Immune targeting of filarial glutaredoxin through a multi-epitope peptide-based vaccine: A reverse vaccinology approach.

Despite the efforts of global programme to eliminate lymphatic filariasis (GPELF), the threat of lymphatic filariasis (LF) still looms over humanity in terms of long-term disabilities, and morbidities across the globe. In light of this situation, investigators have chosen to focus on the development of immunotherapeutics targeting the physiologically important filarial-specific proteins. Glutaredoxin (16.43 kDa) plays a pivotal role in filarial redox biology, serving as a vital contributor. In the context of the intra-host survival of filarial parasites, this antioxidant helps in mitigating the oxidative stress imposed by the host immune system. Given its significant contribution, the development of a vaccine targeting glutaredoxin holds promise as a new avenue for achieving a filaria-free world. Herein, multi-epitope-based vaccine was designed using advanced immunoinformatics approach. Initially, 4B-cell epitopes and 6 T-cell epitopes (4 MHC I and 2 MHC II) were identified from the 146 amino acid long sequence of glutaredoxin of the human filarid, Wuchereria bancrofti. Subsequent clustering of these epitopes with linker peptides finalized the vaccine structure. To boost TLR-mediated innate immunity, TLR-specific adjuvants were incorporated into the designed vaccine. After that, experimental analyses confirm the designed vaccine, Vac4 as anefficient ligand of human TLR5 to elicit protective innate immunity against filarial glutaredoxin. Immune simulation further demonstrated abundant levels of IgG and IgM as crucial contributors in triggering vaccine-induced adaptive responses in the recipients. Hence, to facilitate the validation of immunogenicity of the designed vaccine, Vac4 was cloned in silico in pET28a(+) expression vector for recombinant production. Taken together, our findings suggest that vaccine-mediated targeting of filarial glutaredoxin could be a future option for intervening LF on a global scale.

Designing efficient multi-epitope peptide-based vaccine by targeting the antioxidant thioredoxin of bancroftian filarial parasite.

Thioredoxin is a low molecular weight redox-active protein of filarial parasite that plays a crucial role in downregulating the host immune response to prolong the survival of the parasite within the host body. It has the ability to cope up with the oxidative challenges posed by the host. Hence, the antioxidant protein of the filarial parasite has been suggested to be a useful target for immunotherapeutic intervention of human filariasis. In this study, we have designed a multi-epitope peptide-based vaccine using thioredoxin of Wuchereria bancrofti. Different MHC-I and MHC-II epitopes were predicted using various web servers to construct the vaccine model as MHC-I and MHC-II epitopes are crucial for the development of both humoral and cellular immune responses. Moreover, TLRs specific adjuvants were also incorporated into the vaccine candidates as TLRs are the key immunomodulator to execute innate immunity. Protein-protein molecular docking and simulation analysis between the vaccine and human TLR was performed. TLR5 is the most potent receptor to convey the vaccine-mediated inductive signal for eliciting an innate immune response. A satisfactory immunogenic report from an in-silico immune simulation experiment directed us to propose our vaccine model for experimental and clinical validation. The reverse translated vaccine sequence was also cloned in pET28a(+) to apply the concept in a wet lab experiment in near future. Taken together, this in-silico study on the design of a vaccine construct to target W. bancrofti thioredoxin is predicted to be a future hope in saving human-being from the threat of filariasis.