Virus-binding proteins in water environments: Natural ligands for human viruses

Virus-binding proteins (VBPs) are bacterial proteins to which human viruses preferentially adsorb in water environments. VBPs were discovered from a bacterial culture derived from activated sludge with affinity chromatography assay in which a viral capsid peptide was used as a ligand. As an example of the VBP isolation, the recovery and characterization of Adenovirus-binding proteins (AdVBPs) were introduced. The significant adsorption of infectious Adenovirus (AdV) particles to the isolated AdVBPs was confirmed with enzyme-linked immunosorbent assay (ELISA). A number of AdVBPs were successfully obtained from crude proteins extracted from activated sludge culture, which was revealed by two-dimensional electrophoresis. The determination of the N-terminal amino acid sequence of AdVBP indicates that some AdVBPs are derived from outer membrane proteins of bacteria, and exhibit virus-binding ability under conditions of water environments. The methodology for acquiring VBP gene from a genomic DNA library of activated sludge microorganisms was also described. The consensus-degenerate hybrid oligonucleotide primer (CODEHOP) method, touchdown PCR, seminested PCR and inosine-incorporated primers were employed to effectively screen the VBP gene from a genomic DNA library. Since VBPs are expected to be stable under conditions of water environments, VBPs might be utilized as feasible and inexpensive viral adsorbents in technologies for virus detection and enrichment from water specimens. In order to utilize VBPs as viral adsorbents in various technologies, it is desirable to prepare VBPs for key viruses responsible for waterborne infectious diseases, or to discover VBPs with a broad affinity to several species of pathogenic viruses, though significant research progress is required to find the VBPs with a broad affinity.