Aggregation of virus particles

Viral aggregation is affected by several physicochemical parameters of the aqueous medium, including but not limited to pH, ionic strength and composition, and temperature. Some studies investigating these parameters have shown that aggregation can be reversible for some viruses. For some viruses, these parameters also govern the degree of reversibility of viral aggregation.

Viruses are colloidal particles, and as such, their Brownian motion and subsequent collision rate rise at higher temperatures leading to more aggregation. Several studies exploring the kinetics of viral aggregation as a function of these physicochemical parameters show that the process is mainly virus-specific and depends on the surface properties of viral particles. For instance, four genogroups of F-specific RNA bacteriophages, MS2, GA, Qβ, and SP, showed different aggregation behaviors over a broad range of pH (1.5–7.5) and ionic strength (1–100 mM NaNO3) conditions tested.. While MS2 only aggregated near their isoelectric point (pH = 4) regardless of the ionic strength, Qβ aggregated at low pH and high ionic strength, and GA and SP both aggregated over the entire range of tested conditions.

Models describe the energies of interaction between viruses using the extended DLVO theory. We present a model considering collisions between virus particles with double layers. The results are compared with experimental observations.