Glycosylation of the HIV-1 Env V1V2 loop to form a native-like structure may not be essential with a nanoparticle vaccine

Karch, Christopher P; Matyas, Gary R; Burkhard, Peter; Beck, Zoltan

Although the importance of glycosylation for viral maturation and folding of envelope proteins is clear, it remains unclear if proper glycosylation or some level of glycosylation of the immunogen is necessary for inducing protective immune response by an HIV-1 vaccine. Some attempts have been carried out to correlate the glycosylation status of the HIV-1 antigen and the immune response [37] [38] [39] . It is hypothesized that for protective immune response to HIV-1, generation of conformational antibodies is required. These antibodies can be generated only by properly folded immunogens that have either the native glycosylation pattern or are displayed on a nanoparticle carrier to enable the native-like trimeric antigen conformation. Producing subunit vaccine candidates in mammalian cells to generate glycosylation is difficult; the yield tends to be lower, and cost tends to be higher. The glycosylation pattern obtained in expression systems may be different than those present on the virion, ultimately affecting the structure of the antigen [40] . By using the SAPN technology, we were able to produce a vaccine candidate in E. coli capable of raising high titers of antibodies to the V1V2 loop. The structure of the antigen was determined to be native-like by the binding to known conformational V1V2 antibodies such as PG9, PG16 and PGT145 [31] . We hypothesize that vaccination with unglycosylated HIV-1 Env V1V2 antigens that fold into native-like confirmation may generate functional antibodies at higher titers with higher affinity, ideally leading to a better vaccine candidate. To validate this hypothesis, further studies are required to compare the functionality of antibodies from animals vaccinated with unglycosylated and glycosylated SAPN immunogens. A prime boost strategy with a vaccination using unglycosylated immunogen followed by a glycosylated immunogen can be used in an attempt to generate high titers of anti-V1V2 antibodies that recognize the virion, regardless of the glycosylation status. P Burkhard has an interest in the company Alpha-O Peptides that has patents or patents pending on the technology. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.