The 3' and 5'-terminal sequences of influenza A, B and C virus RNA segments are highly conserved and show partial inverted complementarity

The NS1 gene from bat-derived influenza-like virus H17N10 can be rescued in influenza A PR8 backbone

“…Each influenza virus segment is composed of one or more ORFs flanked by NCRs at their 3¢ and 5¢ ends; the NCRs are important for virus replication and are highly conserved among different influenza A virus strains (Desselberger et al, 1980;Tiley et al, 1994;Zheng et al, 1996). Considering that there are several base differences in the NCR sequences of H17N10 and PR8, we constructed eight chimeric segments that contained the NCR sequences from PR8, while the rest of the sequences were H17N10 derived.…”

Complete structure of the hemagglutinin gene from the human influenza A/Victoria/3/75 (H3N2) strain as determined from cloned DNA

“…The presence of the sequence 5'-AGCAAAAGCAGG at the 5' end of the pVHA14 insert proves that the complete information starting from the 3' end of the viral RNA (negative strand) has been cloned, as the complementary sequence has been found at the 3' end of all influenza A viral RNAs studied thus far (Skehel and Hay, 1978;Robertson, 1979;Both and Air, 1979;Desselberger et al, 1980;McCauley et al, 1979;Porter et al, 1979). The only nucleotide which is variable in the first segment of 12 residues is nucleotide 4, which can be A (FPV; X31; HA, NP and NS from PR8; HA from A/RI/5/57) or G (the five other genes of PR8).…”

“…Overlapping information determined by sequencing the 5' end of the viral RNA by reverse transcription using a labeled restriction fragment as primer revealed that 23 nucleotides are missing from the pVHA14 insert and 22 from pVHA10. The first 22 nucleotides at the 5' end of the virion RNA--except for residues 14, 15 and 16--are highly conserved in all genes of all A-type viruses examined thus far (Skehel and Hay, 1978;Robertson, 1979;Desselberger et al, 1980). The addition of 23 residues makes the exact length of the viral RNA 1.768 nucleotides, which is very similar to the length of the FPV hemagglutinin RNA--that is, 1742 nucleotides (Porter et al, 1979 …”

In vitro transcription and polymerase binding studies of the termini of influenza A virus cRNA: evidence for a cRNA panhandle

“…vRNA has been extensively studied with regard to sequence elements to which the influenza virus polymerase complex binds and initiates transcription of the two types of positive-stranded RNA. Short conserved sequences are found at both termini of vRNA which display partial inverted complementarity (Robertson, 1979;Desselberger et al, 1980). These sequences are able to base-pair with each other, both in virions and in infected cells, forming a panhandle structure (Hsu et al, 1987).…”