NS1 Influenza Protein - Avian

Avian

The NS1 protein of the highly pathogenic avian H5N1 viruses circulating in poultry and waterfowl in Southeast Asia is currently believed to be responsible for the enhanced virulence of the strain. H5N1 NS1 is characterized by a single amino acid change at position 92. By changing the amino acid from glutamic acid to aspartic acid, researchers were able to annul the effect of the H5N1 NS1. This single amino acid change in the NS1 gene greatly increased the pathogenicity of the H5N1 influenza virus. However, the effect of residue 92 on the function of H5N1 NS1 appears to be questionable as noted by Nature Medicine editors: “The above paper originally reported that H5N1 viruses are resistant to interferon in the SJPL cell line. The editors wish to alert our readers about three facts that may affect this conclusion. First, Ngunjiri et al. have recently found that aliquots of the SJPL cell line obtained from the American Type Culture Collection were heavily contaminated with mycoplasma. Although the mycoplasma status of the cells used in the original paper is unknown, it is not possible to rule out that they were contaminated. Second, SJPL cells were originally reported to be of porcine origin, but a recent analysis has indicated that they are of simian origin. Third, Ngunjiri et al. have found H5N1 viruses to be sensitive to interferons in all cell lines tested from multiple species.”