The mechanism of hemagglutination by influenza virus

George K, Hewlett IK, Linnen JM, Norris PJ. Sensitive detection assays for influenza RNA do not reveal viremia in US blood donors

BACKGROUND

There have been anecdotal reports of influenza viremia since the 1960s. We present an assessment of the prevalence of seasonal and 2009 H1N1 influenza viremia (via RNA testing) in blood donor populations using multiple sensitive detection assays.

METHODS

Several influenza RNA amplification assays, including transcription-mediated amplification (TMA) and 2 reverse-transcription polymerase chain reaction (RT-PCR) assays, were evaluated and used to test donor samples. Retrospective samples from 478 subjects drawn at sites with high influenza activity were tested. Prospective samples were collected from 1004 blood donors who called their donation center within 3 days of donation complaining of influenza-like illness (ILI). The plasma collected on the day of donation for these subjects was tested.

RESULTS

Of the repository samples, 2 of 478 plasma samples were initially reactive but not repeat reactive by influenza TMA. Of blood donors reporting ILI symptoms postdonation, 1 of 1004 samples was TMA initially reactive but not repeat reactive; all samples were nonreactive by RT-PCR testing.

CONCLUSIONS

Targeting blood donor populations most likely to have influenza infection, we failed to detect influenza RNA in 1482 donor samples, with most tested by 3 different RNA assays. Seasonal influenza does not appear to pose a significant contamination threat to the blood supply.

Characteristics of para-influenza 1 (HA-2) virus. III. Antigenic relationships, growth, interaction with erythrocytes, and physical properties

Dick, Elliot C. (Tulane University School of Medicine, New Orleans, La.) and William J. Mogabgab. Characteristics of para-influenza 1 (HA-2) virus. III. Antigenic relationships, growth, interaction with erythrocytes, and physical properties. J. Bacteriol. 83:561-571. 1962-Hemagglutination-inhibition tests with rabbit and rooster immune sera showed HA-2-like strains of para-influenza 1 to be nearly as closely related antigenically to para-influenza 3 (HA-1) virus as to the Sendai strain of para-influenza 1; however, convalescent sera from humans infected with para influenza 1 virus exhibited four-fold or greater increases in antibody to HA-2 and Sendai viruses, but seldom to HA-1.Para-influenza 1 (HA-2) infectivity was destroyed within 2 hr at temperatures approaching 50 C; at 36 C, infective virus disappeared by 80 hr. At a temperature of 44 C or below, the hemagglutinin (HA) titer remained unchanged for 100 hr; but at temperatures above this, hemagglutinin was destroyed rapidly. Virus infectivity was found to be most stable at very slightly acid or neutral pH and to be increasingly labile at pH values more extreme than 5.7 and 8.7. Hemagglutinin was generally more resistant than infectivity to extremes of reaction; this was most notable in the alkaline range. In primary monkey-kidney tissue culture, virus was adsorbed in 5 hr, new infective virus was noted in 11 to 15 hr, and maximal amounts were detected at 60 hr and maintained through 132 hr. Production of hemagglutinin paralleled that of infectivity. The tcid(50)/HA ratio was approximately 4.5. With human type "O" erythrocytes, the HA titer of Copenhagen 222 virus suspensions was raised two- to fourfold by increasing the temperature of reaction and sedimentation from 4 C to room temperature. It could not be demonstrated that this thermal effect was due either to an increased total adsorption at an elevated temperature or to a greater rate of adsorption; the rate of hemagglutination was, however, increased by fourfold at the higher temperature.

AN ELECTRON MICROSCOPE EXAMINATION OF URINARY MUCOPROTEIN AND ITS INTERACTION WITH INFLUENZA VIRUS

A hemagglutination-inhibitory mucoprotein from human urine has been studied with the electron microscope. It consists of filaments, with diameters of 40 to > 240 A, composed of smaller fibrils. In the two-dimensional projection of the electron micrographs, the single fibrils often show a zig-zag course with a periodicity of 100 to 140 A; the single branch of a zig-zag measures about 60 A in length and either 20 or 40 A in width. Still thinner fibrillar elements are observable with diameters of 10 A or less. In three-dimensional aspect, the zig-zag structure might be a helix. The fibril-bundle (or filament) reveals a complicated configuration. Heat treatment at 70 degrees C shows some indication of denaturation (e.g. filaments are shorter), whereas at 80 degrees C almost complete degradation of the protein into individual zig-zag elements or smaller pieces is attained. The interaction between influenza virus particles and inhibitory mucoprotein consists of the attachment of a fiber molecule to the virus projections at several sites and frequently on more than one virus particle.

A study of the cell surface of tumour, foetal and lymph-node cells by cell electrophoresis after antibody and enzymic treatment

1. Rabbit anti-(rat foetal liver) serum, absorbed with adult rat liver cells, decreased the electrophoretic mobility of foetal liver cells by 51% and rat hepatoma cells by 45%, indicating the presence of a foetal-type antigen on the hepatoma cell membrane. 2. The chemical nature of the surface antigen was investigated. Incubation with neuraminidase had no effect on adult liver cells but decreased the electrophoretic mobility of foetal liver cells by 51% and of hepatoma cells by 34%; the effect of antiserum was decreased to one-fifth. 3. Sialic acid, or the supernatant from neuraminidase-treated cells, partially blocked the decrease in electrophoretic mobility induced by antiserum. 4. The pH-electrophoretic mobility curves of hepatoma cells treated with antisera were consistent with a sialic acidcontaining antigen on the surface of the tumour cells. 5. Treatment with ribonuclease did not decrease the electrophoretic mobility of adult-liver cells, but decreased that of the foetal liver cells by 17% and hepatoma cells by 29%. 6. In parallel studies made with mouse BP8 ascites-tumour cells ribonuclease decreased the electrophoretic mobility by 39%, that of normal mouse lymph-node cells by 4.8% and allergized mouse lymph-node cells by 13.3%. 7. Trypsin treatment also decreased the electrophoretic mobility of hepatoma cells by 22%.

Virus-erythrocyte interactions

This chapter summarizes the experimental evidence bearing on the nature of virus-erythrocyte reactions characteristic of several taxonomic groups.. Such evidence is culled from (1) the study of conditions necessary for hemagglutination; (2) the examination of specific factors affecting either the cell or the virion to enhance, alter, or abolish the reaction; and (3) the direct physicochemical analysis of cells, viruses, and “receptor analogs.” The hemadsorption phenomenon also provides evidence for virus-erythrocyte interactions, which is based on the attachment of erythrocytes to infected cells in culture having hemagglutinin at their surfaces. This phenomenon reflects the interaction between erythrocytes and viral envelope components. The major virus groups that react with erythrocytes include myxoviruses, paramyxoviruses, pseudomyxoviruses, adenoviruses, arboviruses, reoviruses, enteroviruses, and miscellaneous hemagglutinating viruse (rubella virus, coronaviruses, rhabdoviruses, and oncogenic viruses). The agglutination of erythrocytes by the direct action of viral particles was first described in connection with myxoviruses. This led directly to the discovery of viral neuraminidase—a property unique to myxoviruses and paramyxoviruses. A number of viruses unrelated to myxoviruses have since been shown to agglutinate erythrocytes of various species. The visible result of viral hemagglutination is the “pattern” formed at the bottom of a test tube or well plate by lattices of red cells lightly conjoined by viral hemagglutinin. Hemagglutination serves as a useful direct means of titering intact viral particles or hemagglutinating subunits.