Background: The shrimp Litopaneus vanammei is an important source of food allergens but its allergenic repertoire is poorly characterized. Cross reactivity between crustacean and mites has been characterized, with tropomyosin, the most relevant allergen involved. The aim of this study was the structural and immunological characterization of an allergen belonging to the Fatty Acid Binding Protein (FABP) family from L. vannamei (LvFABP). Methods: ELISA, skin prick test (SPT) and basophil activation assays were performed to determine IgE reactivity and allergenicity of LvFABP. LC-MS/MS and Circular Dichroism experiments were done for structural analysis. B-cell epitope mapping with overlapping peptides, and cross-inhibition studies using human sera were done to identify antigenic regions and cross-reactivity. Results: The recombinant LvFABP showed IgE reactivity in 27% of allergic patients tested and showed allergenic activity when tested for basophil activation and SPT in shrimp sensitized patients. CD-spectroscopy of LvFABP revealed that the protein is folded with a secondary structure composed of mainly β-strands and a smaller fraction of  helices. This is consistent with molecular modelling results, which exhibit a typical β barrel fold with two α-helices and ten β-strands. Epitope mapping identified two IgE binding antigenic regions and inhibition assays found high cross reactivity between LvFABP and Blo t 13, mediated by the antigenic region involving amino acids 53 to 73. Conclusions: Our results support LvFABP as an allergen with cross reactivity with the allergen Blo t 13. This new allergen could help to understand new mechanisms of sensitization to seafood such as shrimp.

Background: Current cost-effectiveness evaluations of the house dust mite (HDM) allergen immunotherapy fail to account for its effect on the reduction of exacerbations and medications while considering potential differences across patient populations. We aimed to evaluate the cost-effectiveness of subcutaneous immunotherapy (SCIT) plus inhaled corticosteroids (ICS) vs ICS for pediatric and adult patients with allergic asthma (AA) and AA with Allergic rhinitis (AR) from the health care system perspective. Methods: A Markov model with a 3-month cycle length and a 10-year time horizon was developed. A hypothetical cohort of eight years old patients with controlled (or partially controlled) AA was the base case population. Health states were: treatment with GINA Step-3, Step-2, medication-free asthma, and all-cause death. Effectiveness was measured by the reduction in medication doses and exacerbations. Scenario analyses were conducted considering allergic AR as a comorbid condition and an 18-years old cohort at baseline with or without AR. Results: In the base case, the SCIT+ICS would avert 847 exacerbations per 1,000 patients treated and generate additional 0.37 quality-adjusted life years (QALYs) and $836 costs per patient (SCIT+ICS=6.79 QALYs at a cost of $1,438/patient, ICS=6.42 QALYs at a cost of $601/patient). An incremental cost-effectiveness ratio (ICER) of $2,238 per QALY that fall below the willingness to pay threshold was obtained. The SCIT+ICS was also cost-effective among sub-groups of interest: adults win AA (ICER=$2,227) and AA+AR patients (8-years old cohort=$1,628, 18-years old cohort=$1,617). Conclusion: the SCIT+ICS can be cost-effective for pediatric and adult patients with AA with or without AR