Usefulness of the Allergen Specific Nasal Provocation Test in the Diagnosis of Shellfish Allergy

Background: Shellfish allergy is an important cause of food allergy and anaphylaxis worldwide. Several allergenic proteins have been described in the last few years, but the only diagnostic tool that allows discrimination between allergic and non-allergic sensitized subjects is still the oral food challenge (OFC). Objective: The aim of this study was to evaluate the usefulness of nasal allergen provocation test (NAPT) as a diagnostic tool in the diagnosis of shellfish allergy. Methods: Forty-five subjects with confirmed sensitization to shrimp by a positive skin prick test (SPT) to a commercial shrimp extract were recruited and classified as Sensitized-Allergic or non-Allergic based on current tolerance to shrimp intake, the result of an OFC with a freeze-dried cooked shrimp mixture extract, or recent history of anaphylaxis from shrimp ingestion. These subjects and ten controls without shrimp sensitization were subjected to a NAPT with a freeze-dried cooked shrimp mixture extract. The response was evaluated by means of acoustic rhinometry (AcRh) and visual analogue scale scores (VAS). Results: Significant differences (p=.001) were found between the Sensitized-Allergic group (18/20 positive NAPT, 90%) compared to both Sensitized-non-Allergic (2/18 positive NAPT, 11.1%) and Control (0/10 positive NAPT) groups. NAPT allows differentiation between allergic and non-allergic subjects with a S: 90%, E: 89%, PPV: 90% and NPV: 89%. Conclusions: According to the study results NAPT may be a useful diagnostic tool that allows differentiating sensitized symptomatic subjects from sensitized tolerant. It could be a valuable test to consider when conducting a shrimp allergy study.

A Failure of Rapid Drug Desensitization

ABSTRACT We present the case of a patient who was unable to tolerate rapid drug desensitization protocol to receive a continuous penicillin (PCN) G infusion for the treatment of neurosyphilis. A 38-year-old male with past medical history for human immunodeficiency virus, migraines, PCN allergy, doxycycline allergy, shellfish allergy, and untreated latent syphilis presented to the emergency room for a posterior migraine with associated nausea, vomiting, photophobia, right-sided paresthesias, and “shaky” vision. He was diagnosed with neurosyphilis and underwent rapid drug desensitization with the goal to receive a continuous infusion of PCN G. The patient’s hospital course was complicated by intermittent drug reactions consisting of tachycardia, rash, and dyspnea, followed by periods of being able to tolerate the infusion. After being able to tolerate the recommended dose of PCN infusion, the patient was discharged home to complete the course. However, he returned almost immediately after a recurrence of symptoms at home requiring the use of intramuscular epinephrine. Ultimately, the patient was transitioned to ceftriaxone and completed the infusion course as an inpatient because of continued intermittent recurrence of drug reaction symptoms.

Novel Allergen Discovery through Comprehensive De Novo Transcriptomic Analyses of Five Shrimp Species

Shellfish allergy affects 2% of the world’s population and persists for life in most patients. The diagnosis of shellfish allergy, in particular shrimp, is challenging due to the similarity of allergenic proteins from other invertebrates. Despite the clinical importance of immunological cross-reactivity among shellfish species and between allergenic invertebrates such as dust mites, the underlying molecular basis is not well understood. Here we mine the complete transcriptome of five frequently consumed shrimp species to identify and compare allergens with all known allergen sources. The transcriptomes were assembled de novo, using Trinity, from raw RNA-Seq data of the whiteleg shrimp (Litopenaeus vannamei), black tiger shrimp (Penaeus monodon), banana shrimp (Fenneropenaeus merguiensis), king shrimp (Melicertus latisulcatus), and endeavour shrimp (Metapenaeus endeavouri). BLAST searching using the two major allergen databases, WHO/IUIS Allergen Nomenclature and AllergenOnline, successfully identified all seven known crustacean allergens. The analyses revealed up to 39 unreported allergens in the different shrimp species, including heat shock protein (HSP), alpha-tubulin, chymotrypsin, cyclophilin, beta-enolase, aldolase A, and glyceraldehyde-3-phosphate dehydrogenase (G3PD). Multiple sequence alignment (Clustal Omega) demonstrated high homology with allergens from other invertebrates including mites and cockroaches. This first transcriptomic analyses of allergens in a major food source provides a valuable resource for investigating shellfish allergens, comparing invertebrate allergens and future development of improved diagnostics for food allergy.

Shellfish Allergy: Unmet Needs in Diagnosis and Treatment

Seafood is a major cause of food allergy and anaphylaxis worldwide. Shellfish is included among the “big eight” food groups, which are responsible for more than 90% of all cases of food allergy. Approximately 2.5% of the world’s population has experienced an adverse reaction to seafood. Seafood allergy is one of the most frequent and lethal allergies that exist. The several allergenic proteins involved in allergic reactions that have been described in recent years include tropomyosin, arginine kinase, myosin light chain, and sarcoplasmic calcium-binding protein. Despite all the data reported in the last few years, shellfish allergy is still diagnosed and treated as it was 50 years ago. The only effective treatment to prevent allergic reactions to shellfish is avoidance. This review aims to update recently published data on shellfish allergy and to highlight those areas that have yet to be resolved.

A rare case report on pediatric shellfish allergy

Shellfish are extensively consumed worldwide because of their nutritional value. In general they are good sources of low-fat protein rich in several essential vitamins and minerals as well as in the essential nutrients omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFAs) [1]. Shellfish belongs to “The Big 8” food groups causing allergy, which often does not outgrow during childhood. However, increase in IgE – mediated sea food allergy has been linked to shellfish. Seafood- associated shellfish include crustaceans & molluskans [2]. These may cause mild local symptoms & lead to severe systemic anaphylactic reactions by ingestion, inhalation, or contact. Globally, the prevalence of shellfish allergy estimated to be 0.5% to 2.5% of the general population [3]. There are limited data showing the prevalence of shellfish allergy in children.

Novel allergen discovery through comprehensive de novo transcriptomic analyses of 5 shrimp species

Shellfish allergy affects up to 2% of the world’s population and persists for life in most patients. The diagnosis of a shellfish allergy, in particular shrimp, is however often challenging due to the similarity of allergenic proteins in other invertebrates. Despite the clinical importance, the complete allergen repertoire of allergy-causing shrimps remains unclear. Here we mine the complete transcriptome of five frequently consumed shrimp species to identify and compare allergens with all known allergen sources. The transcriptomes were assembled de novo from raw RNA-Seq data of the whiteleg shrimp (Litopenaeus vannamei), black tiger shrimp (Penaeus monodon), banana shrimp (Fenneropenaeus merguiensis), king shrimp (Melicertus latisulcatus), and endeavour shrimp (Metapenaeus endeavouri). Trinity was used to assemble the transcriptome, and Transrate and BUSCO applied to verify the assembly. Blast search with the two major allergen databases, WHO/IUIS Allergen Nomenclature and AllergenOnline, successfully identified all seven known crustacean allergens. Salmon was utilised to measure their relative abundance, demonstrating sarcoplasmic calcium-binding protein, arginine kinase and myosin light chain as highly abundant allergens. In addition, the analyses revealed up to 40 unreported allergens in different shrimp species, including heat shock protein (HSP), alpha-tubulin, chymotrypsin, cyclophilin, beta-enolase, aldolase A, and glyceraldehyde-3-phosphate dehydrogenase (G3PD). Multiple sequence alignment, conducted in Jalview 2.1 with Clustal Omega, demonstrated high homology with allergens from other invertebrates including mites and cockroaches. This first transcriptomic analyses of allergens in a major food source provides a valuable genomic resource for investigating shellfish allergens, comparing invertebrate allergens and developing improved diagnostics and novel immunotherapeutics for food allergy.