Selection of single-chain antibodies that specifically interact with vesicular stomatitis virus (VSV) nucleocapsid and inhibit viral RNA synthesis.

The RNA genome of non-segmented negative-strand RNA viruses is completely covered by the nucleoprotein (N) forming a ribonucleoprotein complex, the nucleocapsid. The nucleocapsid functions as the template for viral RNA synthesis that is mediated by a viral RNA-dependent RNA polymerase. It is postulated that the selection of molecules that would specifically target the nucleocapsid and thus inhibit the viral polymerase activity could represent a common approach to block negative-strand RNA viruses. Two single-chain antibody fragments (scFv) that were selected using the phage display technology and interacted specifically with vesicular stomatitis virus (VSV) nucleocapsid were characterized. The two recombinant antibodies recognize a conformational epitope on the nucleocapsid and immunoprecipitate specifically nucleocapsids from infected cell extracts. Both antibodies have a strong inhibitory effect on VSV transcription activity in vitro. Thus, they represent starting molecules for future development of in vivo viral RNA synthesis inhibitors.