Haemagglutinin and neuraminidase characterization of low pathogenic H5 and H7 avian influenza viruses isolated from Northern pintails (Anas acuta) in Japan, with special reference to genomic and biogeographical aspects

Abstract

Pintails constitute an important host of avian influenza viruses (AIVs). Genetic, molecular, and antigenic characteristics of H5 and H7 AIVs, which we isolated from northern pintails (Anas acuta) wintering in Japan, were analyzed and found to be linked to various ecological features, chiefly in terms of gene geography, as shaped by various migratory aquatic host species. Although all the isolates were found to be of low pathogenicity (LP), we explored gene predispositions that may potentially underlie tentative transition to high pathogenicity (HP). Evolutionarily, the HA and NA genes of the isolates affiliated mostly with Eurasian lineage. The viruses closely related to ours were derived from China, Korea, Mongolia, Japan, and Australia. Comprehensive ecophylogenetic evaluations revealed that the pintail populations we sampled might have given rise to or been involved in the emergence of a LPAI H7N6 subtype that caused outbreaks in quail (Coturnix japonica) farms in Japan, as well as of the first H5N9 subtype ever isolated in Asia. The latter strain isolated by us showed, yet, notable affinity to certain North American and Australian strains, thereby signifying apparent intercontinental interfaces accounted for by extensive water-bird flyways. Noticeable conservation of certain antigenic sites within both Eurasian and North American H7 HAs is apparently an outcome of their advantageous survival value, in terms of restricted immunogenicity. Besides, the Japanese-Korean-Siberian regional axis seems to be particularly important for ongoing generation of novel viral strains due to conveyance of certain genes and genomes by migratory ducks, including such that circulate among pigs and human.

Evidence of persistence and multiple genetic modifications of H7N7 low-pathogenic avian influenza virus in wild mallards in Poland provided by phylogenetic studies

“…Interestingly, Jahangir et al (2009) found a high isolation rate of AIV H7N7 in northern pintails (Anas acuta) in wintering season 2007/ 08 in Japan, and similarly to our studies, on one occasion the virus was detected twice at one site, 2 months apart. A phylogenetic study of H7 and N7 genes revealed that these isolates were very similar or virtually identical (Jahangir et al, 2010).However, the high frequency of H7N7 isolation in that region was noted exclusively in one wintering season as opposed to our study in which we demonstrated the presence of AIV with genetically related genes between two consecutive winter seasons in the same area.…”

“…Despite the great importance, there are few reports describing phylogenetic analysis of H7N7 strains isolated from their natural reservoir (Campitelli et al, 2008;Jahangir et al, 2010;Metreveli et al, 2010). Furthermore, there is still little information dealing with virushost ecology.…”

Genetic Analysis of Avian Influenza Viruses: Cocirculation of Avian Influenza Viruses with Allele A and B Nonstructural Gene in Northern Pintail (Anas acuta) Ducks Wintering in Japan

“…Also, we analyzed the NS genes of H5 and H7 subtypes, in addition to the above-mentioned AIVs. Moreover, polymerase acid (PA), nucleoprotein (NP), M, and NS genes of H5N9 strain, an uncommon antigenic combination which we isolate for the first time in Asia [19], were further looked into in the present study.…”

Efficacy of scallop shell powders and slaked lime for inactivating avian influenza virus under harsh conditions

“…The transmission of AIVs is possible between migrating birds and domestic poultry through synanthropic avian species or direct contact with birds in poultry farms [11]. Some countries have decided to use vaccination as the strategy to stop the disease from spreading [3,14,22,24,28,33].…”

“…Madin-Darby canine kidney (MDCK) cells were employed for culturing of low-pathogenic AIV (LPAIV) H7N1 (A/duck/Aomori/395/04) [11]. The cells were cultured in Eagle's minimum essential medium (EMEM; Nissui Pharmaceutical Co., Ltd., Tokyo, Japan), supplemented with 0.3 % of tryptose phosphate broth, 5 % fetal of bovine serum (FBS), L-glutamine (0.3 mg/mL), NaHCO 3 (1.4 mg/mL), and antibiotic-fungicide cocktail (penicillin [100 IU/mL], streptomycin [0.1 mg/mL] and amphotericin B [0.5 lg/mL]).…”