[Virus-like particles as a source for obtaining antigens for diagnosing rubella]

Rubella diagnostic agents for hemagglutination inhibition (HI) and enzyme immunoassay (EIA) based on rubella virus-like particles (RVLP) have been developed. Noninfectious RVLPs containing three structural E1, E2, and C proteins were expressed in transfected CHO24S cell culture. HI titer in culture medium was 1:256. Tween-80 treatment and ether increased HI titer 4-6-fold and rendered the antigen higher stability. Immunogenic properties of RVLPs were similar to the native rubella virus in HI test with international reference human rubella serum and sera from convalescents after rubella. Serum of mice immunized with RVLP reacted similarly with RVLP antigens and native virus. Antigen for EIA from RVLP was prepared by concentrating RVLP from culture fluid and partial purification by ultracentrifugation. The results of human sera testing by HI and EIA with RVLP and native virus antigens coincided. RVLP are identical to antigenic structure of the virus, are stable and easily purified, and can therefore be used for commercial production of HI and EIA antigens.