Abstract Title
Genetic and antigenic characterization of clade 2.3.4.4b highly pathogenic avian influenza A(H5N1) viruses isolated from human cases in the United States in 2024
Abstract
Highly pathogenic avian influenza (HPAI) A(H5N1) clade 2.3.4.4b viruses have been circulating in the United States since 2022 and caused poultry outbreaks. The recent dairy cattle outbreak in the United States was caused by HPAI A(H5N1) clade 2.3.4.4b genotype B3.13. As of October 17, 2024, HPAI A(H5N1) virus infection was confirmed in 304 dairy herds in farms across 14 states and in 15 human cases with exposure to dairy cattle in 4 states. From March 25, 2024 to October 17, 2024, HPAI A(H5N1) infection was also confirmed in 65 poultry flocks across 14 states and in 9 human cases with exposure to poultry in Colorado. In addition, HPAI A(H5N1) virus infection was confirmed in one human case from Missouri with unknown exposure. Phylogenetic analysis showed that the available HA sequences from the human cases in Texas, Michigan, Colorado and California were closely related to those from dairy cattle. Compared to the WHO recommended candidate vaccine virus, IDCDC-RG78A (A/American Wigeon/South Carolina/22-000345-001/2021), the available HA1 sequences from those human cases all had conserved amino acid changes at L115Q and T195I. In addition, the human cases in California all had conserved changes in HA1 at D88G and S320N and the human case in Missouri had P136S and A156T changes in antigenic sites. Ferret antisera raised to IDCDC-RG78A showed good cross-reactivity with available virus isolates from human cases in Texas, Michigan, Colorado and California. A virus isolate was not available for the Missouri human case but characterization with a reverse genetic virus demonstrated reduced cross-reactivity because of the A156T mutation.
Co-Author(s)
Juan De La Cruz1, Yasuko Hatta1, Yunho Jang1, Julia Frederick1, Kristine Lacek1, Jimma Liddell1, Kay Radford1, Elizabeth Pusch1, Natasha Burnett1, Dan Cui1, Lisa Keong1, Sydney Sheffield1, Malania Wilson1, Phili Wong1, Monique Johnson1, Sabrina Schatzman1, Benjamin Rambo-Martin1, Marie K. Kirby1, Todd Davis1, Han Di1
1 Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
Abstract Category
Avian influenza in mammals, pandemic preparedness, and one health