IMPROVING PRE-ANALYTIC COLLECTION SYSTEMS: INACTIVATION AND PRESERVATION OF INFLUENZA A FOR RAPID TESTING

Abstract

Objective:

An alternative sample collection system that would render a virus non-infectious but permit rapid identification by direct immunofluorescence (DFA) or molecular methods would be beneficial during a pandemic. In this study, the CyMol collection system was evaluated for its ability to inactivate influenza A and preserve the sample for molecular testing.

Methods:

CyMol (COPAN) is an alcohol-based medium that preserves cells for DFA. Flocked nasopharyngeal swabs (NPS) collected in universal transport media (UTM®) were compared to NPS collected in CyMol. Aliquots of Influenza A viral lysate were absorbed onto duplicate flocked swabs and placed into the UTM® and CyMol collection systems. Inactivation of the virus after exposure to each collection medium was assessed by inoculation of the mocked samples into R-mix shell vial culture followed by immunofluorescent staining at 48 hours. Inactivation was assessed for 5 influenza A subtypes. The stability and recovery of influenza A nucleic acid (NA) was also assessed after 1, 7, 14 and 21 days at 40C, -200C, room temperature (RT) and 370C. Aliquots of mocked specimens were extracted by easyMAG (bioMérieux) and 5 uL of purified NA tested by quantitative RT-PCR on the Roche LightCycler.

Results:

In contrast to the UTM®, the influenza A virus was inactivated on exposure to the CyMol collection medium and failed to grow in shell vial culture. Influenza A RNA levels were stable for up to 14 days in both the UTM® and CyMol collection systems at -200C, 40C and RT. The stability of Influenza A RNA declined in both systems at 370C.

Conclusions:

The Copan CyMol medium inactivates influenza A virus while stabilizing RNA for molecular testing for up to 14 days at -200C, 40C and RT. CyMol is a potential alternative for safe sample collection during an influenza pandemic situation.