Evolution of H5N1 avian influenza viruses in Asia World Health Organization Global Influenza Program Surveillance Network, /; Aubin, Jean-Thierry; Azebi, Saliha ...
Emerging infectious diseases,
10/2005, Volume:
11, Issue:
10
Journal Article
Peer reviewed
Open access
An outbreak of highly pathogenic avian influenza A (H5N1) has recently spread to poultry in 9 Asian countries. H5N1 infections have caused > or =52 human deaths in Vietnam, Thailand, and Cambodia ...from January 2004 to April 2005. Genomic analyses of H5N1 isolates from birds and humans showed 2 distinct clades with a nonoverlapping geographic distribution. All the viral genes were of avian influenza origin, which indicates absence of reassortment with human influenza viruses. All human H5N1 isolates tested belonged to a single clade and were resistant to the adamantane drugs but sensitive to neuraminidase inhibitors. Most H5N1 isolates from humans were antigenically homogeneous and distinct from avian viruses circulating before the end of 2003. Some 2005 isolates showed evidence of antigenic drift. An updated nonpathogenic H5N1 reference virus, lacking the polybasic cleavage site in the hemagglutinin gene, was produced by reverse genetics in anticipation of the possible need to vaccinate humans.
1 Unité de Virologie Médicale, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cédex 15,
2 Laboratoire de Virologie, Université Lariboisère-St Louis, Paris VII, Hôpital St Lazare, 75010 Paris, ...France
and 3 Istituto di Microbiologia, Università di Bologna, Policlinico S. Orsola, Via Massarenti 9, 40138 Bologna, Italy
A monoclonal antibody (MAb), N2, neutralized human cytomegalovirus (HCMV) infectivity in the absence of complement and recognized a normal cell protein. By immunofluorescence, MAb N2 detected antigens in uninfected human cells, but not in cells of non-human origin. Antigens were present at the membrane and were dispersed diffusely within the cytoplasm. MAb N2 immunoprecipitated a glycoprotein with an M r of 94K from uninfected and infected cells. In infected cells only, it also recognized a protein of M r 34K which was not linked to the 94K M r glycoprotein by disulphide bonds. N2 neutralized both laboratory and field isolates of HCMV. A study of the distribution of the N2 neutralization epitope recognized among fresh isolates of HCMV showed that only 67% of the isolates could be neutralized by this antibody. There was no correlation between the number of in vitro passages and the level of neutralization. The 34K M r polypeptide was present in cells infected by all isolates. It thus appears that, during virus assembly, HCMV acquires a normal cell protein that bears a neutralization epitope.
Keywords: CMV, human, MAb, neutralization
Received 19 April 1988;
accepted 2 November 1988.
Human cytomegalovirus, a DNA virus whose genome contains a fragment of transforming DNA, induces a threonine‐serine protein kinase having a molecular mass of 68 kDa (p68). p68 was extracted from ...cells 96–144 h after infection, and immunoprecipitated with a monoclonal antibody (F6b). Antibody‐enzyme complexes were immobilized on heat/formaldehyde‐inactivated Staphylococcus aureus.
The best substrates for p68 were acidic proteins, phosvitin and casein. Glycogen synthase, phosphorylase a and histones were phosphorylated at rates not higher than 1–4% that obtained with phosvitin as substrate. ATP and GTP were equally good substrates of p68. p68 is able to autophosphorylate at the same residues (i.e. threonine and serine) as the protein substrates. Autophosphorylation does not seem to represent an intermediate in substrate phosphorylation.
The protein kinase activity of p68 was not enhanced by cAMP, calcium ions, or polyamines like spermine or spermidine. Only at low Mg2+ concentration spermine enhanced by 68% the rate of casein phosphorylation. Heparin, a potent inhibitor of casein kinase II, inhibits p68 activity too, but ten‐times higher concentrations were required for the same degree of inhibition. Quercetin, a bioflavonoid, acts as a strong inhibitor of p68 protein kinase activity. The inhibitory effect of quercetin was competitive towards the nucleotide substrate (Ki= 2.8 μM), and non‐competitive towards the protein substrate (Ki= 15 μM).
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