Therefore, our findings indicate that the nucleotide variation at position 5 in the 3' end of the vRNA promoter between FluA and FluB viruses contributes to their RNP incompatibility, which may shed new light on the mechanisms of intertypic exclusion of reassortment between FluA and FluB viruses.<b>IMPORTANCE</b> Genetic reassortment of influenza virus plays a key role in virus evolution and the emergence of pandemic strains.
The segmentation of the influenza genome makes these additional trafficking requirements especially challenging, as each viral RNA (vRNA) gene segment must navigate the network of cellular membrane barriers during the processes of entry and assembly.