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Biomedical subjects

H Thormar

Publications and source records attributed to H Thormar.

At least 91 records · Page 5Linked to original sources
PubMed1974

Neutralizing activity in isolated serum antibody fractions from visna-infected sheep.

The neutralization technique was used to detect specific antibodies against visna virus in isolated immunoglobulin (Ig) G(1), IgG(2), and IgM fractions of visna-infected sheep serum. The neutralizing antibodies were present chiefly in the IgG(1) class. Low amount of activity was demonstrated in the IgM class, but no significant activity was seen in the IgG(2) class.

Animals↗
PubMed1974

Substructures and polypeptides of Visna virus.

The protein of Visna virus, disrupted by 8 M guanidine hydrochloride and heating, was resolved into 10 polypeptides by agarose gel column chromatography in 6 M guanidine hydrochloride. Two of the peaks contained glycopolypeptides. Nonidet-disrupted virions were resolved into two fractions by potassium tartrate gradient centrifugation, with densities of 1.08 and 1.24 g/ml, respectively. About 70% of the viral DNA polymerase directed by added template was released into the light fraction, in which very little endogenous enzyme activity was detected. Also released into the light fraction were all of the glycopolypeptides, 50% of the viral RNA, and a part of each of the other viral protein components. The data indicate that extensive degradation of subviral structures occurred, even under mild conditions for virion disruption. The 1.24-g/ml fraction was composed of 50% of the viral RNA, most of the endogenous DNA polymerase activity (80%), and a major internal polypeptide (GuHCl6) with an estimated mol wt of 28,000. Two other polypeptides were also consistently detected in the heavy fraction, but they constituted less than 25% of the ribonucleoprotein complex, compared with 75% for GuHCl6.

Amino Acids↗
PubMed1972

Properties of maedi nucleic acid and the presence of ribonucleic acid- and deoxyribonucleic acid-dependent deoxyribonucleic acid polymerase in the virions.

Maedi virus contains a ribonucleic acid (RNA) which can be resolved into three major components, namely, 62S, 33S, and 13S, by sucrose gradient centrifugation. The presence of RNA- and deoxyribonucleic acid (DNA)-dependent DNA polymerase in virions of maedi virus was demonstrated. The enzyme product could be converted into acid-soluble form by pancreatic deoxyribonuclease, but was resistant to digestion by pancreatic ribonuclease and to hydrolysis by NaOH.

Animals↗
PubMed1971

Antibodies produced by rabbits immunized with visna virus.

Immunization of New Zealand White rabbits with purified visna virus elicited antibody activity demonstrated by passive hemagglutination (PHA), complement fixation (CF), and indirect immunofluorescent tests. The antibody activities of hyperimmune sera and Sephadex G-200 fractions of the sera were studied. It was found that the PHA test was 10 to 100 times more sensitive than the CF test in detecting visna antibodies in rabbits. It was also found that the immunoglobulin M fractions from Sephadex G-200 filtration displayed greater PHA activity than did the immunoglobulin G fractions. Although neutralizing antibody was demonstrated in the serum of the natural host (sheep), our attempts to demonstrate neutralizing antibody in the sera from hyperimmunized rabbits (non-natural host) so far have failed.

Animals↗
PubMed1971

Characterization of ribonucleic acid from visna virus.

A single-stranded ribonucleic acid(s) has been isolated from purified virions of visna virus. It consists of two major components, namely 63S and "4S," under the conditions employed for ribonucleic acid (RNA) extraction. The 63S component can be converted to subunits by heat and dimethylsulfoxide treatments. Analyses by base composition indicate that the "4S" RNA isolated from visna virus is not a random breakdown product of the 63S component as a result of extraction, nor is it randomly derived from cellular RNA.

Animals↗