Overview of NS derivatives constructed from influenza C/JJ/50 and C/JHB/1/66 viruses. Sequences are shown in positive sense. NS1(SAM)-JJ and NS1(SAM)-JHB have wild type-like sequence lengths but are splice acceptor site-mutated (SAM) to prevent NEP/NS2 expression. Start and stop codons - whether native or introduced by cloning - are depicted. Black bars: noncoding ends. All primer sequences are available upon request.