Estanislao Nistal
Professor of Microbiology at the Faculty of Pharmacy
The study is relevant and interesting in that it identifies in different people the presence of B lymphocytes capable of producing antibodies that block the entry of an H5N1 virus that has not yet produced a pandemic outbreak in humans. It is particularly noteworthy that these people have never been infected by H5N1, but it is still possible to have both these B lymphocytes and the antibodies they can generate against the virus, to have a defense against the virus without ever having seen it.
However, this would most likely not be enough in some people in case of infection. Infection by a new virus such as H5N1 that has a high capacity for replication and transmission will require that these B lymphocytes be stimulated to proliferate and increase antibody production considerably, and thus better prevent infection or reduce the disease it causes and the transmission. The study serves as evidence of the potential to stimulate the production of antibodies that can block the virus.
The description fits the expectation that we may have the potential to produce antibodies to viruses, infectious agents or antigens in general that we have never seen before. It is an intrinsic capacity of B lymphocytes that allows us to develop immune responses to potentially a much larger number of antigens than we will ever detect in our lifetime. This is also true for the hemagglutinin of the H5N1 viruses. The capacity of some of these antibodies to block hemagglutinin and to describe mechanistically how they do so at the structural level is interesting. This could be useful if they are better characterized as an antiviral tool in case of need, or to improve or adapt these antibodies to the needs that may arise in case of trying to contain an outbreak.
[Regarding possible limitations] The study could have considered the potential evolutionary diversity of the hemagglutinin of H5N1 viruses. These viruses are currently circulating worldwide in birds and their ability to infect some mammals, both wild and farmed, has been described. In this infection of mammals, such as pigs or cows, the virus is accumulating mutations that can potentially adapt to further transmission between animals, including humans. Some of the mutations that the virus must acquire in its hemagglutinin are known. It would have been interesting to determine whether any of the antibodies described could block this hemagglutinin with greater transmission potential with the possibility of being used against an H5N1 virus with greater capacity for transmission between humans.