Detection of poliovirus by ICC/qPCR in concentrated water samples has greater sensitivity and is less costly using BGM cells in suspension as compared to monolayers

Viral infection is suspected in 50% of all acute gastrointestinal illness [1] with the public being at greatest risk acquiring infection through wastewaters that contaminate drinking water sources, recreational waters and shellfish harvesting waters [2].ICC/qRT-PCR is a proven method for the rapid detection of infective enteroviruses in environmental waters [3,4]. With this technique viruses, which are generally present in low numbers, are propagated in monolayers of a host cell line which increases the PCR target. Little published research is available using cell culture systems other than monolayers to screen environmental samples [5,6]. One study reported the development of a BGM shaker culture where the cells were adapted to a suspension culture by serial passaging and using special medium and a gyratory shaker. Infectivity was compared between the adapted cells and BGM monolayers by inoculating with poliovirus 1, 2 and 3 (as well as other viruses). The suspensions showed higher log 10 plaque forming units per mL (PFU/mL) than the monolayers [6]. In another (clinical) study, cells were infected with herpes simplex virus (HSV) in what was described as a simultaneous seeding and infection (suspension-infection) method which yielded a mean time to diagnosis of 1 day. This method became routinely used in the authors' laboratory because of its ease, sensitivity and timeliness [7]. Here we describe a comparable suspension-infection technique for detecting viruses in environmental samples that doesn't involve adapting and maintaining cells in suspension or the manipulations and procedural steps associated with conventional monolayer cell culture.For this study the BGM cell line was chosen to demonstrate proof of concept due to its high susceptibility to enteroviruses in water samples [5,6,8] and the concomitant use of poliovirus as a standard experimental model. In addition enumeration of poliovirus in BGM monolayers is easily accomplished via neutral red plaque assay.