This work demonstrates that the human virgin B cell repertoire contains a high frequency of cells capable of recognizing with significant affinity the main specific antigens of the highly pathogenic H5N1 viruses causing avian influenza. In addition, it is shown that they recognize the different known variants of H5 and that 35% of the antibodies produced by these virgin lymphocytes can neutralize the virus. In summary, the work provides very relevant information in three aspects:  

  1. The presence of virgin B cells in our lymphocyte repertoire, capable of recognizing H5N1 virus antigens, would constitute a first line of defense against this potentially pandemic virus. 
  2. The study of the virgin lymphocyte repertoire of humans can help to understand the characteristics of the course and pathogenesis of infection, not only by H5N1 viruses, but also by other infectious agents. 
  3. It provides key information for the rational design of effective vaccines against viruses.
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