| dc.description.abstract | Full text Embargo upto 12/12/2026
Human Immunodeficiency Virus type 1 (HIV-1) remains one of the most persistent global
health threats, despite significant efforts in the development of vaccines and major strides in
antiretroviral therapy. The envelope glycoprotein (Env) is the major component for the
infection to occur and is composed of the surface unit gp120 and the transmembrane unit gp41.
While Env has long been recognized as a prime target for both vaccine design and therapeutic
inhibition, its high genetic variability, conformational plasticity, and extensive glycosylation
make it a challenging candidate for eliciting broad and lasting immune responses. In particular,
the gp41 subunit, responsible for membrane fusion during viral entry, represents a structurally
conserved region with therapeutic potential that has yet to be fully harnessed.
One of the chapters focus on quantitating residue specific interactions in the gp41 fusion
machinery of HIV-1. By employing deep mutational scanning strategies, key residues in the N
terminal and C-terminal heptad repeat regions were systematically probed to identify mutations
that perturb the stability of the six-helix bundle intermediate. These insights can be used to
rationally engineer synthetic peptide inhibitors with improved biophysical characteristics,
offering avenues for antiviral development against HIV-1 virus.
In addition to therapeutic targeting, the thesis explores immunogen design strategies aimed at
enhancing the stability, yield, and humoral immune response against HIV-1 Env. Using a
ferritin-like nanoparticle scaffold to display trimeric envelope proteins, the immunogenicity of
multivalent formulations was assessed in murine models. The nanoparticle presentation
increased early antibody titers and improved antigen recognition, although the durability of the
response remained limited. These findings underscore the importance of scaffold architecture
and immunogen stability in designing next-generation HIV vaccines.
The thesis also focuses on vaccine development strategies against other enveloped viruses,
such as SARS-CoV-2 and Respiratory Syncytial Virus (RSV). Both viruses rely on surface
glycoproteins spike and F protein, respectively, for host cell entry. Stabilization of the prefusion
state, has been instrumental in eliciting potent neutralizing responses, but mutations used in
these licensed vaccines are protected by intellectual property. Thus, a novel strategy of
prefusion stabilization of both the surface glycoproteins of these viruses using aspartic acid
substitutions to destabilize the postfusion form was utilised. The strategy was found to stabilize
the prefusion conformation, increasing the yields of proteins and in the case of spike, without
decreasing immunogenicity and protective efficacy.
Finally, the thesis evaluates the use of mRNA-based platforms for the delivery of stabilized
viral antigens, which offer rapid and scalable alternatives to traditional vaccine technologies.
As part of this work, various mRNA constructs encoding engineered antigens of the Spike
protein from SARS-CoV-2 and Hemagglutinin from the Influenza virus were generated and
formulated into lipid nanoparticles. The resultant formulations were biophysically
characterized, and expression efficiency was evaluated. Immunogenicity and protective
efficacy of these mRNA-LNPs were also evaluated in small animals. The data support the
feasibility of mRNA delivery systems for tailored vaccine candidates against rapidly evolving
pathogens.
Collectively, the research done in this thesis contributes to a growing body of knowledge aimed
at combating global viral threats. By combining structural virology, rational protein
engineering, and emerging delivery technologies, it offers new directions for combating
chronic viral infections and strengthening pandemic preparedness. | en_US |
