Importantly, during an ongoing infection the switch from a transcribing FluPol(T) to a replicating FluPol(R) can occur only after de novo synthesised FluPol and NP are imported into the nucleus (Fig. 6D) and an asymmetric FluPol(R)-ANP32A-FluPol(E) complex is assembled, ensuring encapsidation of the nascent viral RNA by the FluPol(E) moiety in conjunction with the NP. Here, ANP32A is linked to infection.