ABSTRACT
Influenza viruses belonging to the Orthomyxoviridae family are enveloped viruses with segmented negative sense RNA genome surrounded by a helical symmetry shell. Influenza viruses, especially the highly pathogenic avian influenza virus (HPAI) such as H5 or H7 subtype are important pathogens for the poultry industry. Due to genetic reassortments between avian and human influenza viruses, global pandemics may emerge and the naive human immunity could not be ready for them. The full-length HA-encoding gene of H5N2 AIV was inserted into a secretory pPICZalphaA vector and integrated into the genome of Pichia pastoris by heterologous recombination. The HA protein secretion into the medium was induced with methanol. Besides the expected 69kDa protein, another smaller fragment about 47kDa was recognized by an anti-AIV-HA monoclonal antibody in Western blot assay. This is the first report on the cleavage of HA(0) into HA(1) and HA(2) in the methylotrophic yeast P. pastoris. This possibly was due to digestion by proteases from P. pastoris based on the amino acid sequences at the predicted cleavage site, (326)R-X-K-R(329). With similar modifications to the eukaryotes, large quantity, proper antigenicity, and low cost, this expression system may provide a simple tool to produce HA proteins for further use in preparation of ELISA kits and subunit vaccines.
Subject(s)
Hemagglutinin Glycoproteins, Influenza Virus/immunology , Hemagglutinin Glycoproteins, Influenza Virus/metabolism , Influenza A Virus, H5N2 Subtype/immunology , Pichia/genetics , Antibodies, Monoclonal/immunology , Antibodies, Viral/immunology , Blotting, Western , Epitopes , Genes, Viral , Genetic Vectors , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Influenza A Virus, H5N2 Subtype/genetics , Peptide Hydrolases/metabolism , Pichia/metabolism , Plasmids , Recombinant Proteins/metabolism , Recombination, Genetic , Transformation, GeneticABSTRACT
RNA interference (RNAi) was used to suppress bovine ephemeral fever virus (BEFV). Plasmids expressing continuously shRNAs were used against G gene of BEFV to induce RNA interference in cultured cells. A GFP reporter assay was established to determine the efficiency and specificity of siRNA and the potential of BEFV to hamper RNAi. Two of five small interfering RNAs (siRNAs) were shown to suppress BEFV. Suppression of the G gene of BEFV corresponded with reduction of viral plaques and progeny titer. The results suggest that RNAi has the potential for use in suppression of BEFV infection with possible therapeutic implications.
