Pathobiology of A/Chicken/Hong Kong/220/97 (H5N1) Avian Influenza Virus in Seven Gallinaceous Species

Abstract

Abstract. Direct bird-to-human transmission, with the production of severe respiratory disease and human mortality, is unique to the Hong Kong-origin H5N1 highly pathogenic avian influenza (HPAI) virus, which was originally isolated from a disease outbreak in chickens. The pathobiology of the A/chicken/Hong Kong/ 220/97 (H5N1) (HK/220) HPAI virus was investigated in chickens, turkeys, Japanese and Bobwhite quail, guinea fowl, pheasants, and partridges, where it produced 75-100% mortality within 10 days. Depression, mucoid diarrhea, and neurologic dysfunction were common clinical manifestations of disease. Grossly, the most severe and consistent lesions included splenomegaly, pulmonary edema and congestion, and hemorrhages in enteric lymphoid areas, on serosal surfaces, and in skeletal muscle. Histologic lesions were observed in multiple organs and were characterized by exudation, hemorrhage, necrosis, inflammation, or a combination of these features. The lung, heart, brain, spleen, and adrenal glands were the most consistently affected, and viral antigen was most often detected by immunohistochemistry in the parenchyma of these organs. The pathogenesis of infection with the HK/220 HPAI virus in these species was twofold. Early mortality occurring at 1-2 days postinoculation (DPI) corresponded to severe pulmonary edema and congestion and virus localization within the vascular endothelium. Mortality occurring after 2 DPI was related to systemic biochemical imbalance, multiorgan failure, or a combination of these factors. The pathobiologic features were analogous to those experimentally induced with other HPAI viruses in domestic poultry.

Persistence of highly pathogenic avian influenza virus (H7N1) in infected chickens: feather as a suitable sample for diagnosis

“…Similarly, H5N1 HPAIV has also been detected in feather follicles of gallinaceous species at 1 day p.i. (Perkins & Swayne, 2001). However, information on other HPAIV subtypes is scarce.…”

Infectious and Lethal Doses of H5N1 Highly Pathogenic Avian Influenza Virus for House Sparrows (Passer Domesticus) and Rock Pigeons (Columbia Livia)

“…Procedures used to perform and interpret the IHC examination followed those previously described. 23 …”

A comparative evaluation of feathers, oropharyngeal swabs, and cloacal swabs for the detection of H5N1 highly pathogenic avian influenza virus infection in experimentally infected chickens and ducks

“…7,8 In contrast to low pathogenic avian Influenza A virus (LPAI virus) infection, in which replication is associated primarily with the mucosa of the gastrointestinal and respiratory tracts, 25 the H5N1 HPAI virus is found in multiple organs of infected birds. 2,25,31 The case fatality in chickens is ~100%, 9,11,14 while in ducks it is less severe and may not even induce clinical signs, 2,11,27,31 although some viruses have been reported to cause high fatality in ducks. 23,28 Findings have shown that the virus is able to replicate in feather structures of infected ducks and chickens, as indicated by either the isolation of virus or the presence of viral antigen in feather structures.…”

“…23,28 Findings have shown that the virus is able to replicate in feather structures of infected ducks and chickens, as indicated by either the isolation of virus or the presence of viral antigen in feather structures. 2,14,38,39 Several diagnostic methods, such as virus isolation (VI) and antigen and RNA detection tests, have been used to detect H5N1 virus in infected birds. 21,36 Oropharyngeal and cloacal swabs are the samples recommended for detecting avian influenza viruses, 17,34,36 and have been widely used for avian influenza surveillance.…”