4 Attachment, Ejection and Penetration Stages of the RNA Phage Infectious Process

Abstract

INTRODUCTION
It is perhaps ironical, in view of our present level of understanding of the RNA phage replicative processes, that the molecular mechanisms involved in the adsorption and penetration stages of RNA phage infection are relatively poorly understood. This irony becomes even more acute when it is realized that the total sequence analysis of all the structural components of the phage is almost at hand, and that the synthesis and assembly of infectious particles in cell-free systems is on the edge of becoming a reality.

Early efforts to study the RNA phage attachment and penetration processes were seriously hindered by an inexplicable lack of experimental reproducibility, which seemed to be an inherent aspect of the RNA phage-host system, and the problem that only 5–10% of phage populations were infectious. This suggested that the adsorption and penetration stages of the RNA phage system might be different from those of the other phage systems known at that time. It was therefore not surprising when Crawford and Gesteland (1964) demonstrated that RNA phages do not adsorb directly to the bacterial cell wall, as do most other known bacteriophages, but to long filamentous structures now known as F pili. Other investigators (Brinton, Gemski and Carnahan 1964) quickly confirmed this finding, and it soon became evident that the frustrating experimental irreproducibility that had been experienced earlier had been due to the extreme fragility of these structures towards such procedures as the vigorous aeration of bacterial cultures or the routine washing of bacterial cells. Unfortunately,...