Replication and pathogenesis associated with H5N1, H5N2, and H5N3 low-pathogenic avian influenza virus infection in chickens and ducks

Abstract

A comparative study examining replication and disease pathogenesis associated with low-pathogenic H5N1, H5N2, or H5N3 avian influenza virus (AIV) infection of chickens and ducks was performed. The replication and pathogenesis of highly pathogenic AIV (HPAIV) has received substantial attention; however, the behavior of low-pathogenic AIVs, which serve as precursors to HPAIVs, has received less attention. Thus, chickens or ducks were inoculated with an isolate from a wild bird [A/Mute Swan/MI/451072/06 (H5N1)] or isolates from chickens [A/Ck/PA/13609/93 (H5N2), A/Ck/TX/167280-4/02 (H5N3)], and virus replication, induction of a serological response, and disease pathogenesis were investigated, and the hemagglutinin and neuraminidase (NA) gene sequences of the isolates were determined. Virus isolated from tracheal and cloacal swabs showed that H5N1 replicated better in ducks, whereas H5N2 and H5N3 replicated better in chickens. Comparison of the NA gene sequences showed that chicken-adapted H5N2 and H5N3 isolates both have a deletion of 20 amino acids in the NA stalk region, which was absent in the H5N1 isolate. Histopathological examination of numerous organs showed that H5N2 and H5N3 isolates caused lesions in chickens in a variety of organs, but to a greater extent in the respiratory and intestinal tracts, whereas H5N1 lesions in ducks were observed mainly in the respiratory tract. This study suggests that the H5N1, H5N2, and H5N3 infections occurred at distinct sites in chicken and ducks, and that comparative studies in different model species are needed to better understand the factors influencing the evolution of these viruses.

Role of Poultry in the Spread of Novel H7N9 Influenza Virus in China

“…The results of these studies are consistent with those of previous studies indicating that chicken-adapted AIVs replicate better in chickens than in ducks (45,46). The underlining mechanism is not clear, but a shorter neuraminidase protein due to a deletion in the stalk region may be linked to this feature (47)(48)(49).…”

Receptor-Binding Profiles of H7 Subtype Influenza Viruses in Different Host Species

“…Thus, deletions in the stalk of the NA that affect its catalytic activity are commonly observed in H5 and H7 poultry influenza viruses but not in their putative duck precursors (2,8,31,33). Emergence of the NA stalk deletions as the first essential change in the duck influenza viruses during their experimental adaptation to poultry was confirmed in several independent studies (22,26,30,40). In addition to deletions in the NA, HA mutations leading to emergence of new glycosylation sites near the RBS of H5 and H7 influenza viruses correlate with virus isolation from poultry.…”

A Genetically Engineered Waterfowl Influenza Virus with a Deletion in the Stalk of the Neuraminidase Has Increased Virulence for Chickens

“…Like for low-pathogenicity viruses, nephrotropism and nephropathogenicity were observed mostly upon intravenous inoculation in chickens (12,67,68). The presence of viral RNA in the kidneys, or renal and liver lesions, was reported following intranasal inoculation of chicken-origin H9N2 or H5N2 virus, respectively (43, 44), but was not observed following intratracheal or intranasal inoculation of waterfowl viruses (44,67). Our present data demonstrate that the liver as well as kidneys can become sites of active viral replication following intratracheal inoculation of a low-pathogenicity duck-origin influenza virus.…”