Electrostatically induced polyelectrolyte association of rodlike virus particles

Calculations of the electrostatic osmotic pressure for a closely packed phase of laterally ordered rodlike fd or M13 virus particles at equilibrium with a bulk salt solution have been performed using grand canonical Monte Carlo simulations. With increasing concentration of divalent counterions, the pressure becomes attractive. The attraction is stronger for higher surface charge density (of fd virus as opposed to M13 virus) and smaller counterion radius. The calculations agree with the results from light scattering measurements, which sensitively detect the formation of laterally ordered virus aggregates. [S0031-9007(98)07969-1].