Linda Ho-Terry

Localization of the rubella E1 epitopes

SummaryThree 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.

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.

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

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

The role of glycosylation on haemagglutination and immunological reactivity of rubella virus.

SummaryTreatment of purified rubella virus with mixed glycosidases resulted in loss of haemagglutinating (HA) activity but the capacity to combine with haemagglutination inhibiting (HI) and other antibodies was retained. Electrophoretic analysis revealed a greater effect on VPI than VPII.

A bio-engineered rubella E1 antigen

SummaryThe 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 ofStaphylococcus aureus protein A inEscherichia 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.

Immunological characterisation of the rubella E 1 glycoprotein

SummaryThree 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.

Rubella virus RNA: effect of high multiplicity passage.

SummaryEvidence 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.

Rubella virus haemagglutinin: Association with a single virion glycoprotein

SummaryUndenatured rubella virus envelope glycoproteins released by Tweenether and trypsin treatment have been separated by Fast Protein Liquid Chromatography. Red cell adsorption located the haemagglutinin on VPI and its 13K cleavage product.

Reactivity of a recombinant rubella E1 antigen expressed inE. coli

SummaryThe E1 nucleic acid sequence of rubella virus strain Judith (RJ) has been cloned into anE. coli expression vector LB03. The reactivity of the expressed unglycosylated antigen (E1J) was compared with its glycosylated counterpart in native virus (RJ) usind 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.

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

SummaryTween-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.