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Asian lineage highly pathogenic avian influenza virus (H5N1) continues to cause mortality in poultry and wild bird populations at a panzootic scale. However, little is known about its persistence in contaminated tissues derived from infected birds. We investigated avian influenza virus (H5N1) persistence in feathers detached from bodies of infected ducks to evaluate their potential risk for environmental contamination. Four-week-old domestic ducks were inoculated with different clades of avian influenza virus (H5N1). Feathers, drinking water, and feces were collected on day 3 postinoculation and stored at 4°C or 20°C. Viral persistence in samples was investigated for 360 days by virus isolation and reverse transcription-PCR. Infectious viruses persisted for the longest period in feathers, compared with drinking water and feces, at both 4°C and 20°C. Viral infectivity persisted in the feathers for 160 days at 4°C and for 15 days at 20°C. Viral titers of 104.3 50% egg infectious doses/ml or greater were detected for 120 days in feathers stored at 4°C. Viral RNA in feathers was more stable than the infectivity. These results indicate that feathers detached from domestic ducks infected with highly pathogenic avian influenza virus (H5N1) can be a source of environmental contamination and may function as fomites with high viral loads in the environment. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the two H5N1 highly pathogenic avian influenza (HPAI) virus infected whooper swans found in Akita, Japan. The researchers pathologically studied the subjects, one of which is an adult while the other a young bird. The study found the adult bird with severe necrotizing pancreatitis and mild nonpurulent encephalitis while the young bird had severe nonpurulent encephalitis and nonpurulent enteric ganglionitis and intestinal venous wall thickening. Also, the researchers had detected virus antigens in both swans. Moreover, from the gathered evidences, the researchers found that the swans died or became moribund due to neurological disorders and necrotizing pancreatitis caused by avian influenza virus.

The article discusses the susceptibility of whooper swans on contacting the avian flu virus (H5N1) due to its migration behaviors. It notes that the swans infected with H5N1 display asymptomatic characteristics. The immunohistochemical tests demonstrate the presence of virus antigens on feather epidermis. It cites the application of genetic sequence using paraffin section which confirmed the avian influenza virus on swans. Moreover, it suggests that feathers increase the risk of zoonotic infection on wild swans.

On April 21, 2008, four whooper swans were found dead at Lake Towada, Akita prefecture, Japan. Highly pathogenic avian influenza virus of the H5N1 subtype was isolated from specimens of the affected birds. The hemagglutinin (HA) gene of the isolate belongs to clade 2.3.2 in the HA phylogenetic tree. [ABSTRACT FROM AUTHOR]

We examined feathers of domestic ducks and geese inoculated with 2 different avian influenza virus (H5N1) genotypes. Together with virus isolation from the skin, the detection of viral antigens and ultrastructural observation of the virions in the feather epidermis raise the possibility of feathers as sources of infection. [ABSTRACT FROM AUTHOR]

Abstract: At the end of May 2005, a low-pathogenicity avian influenza (LPAI) virus of subtype H5N2 was isolated for the first time from chickens in Japan. Through active and epidemiological surveillance, 5.78 million chickens on 41 farms were found to be affected and 16 H5N2 viruses were isolated. Antigenic analysis revealed antigenic similarity of these isolates. Phylogenetic analysis showed that they originated from a common ancestor and clustered with the H5N2 strains prevalent in Central America that have been circulating since 1994. Experimental infection of chickens with the index isolate (A/chicken/Ibaraki/1/05) demonstrated that this virus replicated efficiently in the respiratory tract without clinical signs, and dust-borne and/or droplet-borne transmission was considered as a possible mode of transmission. These results suggested that the H5N2 LPAI viruses isolated in Japan were highly adapted to chickens. [Copyright &y& Elsevier]

Abstract: The effect of cotton textiles containing Cu2+ held by zeolites (CuZeo-textile) on the inactivation of H5 subtype viruses was examined. Allantoic fluid (AF) containing a virus (AF virus) (0.1ml) was applied to the textile (3×3-cm), and incubated for a specific period at ambient temperature. After each incubation, 0.9ml of culture medium was added followed by squeezing to recover the virus into the medium. The recovered virus was titrated using Madin–Darby canine kidney (MDCK) cells or 10-day-old embryonated chicken eggs. The highly pathogenic H5N1 and the low pathogenic H5N3 viruses were inactivated on the CuZeo-textile, even after short incubation. The titer of A/chicken/Yamaguchi/7/04 (H5N1) in MDCK cells and in eggs declined by >5.0 log10 and 5.0log10, respectively, in 30s. The titer of A/whooper swan/Hokkaido/1/08 (H5N1) in MDCK cells declined by 2.3 and 3.5 in 1 and 5min, respectively. When A/whistling swan/Shimane/499/83 (H5N3) was treated on the CuZeo-textile for 10min, the titer declined by >5.0log10 in MDCK cells and by >3.5log10 in eggs. In contrast, no decrease in the titers was observed on cotton textiles containing zeolites alone (Zeo-textile). Neither cytopathic effects nor NP antigens were detected in MDCK cells inoculated with the H5N1 virus treated on the CuZeo-textile. The viral genes (H5, N1, M, and NP) were amplified from the virus treated on the CuZeo-textile by RT-PCR. The hemagglutinating activity of the CuZeo-textile treated virus was unaffected, indicating that virus–receptor interactions were maintained. Electron microscopic analysis revealed a small number of particles with morphological abnormalities in the H5N3 virus samples recovered immediately from the CuZeo-textile, while no particles were detectable in the 10-min treated sample, suggesting the rapid destruction of virions by the Cu2+ in the CuZeo-textile. The loss of infectivity of H5 viruses could, therefore, be due to the destruction of virions by Cu2+. Interestingly, CuCl2 treatment (500 and 5000μM) did not have an antiviral effect on the AF viruses (H5N1 and H5N3) even after 48h of incubation, although the titer of the purified H5N3 virus treated with CuCl2 declined greatly. The antiviral effect was inhibited by adding the AF to the purified H5N3 virus prior to the CuCl2 treatment. The known antibacterial/antifungal activities of copper suggest that the CuZeo-textile can be applied at a high level of hygiene in both animals and humans. [Copyright &y& Elsevier]

Abstract: From February to March 2009, six strains of H7N6 subtype avian influenza virus were isolated from quails in three farms in Aichi prefecture in Japan. The isolates were shown to be low pathogenic for chicken by the examination performed using the “Manual of Standards for Diagnostic Tests and Vaccines” by World organisation for Animal Health (OIE). The deduced amino acid sequence at the cleavage site was PE (I/Q/L) PKRR (nucleotide sequences were cct gaa (a/c) (t/a) a cc (a/g) aaa aga aga), suggesting persistence in domestic poultry for some time. The direct putative ancestor strain could not be elucidated by phylogenetic analysis of all genome segments of the quail isolates. Diverged date from a putative common ancestor in a non-rooted phylogenetic tree among quail viruses was estimated between March 2002 and July 2004. Three putative N-linked glycosylation sites resided in the vicinity of the receptor binding pocket of HA1 region. They are considered to decrease the reactivity of neutralizing antibody against the virus. Experiments for the infectivity and pathogenicity of a quail strain to poultry indicated that the quail isolate had higher infectivity to quails than chickens and ducks. Direct and dust-borne and/or droplet-borne transmissions among quail were proven in quails with and without direct contact with experimentally infected quails. The virus is seldom transmitted among chickens either directly or indirectly, and indirect transmission from infected quails to chickens was not observed. The pathogenicity of the quail strain for mammalian, pig and mouse was low, although it could replicate in those animals. [ABSTRACT FROM AUTHOR]