NPB and infection: Compared to NPB, hma5 was the most susceptible to infection, as shown by growth retardation and accumulation of RSV RNAs and CP; by contrast, the spl9 single mutant and the spl9/hma5 double mutant were more resistant to viral infection than hma5 and NPB, with the spl9/hma5 mutant almost displaying the level of virus resistance as spl9 (Fig. 3, G to J).