Human Immunodeficiency Virus Infection: Affinity-Mediated Immunoblot Detects Intrathecal Synthesis of Oligoclonal IgG Specific for Individual Viral Proteins

An affinity-mediated immunoblot (AMI) is introduced, able to identify virus-specific, oligoclonal IgG in unconcentrated cerebrospinal fluid (CSF) of patients infected by HIV. CSF specimens are isoelectrically focused in agarose gels and blotted to nitrocellulose (NC) strips coated with E. coli recombinant HIV-specific proteins. Virus-specific antibody clones transferred to the filter are detected by solid-phase enzyme immunoassay (EIA). Only 0.5 μg IgG is sufficient to demonstrate the clonal distribution of antibodies specific for an individual HIV protein. Intrathecal synthesis of oligoclonal antibodies is seen by AMI, comparing equal quantities of serum- and CSF-derived IgG. Because of its excellent sensitivity and specificity, AMI detects autochthonous HIV-specific IgG synthesis even when comparative EIA fails. Because multiple specimens can be processed within a few hours by AMI, this technique is recommendable for routine diagnosis.