Development of an elution device for ViroCap virus filters

Abstract

Environmental surveillance of waterborne pathogens is vital for monitoring the spread of diseases, and electropositive filters are frequently used for sampling wastewater and wastewater-impacted surface water. Viruses adsorbed to electropositive filters require elution prior to detection or quantification. Elution is typically facilitated by a peristaltic pump, although this requires a significant startup cost and does not include biosafety or cross-contamination considerations. These factors may pose a barrier for low-resource laboratories that aim to conduct environmental surveillance of viruses. The objective of this study was to develop a biologically enclosed, manually powered, low-cost device for effectively eluting from electropositive ViroCap™ virus filters. The elution device described here utilizes a non-electric bilge pump, instead of an electric peristaltic pump or a positive pressure vessel. The elution device also fully encloses liquids and aerosols that could contain biological organisms, thereby increasing biosafety. Moreover, all elution device components that are used in the biosafety cabinet are autoclavable, reducing cross-contamination potential. This device reduces costs of materials while maintaining convenience in terms of size and weight. With this new device, there is little sample volume loss due to device inefficiency, similar virus yields were demonstrated during seeded studies with poliovirus type 1, and the time to elute filters is similar to that required with the peristaltic pump. The efforts described here resulted in a novel, low-cost, manually powered elution device that can facilitate environmental surveillance of pathogens through effective virus recovery from ViroCap filters while maintaining the potential for adaptability to other cartridge filters.

Keywords: Electropositive filter; Environmental surveillance; Poliovirus; ViroCap filter; Virus elution; Wastewater.

Fig. 1

ViroCap filter. Arrows indicate fluid flow. Sample enters through inlet (a). Liquid outside filter cartridge is at relatively high level (b). Liquid passes through filter cartridge to relatively low level inside (c). Metal insert prevents air from entering liquid exiting filter cartridge (d). Liquid passes up filter cartridge by vacuum (e). Liquid exits through the top outlet (Fagnant et al. 2017b) (f)

Fig. 2

Peristaltic pump elution photo. Peristaltic pump controller (a-I), peristaltic pump (a-II), inlet tubing (b), ViroCap filter (c), and open collection bottle (d)

Fig. 3

Elution device photo. Injection tubing inlet (a), hydrophobic filter (b), “Y”-tubing (c), ViroCap filter (d), collection cup (e), hydrophobic filter (f), bilge pump (g), and filter stand (h)