Hong Kong: study shows HK 1997 flu originates from single mutation

摘要

According to researchers, the 1997 Hong Kong flu outbreak from a flu strain called H5N1, which killed six people and made 18 people sick, resulted from a single mutation in one base pair of the NS1 gene. Asst. Prof. Robert Webster of St. Jude Children's Hospital, Memphis, whose team did the research, said "If this mutated gene is put into an ordinary strain of flu you turn it into a nasty virus." Prof. Webster and his team found that the mutation allows the virus to evade the anti-viral effects of two controlling factors of the immune system: interferons and tumor necrosis factor alpha. They examined the DNA of the H5N1 viruses in pigs and found a mutation on a gene called NS1. This mutation creates a protein called nonstructural 1, which lets thevirus shut down a part of the body's natural defenses known as cytokines.