Unveiling the functional epitopes of cobra venom cytotoxin by immunoinformatics and epitope-omic analyses

Abstract

Approximate 70% of cobra venom is composed of cytotoxin (CTX), which is responsible for the dermonecrotic symptoms of cobra envenomation. However, CTX is generally low in immunogenicity, and the antivenom is ineffective in attenuating its in vivo toxicity. Furthermore, little is known about its epitope properties for empirical antivenom therapy. This study aimed to determine the epitope sequences of CTX using the immunoinformatic analyses and epitope-omics profiling. A conserved CTX was used in this study to determine its T-cell and B-cell epitope sequences using immunoinformatic tools and molecular docking simulation with different Human Leukocyte Antigens (HLAs). The potential T-cell and B-cell epitopes were 'KLVPLFY,' 'CPAGKNLCY,' 'MFMVSTPTK,' and 'DVCPKNSLL.' Molecular docking simulations disclosed that the HLA-B62 supertype exhibited the greatest binding affinity towards cobra venom cytotoxin. The namely L7, G18, K19, N20, M25, K33, V43, C44, K46, N47, and S48 of CTX exhibited prominent intermolecular interactions with HLA-B62. The multi-enzymatic-limited-digestion/liquid chromatography-mass spectrometry (MELD/LC–MS) also revealed three potential epitope sequences as 'LVPLFYK,' 'MFMVS,' and ‘TVPVKR’. From different epitope mapping approaches, we concluded four potential epitope sites of CTX as ‘KLVPLFYK’, ‘AGKNL’, ‘MFMVSTPKVPV’ and ‘DVCPKNSLL’. Site-directed mutagenesis of these epitopes confirmed their locations at the functional loops of CTX. These epitope sequences are crucial to CTX’s structural folding and cytotoxicity. The results concluded the epitopes that resided within the functional loops constituted potential targets to fabricate synthetic epitopes for CTX-targeted antivenom production.

Multi-epitopes vaccine design for surface glycoprotein against SARS-CoV-2 using immunoinformatic approach

“…For effective B-cell epitopes, good surface accessibility is an essential factor. The surface accessibility was predicted by Emini surface accessibility tool [ 47 ], which has the lowest value 0.042 and a maximum value of 6.065 with an average observed value 1.00 ( Fig. 3 c).…”

Specific Amino Acid Residues in the Three Loops of Snake Cytotoxins Determine Their Membrane Activity and Provide a Rationale for a New Classification of These Toxins

“…CTs are believed to target non-protein components of biological membranes [ 39 , 40 , 41 ]. An alternative viewpoint ascribing them capability to interact with some proteins, affecting their function, has not yet been supported experimentally [ 42 , 43 , 44 ]. The diversity of action targets makes toxins in the CT group extremely diverse in their effects on living cells, organs, and tissues [ 39 ].…”

Editorial: Experimental and computational aspects of bioactive proteins from animal venoms: an insight into pharmacological properties and drug discovery

“…Although we observe great therapeutic potentials in certain animal venom toxins, we also appreciate that it is the diversity of the animal venom toxins which can make the treatment of envenoming challenging. One of these challenges is the immunogenicity of venom toxins, which requires study to develop better antivenoms targeting specific toxins (Hiu et al, 2023) and exhibiting broader neutralising potency. In this regard, Chan et al examined immunogenicity of α-neurotoxins from elapid venoms.…”