June 18, 2025

New article explores transmissibility of bovine-derived HPAI H5N1 virus in pigs

An article co-authored by the Director of the Center of Excellence for Emerging and Zoonotic Animal Diseases (www.ceezad.org) and the Center on Emerging and Zoonotic Infectious Diseases (CEZID; https://www.k-state.edu/cezid/) contributes to the understanding of the pathogenicity and transmissibility of the bovine-derived HPA1 H5N1 virus in pigs.

The article was co-authored by Dr. Juergen A. Richt, Regents and University Distinguished Professor at Kansas State University and director of CEEZAD and CEZID. It was published in the April 2025 edition of the Journal of Virological Methods. Other co-authors include Taeyong Kwon, Jessie Trujillo, Konner Cool, Eu Lum Lyoo, Gagandeep Singh, Sujan Kafle, Shanmugasundaram Elango, Govindsamy Vediyappan, Franco S. Matias-Ferreyra, Igor Morozov, and Natasha Gaudreault, all of CEEZAD, and Lisa Hensley of the National Bio and Agro-defense Facility in Manhattan, KS.

Since the first emergence of highly pathogenic avian influenza (HPAI) H5N1 viruses in dairy cattle, the virus has continued to spread, reaching 17 states and at least 1000 dairy herds in the United States. Subsequently, spillovers of the virus from dairy cattle to humans have been reported.

Pigs are an important reservoir in influenza ecology because they serve as a mixing vessel in which novel reassortant viruses with pandemic potential can be generated.

In this study, CEEZAD scientists show that oro-respiratory infection of pigs resulted in productive replication of a bovine-derived HPAI H5N1 B3.13 virus. Infectious virus was mainly identified in the lower respiratory tract of principal infected pigs, and sero-conversion was observed in most of the principal pigs at later time points.

In one animal, researchers detected the emergence of a mutation in hemagglutinin (HA) previously associated with increased affinity for "mammalian-type" α2,6-linked sialic acid receptors, but this mutation did not reach consensus levels. Sentinel contact pigs remained sero-negative throughout the study, indicating lack of transmission. The results support the conclusion that pigs are susceptible to a bovine-derived HPAI H5N1 B3.13 virus, but this virus did not replicate as robustly in pigs as and swine-adapted influenza viruses.

Pathogenicity and transmissibility of bovine-derived HPAI H5N1 B3.13 virus in pigs - PubMed