Adenovirus aggregation and preservation in extracellular environment

The conditions of adenovirus aggregations are analyzed. Adenovirus type 2 was propagated on Hep2 cells; virion aggregation analysis was performed by sedimentation velocity on sucrose gradients. The results show that aggregation depends on: 1) Ionic strength: aggregate formation was verified between 0.005 M and 0.05 M NaCl; 2) pH: at pH 7.1 virus particles are dispersed, 90 per cent of particles are aggregated at pH 4--5; at pH lower than 4 aggregation is not reversible; 3) Particle concentration: the dilution of a stock containing 5 X 10(11) particles/ml decrease rate of aggregate formation until all aggregation is inhibited; 4) Temperature: the degree of aggregation in the 25 to 37 degrees C range is constant but decreases when the temperature falls below 20 degrees, at +4 C there is no aggregation. The aggregation reaction presents a positive deltaH of 17.9 Kcal/mol and a deltaG of --1.32 Kcal/mol.