KPNA1 and infection: Infection of MDCKII cells with rCH2 at a multiplicity of infection (MOI) of 0.001 resulted in a 35-fold reduction in viral titres 24 h post infection (h.p.i.)(Fig. 1d), indicating that although the CH2 chimeric NP supported the generation of infectious IAV, the resulting rCH2 virus was attenuated in viral growth.