Abstract:
Broadly neutralising antibodies (bNAbs) against human immunodeficiency virus type 1 (HIV-1), such
as CAP256-VRC26 are being developed for HIV prevention and treatment. These Abs carry a unique
but crucial post-translational modification (PTM), namely O-sulfated tyrosine in the heavy chain
complementarity determining region (CDR) H3 loop. Several studies have demonstrated that plants
are suitable hosts for the generation of highly active anti-HIV-1 antibodies with the potential to
engineer PTMs. Here we report the expression and characterisation of CAP256-VRC26 bNAbs with
posttranslational modifications (PTM). Two variants, CAP256-VRC26 (08 and 09) were expressed
in glycoengineered Nicotiana benthamiana plants. By in planta co-expression of tyrosyl protein
sulfotransferase 1, we installed O-sulfated tyrosine in CDR H3 of both bNAbs. These exhibited similar
structural folding to the mammalian cell produced bNAbs, but non-sulfated versions showed loss
of neutralisation breadth and potency. In contrast, tyrosine sulfated versions displayed equivalent
neutralising activity to mammalian produced antibodies retaining exceptional potency against some
subtype C viruses. Together, the data demonstrate the enormous potential of plant-based systems for
multiple posttranslational engineering and production of fully active bNAbs for application in passive
immunisation or as an alternative for current HIV/AIDS antiretroviral therapy regimens.
