I have attempted to illustrate the many different properties of retroviruses and their presence in a wide variety of animal species including humans. Since the turn of this century, progress in the field of retrovirology has been noteworthy and many new and important scientific observations have been made (Table 7). Along the way, certain dogmas were replaced with new tenets. The recent recognition of retroviruses associated with human cancer and immunodeficiency places them into consideration as potential agents responsible for other human diseases such as autoimmunity and multiple sclerosis. Not only can retroviruses be oncogenic or cytopathic agents but they can also exist highly conserved as endogenous genes in the chromosomal DNA of many different species and not cause disease. In fact, this latter group appears to be predominant, suggesting their role in normal developmental processes and as progenitors of the pathogenic types. The virus-like genomes recognized in Drosophila and other lower animal species could be examples of this fact and may represent important biological entities throughout nature. The genetic material of retroviruses resembles transposons and may reflect the ability of these viruses to be passed within the host and to affect the evolutionary pathway. They could, as transposable elements, be transmitted as well to many different animal species. By their ability to move within the genetic machinery of the cell, these viruses could influence development in animals through promotion, enhancement, or suppression of specific cellular genes. This idea has been proposed for the noninfectious type A particles that have been observed to show these effects in cultured cells. One important observation is that the effect of retroviruses on cells has a varied pattern which may be emphasized by one group (e.g., vacuolization by foamy virus) or shared by other groups (e.g.., syncytial cell formation by type C and type D oncovirinae, spumavirinae, and lentivirinae) (Table 6). Moreover, the heterogeneity of the lentiviruses and the transduction of normal cellular genes by many of the oncogenic viruses indicate the changes that can occur as retroviruses infect and replicate within the cell. The overview is very informative. Virus-cell interaction can lead to biological expressions that depend on the phenotype of the cell and the viral genetic structure. Throughout its existence in nature the retrovirus has been evolving, conserving certain features while developing new ones with different properties; it clearly emerges as a multifaceted agent.
我试图阐述逆转录病毒的多种不同特性，以及它们在包括人类在内的多种动物物种中的存在情况。自本世纪初以来，逆转录病毒学领域取得了显著进展，有许多新的重要科学发现（表7）。在此过程中，某些教条被新的原则所取代。最近对与人类癌症和免疫缺陷相关的逆转录病毒的认识，使它们被视为可能导致自身免疫和多发性硬化症等其他人类疾病的潜在病原体。逆转录病毒不仅可以是致癌或致细胞病变的病原体，它们还可以作为高度保守的内源基因存在于许多不同物种的染色体DNA中，而不引发疾病。事实上，后一组似乎占主导地位，这表明它们在正常发育过程中的作用以及作为致病类型的前身。在果蝇和其他低等动物物种中识别出的病毒样基因组可能就是这一事实的例证，并且可能代表了自然界中重要的生物实体。逆转录病毒的遗传物质类似于转座子，可能反映了这些病毒在宿主内传递并影响进化途径的能力。它们作为转座元件，也可以传播到许多不同的动物物种。通过它们在细胞遗传机制内移动的能力，这些病毒可以通过促进、增强或抑制特定细胞基因来影响动物的发育。对于在培养细胞中已观察到显示这些效应的非感染性A型颗粒，人们已提出了这一观点。一项重要的观察结果是，逆转录病毒对细胞的影响具有多种模式，其中一种模式可能在某一组中较为突出（例如，泡沫病毒导致空泡化），或者为其他组所共有（例如，C型和D型肿瘤病毒亚科、泡沫病毒亚科和慢病毒亚科导致合胞体细胞形成）（表6）。此外，慢病毒的异质性以及许多致癌病毒对正常细胞基因的转导表明，逆转录病毒在细胞内感染和复制时会发生各种变化。这一综述信息量很大。病毒与细胞的相互作用可以导致取决于细胞表型和病毒遗传结构的生物学表现。在其自然界的生存过程中，逆转录病毒一直在进化，保留某些特征的同时发展出具有不同特性的新特征；它显然是一种具有多面性的病原体。
