Reacción a "Avian influenza viruses can resist fever"

This avian influenza study focusses on the influence of the host's body temperature, in this case using mice as a model, on the proliferative capacity of influenza A viruses of avian or mammalian origin. Influenza viruses multiply most effectively in the animal species to which they have adapted during their biological cycle. However, their replicative efficiency is reduced to a greater or lesser extent in other species, depending on various factors, including the cellular and tissue tropism of the virus, the presence of appropriate viral receptors, and other anatomical or physiological factors, such as the host's body temperature, which facilitate or condition the fitness of the virus.

This differential adaptation is clearly evident between avian and mammalian influenza viruses, which does not prevent an avian strain from successfully infecting a mammal, including humans, and vice versa, under certain conditions. This host promiscuity is a hallmark of Influenza A viruses and has a disturbing example in the current highly pathogenic H5N1 subtype strain circulating among wild birds worldwide, which has been able to infect various mammalian species and threatens to cause a pandemic at any time.

The authors of the study, from laboratories in Great Britain, the US, Japan and Australia, demonstrate that the PB1 protein, involved in viral replication in avian viruses, is adapted to the temperatures typical of birds, 40o-42o, and therefore is not significantly affected by human physiological temperatures (33°C in the upper respiratory tract and 37°C in the lower respiratory tract), even in a feverish state (40°C). In addition, researchers have found that this is also true for the PB1 proteins of avian viruses that caused the pandemics of 1918, 1957 and 1968.

One consequence of these findings is the loss of the defensive function of increased body temperature (fever), which mammals, including humans, use to curb infections from pathogens, including influenza viruses. The authors warn of the clinical and epidemiological implications that this particular feature of avian influenza viruses may have in terms of potential transmission to humans.