV-1是致癌的，而MDV-2是非致癌的。为了从基因水平上了解MDV-2持续感染和致癌的机制，我们对MDV-2基因组进行了90%以上的测序。4.疱疹病毒的即刻早期(IE)基因产物被认为在调节潜伏感染中发挥着重要作用。我们证明了猫疱疹病毒1型(FHV-1)产生一个编码FHV-1ICP4的即刻早期(IE)转录本，并且FHV-1ICP4基因由两个启动子交替调节。进一步的研究表明，在两个启动子之间存在一个由20个碱基组成的负调控元件。5.建立了CDV柳中株持续感染的B95a细胞系。从该载体培养物中回收的病毒对新鲜的B95a细胞具有感染性，并可持续感染而不表现出CPE。该病毒被命名为柳中-BP株。免疫沉淀结果显示，YANAKA和YANAKA-BP株的H或F蛋白分子量相同。对F基因的序列分析表明，YANAKA-BP株缺少被认为是Onderstepoort F基因体外翻译所需的第三个框内ATG三联体。较少

In persistent infection, virus can hidden in body and escape from immunological pressure, in spite of the presence of immunity. However, the virus is sometimes reactivated to produce diseases in host. Following results were obtained.1.We established an in vitro model for a persistent infection of feline immunodeficiency virus (FIV) using a human T-lymphoid cell line (MOLT-4). FIV-specific RNA expression could not be detected in the infected MOLT-4 cells, suggesting that the viral replication was blocked in the early stage of virus life-cycle. Furthemore, it was demonstrated that infectious virus was rescued by treatment of the infected MOLT-4 cells with a phorbol ester (TPA).2.Three specific pathogen-free cats experimentally infected with FIV subtypes A (Petaluma strain) and B (TM1 and TM2 strains) respectively were observed for over 8 years. The cat infected with FIV subtype A died with hemoperitoneum at 8 years and 8 months post-infection (p.i.), while those with FIV subtype B are st … More ill clinically healthy over 9 years p.i.. In persistent infection of FIV,the difference of pathogenicity among subtypes and the environment where animals kept were suggested to be important factors to develop AIDS.3.Marek's disease virus (MDV) can be serologically and genetically devided into 3 serotypes and all cause persistent infection in chickens. MDV-1 is oncogenic whereas MDV-2 is non-oncogenic. To understand the mechanisms of persistent infection and oncogenicity at genetic levels, we sequenced over 90% of MDV-2 genome.4.The immediate-early (IE) gene products of herpesviruses are thought to play an important role in regulating latent infection. We demonstrated that feline herpesvirus type 1 (FHV-1) produced a single immediate-early (IE) transcript encoding FHV-1 ICP4 and that FHV-1 ICP4 gene was alternatively regulated by the two promoters. Furthermore, it was shown that a negative regulatory element, which was composed of a 20 bp direct repeat unit, was located between the two promoters.5.A persistently infected B95a cell line with the Yanaka strain of CDV was established. The virus recovered from this carrier culture has infectivity to fresh B95a cells, and causes persistent infection without showing CPE.This virus was designated as the Yanaka-BP strain. Immunoprecipitation revealed identical molecular mass of the H or F proteins of the Yanaka and Yanaka-BP strains. Sequence analysis of the F gene showed that the third in-frame ATG triplet which considered to be selectively required for in vitro translation of the Onderstepoort F gene was lacked in the Yanaka-BP strain. Less