Measles virus (MV) belongs to the genus Morbillivirus of the family Paramyxoviridae. A number of paramyxoviruses inhibit host interferon (IFN) signaling pathways in host immune systems by various mechanisms. Inhibition mechanisms have been described for many paramyxoviruses. Although there are inconsistencies among previous reports concerning MV, it appears that P/V/C proteins interfere with the pathways.
This study confirms the effects of MV P gene products of a wild MV strain on IFN pathways and examined that of other viral proteins on it. The authors found that N protein acts as an IFN-α/β and γ-antagonist as strong as P gene products. They investigated the mechanisms of MV-N inhibition, and revealed that MV-N blocks the nuclear import of activated STAT without preventing STAT and Jak activation or STAT degradation, and that the nuclear translocation of MV-N is important for the inhibition. The inhibitory effect of the N protein was observed as a common feature of other morbilliviruses. These results suggest that N protein of MV as well as P/V/C proteins is involved in the inhibition of host IFN signaling pathways.