Domingo E
Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas, Universidad Autonoma de Madrid, Cantoblanco, Spain.
Clin Diagn Virol. 1998 Jul 15;10(2-3):97-101. doi: 10.1016/s0928-0197(98)00032-4.
In the 1970s Manfred Eigen and colleagues proposed a new model of molecular evolution to explain adaptability and rapid evolution of simple replicons, as those that probably populated the earth at the onset of life. This model of evolution placed emphasis on mutant generation, to the point of invalidating the concept of wild-type genomes as a defined sequence of nucleotides. In striking similarity with the proposals for such early replicons, present-day RNA viruses consist of complex distributions of nonidentical but closely related genomes termed quasispecies.
To discuss indeterminations inherent to a quasispecies structure and to the analytical procedures to define it, biological implications of quasispecies, and the need to take into account this type of population structure, in order to design effective strategies to prevent and control diseases caused by highly variable viruses.
Quasispecies have many biological implications, extending from viral pathogenesis to the emergence of new pathogens, rapid antigenic variation, and alterations in cell tropism, virulence, host range and viral gene expression.
Diseases caused by highly variable RNA viruses prove very difficult to control and vaccine development against such viruses are largely unsuccessful. It is important to understand quasispecies composition and dynamics, as quasispecies are an important step in the natural history of RNA viruses.
20世纪70年代，曼弗雷德·艾根及其同事提出了一种新的分子进化模型，以解释简单复制子的适应性和快速进化，这些复制子可能在生命起源时就已遍布地球。这种进化模型强调突变产生，甚至使野生型基因组作为特定核苷酸序列的概念失效。与早期复制子的提议惊人相似的是，当今的RNA病毒由称为准种的非同一但密切相关的基因组的复杂分布组成。
讨论准种结构及其定义分析程序所固有的不确定性、准种的生物学意义，以及考虑这种种群结构类型以设计有效策略来预防和控制由高度可变病毒引起的疾病的必要性。
准种具有许多生物学意义，从病毒发病机制到新病原体的出现、快速抗原变异以及细胞嗜性、毒力、宿主范围和病毒基因表达的改变。
由高度可变的RNA病毒引起的疾病极难控制，针对此类病毒的疫苗开发大多不成功。了解准种组成和动态很重要，因为准种是RNA病毒自然史中的重要一步。
