Rubella serology: a comparison of four methods for exclusion of non-specific serum inhibitors.

The ability of the pyrogenic silica Aerosil 380R to exclude non-specific serum inhibitors (NSI) of rubella virus haemagglutination was evaluated. The developed procedure was compared with the kaolin, heparin/MnCl2 and dextran sulphate/CaCl2 methods. Aerosil and kaolin were found superior for the elimination of non-specific inhibitors and high density lipoproteins (HDL). The other methods left NSI and HDL in a majority of the sera, occasionally in high titres. Aerosil seemed to be somewhat more efficient than kaolin in NSI and HDL exclusion. The Aerosil method offers the opportunity to detect sera with rubella antibody titres less than 10. Among eight such sera, six were shown to contain rubella antibodies, while two were false positives.