Mapping the hemagglutination domain of rotaviruses.

Most strains of animal rotaviruses are able to agglutinate erythrocytes, and the surface protein VP4 is the virus hemagglutinin. To map the hemagglutination domain on VP4 while preserving the conformation of the protein, we constructed full-length chimeras between the VP4 genes of hemagglutinating (YM) and nonhemagglutinating (KU) rotavirus strains. The parental and chimeric genes were expressed in insect cells, and the recombinant VP4 proteins were evaluated for their capacity to agglutinate human type O erythrocytes. Three chimeric genes, encoding amino acids 1 to 208 (QKU), 93 to 208 (QC), and 93 to 776 (QYM) of the YM VP4 protein in a KU VP4 background, were constructed. YM VP4 and chimeras QKU and QC were shown to specifically hemagglutinate, indicating that the region between amino acids 93 and 208 of YM VP4 is sufficient to determine the hemagglutination activity of the protein.     

Comparison of rotavirus strains by hemagglutination inhibition.

Rotaviruses have been shown to be of importance as aetiologic agents of gastroenteritis in infants and in domestic animals of several species. Hemagglutinins were prepared from two Canadian isolates of bovine rotavirus and from one isolate of a simian rotavirus. A United Kingdon isolate of bovine rotavirus was shown not to possess hemagglutinating activity, indicating a strain difference between a Canadian and United Kingdom bovine rotavirus. In hemagglutination-inhibition (HAI) tests a rabbit hyperimmune (two injections) serum, prepared to one of the bovine rotaviruses, was not helpful in distinguishing the two bovine viruses because of cross-reactions between the viruses. However, it was possible to distinguish the bovine viruses from the simian virus with this serum. When guinea pig immune sera were prepared to the four rotavirus strains and tested with the three hemagglutinins in the HAI test, antigenic differences between the four strains of rotavirus were demonstrated. Hyperimmune guinea pig serum prepared to a strain of human rotavirus did not inhibit any of three hemagglutinins indicating that the human strain is different from the three rotavirus strains which gave hemagglutinins.     

Fibrinogen-fibrin degradation products: hemagglutination inhibition immunoassay in plasma.

Immunoassay for fibrinogen and/or fibrin degradation products (FDP) is generally in the clot and hence assay of serum may not reveal the true concentration of FDP in blood. We have developed a hemagglutination inhibition immunoassay for FDP in human plasma. D fragment appears to possess an antigenic determinant, called D-neoantigen, not found in native fibrinogen. Rabbit antiserum produced against D fragment was absorbed with immunosorbent columns coupled with fibrinogen and normal human serum, respectively, so that it contained only those antibodies directed against the neoantigenic determinant of D fragment. In this immunoassay, sheep erythrocytes (SRBC) were stabilized with glutaraldehyde and subsequently sensitized with D fragment by means of tannic acid. Hemagglutination of absorbed anti-D-neoantigen serum against SRBC sensitized with D fragment was titered to be 1:256. The hemagglutination was inhibited by D fragment but not by fibrinogen; the sensitivity of detecting D fragment was 8 mug/ml. Human plasma from normal subjects did not inhibit. This appears to be the first report of a hemagglutination inhibition immunoassay for FDP in plasma.     

Detection of antibody to Varicella-Zoster virus by immune adherence hemagglutination.

A serologic test for measurement of antibody to V-Z virus by immune adherence hemagglutination is described. Initial evaluation of the test has shown it to be highly sensitive, specific, rapid, and simple to perform. The V-Z antigen may be stored at -70 degrees, and the test could be performed in any routine serology laboratory.