Newcastle disease incubation

In a typical labeling procedure (Wisnieski and Bramhall, 1981), Newcastle disease vims (0.045 mg protein ml-1), the particles of which are bounded by a membrane, were incubated with 12-(4-azido-2-nitrophe-noxy)stearoylglucosamine (50 mCi mmol- ) at a concentration of 1.3 pM. After 15 min at 37°C the sample was irradiated. 

Reports of antiviral activity have been mainly confined to (XXV), R = p -Cl and R = p-OMe). The compounds were active in vitro only when pre-incubated with virus and have no effect on the replicative cycle of influenza, parainfluenza, measles, herpes and Newcastle disease viruses. There was however, some inhibition of growth of ECHO, rhinovirus, rubella and respiratory syncytial virus when the compounds were added... 

Quinoline-4,7-bisthiocarboxamide (XXXVIl) is said to inhibit the infec-tivity of Newcastle disease virus completely after 1 hour of extracellular incubation at 1 mg/ml [180]. By analogy with the dihydroisoquinolines this compound may be active in vivo. A series of 2,6-dialkoxypyrans and 2,6-alkoxy-d -dihydropyrans were also examined for extracellular virus inhibitory activity. The most active compound of the series against infiuenza virus was (XXXVIll) but no details of the test were given [181]. Further compounds in this series have recently been reported [182]. 

Figure 3. Human conjunctival mucosa following reaction with FITC labeled lectins. Controls. Pretreatment with neuraminidases of sections (3a Vibrio cholerae prior to LFA incubation, 3c Newcastle disease virus prior to MAA incubation) and preincubation of lectins with Fetuin (3b with LFA, 3d with MAA) reduced or abolished the labeling results. Bar equals 50/xm. 

One of the problems encountered in studies of viral cytopathic effects is to quantitate the number of cells undergoing changes or dying. Some indication of the number of cells involved can be obtained by estimating those that fail to exclude dyes because of altered membrane impermeability. A more accurate, but somewhat tedious technique was designed by Marcus and Puck (1958). These authors devised a means to study quantitatively the destruction of mammalian cell reproductive capacity by scoring the fraction of monodisperse HeLa cells infected with Newcastle disease virus to survive and form colonies over a period of 8-10 days incubation. They concluded that one virus particle was sufficient to kill a single cell. This method has been extended to other viruses by Marcus (1959) and can be used to... 

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