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Biomedical subjects

L Ho-Terry

Publications and source records attributed to L Ho-Terry.

At least 19 recordsLinked to original sources
PubMed1995

Sequence variation and biological activity of rubella virus isolates.

Haemagglutination (HA) by rubella virus is mediated by the E1 glycoprotein. Rubella isolates which haemagglutinate with different avidity have been characterised. A significant reduction of HA titre at pH 6.0 was observed in one isolate in which isoleucine is substituted for threonine at rubella E1 residue 280. This residue is located in an epitope (EP1) which we have previously identified and shown to bind HA inhibiting (HA1) monoclonal antibodies. The isolates studied are also distinguishable by plaque size but no sequence variations in the immunogenic region of E1 were identified which might account for this difference. No correlation was observed between infectivity and binding affinity of neutralising monoclonal antibodies for different rubella virus strains.

Animals↗
PubMed1992

Reactivity of a recombinant rubella E1 antigen expressed in E. coli.

The E1 nucleic acid sequence of rubella virus strain Judith (RJ) has been cloned into an E. coli expression vector LB03. The reactivity of the expressed unglycosylated antigen (E1J) was compared with its glycosylated counterpart in native virus (RJ) using rabbit and human sera. Rabbit antisera raised against RJ and E1J reacted differently with wild type, RJ (laboratory strain) and RA27/3 (vaccine virus) strains in a kinetic neutralisation test. Reciprocally, human post RA27/3 vaccination sera were also found to differ from post infection or post re-infection sera in their reactivity with RJ and E1J antigens. Our observations suggest that E1, in the conformation adopted in the RA27/3 virion may have unique antigenic properties.

Animals↗
PubMed1990

Diagnosis of foetal rubella virus infection by polymerase chain reaction.

We have used the polymerase chain reaction (PCR) to provide a very sensitive and unequivocal test for diagnosis of foetal rubella virus infection. RNA extracted from biopsy specimens (chorionic villi), placenta or products of conception was reverse-transcribed using a rubella virus-specific oligonucleotide primer and the cDNA was amplified by PCR. The specificity of the amplified fragment was confirmed by Southern blotting. Detection of rubella virus infection in five out of 41 clinical specimens examined by this approach was shown to be entirely consistent with clinical history and other methods of laboratory diagnosis in current use. The sensitivity of the test and the unequivocal nature of the results obtained could be invaluable in providing prenatal counselling following rubella virus infection during pregnancy.

Animals↗
PubMed1989

Detection of rubella virus in fetal and placental tissues and in the throats of neonates after serologically confirmed rubella in pregnancy.

From 35 therapeutic abortions performed because rubella had occurred at 2-19 weeks of pregnancy, 120 fetal organs, 12 specimens of mixed products of conception, and 15 placentae were tested for rubella virus. Virus was isolated from 10 out of 11 fetuses (91 per cent) from women infected at 2-8 weeks, from 5 out of 8 (63 per cent) infected at 9-10 weeks, and from 2 out of 16 (13 per cent) infected at 11-19 weeks. Hybridization tests for viral RNA on 39 fetal organs from eight cases revealed infection in four additional fetuses. Virus was isolated from only 3 out of 15 aborted placentae, but hybridization tests on six placentae revealed infection in three additional specimens. Hybridization was superior to virus isolation for detecting rubella infection in products of conception and is therefore potentially the better method for examining chorionic villus biopsies. Rubella virus was isolated from the throats of 4 out of 9 infants (44 per cent) infected during the first 12 weeks of gestation, but from none of 13 infected after 17 weeks. Infants in the latter group are unlikely to infect susceptible contacts.

Abortion, Therapeutic↗
PubMed1989

A bio-engineered rubella E1 antigen.

The major rubella envelope protein, E1, and a segment of it, comprising amino acids 207-353, have been separately expressed as fusion proteins with the IgG binding region of Staphylococcus aureus protein A in Escherichia coli. The proteins carry E1-specific antigenicity recognized by monoclonal antibodies raised against whole virus confirming that correct glycosylation is not required for antigenicity. The use of these bioengineered antigens in immunoassays for diagnosis of rubella infection and for immunization in experimental animals is described.

Amino Acid Sequence↗
PubMed1988

Diagnosis of fetal rubella infection by nucleic acid hybridization.

The efficacy of nucleic acid hybridization for the diagnosis of rubella infection in experimental and clinical materials was compared with immunoblot and virus isolation techniques. Our results showed that nucleic acid hybridization is specific and rapid but gives false-negative results when compared with conventional virus isolation in some experimental although not in clinical materials so far examined. For this reason, a failure to demonstrate rubella virus in fetal specimens by this method alone cannot yet be taken as a sole criterion for ruling out fetal rubella infection.

Abortion, Spontaneous↗
PubMed1988

Localization of the rubella E1 epitopes.

Three epitopes which react with haemagglutination inhibition and neutralizing antibodies have been located between amino acids 245-285 in the predicted amino acid sequence of rubella envelope glycoprotein E1.

Amino Acid Sequence↗
PubMed1986

First trimester prenatal diagnosis of congenital rubella: a laboratory investigation.

Acute primary maternal infection with rubella virus during pregnancy often, but not invariably, leads to the congenital rubella syndrome. Diagnosis by detection of virus specific IgM in the mother is not always possible, and in those cases in which IgM is detected the fetus has not necessarily also been infected. A method for direct, prenatal detection of fetal infection would allow more accurate early diagnosis of congenital rubella syndrome. In this study a case of suspected preconception rubella infection that was not referred until 14 weeks after the appearance of a rash was studied to determine whether a retrospective serological diagnosis of primary rubella could be made, and whether direct evidence of fetal infection could be obtained from a chorionic villus biopsy specimen by detecting virus specific antigens or ribonucleic acid (RNA) sequences. Monoclonal antibodies and a cloned complementary deoxyribonucleic acid probe were used successfully to detect antigens to rubella virus antigens and RNA sequences in the chorionic villus biopsy specimen, which was taken at 15 weeks' gestation. This method should serve as a new approach to the diagnosis of congenital rubella syndrome in utero.

Adult↗
PubMed1986

Immunological characterisation of the rubella E 1 glycoprotein. Brief report.

Three epitopes have been identified on rubella virion envelope polypeptide E 1 using monoclonal antibodies. Antibodies to two of the epitopes, E 1EP1 and E 1EP2, show both haemagglutination inhibition and neutralization activities whereas antibodies to the remaining epitope, E 1EP3, show neutralizing activity only.

Animals↗
PubMed1985

Rubella virus RNA: effect of high multiplicity passage.

Evidence for the amplification of defective interfering particles of rubella virus after passage at high multiplicity has been obtained. The process is associated with the production of subgenomic rubella RNA species.

Animals↗
PubMed1984

Immunological characterisation of rubella virion polypeptides.

Antibodies specific for rubella virion polypeptide, VPI, secreted by clones of hybridoma cells or produced in rabbits in response to specific antigenic stimulation, located determinants for haemagglutination inhibiting (HI) and neutralising (Nt) antibodies on this envelope component.

Antibodies, Viral↗
PubMed1982

Rubella virion polypeptides: characterization by polyacrylamide gel electrophoresis, isoelectric focusing and peptide mapping.

Four polypeptides with molecular weights of 55 K, 47 K, 45 K, and 33 K have been resolved by polyacrylamide gel electrophoresis of immune precipitated rubella virus. The 47 K and 45 K components have similar peptide maps but different isoelectric points so that the same polypeptide may exist in more than one charged form. The 55 K and 45 K components have similar isoelectric points but different peptide maps showing that similarity of isoelectric point is not evidence of identity.

Electrophoresis, Polyacrylamide Gel↗
PubMed1981

Effect of 2-mercaptoethanol on the haemagglutinating activity and antigenic properties of rubella virus.

Tween-ether treated rubella virus extract treated with 2-mercaptoethanol no longer haemagglutinates and its ability to combine with antibody is reduced although its sedimentation characteristics and the electrophoretic mobilities of the envelope glycoproteins are unaffected. The role of disulphide bonds in maintaining the structural and functional integrity of rubella virus is discussed.

Antigens, Viral↗