When two or more strains of a virus infect the same person, they can exchange genetic material and create new, more dangerous variants of a disease through a process called reassortment.

That scenario is caused by “reassortment,” the exchange of genetic material when hosts are infected with multiple versions of a virus. The U.S. Agriculture Department’s Animal and Plant ...

Genetic analysis confirms that a reassortment event in wild birds preceded a single transmission to cattle, after which asymptomatic or presymptomatic cattle facilitated the virus's spread across ...

But the best tests of any theory are its accuracy at making experimental predictions in settings not directly related to those in which it was formulated, and its ability to explain previously ...