Comparative glycoprofiling of HIV gp120 immunogens by capillary electrophoresis and MALDI mass spectrometry

The human immunodeficiency virus (HIV) envelope glycoprotein (Env) is the primary antigenic feature on the surface of the virus and is of key importance in HIV vaccinology. Vaccine trials with the gp120 subunit of Env are ongoing, with the recent RV144 trial showing moderate efficacy. gp120 is densely covered with N-linked glycans that are thought to help evade the host's humoral immune response. To assess how the global glycosylation patterns vary between gp120 constructs, the glycan profiles of several gp120s were examined by CE with LIF detection and MALDI-MS. The glycosylation profiles were found to be similar for chronic versus transmitter/founder isolates and only varied moderately between gp120s from different clades. This study revealed that the addition of specific tags, such as the herpes simplex virus glycoprotein D tag used in the RV144 trial, had significant effects on the overall glycosylation patterns. Such effects are likely to influence the immunogenicity of various Env immunogens and should be considered for future vaccine strategies, emphasizing the importance of the glycosylation analysis approach described in this paper.