Background: NEP stimulates viral RNA synthesis and nuclear vRNP export. Results: NEP is required to stabilize M1-vRNP binding for nuclear export. Deletion of the last three amino acids of NEP abrogates nuclear export and the polymerase-enhancing function of NEP. Conclusion:The polymerase-enhancing function and the nuclear export function of NEP are linked functionally. Significance: This study provides new insights into the assembly of the nuclear export complex.