Highly conserved protective epitopes on influenza B viruses.

Identification of broadly neutralizing antibodies against influenza A viruses has raised hopes for the development of monoclonal antibody-based immunotherapy and "universal" vaccines for influenza. However, a substantial part of the annual flu burden is caused by two cocirculating, antigenically distinct lineages of influenza B viruses. Here, we report human monoclonal antibodies, CR8033, CR8071, and CR9114, that protect mice against lethal challenge from both lineages. Antibodies CR8033 and CR8071 recognize distinct conserved epitopes in the head region of the influenza B hemagglutinin (HA), whereas CR9114 binds a conserved epitope in the HA stem and protects against lethal challenge with influenza A and B viruses. These antibodies may inform on development of monoclonal antibody-based treatments and a universal flu vaccine for all influenza A and B viruses.

In vivo degradation of heparan sulfates in the glomerular basement membrane does not result in proteinuria.

Heparan sulfates (HS) are long, unbranched, negatively charged polysaccharides that are bound to core proteins. HS in the glomerular basement membrane (GBM) is reported to be important for charge-selective permeability. Aberrant GBM HS expression has been observed in several glomerular diseases, such as diabetic nephropathy and membranous glomerulopathy, and a decrease in HS generally is associated with proteinuria. This study, with the use of a controlled in vivo approach, evaluated whether degradation of HS in rat GBM resulted in acute proteinuria. Rats received two intravenous injections of either heparinase III to digest HS or neuraminidase to remove neuraminic acids (positive control). Urine samples were taken at various time points, and at the end of the experiment, kidneys were removed and analyzed. Injection with heparinase III resulted in a complete loss of glomerular HS as demonstrated by immunofluorescence staining using anti-HS antibodies and by electron microscopy using cupromeronic blue in a critical electrolyte concentration mode. In the urine, a strong increase in HS was found within 2 h after the first injection. Staining for agrin, the major HS proteoglycan core protein in the GBM, was unaltered. No urinary albumin or other proteins were detected at any time point, and no changes in glomerular morphology were noticed. Injection of rats with neuraminidase, however, resulted in a major increase of urinary albumin and was associated with an increase in urinary free neuraminic acid. An increased glomerular staining with Peanut agglutinin lectin, indicative of removal of neuraminic acid, was noted. In conclusion, removal of HS from the GBM does not result in acute albuminuria, whereas removal of neuraminic acid does.