The zoonotic potential of avian influenza viruses isolated from wild waterfowl in Zambia

Abstract

Whilst remarkable progress in elucidating the mechanisms governing interspecies transmission and pathogenicity of highly pathogenic avian influenza viruses (AIVs) have been made, similar studies focusing on low pathogenic AIVs isolated from the wild waterfowl reservoir are limited.We previously reported that two AIV strains (subtypes H6N2 and H3N8) isolated from wild waterfowl in Zambia harbored some amino acid residues preferentially associated with human influenza virus proteins (so-called human signatures) and replicated better in the lungs of infected mice and caused more morbidity than a strain lacking such residues. To further substantiate these observations, we infected chickens and mice intranasally with AIV strains of various subtypes (H3N6, H3N8, H4N6, H6N2, H9N1 and H11N9) isolated from wild waterfowl in Zambia. Although some strains induced seroconversion, all the tested strains replicated poorly and were nonpathogenic for chickens. In contrast, most of the strains having human signatures replicated well in the lungs of mice, and one of these strains caused severe illness in mice and induced lung injury that was characterized by a severe accumulation of polymorphonuclear leukocytes. These results suggest that some strains tested in this study may have the potential to directly infect mammalian hosts without adaptation, which might possibly be associated with the possession of human signature residues. Close monitoring and evaluation of host-associated signatures may help elucidate the prevalence and emergence of AIVs with potential of causing zoonotic infections.

Evolution and pathogenicity of H6 avian influenza viruses isolated from Southern China during 2011 to 2017 in mice and chickens

“…The replication and transmission of H6N2 and H6N6 viruses were limited in SFP chicken in this study, although the pathological changes caused by H6N2 in chickens were reported in California 13 . Previous study showed that H6N2 isolates caused seroconversion in infected chickens, but no virus was recovered from the tissue samples, which suggested that the H6N2 strains replicated poorly and were nonpathogenic to chickens 52 . Our findings showed that the five H6 strains selected from different genotypes caused no clinical signs in any of the inoculated chickens, but the serological test results suggested that chickens in four groups have been infected despite limited recovery of inoculated viruses from the tissue samples.…”

Bushmeat and Emerging Infectious Diseases: Lessons from Africa

“…Cleaveland et al ( 2007 ), in their assessment of the risk of disease emergence by taxa, found that the relative risk of disease emergence was highest for bats, followed closely by primates, then ungulates and rodents. There have been surprisingly few studies of the connection between hunting of birds or other vertebrates and EIDs, especially in Africa, but surveillance for zoonotic pathogens in African birds is strongly needed (e.g., for avian infl uenza tracking see Simulundu et al 2011Simulundu et al , 2014.…”

Serologic Evidence of Occupational Exposure to Avian Influenza Viruses at the Wildfowl/Poultry/Human Interface

“…Human antibodies against the AIV-H13 subtype, previously detected in Asia, have been scarcely reported [ 9 ]. More frequent are cases of seropositivity to the AIV-H11 subtype that, as experimentally shown, has zoonotic potential to mammalian hosts [ 71 ]. Serological evidence of H11 infections have been previously reported in poultry workers [ 32 , 33 , 41 ] and—interestingly—in humans frequently exposed to wild birds for occupational or recreational purposes [ 69 , 72 ].…”