Presence of EBV-DNA sequences in nasopharyngeal cells of individuals without IgA-VCA antibodies.
Exfoliated nasopharyngeal (NP) cells from 62 normal Cantonese Chinese having IgA/VCA antibodies for more than a year and from 39 similar persons without IgA/VCA antibodies, were tested for the presence of EBV/DNA sequences by spot followed by blot hybridization tests, using the cloned internal repeat of B95-8 viral DNA as probe. Thirteen out of 62 specimens from IgA/VCA-positive (21%) and six out of 39 specimens (15.4%) from IgA/VCA-negative individuals were found to contain EBV/DNA sequences. Forty-six cases (20 IgA/VCA-positive and 26 IgA/VCA-negative) were followed a year later for EBV/DNA sequences and EBV serology. Half of the individuals having EBV/DNA sequences in their exfoliated NP cells in 1981 did not have detectable EBV sequences a year later, and to out of 15 negative individuals became EBV/DNA-positive. There was no obvious correlation between EBV/DNA detectability and EBV serology. (We conclude that the best marker for NPC risk remains the increasing IgA/VCA and/or EA antibody titers.