ABSTRACT
Brefeldin A (BFA) decreased the expression of influenza A virus haemagglutinin (HA) and M2 protein on the plasma membrane of virus-infected MDCK cells. It caused a retention of M1 protein in the cell nucleus and a decrease of its expression on the plasma membrane. On the other hand, an increased labelling of the cytoplasmic domain of M2 protein on the plasma membrane in BFA-treated cells was observed in contrast to the labelling in BFA-untreated cells. The effects of BFA on the microtubules and cellular motors are discussed.
Subject(s)
Cyclopentanes/pharmacology , Hemagglutinins, Viral/metabolism , Viral Matrix Proteins/metabolism , Animals , Antigens, Surface/metabolism , Biological Transport/drug effects , Brefeldin A , Cell Compartmentation/drug effects , Cell Line , Dogs , Immunohistochemistry , Ion Channels/metabolism , Membrane Proteins/metabolismABSTRACT
The influenza virus M2 protein has an ion channel activity that permits ions to enter the virion during its uncoating and also modulates pH of intracellular compartments. M2 protein is a homotetramer consisting of either a pair of disulfide-linked dimers or a disulfide-linked tetramer. The M2 trans-membrane domain peptide adopts an alfa helical secondary structure. In polarized cells, M2 protein is expressed at the apical cell surface. The amantadine-induced, M2-mediated conversion of influenza A virus haemagglutinin (HA) to the low pH conformation occurs in an acidic trans-Golgi compartment. The M2 protein ion channel activity can affect the conformation of cleaved HA during intracellular transport. The equine influenza virus 1 HA expressed from cDNA does not require coexpression of a functional M2 protein to maintain HA in its native conformation.
Subject(s)
Hemagglutinins, Viral/metabolism , Viral Matrix Proteins/metabolism , Animals , Biological Transport , Hemagglutinin Glycoproteins, Influenza Virus , Hemagglutinins, Viral/chemistry , Humans , Influenza A virus/metabolism , Ion Channels , Membrane Fusion , Protein Conformation , Viral Matrix Proteins/chemistryABSTRACT
Using horseradish peroxidase (HRP)-conjugated lectins for pre-embedding labelling we have shown differences in ultrastructural localization of saccharides in cell compartments of fowl plague (FP) virus-infected and uninfected MDCK cells. Lectinochemical staining of the cell compartments in the case of FP virus-infected MDCK cells was less intensive as compared with uninfected cells. Also certain differences in the staining of subcompartments of cell organells were seen. Staining of uninfected cells with Pisum sativum agglutinin (PSA)-HRP revealed an extensive visualization of Golgi complex, mainly its cis-part, TGN vesicles and lysosomes. Staining of FP virus-infected cells with the same lectin marked very lightly rough endoplasmic reticulum and not at all the Golgi complex. Staining with Erythrina cristagalli agglutinin (ECA)-HRP revealed a picture very similar to PSA-HRP staining of uninfected and FP virus-infected cells. The differences in the lectinochemical staining of cell organelles of FP virus-infected and uninfected cells may be connected with the inhibition of cell protein synthesis during FP virus morphogenesis.
