Abstract
The need for paired acute and convalescent phase sera for diagnostic purposes in virology has long been recognized. Along these lines, some important problems are: (a) getting an early enough acute phase serum, (b) obtaining only a convalescent phase serum perhaps none at all, (c) choice of most suitable test method (s) to use with likely small quantities of specimen(s) obtained and (d) perhaps most important of all, furnishing a diagnostically useful result to the attending physician at the time he needs it. This latter requirement is incompatable with awaiting a convalescent phase serum. Furthermore, unless the physician's early needs are met, his subsequent lack of cooperation further complicates obtaining the needed sera from the next patient.
The solution in so far as serology is concerned apparently lies in the detection of early specific antibody in the IgM globulin fraction and distinguishing this from that of any preexisting antibody in the IgG globulin which may also react with the antigen used.
Since fractionation procedures to separate IgG or selectively inactivate IgM are time consuming or impractical in large scale routine diagnostic work, the indirect fluorescent antibody technique employing highly specific conjugates against human IgM and human IgG appears to be most desirable. Diagnostic use of such a procedure in virology was introduced by Brown and his associates in 1968 (1, 2) for mumps, but to our knowledge this has not been applied in diagnostic arbovirology prior to the studies reported here.
The major interest in this laboratory is in the area of the arboviruses and currently in the dengue (DEN) subgroup of group B most specifically, therefore these viruses were employed. Another reason for selecting group B and the DEN subgroup relates to the lack of type specificity, using current serological tests, of sera of persons having a second or subsequent infection with a group B virus.
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