DETECTION OF IGM AND IGA HIV ANTIBODIES AFTER REMOVAL OF IGG WITH RECOMBINANT PROTEIN-G

Indirect assays for IgM and IgA antibodies often lack sensitivity and specificity due to interference from IgG antibodies. To overcome this problem we have developed a simple procedure using recombinant protein G coupled to agarose beads to remove the interfering IgG. A series of HIV seroconversion panels was tested by IgM and IgA immunoblot after protein G treatment in order to evaluate IgG removal and to study appearance of IgM and IgA antibodies in early HIV infection. Protein G treatment removed 99.9% of the IgG and reduced IgG anti-HIV titers of over 1/100,000 to undetectable levels. Both IgM and IgA HIV antibodies were detected as early in seroconversion as were IgG HIV antibodies. IgA HIV antibodies persisted for a longer period of time, reacted with more HIV proteins, and showed more intense staining than IgM HIV antibodies. © 1990.