2 Taxonomy of Retroviruses

Abstract

I. INTRODUCTION
Although the bulk of this text is concerned with the biology and molecular biology of the RNA tumor viruses, we consider here and, to some extent, in Chapters 6 and 8 the entire Retroviridae virus family. The family encompasses all viruses containing an RNA genome and an RNA-dependent DNA polymerase (reverse transcriptase) enzymic activity (Fenner 1975). The family is divided into three subfamilies: (1) Oncovirinae, including all the oncogenic members and many closely related nononcogenic viruses; (2) Lentivirinae, the “slow” viruses, such as visna virus; and (3) Spumavirinae, the “foamy” viruses that induce persistent infections without any clinical disease. The latter two subfamilies are generally given summary treatment in discussions on retroviruses and, therefore, we propose to present at least some of their salient features. The spumaviruses provide an excellent model system for chronic viral disease, whereas the lentiviruses are in the mystical realm of slow neurological diseases.

To some extent, a taxonomical description is, of necessity, a tedious job and relatively unimaginative, since the essence of the matter is covered in the chapters to follow. What we propose to do here is to cover the viruses isolated (or particles seen but without infectious transmission) in the different invertebrate and vertebrate genera. Obviously, much of the focus in later chapters is devoted to the viruses from the best-characterized systems: chickens, mice, cats, cattle, and monkeys. Therefore, the coverage here of the more familiar isolates may seem disproportionately small with respect to the plethora of available data; needless to...