Virulence of Newcastle disease virus is determined by the cleavage site of the fusion protein and by both the stem region and globular head of the haemagglutinin-neuraminidase protein

Virulence of Newcastle disease virus (NDV) is mainly determined by the amino acid sequence surrounding the fusion (F) protein cleavage site, since host proteases that cleave the F protein of virulent strains are present in more tissues than those that cleave the F protein of non-virulent strains. Nevertheless, comparison of NDV strains that carry exactly the same F protein cleavage site shows that significant differences in virulence still exist. For instance, virulent field strain Herts/33 with the F cleavage site 112RRQRRF117 had an intracerebral pathogenicity index of 1.88 compared with 1.28 for strain NDFLtag, which has the same cleavage site. This implies that additional factors contribute to virulence. After generating an infectious clone of Herts/33 (FL-Herts), we were able to map the location of additional virulence factors by exchanging sequences between FL-Herts and NDFLtag. The results showed that, in addition to the F protein cleavage site, the haemagglutinin-neuraminidase (HN) protein also contributed to virulence. The effect of the HN protein on virulence was most prominent after intravenous inoculation. Interestingly, both the stem region and the globular head of the HN protein seem to be involved in determining virulenc

Determination of the shear strength of tropical hardwood timber

The current shear strength values for high density tropical hardwoods are very low compared to the values for softwoods, according to European strength class tables. The reason for this is that standardized tests according to European standard EN 408 have not been performed yet for tropical hardwoods. In this research, tropical hardwood species massaranduba was investigated according to EN 408. The test results give a 5%-value for the shear strength of massaranduba that is twice as high as the standardized value for strength class D70. No relation was found between the density and the shear strength for massaranduba. Shear strength was proportional to the density when compared to spruce. Steel & Composite Structure

Determination of the shear strength of tropical hardwood timber

The current shear strength values for high density tropical hardwoods are very low compared to the values for softwoods, according to European strength class tables. The reason for this is that standardized tests according to European standard EN 408 have not been performed yet for tropical hardwoods. In this research, tropical hardwood species massaranduba was investigated according to EN 408. The test results give a 5%-value for the shear strength of massaranduba that is twice as high as the standardized value for strength class D70. No relation was found between the density and the shear strength for massaranduba. Shear strength was proportional to the density when compared to spruce. </p