Immunochemical properties of the West Nile virus prM protein and the C-terminal fragment of the M protein

Abstract

The cDNA fragments 466–966 and 878–1088 coding for the precursor M (prM) protein and polypeptide M31–75-E1–30 of the Russian strain LEIV-Vlg99-27889-human of the West Nile virus (WNV) were synthesized and cloned. The corresponding prM and M31–75-E1–30 recombinant polypeptides were purified by affinity chromatography. The prM polypeptide interacted with a polyclonal serum against WNV in ELISA and immunoblotting, demonstrating the immunochemical similarity of the recombinant polypeptide and the native WNV prM protein. Six species-specific monoclonal antibodies (mAbs) against the prM recombinant polypeptide recognized at least four epitopes on the recombinant polypeptides. In addition, mAb 7D11 displayed a virus-neutralizing activity. The patterns of mAb interactions with the prM, M31–75-E1–30, E1–180, and E260–466 recombinant polypeptides revealed cross-reacting epitopes in regions 260–466 of the E protein and 31–75 of the M31–75-E1–30 polypeptide and the WNV prM protein. A spatial model revealed structural similarity of the C-terminal regions of the E and M proteins of WNV, supporting the results of immunochemical experiments. Based on virus neutralization by mAb 7D11, which recognized an epitope mapping to region 31–75 of the WNV M protein, an important function in virus penetration into the cell was assumed for the C-terminal region of the M protein.