Nucleotide sequence of influenza virus RNA segment 8 indicates that coding regions for NS1 and NS2 proteins overlap.

Abstract

The smallest RNA segment of influenza A viruses (vRNA segment 8) codes for 2 unrelated nonstructural proteins (NS1 and NS2) translated from separate mRNA. Molecular weight considerations indicated that there might not be enough space on vRNA segment 8 for the 2 coding regions unless they overlap. Several genes of an avian influenza A virus, fowl plague virus (FPV) were recently cloned in bacterial plasmids, and now the complete nucleotide sequence of FPV RNA segment 8 largely determined from the cloned DNA is presented. The DNA sequence predicts 2 open protein synthesis reading frames that can be translated into polypeptides of sizes similar to those of NS1 and NS2. The coding regions for these polypeptides overlap by the equivalent of 43-60 amino acids, the exact amount depending on which of several possible methionines initiates the synthesis of NS2.