An Immunoinformatic Approach to a Protease-Resistant Epitope Design for a Giardiasis Vaccine

Giardiasis, a pervasive waterborne parasite infection caused by Giardia lamblia, with an estimated 200 million annual infections and substantial morbidity (Mohamed et al., 2019 and Hajare et al., 2022). Current therapies face growing issues with drug resistance, highlighting the urgent need for a new vaccine. This study employs computational methods to predict immunogenic, protease-resistant, surface-exposed epitopes on the alpha-1 giardin protein, essential for vaccine efficacy. B-cell and T-cell epitopes were predicted using tools like IEDB Bepipred and Vaxign. ExPASy was used as a stringent filter to validate protease stability against trypsin and pepsin (Cohen, 1973). Epitopes were also assessed for conservation across Giardia strains (NCBI BLAST) and surface exposure using SWISS-MODEL and RCSB visualization tools. Epitopes passing the B-cell filter but failing other criteria were modified via a mutagenesis protocol. The methodology was reapplied for the mutated sequence to optimise scores across all assessment criteria. Three of 34 predicted epitopes were identified as viable after passing all assessment criteria. A chi-square test comparing observed and expected viable epitopes yielded a statistically significant p-value of 9.37x10^-8, demonstrating that the selection method was highly effective and not due to chance. The identified epitopes serve as a validated blueprint for a to mitigate the global impact of giardiasis.