Method for increasing the diagnostic capacity of the complement fixation test in some resporatory virus infections.

Abstract

SummaryThe effect of adding dextran T 80 (av mol. wt. 80,000) in certain concentrations to the mixture of antigen, complement (C) and serum in the diagnostic CF test for RS and parainfluenza (P) virus infections has been investigated. Preliminary experiments showed that the diluent employed (Veronal buffered saline, VBS) had to be used with hypertonic salt concentrations to prevent C consumption from increasing when dextran was added to the test system. Sera from infants and children with respiratory infections were titrated in parallel CF tests using either regular VBS without dextran (CF-v) or hypertonic VBS supplemented with dextran (CF-d). In the majority of sera examined the CF-d titers were significantly higher than the corresponding CF-v titers. Furthermore, using dextran, a rise in titer in the second of a pair of sera was obtained, which was not found in regular CF tests without dextran. Addition of dextran was also able to increase the CF titers in tests with LCM antigen and immune sera from mice.