ABSTRACT
Four new H9N2 avian influenza viruses (AIVs) were isolated from domestic birds in Guangdong between December 2015 and April 2016. Nucleotide sequence comparisons indicated that most of the internal genes of these four strains were highly similar to those of human H7N9 viruses. Amino acid substitutions and deletions found in the HA and NA proteins indicated that all four of these new isolates may have an enhanced ability to infect humans and other mammals. A cross-hemagglutinin-inhibition assay, conducted with two vaccine strains that are broadly used in China, suggested that antisera against vaccine candidates could not provide complete inhibition of the new isolates.
Subject(s)
Antigens, Viral/genetics , Evolution, Molecular , Influenza A Virus, H9N2 Subtype/genetics , Influenza in Birds/virology , Poultry Diseases/virology , Animals , China , Ducks , Geese , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Humans , Influenza A Virus, H9N2 Subtype/classification , Influenza A Virus, H9N2 Subtype/isolation & purification , Influenza, Human/virology , Open Reading Frames , PhylogenyABSTRACT
We report the full-length sequence of two chicken source influenza A (H7N9) viruses found in Guangdong live poultry market (LPM) during the most recent wave of human infections (from October 2016 to the present time). These viruses carry insertion of poly-basic amino acids (KGKRTAR/G) at the protease cleavage site of the HA protein, which were previously found in the highly pathogenic (HP) human influenza A (H7N9) [IAV(H7N9)] strains. Phylogenetic analysis of these two novel avian influenza viruses (AIVs) suggested that their genomes reassorted between the Yangtze River Delta (YRD) and Pearl River Delta (PRD) clades. Molecular clock analysis indicated that they emerged several months before the HP human strains. Collectively, our results suggest that IAV(H7N9) viruses evolve in chickens through antigenic drift to include a signature HP sequence in the HA gene, which highlights challenges in risk assessment and public health management of IAV(H7N9) infections at the human-animal interface.
Subject(s)
Amino Acids, Basic/genetics , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Influenza A Virus, H7N9 Subtype/genetics , Influenza A Virus, H7N9 Subtype/isolation & purification , Influenza in Birds/virology , Mutagenesis, Insertional , Animals , Chickens , Evolution, Molecular , Genome, Viral , Phylogeny , Reassortant Viruses/genetics , Reassortant Viruses/isolation & purification , Whole Genome SequencingABSTRACT
The analytical method of melamine in milk and milk powder by high performance liquid chromatography (HPLC) was established. The sample was purified by a cation exchange solid-phase extraction column, separated on a Diamonsil C18 column (4.6 mm x 200 mm, 5 microm) with acetonitrile-0.01 mol/L sodium heptanesulfonate (pH 3.3) (10:90, v/v) as mobile phase at a flow rate of 1.0 mL/min, and determined by a photodiode array detector. A linear calibration curve was obtained in the concentration range of 1 - 500 mg/L. The qualification limit was 0.2 mg/kg, and the quantification limit was 1 mg/kg. The recovery was 81.4% -83.7%.