Experimental Infection of Bar-Headed Geese (Anser indicus) and Ruddy Shelducks (Tadorna ferruginea) With a Clade 2.3.2 H5N1 Highly Pathogenic Avian Influenza Virus

Abstract

Since 2005, clade 2.2 H5N1 highly pathogenic avian influenza (HPAI) viruses have caused infections and morbidity among numerous species of wild waterfowl in Eurasia and Africa. However, outbreaks associated with clade 2.3.2 viruses have increased since 2009, and viruses within this clade have become the dominant strain of the H5N1 HPAI virus detected in wild birds, reaching endemic status in domestic birds in select regions of Asia. To address questions regarding the emergence and expansion of clade 2.3.2 viruses, 2 waterfowl species repeatedly involved in outbreaks of H5N1 HPAI viruses, bar-headed geese (Anser indicus) and ruddy shelducks (Tadorna ferruginea), were inoculated with a representative virus. All of 3 infected ruddy shelducks exhibited neurologic signs and died within 4 to 5 days. Two of 3 infected bar-headed geese had transient weakness but all survived. Viral shedding was predominately via the oropharynx and was detected from 1 to 7 days after inoculation. The severity and distribution of microscopic lesions corresponded with clinical disease and influenza-specific immunohistochemical staining of neurons. The predominant lesions were in the brain and were more severe in ruddy shelducks. Increased caspase-3 reactivity in the brains of all infected birds suggests a role for apoptosis in H5N1 HPAI virus pathogenesis in these species. These results demonstrate that similar to clade 2.2 viruses, a clade 2.3.2 H5N1 HPAI virus is neurotropic in some waterfowl species and can lead to neurologic disease with varying clinical outcomes. This has implications for the role that wild waterfowl may play in transmission of this virus in endemic regions.

Pathogenicity and tissue tropism of currently circulating highly pathogenic avian influenza A virus (H5N1; clade 2.3.2) in tufted ducks ( Aythya fuligula )

“…The findings are also in accordance with natural infection of tufted ducks with clade 2.2 virus (Bröjer et al, 2009) and clade 2.3.3 virus (Abdo et al, 2014). Lesions are also comparable to those seen in whooper swans (Ogawa et al, 2009;Okamatsu et al, 2010) and in ruddy shelducks and bar-headed geese experimentally infected with clade 2.3.2HPAI-H5N1 virus (A/bar-headed goose/ Mongolia/X53/2009) (Nemeth et al, 2013).…”

“…Studies in naturally infected whooper swans (Cygnus cygnus) (Ogawa et al, 2009;Okamatsu et al, 2010) in Japan as well as experimentally infected domestic ducks , ruddy shelducks (Tadorna ferruginea) and bar-headed geese (Nemeth et al, 2013) showed that the clade 2.3.2 viruses are highly pathogenic in wild birds. On the other hand, other data suggest that some of the clade 2.3.2 viruses are not as highly pathogenic since they were demonstrated in apparently healthy ducks (Kajihara et al, 2011;Kim et al, 2011).…”

Pathogenicity and Transmission of H5 and H7 Highly Pathogenic Avian Influenza Viruses in Mallards

“…Many studies have examined the pathogenicity of Gs/GD H5N1 HPAI viruses in domestic duck species and captive reared mallards (reviewed in reference 10), but only a limited number of studies have investigated the pathogenicity of other H5 and H7 HPAI viruses in domestic ducks species (38, 40, 43-46, 53, 54) and in nondomestic ducks (17,18,47,48,55,56). In most of these studies, virus infection, shedding, and transmission were not thoroughly examined.…”

Corneal Opacity in Domestic Ducks Experimentally Infected With H5N1 Highly Pathogenic Avian Influenza Virus

“…2,3,4,17,20,[27][28][29]40,52 Except for our previous reports using the same duck species as in the present study, 51,54 to our knowledge only 1 report of immunohistochemical findings in waterfowl is available, where viral antigen was detected in the corneal and ciliary epithelial cells of Muscovy ducks experimentally infected with H5N1 HPAI virus. 31 However, Muscovy ducks were histologically examined only on day 2 PI in this study and lacked the description of morphologic change of the eye.…”