Characterization of murine leukemia virus recombinants that express H5N1 subtype avian influenza virus hemagglutinin glycoproteins

One highly pathogenic strain of avian influenza virus (AIV) was isolated from goose in China recently, designated as F 3 In order to study the viral entry mechanisms, the hemagglutinin(HA) gene of H5N1 subtype AIV isolate was amplified by RT PCR, and then cloned into pGEM D○R T vector and sequenced. The sequencing result has logging in GenBank, the accession number was AY639405 The HA gene of F 3 had a complete open reading frame (ORF) and composed of 1707 nucleotides, coding for 568 amino acids. The deduced amino acid sequence at the cleavage site of the HA protein was RKKR↓GLF, matched to the characteristic of virulent avian influenza strain. The HA gene were subcloned into pcDNA3, so the plasmid pcDNA HA can express the HA glycoprotein. Co transfected pcDNA HA, pHIT60(include Murine Leukemia Virus structural genes,namely gag and pol) and pHIT111(retroviral vector genome,containing LacZ as a reporter) into 293T cells. The retroviral supernatant were harvested 48 hours post transfection, filtered through 0 45μmol/L filter. The supernatant were used to analysis the characteristic of the pseudotyping virions by Western blotting and infection test. Western blotting revealed the HA glycoproteins can be expressed on the virions, indicated the glycoproteins were incorporated onto the retroviral virions. Infection test were performed on 293T、NIH3T3 and COS 7, all the three kinds of cells infected were lacZ positive, indicating viral entry, and revealed the pseudotype virions of MuLV HA were infectious. So the pseudotype system of MuLV particles with AIV Hemagglutinin proteins were setted up and it can be used to study the entry of avian influenza virus isolated from goose in China.