Newcastle disease virus (NDV) is one of the most important infectious agents in the poultry industry, and vaccines against it have been widely used for prevention and control. Live vaccines, which can replicate in the respiratory and digestive systems, have been especially needed in areas with outbreaks of viscerotropic velogenic Newcastle disease. Towards the goal of searching for a new live vaccine candidate, avian paramyxovirus type 1 (APMV-1) was isolated from the faeces of wild birds. Three APMV-1 strains thus isolated were characterized in terms of phylogeny, pathogenicity, immunogenicity and tissue tropism, and on the basis of these analyses were classified as lentogenic genotype I NDV. CBU2179, one of the three APMV-1 strains, was selected and was evaluated in terms of its efficacy and safety in specific pathogen-free chickens and commercial broilers. The manufactured trial vaccine from this strain, also called CBU2179, induced similar immune responses to those of VG/GA and B1 commercial vaccines, and provided 100% protection against challenge from viscerotropic velogenic NDV, KJW/49 strain (the official challenge strain in Korea). Also, the CBU2179 virus was re-isolated and persisted as long as or longer than other vaccine strains in both the respiratory and alimentary tracts. Therefore, the CBU2179 strain may represent a good candidate for a live Newcastle disease vaccine to protect chickens against viscerotropic velogenic NDV.
Growth behavior of tin whiskers from pure tin and tin-bismuth plated leadframe (LF) packages for elevated temperature and high humidity storages and during thermal cycling was observed. In the storage at 60°C/93% relative humidity (RH) and 85°C/85%RH the galvanic corrosion occurred at the outer lead toes and shoulders where the base LF material is exposed, forming tin oxide layers of SnO 2 . The corroded layers spread inside the film and formed whiskers around the corroded islands. Many whiskers were observed to grow from grain boundaries for the Fe-42Ni alloy (alloy42) LF packages. It was confirmed that the corrosion tends to occur on the side surfaces of outer leads adjacent to the mold flash. The contribution of ionic contaminants in epoxy mold compound (EMC) to the corrosion was not identified. During thermal cycling between À65°C and +150°C whiskers grew out of as-deposited grains for pure tin plated alloy42 LF packages and they grew linearly with an increase of number of cycle. Growth mechanisms of the whiskers from grain boundaries and asdeposited grains were discussed from the deformation mechanism map for tin and mathematical calculation with a steady-state diffusion model.
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