How is the effect of Humic Acid on viruses?

“With most viruses, the inhibitory effect of (Humic Acid) is directed specifically against an early stage of virus replication, namely virus attachment to cells (Klocking and Sprosig, 1975; Schols et al., 1991; Neyts et al., 1992).”

“…it appears likely that the poly-anionic Humic Acids occupy positively charged domains of the viral envelope glycoproteins, which are necessary for virus attachment to the cell surface (Neyts et al., 1992).”