Preparation of purified, sterilized, and stable adenovirus vectors using albumin

Cesium chloride ultracentrifugation combined with dialysis is a standard method for preparing a high titer of purified recombinant adenovirus. However, it was found that sterilization of the filter membrane after dialysis led to a complete loss of adenovirus activity. A virus pellet was visualized after centrifugation shortly and electron microscopy revealed an aggregation of recombinant virus within the filter membrane following dialysis with 10% (V/V) glycerol in phosphate buffered saline. The entrapment of aggregated adenovirus by the filter membrane explains why adenovirus activity is lost following sterilization. The addition of 1% albumin prevented viral aggregation and allowed the purified virus to retain its activity after filter sterilization. Furthermore, viral activity was retained within the 1% albumin solution for at least 1 week at 37 degrees C and for 2 weeks at 4 degrees C, whereas viral activity within the albumin-free solution was quickly lost.