Stability of influenza virus as evaluated by integrity of its RNA

Various methods of handling samples of avian influenza prior to detecting influenza viruses can significantly influence both, the detection of the virus and the quantification of viral nucleic acids. The quantity of influenza viral RNA remaining in different collecting buffers and kept at temperatures of -20°C, +4°C or +22°C for various lengths of time, was determined. The quantity of viral RNA remained the same for 120 days at -20°C, but decreased when the samples were stored at either +4°C or +22°C. The quantity of RNA was influenced by the composition of the collecting buffer. The influenza virus sample that is to be used for RNA quantification can be stored at +4°C and freeze and thaw cycles should be avoided during transport. Our results clearly indicate that the quality and quantity of influenza virus nucleic acid depends on the chemical composition of used buffer and also that the samples can be protected from degradation even if they are not stored at ultra-low temperatures. However, repeated thaw and freeze cycles will damage viral RNA even if kept in stabilizing buffers.

influenza virus; degradation; RNA; buffer.