Chlamydial hemagglutinin identified as lipopolysaccharide.

Chlamydial lipopolysaccharide (LPS) agglutinated mouse and rabbit erythrocytes but not human, guinea pig, or pronghorn antelope erythrocytes. Hemagglutination was not specific for Chlamydia spp., as rough LPSs from Coxiella burnetii and Escherichia coli also agglutinated erythrocytes from the same animal species. Nonagglutinated and agglutinated erythrocytes bound equivalent amounts of LPS, indicating that hemagglutination was not due to a specific interaction of chlamydial LPS with erythrocytes. Thus, hemagglutination by chlamydial LPS is not mediated by specific receptor-ligand interactions but is a property of the altered surface of the LPS-coated erythrocytes.     

Chitin-binding hemagglutinin produced by Conidiobolus strains.

A hemagglutinin was produced by strains of Conidiobolus which also produce beta-N-acetylglucosaminidase. Activity of the hemagglutinin was inhibited by D-glucosamine, N-acetyl-D-glucosamine, D-mannosamine, and beta-N-acetyl-D-glucosaminides but not by D-glucose, D-mannose, and alpha-N-acetyl-D-glucosaminides.     

Hierarchical analysis of influenza A hemagglutinin gene sequences.

Five recently sequenced hemagglutinin genes from Influenza A virus strains are studied for similarities in a hierarchical fashion. The sequences are compared for similarity, first on the level of sequence homology, and then on several progressively more general levels. Though the HA1 subsequences contain regions where homology drops to that of a Monte Carlo generated reference value, subsequent tests reveal great similarity due to constraints on the level of amino acid sequence. Other tests detect statistically significant differences between subtypes due to constraints acting below the level of amino acid sequence, such as the 2 degrees structure of the viral RNA, or involving translation of the mRNA. The general applicability of the hierarchical approach to sequence analysis is discussed.     

Physicochemical properties of Nebraska calf diarrhea virus hemagglutinin.

Highly purified Nebraska calf diarrhea virus (NCDV) was prepared by cesium chloride density gradient centrifugation. The effect of temperature, pH, different concentrations of formaldehyde, chloroform, ether, ethyl alcohol, and methyl alcohol on NCDV hemagglutinin and virus morphology was studied. NCDV hemagglutinin was inactivated by temperature, pH 2.0, chloroform, ethyl alcohol, and methyl alcohol.     

Extracellular localization of a nonfimbrial hemagglutinin of Yersinia pseudotuberculosis.

A nonfimbrial hemagglutinin (HA) of Yersinia pseudotuberculosis was observed by immunoelectron microscopy using monospecific HA antiserum and protein A-gold conjugate. The HA, an amorphous but morphologically identifiable entity, was located in a region distal to or detached from the outer edge of bacteria.     

Retrovirus-expressed hemagglutinin protects against lethal influenza virus infections.

An influenza virus hemagglutinin gene, H7, has been expressed in a replication-competent Schmidt-Ruppin Rous sarcoma virus-derived vector. This virus, P1/H7, expressed a glycosylated precursor of the H7 protein which was processed to a mature form and transported to the cell surface. The expressed H7 glycoprotein could not be detected in P1/H7 virus particles. A P1/H7 stock which expressed 5 to 10% of the level of H7 observed in influenza virus-infected chicken embryo fibroblasts was used to immunize 1-month-old chickens. This immunization resulted in low or undetectable levels of hemagglutination-inhibiting and neutralizing antibody. Despite the low serum response, challenge with a highly pathogenic H7N7 virus revealed complete protection against lethal infection.     

Purification and characterization of a hemagglutinin from Arachis hypogeae.

A. hypogaea hemagglutinin was purified by ammonium sulfate fractionation and Sepharose 6 B column chromatography. The homogeneity of the purified hemagglutinin was ascertained by ultracentrifugal analysis and polyacrylamide gel electrophoresis. It has a molecular weight of 106.500 and is a tetramer of a subunit with a molecular weight of 27.000. The purified hemagglutinin agglutinated neuraminidase-treated human erythrocytes regardless of their ABO group type, but did not agglutinate intact erythrocytes. In hapten inhibition assays with simple sugars, the so-called M?kel?'s group 2 sugars, which bear the same configuration of hydroxy groups at C-3 and C-4 as D-galactopyranose, were inhibitors for this hemagglutinin. It does not contain any carbohydrate, in contrast to most phytohemagglutinins except concanavalin A and wheat germ agglutinin.