CDC: sequencing results of H5N1 AI samples from patient
CDC has sequenced the influenza virus genome identified in a specimen collected from the patient in Texas who was confirmed to be infected with highly pathogenic avian influenza A(H5N1) virus and compared these with HPAI A(H5N1) sequences from cattle, wild birds and poultry.
The virus sequences are HA clade 2.3.4.4b HPAI A(H5N1) with each individual gene segment closely related to viruses detected in dairy cattle available from USDA testing in Texas. While minor changes were identified in the virus sequence from the patient specimen compared to the viral sequences from cattle, both cattle and human sequences maintain primarily avian genetic characteristics and for the most part lack changes that would make them better adapted to infect mammals. The genome for the human isolate had one change (PB2 E627K) that is known to be associated with viral adaptation to mammalian hosts, and which has been detected before in people and other mammals infected with HPAI A(H5N1) virus and other avian influenza subtypes (e.g., H7N9), but with no evidence of onward spread among people.