Aerosol Transmission of Gull-Origin Iceland Subtype H10N7 Influenza A Virus in Ferrets

Abstract

Subtype H10 influenza A viruses (IAVs) have been recovered from domestic poultry and various aquatic bird species, and sporadic transmission of these IAVs from avian species to mammals (i.e., human, seal, and mink) are well documented. In 2015, we isolated four H10N7 viruses from gulls in Iceland. Genomic analyses showed four gene segments in the viruses were genetically associated with H10 IAVs that caused influenza outbreaks and deaths among European seals in 2014. Antigenic characterization suggested minimal antigenic variation among these H10N7 isolates and other archived H10 viruses recovered from human, seal, mink, and various avian species in Asia, Europe, and North America. Glycan binding preference analyses suggested that, similar to other avian-origin H10 IAVs, these gull-origin H10N7 IAVs bound to both avian-like alpha 2,3-linked sialic acids and human-like alpha 2,6-linked sialic acids. However, when the gullorigin viruses were compared with another Eurasian avian-origin H10N8 IAV, which caused human infections, the gull-origin virus showed significantly higher binding affinity to human-like glycan receptors. Results from a ferret experiment demonstrated that a gull-origin H10N7 IAV replicated well in turbinate, trachea, and lung, but replication was most efficient in turbinate and trachea. This gullorigin H10N7 virus can be transmitted between ferrets through the direct contact and aerosol routes, without prior adaptation. Gulls share their habitat with other birds and mammals and have frequent contact with humans; therefore, gull-origin H10N7 IAVs could pose a risk to public health. Surveillance and monitoring of these IAVs at the wild bird-human interface should be continued. IMPORTANCE Subtype H10 avian influenza A viruses (IAVs) have caused sporadic human infections and enzootic outbreaks among seals. In the fall of 2015, H10N7 viruses were recovered from gulls in Iceland, and genomic analyses showed that the viruses were genetically related with IAVs that caused outbreaks among seals in Europe a year earlier. These gull-origin viruses showed high binding affinity to humanlike glycan receptors. Transmission studies in ferrets demonstrated that the gullorigin IAV could infect ferrets, and that the virus could be transmitted between ferrets through direct contact and aerosol droplets. This study demonstrated that avian H10 IAV can infect mammals and be transmitted among them without adaptation. Thus, avian H10 IAV is a candidate for influenza pandemic preparedness and should be monitored in wildlife and at the animal-human interface.

The Role of Bcl-xL Protein in Viral Infections

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Characterization of Avian Influenza Virus H10–H12 Subtypes Isolated from Wild Birds in Shanghai, China from 2016 to 2019

“…Avian influenza viruses (AIVs) isolated from birds can be divided into H1–H16 and N1–N9 subtypes based on the antigenic characteristics of the two surface proteins, hemagglutinin (HA) and neuraminidase (NA) [ 1 ]. Wild birds are natural hosts of a variety of AIVs [ 2 ], especially Charadriiformes and Anseriformes, which are distributed throughout the world [ 3 , 4 ]. Some AIV subtypes are rather species specific, such as H5, H7 and H9 subtypes of AIVs that are endemic in poultry [ 5 ].…”

Avian influenza virus prevalence in marine birds is dependent on ocean temperatures

“…In addition, other hosts, particularly marine mammals become infected by avian influenza viruses with periodic mortality events. Recent outbreaks in Northern Europe (Krog et al 2015) and in the northeastern United States (Anthony et al 2012) resulted in the deaths of many harbor seals (Phoca vitulina) with distinct risks of virus adaptation to mammalian hosts and potential to infect nearby human populations (Karlsson et al 2014, Guan et al 2019.…”