13 Scopus citations


The ability to apply reverse genetics technologies to influenza virus now allows us to construct novel viruses containing heterologous sequences. We have engineered two neuraminidase (NA) genes of influenza A/WSN/33 virus containing additional sequences which were inserted downstream of the open reading frame of the NA. These NA genes, NA/EMC and NA/EMC-NS1, possess a 546 and a 917 nucleotide (nt) insertion respectively. Transfectant viruses were rescued following ribonucleoprotein (RNP) transfection of the engineered NA genes into influenza helper-virus-infected cells. The transfectant viruses maintained their artificially introduced sequences stably during three passages. The rescued virus containing the NA/EMC-NS1 gene produced one log fewer infectious virus particles in MDBK cells than did wild type A/WSN/33 virus. The growth characteristics in tissue culture of the virus containing the NA/EMC gene was indistinguishable from that of wild-type influenza virus. Based on these results we conclude that influenza A viruses can tolerate heterologous insertions of at least a kilobase in the NA gene.

Original languageEnglish
Pages (from-to)237-246
Number of pages10
JournalDevelopments in Biological Standardization
StatePublished - 1994


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