Bank vole monoclonal antibodies against Puumala virus envelope glycoproteins: identification of epitopes involved in neutralization

Abstract

Bank vole (Clethrionomys glareolus) monoclonal antibodies (MAbs) against the two envelope glycoproteins (G 1 and G 2) of the Puumala (PUU) virus were generated and characterized. Analyses of the MAbs' antigen and epitope specificities showed non-overlapping reactivities of one anti-G 1 and two anti-G 2 MAbs. A significant neutralizing activity was shown by the anti-G 1 and one of the anti-G 2 MAbs, suggesting the existence of at least one neutralizing domain on each of the two glycoproteins. The two neutralizing MAbs reacted with eight PUU-related (serotype 3) virus strains, but did not react with Hantaan, Seoul, or Prospect Hill viruses in an immunofluorescence assay, indicating reactivity with epitopes unique for PUU virus. The non-neutralizing anti-G 2 MAb also reacted with Seoul virus, revealing the presence of a conserved G 2-epitope common for PUU and Seoul viruses, not involved in neutralization. Competitive binding of the MAbs and sera from nephropathia epidemica patients indicated that the defined neutralizing and non-neutralizing epitopes of the glycoproteins were immunodominant also in humans. In another experiment, magnetic beads coated with two MAbs were bound with the virus glycoproteins and used for selective enrichment of cells secreting anti-glycoprotein antibodies.