Amino acid sequence analysis and identification of mutations in the NS gene of 2009 influenza A (H1N1) isolates from Kenya.

Although the important role of the nonstructural (NS) gene of influenza A virus in virulence and replication is well-established, the knowledge about the extent of variation in the NS gene of 2009 influenza A (H1N1) viruses in Kenya and Africa is scanty. This study analysed the NS gene of 31 isolates from Kenya in order to obtain a more detailed knowledge about the genetic variation of NS gene of 2009 influenza A (H1N1) isolates from Kenya. A comparison with the vaccine strain and viruses isolated elsewhere in Africa was also made. The amino acid sequences of the non-structural protein, NS1 of the viruses from this study and the vaccine strain revealed 18 differences. Conversely, the nuclear export protein (NEP) of the isolates in this study had 11 differences from the vaccine strain. Analysis of the NS1 protein showed only one fixed amino acid change I123V which is one of the characteristics of clade 7 viruses. In the NEP, the amino acid at position 77 was the most mutable with 9 (39%) of all mutations seen in this protein. A mutation A115T which is a characteristic of clade 5 viruses was noted in the isolates from Lagos, Nigeria. The study shows a substantial number of mutations in the NS gene that has not been reported elsewhere and gives a glimpse of the evolution of this gene in the region.