title: Applicability of integrated cell culture quantitative PCR (ICC-qPCR) for the detection of infectious adenovirus type 2 in UV disinfection studies.
abstract: Practical difficulties of the traditional adenovirus infectivity assay such as intensive labor requirements and longer turnaround period limit the direct use of adenovirus as a testing microorganism for systematic, comprehensive disinfection studies. In this study, we attempted to validate the applicability of integrated cell culture quantitative PCR (ICC-qPCR) as an alternative to the traditional cell culture method with human adenovirus type 2 (HAdV2) in a low-pressure UV disinfection study and to further optimize the procedures of ICC-qPCR for 24-well plate format. The relatively high stability of the hexon gene of HAdV2 was observed after exposure to UV radiation, resulting in a maximum gene copy reduction of 0.5 log10 at 280 mJ cm(-2). Two-day post-inoculation incubation period and a maximum spiking level of 10(5) MPN mL(-1) were selected as optimum conditions of ICC-qPCR with the tested HAdV2. An approximate 1:1 correlation of virus quantities by the traditional and ICC-qPCR cell culture based methods suggested that ICC-qPCR is a satisfactory alternative for practical application in HAdV2 disinfection studies. ICC-qPCR results, coupled with a first-order kinetic model (i.e., the inactivation rate constant of 0.0232 cm(2) mJ(-1)), showed that an UV dose of 172 mJ cm(-2) achieved a 4-log inactivation credit for HAdV2. This estimate is comparable to other studies with HAdV2 and other adenovirus respiratory types. The newly optimized ICC-qPCR shows much promise for further study on its applicability of other slow replicating viruses in disinfection studies.
authors.affiliation: a Pegasus Technical Services , Cincinnati , Ohio , USA.
authors.forename: Hodon
authors.initials: H
authors.lastname: Ryu
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Cashdollar
authors.forename: G Shay
authors.initials: GS
authors.lastname: Fout
authors.forename: Karen A
authors.initials: KA
authors.lastname: Schrantz
authors.forename: Samuel
authors.initials: S
authors.lastname: Hayes
mesh_terms: D000256:Adenoviridae / Q000302:isolation & purification* / Q000528:radiation effects*; D000257:Adenoviridae Infections / Q000517:prevention & control*; D018929:Cell Culture Techniques / Q000592:standards; D002478:Cells, Cultured / Q000528:radiation effects*; D004203:Disinfection / Q000379:methods*; D006801:Humans; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D014466:Ultraviolet Rays
keywords: Integrated cell culture quantitative PCR; UV disinfection; adenovirus type 2