Evaluation of adsorbents and eluents for application in virus concentration and adsorption-desorption isotherms for coliphages

Adsorption elution technique is widely used for virus preconcentration before detection and quantification. However, the existing methods do not provide adequate recovery of viruses. DEAE cellulose, and Moringa oleifera seed protein functionalized rice husk ash (F_aRHA) adsorbents were evaluated for the concentration of an enteric virus, Rotavirus A (RVA), an F-specific coliphage, MS2, and a somatic coliphage, SUSP2. Recovery with various adsorbent-eluent pairs was tested using initial coliphage concentration (C_o) 10⁴ PFU/mL. An eluent composed of 1.5 M NaCl, 2% Tween 80, and 0.05 M KH₂PO₄ (pH 9.2) yielded a high recovery of MS2 from DEAE cellulose (82%) and it also yielded high recovery of RVA. However, SUSP2 recovery from DEAE cellulose was ~61%, even after eluent optimization. An eluent comprised of glycine 3X broth, 1.5 M NaCl, 3% Tween 80, and 0.05 M KH₂PO₄ (pH 10.2) yielded high recovery of SUSP2 from F_aRHA (88%). The maximum recovery of MS2 and RVA from F_aRHA was lower (77% and 32%, respectively). The Freundlich model provided a good fit to the adsorption-desorption isotherms for the coliphages. For both the coliphages, the Freundlich capacity parameter, K_F, was two orders of magnitude higher for DEAE cellulose compared to F_aRHA. MS2 recovery from DEAE cellulose was minimally affected by antichaotrophic ions and dissolved organic matter, and higher sorption could be achieved over a wide pH range. For F_aRHA, pH variation and various water matrices had a significant adverse effect on coliphage recovery. Thus, DEAE cellulose is a superior adsorbent for virus preconcentration from water samples.