Use of temperature-sensitive gel for concentration of influenza virus from infected allantoic fluids

Cross-linked, poly(N-isopropylacrylamide) gel was used to concentrate avian influenza virus from allantoic fluid. Placing the gel in virus-infected allantoic fluid at 4 degrees C caused the gel to swell and absorb small molecular weight solutes, while excluding avian influenza virus and other large particles. Warming the gel to 37 degrees C or more caused the gel to collapse. The gel remained functional after sterilization in an autoclave and could be reused to concentrate other samples of allantoic fluid. Using a combined concentration and elution technique, we were able to achieve an average of 84.2% virus recovery, while reducing the fluid volume from 90 ml to 7.6 ml.