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Chapter 81 : Rubella Virus
Rubella virus is antigenically stable, and antigenic variation has so far not been an issue for vaccination or serological diagnosis; the significance of the possible emergence of new international subgenotypes of rubella virus is unknown. Reinfection with the virus can occur, but it is almost always asymptomatic and can be detected by a rise in immunoglobulin g (IgG) antibodies. One approach is to demonstrate rubella virus-specific IgM antibody in the infant's serum, which would be diagnostic of congenital rubella. Since the original description of the hemagglutination inhibition (HI) test for rubella, several modifications have been introduced. Commercial enzyme immunoassay (EIAs) are available for testing whole sera for rubella virus-specific IgM. Few laboratories have the techniques or expertise to culture rubella virus, and when virus detection is clinically important, laboratories may want to consider detection of rubella virus RNA by PCR. The challenge viruses most commonly used for rubella virus isolation in AGMK cells are echovirus 11 and coxsackievirus A9. The presence of rubella virus is indicated by little or no cytopathic effects (CPE) in the inoculated tubes and complete destruction of the control cells infected with challenge virus in the absence of rubella virus. An indirect immunofluorescence staining method has also been shown to be specific and sensitive for identifying rubella virus isolates in these cells. The lack of serological responses to rubella virus vaccine in women who do not have detectable antibodies is often due to low levels of neutralizing antibodies.