TY - JOUR T1 - Growth of H5N1 Influenza A Viruses in the Upper Respiratory Tracts of Mice A1 - Hatta, Masato A1 - Hatta, Yasuko A1 - Kim, Jin Hyun A1 - Watanabe, Shinji A1 - Shinya, Kyoko A1 - Nguyen, Tung A1 - Lien, Phuong Song A1 - Le, Quynh Mai A1 - Kawaoka, Yoshihiro Y1 - 2007/10/05 N2 -
Highly pathogenic avian H5N1 influenza A viruses have spread around the world since 2003, raising serious worldwide concern about their pandemic potential. Although efficient human-to-human transmission of this virus has not yet occurred, the potential of these viruses to acquire the ability is evident. The receptor specificity of the haemmaglutinin (HA) protein is considered a main factor affecting efficient transmission of H5N1 viruses. Yet, some H5N1 viruses isolated from humans that possess human receptor specificity have still failed to spread efficiently among humans. Therefore, amino acid substitutions in viral proteins other than the receptor-binding HA protein must be necessary for efficient growth and person-to-person transmission of avian H5N1 influenza virus. In our study, we defined the contribution of the amino acid at position 627 of the PB2 to efficient replication of H5N1 influenza viruses in the upper respiratory tracts of mice as a mammalian model. Because efficient viral growth in the upper respiratory tract of humans can facilitate virus excretion by coughing and sneezing, a mutation of PB2 amino acid 627, which contributes to efficient growth at this site in a mammal, may be prerequisite for efficient human-to-human transmission.