[en] In an attempt to improve fixation technique for viral RNA detection by in situ hybridization, the authors have quantitatively compared the hybridization signal obtained when measles virus or visna virus infected cell cultures were fixed with eight different fixatives and hybridized with ³⁵S-labeled virus-complementary DNA probes of several size ranges. The highest signals were obtained with periodate-lysine-paraformaldehyde-glutaraldehyde (PLPG) fixed cells hybridized with small probes, and were 1.5- to 6.7-fold greater than those obtained with the commonly used fixative acetic ethanol. PLPG and other glutaraldehyde based fixatives also greatly improved the preservation of cellular morphology compared to acetic ethanol. (Auth.)

[en] A solid-phase radioimmunoassay was developed for the detection of antibodies against a specific region of the VP1 protein of the A24 and O1 serotypes of foot and mouth disease virus. The antibody titers from the radioimmunoassay showed a positive correlation with neutralizing antibody titers determined by a mouse protection assay. The specificity of the assay resides in the peptide used as antigen. The assay is rapid, reproducible and does not require the use of whole virions. (orig.)

[en] Nucleoprotein complexes, containing proteins covalently bound to DNA, were prepared from vaccinia virions irradiated with ultraviolet light. In the electron microscope, these complexes were observed to have a spherical morphology with a density staining central portion, apparently containing proteins cross-linked to DNA, from which loops or fibers of DNA or DNA complexed with protein emerged. (Auth.)

[en] A procedure has been developed which facilitates the detection of measles virus RNA sequences in human brains. The procedure involves isolating subviral components (nucleocapsids) from brain tissues prior to RNA purification, followed by hybridization of these RNAs to cDNA synthesized from measles virus 50 S RNA template. Using these techniques we were able to obtain an RNA fraction which was manyfold enriched in measles virus-specific RNA, relative to unfractionated subacute sclerosing panencephalitis (SSPE) brain RNAs. 70-100% of the measles virus-specific RNA present in these SSPE brain samples were recovered in this enriched fraction. (Auth.)

[en] A modified and improved technique for the detection of hepatitis B virus-specific DNA polymerase activity is described. DNA polymerase is released from Dane particles by mixing samples with the detergent Nonidet P-40 and β-mercaptoethanol. After incubation of pretreated samples with a reaction mixture containing tritiated thymidine-methyl-5'-triphosphate (³H-TTP), DNA is precipitated onto a trichloroacetic acid (TCA)-treated paper. Unincorporated ³H-TTP is then chromatographically eluted with a 5% solution and precipitated counts are determined. A sample is considered positive for DNA polymerase if the incorporated counts are significantly higher than the counts of a group of negative control samples. The modifications include pretreatment of the paper with TCA, chromatographic elution of unincorporated ³H-TTP with TCA solution, prefiltration of the sample through bacteriological filters, and use of sound statistical methods for evaluation of data. These changes have led to a highly reproducible, reliable and sensitive technique. The coefficient of variation of negative control samples from various test runs was in the range of 2.7-8.5%. A linear relationship between incorporated counts and DNA polymerase concentration was shown. (Auth.)

[en] The development of a sensitive solid-phase radioimmunoassay (RIA) procedure for the detection of specific antibodies against varicella-zoster (VZV) is described. The test proved to be about 200 times more sensitive than complement fixation (CF) and far more efficient at detecting low levels of antibody in the sera of individuals with past history of varicella. It is suggested that this RIA-VZV test would be suitable for distinguishing between individuals who are either immune or susceptible to varicella, which could be useful in a variety of clinical situations but particularly in current and future evaluations of varicella vaccines. (Auth.)

[en] A comparatively simple method for the purification of human erythrocyte receptors for encephalomyocarditis and influenza viruses is described. The procedure utilises the fact that these viruses share in common the erythrocyte receptor for wheat germ agglutin (WGA), which enables commercially available WGA-Sepharose to be used in the purification of receptors for these viruses by affinity chromatography. Conditions are also described for introducing either ¹²⁵I into the receptor in situ, or ³H-acetyl residues into the solubilised receptor. (Auth.)

[en] The standardisation of a terminal labelling cytotoxicity assay which used the incorporation of ³H-uridine to measure target cell survival of the effector phase is described. This assay was applied to a preliminary study of the cell-mediated responses of sheep following intravenous inoculation of Pi-3 virus. The assay provided a simple, accurate, and reproducible method to measure cytotoxic responses against Pi-3 infected target cells. The experimental data did not require mathematical corrections for nonspecific effects as in the ⁵¹Cr-release assay. When cytotoxicity could be detected in uninfected target cell cultures it was low and statistically insignificant. (Auth.)

[en] IgM antibody capture radioimmunoassay (MACRIA) and enzyme immunoassay (MACEIA) were compared with immunofluorescence (IF) for detecting specific IgM antibody in 99 sera from 76 infants with confirmed congenital rubella, and 61 sera from a comparative group of 59 infants who had miscellaneous abnormalities but in whom congenital rubella was not confirmed. All of 35 specimens collected from confirmed cases within 12 weeks of birth were positive by all three methods and all but one of 17 specimens collected after the age of 18 months were uniformly negative. At intermediate ages discrepancies occurred in 18 specimens, of which eight were positive and 10 negative by IF. Three of these 18 specimens were negative by both antibody capture procedures but showed weak fluorescence; the other 15 were negative by MACEIA, but positive by MACRIA which appears to be the more sensitive of the antibody capture methods. Sera from five infants in the comparative group were clearly positive by all three methods. These five infants were probably congenitally infected with rubella. Sera from the other 54 infants were negative, except for one that gave a weakly positive result by MACRIA alone. Antibody capture procedures offer several advantages over previous methods for detecting IgM antibody. Although MACRIA was found to be slightly more sensitive than MACEIA, the greater stability of the enzyme label, together with the possibility of both visual and quantitative assessment, could make MACEIA the method of choice for detecting rubella-specific IgM. (Auth.)

[en] The indirect radioimmunoassay (RIA) for detecting and assaying IgG class antibodies against varicella-zoster virus (VZV) can be improved by simple purification of the viral antigen. This is achieved by reducing binding to cellular components present in crude antigens. The purified antigen is particularly useful for testing sera that either bind excessively to normal control antigen or give equivocal results when crude antigens are used. (Auth.)