The cleavage motif in the hemagglutinin (HA) protein of highly pathogenic H5 and H7 subtypes of avian influenza viruses is characterized by a peptide insertion or a multibasic cleavage site (MBCS). Here, we isolated an H4N2 virus from quails (Quail/CA12) with two additional arginines in the HA cleavage site, PEK. RRTR/G, forming an MBCS-like motif. Quail/CA12 is a reassortant virus with the HA and neuraminidase (NA) gene most similar to a duck-isolated H4N2 virus, PD/CA06 with a monobasic HA cleavage site. Quail/CA12 required exogenous trypsin for efficient growth in culture and caused no clinical illness in infected chickens. Quail/CA12 had high binding preference for α2,6-linked sialic acids and showed higher replication and transmission ability in chickens and quails than PD/CA06. Although the H4N2 virus remained low pathogenic, these data suggests that the acquisition of MBCS in the field is not restricted to H5 or H7 subtypes.
Bibliographical noteFunding Information:
We thank Jennifer DeBeauchamp, Jeri-Carol Crumpton, Ira Tigner Jr., and Demetrios Syndetos for excellent technical assistance. We would also like to thank Peter Vogel from the Veterinary Pathology Core facility and staff of the Animal Resource Center for animal care and husbandry assistance. This work was supported by the American Lebanese Syrian Associated Charities (ALSAC) and the National Institutes of Health/National Institute of Allergy and Infectious Diseases (NIH/NIAID) Center of Excellence for Influenza Research and Surveillance ( HHSN266200700005C ).
- Low pathogenic avian influenza
- Multibasic cleavage site