Detection of adeno- and lentiviral (HIV1) contaminations on laboratory surfaces as a tool for the surveillance of biosafety standards

A cautionary tale of cross-contamination among plasmids from commercial suppliers

Many researchers have switched to purchasing their desired plasmids from commercial suppliers to save time and resources, as we did for 17 high-risk human papillomavirus plasmids. To our surprise, they were shown to be cross-contaminated with one another. Comparison between the production schedule and the pattern of contaminations proved that this contamination occurred during the production process, which was also shown for another two sets of commercial plasmids. Our experience indicates that the absolute purity of plasmids obtained from external sources cannot be guaranteed. Extreme caution should be exercised, especially when such plasmids are used for human gene therapies and DNA vaccines, where even a minute amount of contamination may pose significant risks to patients.

Comparison of surface sampling methods for virus recovery from fomites

The role of fomites in infectious disease transmission relative to other exposure routes is difficult to discern due, in part, to the lack of information on the level and distribution of virus contamination on surfaces. Comparisons of studies intending to fill this gap are difficult because multiple different sampling methods are employed and authors rarely report their method's lower limit of detection. In the present study, we compare a subset of sampling methods identified from a literature review to demonstrate that sampling method significantly influences study outcomes. We then compare a subset of methods identified from the review to determine the most efficient methods for recovering virus from surfaces in a laboratory trial using MS2 bacteriophage as a model virus. Recoveries of infective MS2 and MS2 RNA are determined using both a plaque assay and quantitative reverse transcription-PCR, respectively. We conclude that the method that most effectively recovers virus from nonporous fomites uses polyester-tipped swabs prewetted in either one-quarter-strength Ringer's solution or saline solution. This method recovers a median fraction for infective MS2 of 0.40 and for MS2 RNA of 0.07. Use of the proposed method for virus recovery in future fomite sampling studies would provide opportunities to compare findings across multiple studies.