Vaccinia reactive antibodies in a south Indian population

The prevalence of vaccinia virus antibodies was determined in both urban an d rural populations in southern India. The study sample consisted of 211 ad ults and 52 children. The antibody titre was measured in all sera by virus neutralisation and by indirect immunofluorescence assay (IFA). A small pane l of sera was tested by Western blotting. There was no significant differen ce in detection rates between the tests. Generally, seropositivity correlat ed with a previous history of vaccination. All children were negative for v accinia antibodies. Among adults overall, 54% had neutralising antibodies w hereas 60% were positive for antibodies detected by IFA, however, the preva lence of vaccinia antibody by either method was significantly higher (P < 0 .001) among rural subjects than in urban subjects. This higher antibody pre valence among the rural population could be due to exposure to other indige nous orthopoxviruses, possibly buffalo-pox. (C) 2000 Wiley-Liss, Inc.