Mitochondrial genome of Chthamalus challengeri(Crustacea:Sessilia): gene order comparison within Chthamalidae and phylogenetic consideration within Balanomorpha

Acorn barnacles are important model species in researches on intertidal ecology, larval development and biofouling. At present, with the development of mitochondrial genomics, it is helpful to understand the phylogenetic relationship from the mitogenomic level. The complete mitochondrial genome of Chthamalus challengeri was presented. The genome is a circular molecule of 15 358 bp. Compared with other species in Balanomorpha, the non-coding region is longer, while the length of the genes is similar to the other species. The overall A+T content of the mitochondrial genome of C. challengeri is 70.5%. There are variations of initiation and stop codons in the known Balanomorpha mitochondrial genomes. The C. challengeri and C. antennatus within the same genus share the identical gene arrangement. However, the gene arrangement of different genera in Chthamalidae is different, as there is a translocation between two tRNA genes and an inversion involving a large gene block. In particular, both srRNA and lrRNA of the two species in Chthamalus are encoded in the heavy strand, differing from the former Balanomorpha species. The topology and gene arrangement in Chthamalidae support each other. Phylogenetic analysis indicates that the Chthamalidae is monophyletic, while the Balanidae and Archaeobalanidae are polyphyletic.

Screening and identification of mimotopes of the major shrimp allergen tropomyosin using one-bead-one- compound peptide libraries

The one-bead-one-compound （OBOC） combinatorial peptide library is a powerful tool to identify ligand and receptor interactions. Here, we applied the OBOC library technology to identify mimotopes specific to the immunoglobulin E （IgE） epitopes of the major shellfish allergen tropomyosin. OBOC peptide libraries with 8-12 amino acid residues were screened with serum samples from patients with shellfish allergy for IgE mimotopes of tropomyosin. Twenty-five mimotopes were identified from the screening and their binding reactivity to tropomyosin-specific IgE was confirmed by peptide ELISA. These mimotopes could be divided into seven clusters based on sequence homology, and epitope mapping by EpiSearch of the clustered mimotopes was performed to characterize and confirm the validity of mimotopes. Five out of six of the predicted epitopes were found to overlap with previously identified epitopes of tropomyosin. To further confirm the mimicry potential of mimotopes, BALB/c mice were immunized with mimotopes conjugated to keyhole limpet hemocyanin and assayed for their capacity to induce tropomyosin-specific antibodies. BALB/c mice that received mimotope immunization were found to have an elevated level of tropomyosin-specific immunoglobulin G, but not mice that received an irrelevant mimotope. This study pioneers the successful application of the OBOC libraries using whole sera to screen and identify multiple shrimp allergen mimotopes and validates their mimicry potential using in vitro, in vivo, and in silico methods.

Mimotope-based allergen-specific immunotherapy: ready for prime time?

INTRODUCTION Allergen-specific immunotherapy(AIT)is a therapeutic strategy to restore the normal immune response by suppressing inflammatory effector cells and inducing regulatory cells specific to the culprit allergen.Conventionally,AIT is achieved by administering escalating doses of allergen over a long treatment course.However,the use of unmodified allergens for AIT often results in severe anaphylactic side effects,and alternative approaches such as hypoallergens and T-cell epitopes with enhanced safety have been considered.The use of mimotopes in AIT is a relatively new concept,but earlier proof-ofconcept studies showed promising results for mimotopes,with decent safety profiles and immunomodulatory capacity1.While the treatment of cancer with mimotope-based immunotherapy has already been tested in clinical trials2,mimotope-based AIT remains largely in the preclinical stage.Here,we revisit the pros and cons of mimotope-based AIT and describe recent findings concerning the use of mimotopes in AIT.