Three-dimensional elastic compatibility and varieties of twins in martensites.

We model a cubic-to-tetragonal martensitic transition by a Ginzburg-Landau free energy in the symmetric strain tensor. We show in three dimensions (3D) that solving the St. Venant compatibility relations for strain, treated as independent field equations, generates three anisotropic long-range potentials between the two order parameter components. These potentials encode 3D discrete symmetries, express the energetics of lattice integrity, and determine 3D textures. Simulation predictions include twins with temperature-varying orientation, helical twins, competing metastable states, and compatibility-induced elastic frustration. Our approach also applies to improper ferroelastics.

Selective interactions of the human immunodeficiency virus-inactivating protein cyanovirin-N with high-mannose oligosaccharides on gp120 and other glycoproteins.

The virucidal protein cyanovirin-N (CV-N) mediates its highly potent anti-human immunodeficiency virus activity, at least in part, through interactions with the viral envelope glycoprotein gp120. Here we dissect in further detail the mechanism of CV-N's glycosylation-dependent binding to gp120. Isothermal titration calorimetry (ITC) binding studies of CV-N with endoglycosidase H-treated gp120 showed that binding was completely abrogated by removal of high-mannose oligosaccharides from the glycoprotein. Additional ITC and circular dichroism spectral studies with CV-N and other glycoproteins as well showed that CV-N discriminately bound only glycoproteins that contain high-mannose oligosaccharides. Binding experiments with RNase B indicated that the single high-mannose oligosaccharide on that enzyme mediated all of its binding with CV-N (K(d) = 0.602 microM). A finer level of oligosaccharide selectivity of CV-N was revealed in affinity chromatography-liquid chromatography-mass spectrometry experiments, which showed that CV-N preferentially bound only oligomannose-8 (Man-8) and oligomannose-9 isoforms of RNase B. Finally, we biophysically characterized the interaction of CV-N with a purified, single oligosaccharide, Man-8. The binding affinity of Man-8 for CV-N is unusually strong (K(d) = 0.488 microM), several hundredfold greater than observed for oligosaccharides and their protein lectins (K(d) = 1 microM--1 mM), further establishing a critical role of high-mannose oligosaccharides in CV-N binding to glycoproteins.

Cyanovirin-N defines a new class of antiviral agent targeting N-linked, high-mannose glycans in an oligosaccharide-specific manner.

Herein we report that the novel HIV-inactivating protein cyanovirin-N (CV-N) targets specific, N-linked high-mannose oligosaccharides found on the viral envelope of HIV-1. First, we released the oligosaccharides by PnGase-treatment of HIV-gp120 (containing high-mannose, hybrid-type and complex-type oligosaccharides) or HSV-1 gC (containing only complex-type). Then, in an affinity chromatographic system, we found that CV-N bound to the free oligosaccharides from gp120 but not from gC-1, suggesting that high-mannose oligosaccharides constitute a target structure for CV-N. This was supported by the affinity of CV-N for high-mannose glycans released from gp120 by endo-H as well as high-mannose glycans released from castanospermine-treated HSV-1 gC. Furthermore, free Man-8 or Man-9 oligosaccharides partially inhibited the binding of CV-N to gp120, although neither oligosaccharides smaller than Man-7 nor monosaccharides interfered with CV-N/gp120 interaction, thereby establishing the oligosaccharide-specific affinity of CV-N to high-mannose glycans. This affinity for high-mannose oligosaccharides may explain the broad antiviral activity of CV-N against human and primate immunodeficiency retroviruses as well as certain other viruses that carry these oligosaccharides.

Analysis of the interaction between the HIV-inactivating protein cyanovirin-N and soluble forms of the envelope glycoproteins gp120 and gp41.

The novel virucidal protein cyanovirin-N (CV-N) binds with equally high affinity to soluble forms of either H9 cell-produced or recombinant glycosylated HIV-1 gp120 (sgp120) or gp160 (sgp160). Fluorescence polarization studies showed that CV-N is also capable of binding to the glycosylated ectodomain of the HIV-envelope protein gp41 (sgp41) (as well as SIV glycoprotein 32), albeit with considerably lower affinity than the sgp120/CV-N interaction. Pretreatment of CV-N with either sgp120 or sgp41 abrogated the neutralizing activity of CV-N against intact, infectious HIV-1 virions. Isothermal calorimetry and optical biosensor binding studies showed that CV-N bound to recombinant sgp120 with a K(d) value ranging from 2 to 45 nM and to sgp41 with a K(d) value of 606 nM; furthermore, they indicated an approximate 5:1 stoichiometry for CV-N binding to sgp120 and a 1:1 stoichiometry for CV-N binding to sgp41. Circular dichroism studies additionally illuminated the binding of CV-N with both sgp120 and sgp41, providing the first direct evidence that conformational changes are a consequence of CV-N interactions with both HIV-1 envelope glycoproteins.

Japanese encephalitis in Sangli district, Maharashtra.

During the months June to December, 1997, 52 cases of suspected viral encephalitis were admitted at the Government Hospital, Sangli. These cases were from the congested areas of Sangli and the adjoining villages. All age groups and both genders were affected. IgM antibodies to Japanese encephalitis (JE) virus were detected in the sera of five of the 52 cases. Perhaps JE virus has established itself in a new locality in Maharashtra and could cause serious public health problems.