Primary Isolation of Viruses

Abstract

Despite the increasing availability of viral antigen and nucleic acid tests, culture methods remain important, especially in the hospital setting. This chapter focuses on the isolation methods currently used in routine clinical laboratories. Recent innovations in monolayer cell culture include the use of mixtures of two or three different cell lines and genetically altered cells to enhance sensitivity or facilitate detection of virus infection. The materials needed for the isolation of viruses in cell culture are those necessary for the safe handling and inoculation of cell cultures, maintenance and observation of cell cultures, and preservation and storage of clinical specimens and virus isolates. Virus-induced cytopathic effect (CPE) must be distinguished from nonspecific CPE caused by toxicity of specimens, contamination with bacteria or fungi, or old cells. The rapid diagnosis of viral infections is important in patient management. One of the most significant contributions to rapid diagnosis in the clinical laboratory has been the application of centrifugation cultures to viral diagnosis. To get the best results from primary isolation in cell culture, healthy cell cultures susceptible to a spectrum of viruses are essential. In addition, conventional culture should be used for lower respiratory tract and tissue biopsy samples to detect additional or unsuspected viruses. While molecular methods are essential for optimal detection of viruses in spinal fluid and to monitor viral load in blood, virus isolation continues to play an important role in viral diagnosis and patient management, especially when performed locally.