Mammalian sialidase Neu3 overexpression in Cos-7 cells causes a drastic decrease of ndv-cell fusion and virus infectivity

The paramyxovirus Newcastle Disease Virus (NDV) binds to sialic acid-containing glycoconjugates, sialoglycoproteins and sialoglycolipids (gangliosides) of host cell plasma membrane through its hemagglutinin-neuraminidase (sialidase) HN glycoprotein. We hypothesized that the modifications of the cell surface ganglioside pattern determined by over-expression of the mammalian plasma-membrane associated, ganglioside specific, sialidase NEU3 would affect the virus-host cell interactions. Using COS7 cells as a model system, we observed that over-expression of the murine MmNEU3 did not affect NDV binding but caused a marked reduction in NDV infection and virus propagation through cell-cell fusion. Moreover, since GD1a was greatly reduced in COS7 cells following NEU3-over-expression, we added [(3)H]-labelled GD1a to COS7 cells under conditions that block intralysosomal metabolic processing, and we observed a marked increase of GD1a cleavage to GM1 during NDV infection, indicating a direct involvement of the virus sialidase and host cell GD1a in NDV infectivity. Therefore, the decrease of GD1a in COS7 cell membrane upon MmNEU3 over-expression is likely to be instrumental to NDV reduced infection. Evidence was also provided for the preferential association of NDV-HN at 4 degrees C to detergent resistant microdomains (DRMs) of COS7 cells plasma membranes

Forensic DNA typing of human nails at various stages of decomposition

Forensic scientists often face the problem of extracting and typing human DNA from degraded materials such as muscle and bones from decomposed bodies. Bone samples are particularly difficult and time consuming to be analyzed and other body tissues suffer from rapid deterioration. Nails are a well-known source of DNA and their composition makes them less predisposed to decomposition compared to other soft tissues. With the aim of evaluating the usefulness of DNA extracted from aged human nails we analyzed nails taken either from exhumed and partially skeletonised bodies or from nail clippings stored at room temperature for 10-12 years. The adopted DNA extraction procedures yielded enough DNA for reliable PCR results even when no results were obtained either from soft or bone tissues. This study confirms the usefulness of nails as a source of DNA even in cases when PCR failed to amplify DNA extracted from bones