Isolation of a genotypically unique H5N1 influenza virus from duck meat imported into Japan from China

Abstract

An H5N1 influenza A virus was isolated from duck meat processed for human consumption, imported to Japan from Shandong Province, China in 2003. This virus was antigenically different from other H5 viruses, including the Hong Kong H5N1 viruses isolated from humans in 1997 and 2003. Sequence analysis revealed that six genes (PB1, PA, HA, NA, M, and NS) of this virus showed >97% nucleotide identity with their counterparts from recent H5N1 viruses, but that the remaining two genes (PB2 and NP) were derived from other unknown viruses. This duck meat isolate was highly pathogenic to chickens upon intravenous or intranasal inoculation, replicated well in the lungs of mice and spread to the brain, but was not as pathogenic in mice as H5N1 human isolates (with a dose lethal to 50% of mice (MLD50)=5x10(6) 50% egg infectious doses [EID50]). However, viruses isolated from the brain of mice previously infected with the virus were substantially more pathogenic (MLD50=approximately 10(2) EID50) and possessed some amino acid substitutions relative to the original virus. These results show that poultry products contaminated with influenza viruses of high pathogenic potential to mammals are a threat to public health even in countries where the virus is not enzootic and represent a possible source of influenza outbreaks in poultry.

The effect of age on the pathogenesis of a highly pathogenic avian influenza (HPAI) H5N1 virus in Pekin ducks (Anas platyrhynchos) infected experimentally

“…Although the H5N1 viruses isolated in 1997 and subsequent 1997‐like viruses isolated up to 2002 did not replicate efficiently in ducks, 13 , 14 recent H5N1 viruses were found to replicate in multiple organs, particularly the brain, instead of ‘conventional’ gastrointestinal tract replication, and consequently caused death in geese, ducks and swans 15 , 16 , 17 , 18 , 19 , 20 , 21 . However, there is some evidence that HPAI viruses may enter the brain in sub‐clinical infections of ducks 22 .…”

Association of Increased Pathogenicity of Asian H5N1 Highly Pathogenic Avian Influenza Viruses in Chickens with Highly Efficient Viral Replication Accompanied by Early Destruction of Innate Immune Responses

“…These viruses usually kill chickens 3 to 6 days after intranasal inoculation. On the other hand, the recently emerged Asian H5N1 HPAI viruses are more virulent and kill chickens within 1 to 2 days without causing typical clinical signs and gross lesions (5,12,27,33,48,51), although some Asian H5N1 viruses, such as A/Goose/Guangdong/2/96 (23), A/goose/ Hong Kong/437-10/99 (17), and A/chicken/Indonesia/7/03 (58), were less virulent. To successfully control HPAI in poultry, it is important to better understand the mechanisms of increased pathogenicity of recent H5N1 HPAI viruses in chickens.…”

“…However, the roles of proinflammatory cytokines in disease severity and outcomes in chickens infected systemically with HPAI viruses are largely unknown. The less-virulent Asian H5N1 virus, which causes severe clinical signs and gross lesions in chickens (17,23,27,58), would be a valuable tool for investigating the role of proinflammatory cytokines in chickens infected with HPAI viruses, as well as for exploring the pathogenesis of the morevirulent Asian H5N1 HPAI virus, because of the antigenic and molecular similarities between them.…”

Isolation and characterization of an H10N7 avian influenza virus from poultry carcasses smuggled from China into Italy

“…Although HPAI of the H5N1 subtype has been isolated from frozen duck meat imported from China into South Korea (Tumpey et al ., 2002) and from China into Japan (Mase et al ., 2005), this appears to be the first report of isolation of a LPAI virus from an imported poultry product. These findings are in keeping with the experimental findings of Swayne & Beck (2005), who report of the isolation of LPAI H7N2 from the respiratory tract, gut and body washing but not from meat of experimentally infected chickens.…”