Application of mixed cell lines for the detection of viruses from clinical specimens

Abstract

Virus isolation usually requires specimen inoculation into a conventional cell culture tube and daily observation for cytopathic effect (CPE). This process can take from several days to weeks before the results are available. Direct viral antigen detection by staining clinical specimens with specific monoclonal antibodies (MAbs) has contributed enormously to patient management and institution of antiviral therapy. The shell vial technique which combines centrifugation with MAb staining has further reduced the time for virus detection. However, due to the limited optimum sensitivity of a single cell line preparation for different viral pathogens, several different cell lines along with primary monkey kidney (PMK) cells are often included for conventional tube or shell vial culture. This practice is both costly .and time consuming and the preparation of PMK cells may result in cells contaminated with endogenous viruses (1,2). Cost-containment has become a top priority in clinical laboratory practice. For a diagnostic virology laboratory to become cost-effective, use of a mixture of two cell lines in a single diagnostic unit can be a major contribution. If the mixed cell culture works properly, it will increase the number of cultivable viruses, reduce the requirement for multiple cell units, and thereby decrease reagent costs. Several factors determine whether or not a particular mixed-cell unit will perform as expected. The cells lines that are combined should (i) complement each other to broaden the range of viruses detected, (ii) be able to survive in a single unit without interference, (iii) maintain an expected ratio of cells throughout the usable period, and (iv) exhibit the same susceptibility of individual cells to viruses being cultured or even show a synergistic effect. In collaboration with Diagnostic Hybrids Inc. (Athens, OH), we have successfully produced several mixed cell cultures that meet these criteria.