Polyacrylamide gel electrophoresis of the RNAs of new influenza virus strains: an epidemiological tool.

Recently, we have shown by separating the RNAs and proteins of different influenza A viruses on polyacrylamide gels, that influenza A viruses contain 8 genes corresponding to 8 virus specific proteins. By analyzing the RNA patterns and the protein patterns of different recombinant viruses we, subsequently, succeeded in establishing a complete genetic map for influenza A viruses. These techniques were extended to characterize the genome of new influenza virus isolates. Thus it was found that the human isolate A/Wi/263/76 and the two swine virus isolates, A/swine/Wi/49/76 and A/swine/Wi/50/76 possess identical RNA patterns, which differ from the RNA patterns of other recent swine virus isolates. The human (Wi/263) and the two animal isolates (Wi/49 and Wi/50) were obtained on the same farm suggesting that the animal virus was transmitted from swine to man. This proves that swine viruses may occasionally infect humans without causing a pandemic. A comparative analysis of the different RNA patterns of other swine influenza viruses isolated around the same time at different locations and of those of recent human isolates showed that our polyacrylamide gel technique is a valuable epidemiological tool to identify and and characterize different influenza virus isolates.