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The influence of incubation time on adenovirus quantitation in A549 cells by most probable number
Citation:
Cashdollar, J., E. Huff, H. Ryu, AND A. Grimm. The influence of incubation time on adenovirus quantitation in A549 cells by most probable number. JOURNAL OF VIROLOGICAL METHODS. Elsevier Science Ltd, New York, NY, 237:200-203, (2016).
Impact/Purpose:
The detection of adenovirus by cell culture improved when the incubation time was increased from two weeks to three weeks. This is an important consideration when using a culture assay to determine adenovirus concentration, particularly for samples with low concentrations of virus.
Description:
Cell culture based assays used to detect waterborne viruses typically call for incubating the sample for at least two weeks in order to ensure that all the culturable virus present is detected. Historically, this estimate was based, at least in part, on the length of time used for detecting poliovirus. In this study, we have examined A549 cells infected with human adenovirus type 2, and have found that a three week incubation of virus infected cells results in a higher number of detected viruses by quantal assay than what is seen after two weeks of incubation, with an average 955% increase in Most Probable Number (MPN) from 2 weeks to 3 weeks. This increase suggests that the extended incubation time is essential for accurately estimating viral titer, particularly for slow-growing viruses, UV treated samples, or samples with low titers of virus. In addition, we found that for some UV-treated samples, there was no detectable MPN at 2 weeks, but after 3 weeks, MPN values were obtained. For UV-treated samples, the average increase in MPN from 2 weeks to 3 weeks was 1401%, while untreated samples averaged a change in MPN of 674%, leading us to believe that the UV-damaged viral DNA may be able to be repaired such that viral replication then occurs.
