Scientists have found that the bird flu virus has a surprising resistance to the high temperatures that normally stop the human flu. The key factor is a gene called PB1, which allows avian viruses to reproduce even in hot temperatures. Experiments in mice have shown that heat suppresses human flu, but avian strains, especially those with the bird-like PB1 gene, remain active. This finding suggests that gene swapping between viruses could increase the risk of future pandemics. Avian influenza virus is known for its ability to survive in a variety of environments, including droppings and water, and is resistant even at temperatures that inactivate other viruses. Heat inactivation of avian influenza occurs at temperatures around 70 °C, which is important for the safe preparation of poultry products. The research points to the need for further monitoring of genetic changes in avian influenza in view of its potential to threaten human health.