Influenza A virus evolution: Complete sequences of influenza A / NT / 60 / 68 RNA segment 3 and its predicted acidic P polypeptide compared with those of influenza A / PR / 8 / 34
التفاصيل البيبلوغرافية
العنوان:
Influenza A virus evolution: Complete sequences of influenza A / NT / 60 / 68 RNA segment 3 and its predicted acidic P polypeptide compared with those of influenza A / PR / 8 / 34
The complete sequence of RNA segment 3 of a 1968 isolate of influenza A (A/NT/60/ 68) has been determined from a DNA copy of the viral RNA cloned in the E. coli plasmid pBr322. The segment 3 viral RNA is deduced to be 2233 nucleotides long with a single open reading frame of 2148 nucleotides. The predicted primary gene product is an acidic protein, 83,000 daltons, which has a net charge at neutral pH of -16. The A/NT/60/68 segment 3 sequence differs by 159 point mutations (92.7% homology) from that of the 1934 influenza isolate, A/PR/8/34 S. Fields and G. Winter. The predicted primary gene products of the two viruses differ by 28 amino acids corresponding to point mutations involving 1.48% of the sites where nucleotide substitution could cause an amino acid change. By contrast, the other 131 point mutations correspond to 17.5% of the available sites where nucleotide substitution could be silent (i.e., they may not cause an amino acid change). Similar results are obtained by comparing the sequences of RNA segment 5 of the two viruses. These quantitative differences between the coding and silent mutations are most easily interpreted as representing the results of gene product selection. The sequence data obtained for segment 3 of A/NT/60/68 confirm previous analyses that indicated that a 423-nucleotide-long small RNA obtained from virus preparations is a recombinant RNA species B. Moss and G. G. Brownlee.
