Analysis of nonspecific reactions in enzyme-linked immunosorbent assay testing for human rotavirus

Abstract

Solid-phase enzyme immunoassays can be utilized to detect antigens directly in clinical specimens. A small number of stools which were tested for human rotavirus by enzyme-linked immunosorbent assay (ELISA) had nonspecific activity in the absence of rotaviral antigen. Similar nonspecific activity was found in 8 of 8 sera which contained rheumatoid factor. This nonspecific activity was markedly reduced by pretreatment of the specimens with reducing agents, normal goat serum and anti-human IgM. Thus, these specimens probably contain an IgM antibody capable of reacting nonspecifically with the other components of the assay. Although pretreatment with the mild reducing agent N-acetylcysteine markedly reduced this nonspecific activity, such treatment did not reduce the specific ELISA activity due to rotavirus. Other treatments produced a reduction in specific activity. Pretreatment with N-acetylcysteine offers a practical means to increase the specificity of ELISA systems without reducing their sensitivity.