Abstract
Historically, highly pathogenic avian influenza viruses (HPAIV) rarely resulted in infection or clinical disease in wild birds. However, since 2002, disease and mortality from natural HPAIV H5N1 infection have been observed in wild birds including gulls. We performed an experimental HPAIV H5N1 infection of black-headed gulls (Chroicocephalus ridibundus) to determine their susceptibility to infection and disease from this virus, pattern of viral shedding, clinical signs, pathological changes and viral tissue distribution. We inoculated sixteen black-headed gulls with 1 × 104 median tissue culture infectious dose HPAIV H5N1 (A/turkey/Turkey/1/2005) intratracheally and intraesophageally. Birds were monitored daily until 12 days post inoculation (dpi). Oropharyngeal and cloacal swabs were collected daily to detect viral shedding. Necropsies from birds were performed at 2, 4, 5, 6, 7, and 12 dpi. Sampling from selected tissues was done for histopathology, immunohistochemical detection of viral antigen, PCR, and viral isolation. Our study shows that all inoculated birds were productively infected, developed systemic disease, and had a high morbidity and mortality rate. Virus was detected mainly in the respiratory tract on the first days after inoculation, and then concentrated more in pancreas and central nervous system from 4 dpi onwards. Birds shed infectious virus until 7 dpi from the pharynx and 6 dpi from the cloaca. We conclude that black-headed gulls are highly susceptible to disease with a high mortality rate and are thus more likely to act as sentinel species for the presence of the virus than as long-distance carriers of the virus to new geographical areas.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-014-0084-9) contains supplementary material, which is available to authorized users.
Highlights
Highly pathogenic avian influenza viruses (HPAIV) were rarely found in wild birds, and, if they were, they typically did not cause clinical disease [1].in late 2002, highly pathogenic avian influenza viruses (HPAIV) H5N1 outbreaks were described in Hong Kong parks causing disease and death in wild local and migratory birds; concurrently with these outbreaks, HPAIV H5N1 were isolated from dead chickens and human beings [2]
In late 2002, HPAIV H5N1 outbreaks were described in Hong Kong parks causing disease and death in wild local and migratory birds; concurrently with these outbreaks, HPAIV H5N1 were isolated from dead chickens and human beings [2]
The main target organs for viral replication were central nervous system (CNS), pancreas, and adrenal gland, and the duration of the viral shedding after inoculation was in a range of 1 to 10 dpi depending on the isolate, the gull species, and inoculation route
Summary
Highly pathogenic avian influenza viruses (HPAIV) were rarely found in wild birds, and, if they were, they typically did not cause clinical disease [1].in late 2002, HPAIV H5N1 outbreaks were described in Hong Kong parks causing disease and death in wild local and migratory birds; concurrently with these outbreaks, HPAIV H5N1 were isolated from dead chickens and human beings [2]. The main target organs for viral replication were central nervous system (CNS), pancreas, and adrenal gland, and the duration of the viral shedding after inoculation was in a range of 1 to 10 dpi depending on the isolate, the gull species, and inoculation route.
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