Differential sensitivity of two related viruses, Newcastle disease virus and Sendai virus, to interferon in mouse Had-2 cells: selective inhibition of translation of NDV mRNA.

Had-2, a mouse mutant cell line derived from FM3A, constitutively releases interferon-alpha and beta and acquires resistance to Newcastle disease virus (NDV) and other viruses. However, Had-2 was found as susceptible to Sendai virus (HVJ) as FM3A. Even when Had-2 cells were infected simultaneously with NDV and HVJ, only the replication of NDV was inhibited, while that of HVJ was not. Northern blot hybridization analysis indicated that accumulation of NDV-specific primary transcripts was somewhat reduced in Had-2, but the reduction was insufficient to critically suppress the viral replication. Moreover, this decrease was not observed in the presence of cycloheximide, and a closely comparable amount of the primary transcripts was detected in both Had-2 and FM3A cells. The mRNA accumulated in the presence of cycloheximide was translated efficiently on removal of the inhibitor in FM3A cells, but not at all in Had-2 cells. Thus the translation of NDV mRNA was the major target of interferon in Had-2 cells. The fact that the synthesis of HVJ proteins was unaffected in Had-2 cells may imply that a host-cell component that distinguishes between NDV and HVJ mRNAs is involved in their translation.