Cultivation and Assay of Animal Viruses

Abstract

During the last 50 years, virologists have been able to select cell cultures that are susceptible to many commonly encountered viruses and environmental virologists have developed methods to detect very low numbers of viruses in various environments. This chapter reviews these methods and their practical use and describes basic quality control procedures to maximize their level of sensitivity. The main objective of the cultivation and assay of viruses is to optimize detection methods to a level where even a single infectious unit can be detected with confidence. Several methods for detection of viruses in environmental samples have been described: visualization of the virus by microscopy, detection of viral antigens, detection of viral nucleic acids, and detection of viral infectivity. The detection of infective viruses in environmental samples still relies mainly on cell culture as the method of choice. There are several sources for cell cultures that can be used in virology. Plaque assay is used for a very limited number of viruses and has the lowest sensitivity of the available methods. The main advantages of plaque assay are that each individual virus (or aggregate) forms a single plaque and that each plaque is rarely a mixture of several virus types. Viruses isolated by cell culture can be propagated further in cell culture and identified by a variety of methods, including electron microscopy, serum neutralization, molecular methods, and immunoassays.