There is a clinical need to have a rapid and sensitive means to identify persons with immunity to varicella-zoster virus (VZV).
We evaluated a simple-to-perform assay for detecting antibodies to VZV using a commercial latex agglutination (LA) test, in which dilutions of test sera were added to latex particles that had been coated with VZV glycoprotein antigens.
Sera obtained from patients, including recipients of varicella vaccine, whose clinical immune status to VZV was known, were tested by LA and the results compared to those obtained by a standard indirect immunofluorescence assay (FAMA). Using the LA test, long-term persistence of antibodies in leukemic and adult recipients of varicella vaccine were determined.
The LA test compared favorably with FAMA in varicella susceptibles and immunes. 741 acute sera were negative and 741 convalescent varicella sera were positive by LA. Antibodies to VZV were found to persist for as long as 11 years in most recipients of varicella vaccine (n = 145). Geometric mean titers were higher by LA than FAMA. Prozone phenomena were noted in about 5% of antibody-positive sera. Results from this test are available in less than an hour, and no special equipment is required.
This assay is rapid, simple to perform, and inexpensive. It is particularly useful for identifying individuals who are immune to varicella, including those who have been immunized in the distant past. The main problem associated with the test is that prozone phenomena can occur; these may be avoided by testing sera at various dilutions.