Sus s 1
Summary
Sus s 1, the serum albumin of Sus scrofa (domestic pig), is a respiratory and food minor allergen present in dander, meat, milk, and saliva. Sus s 1, a member of the serum albumin family, displays cross-reactivity mainly among mammalian homologues. Sus s 1, a heat-labile protein, is denatured during food processing.
Epidemiology
Worldwide distribution
Contact with S. scrofa occurs mainly during food ingestion, food preparation, and in occupational settings, however it has also been listed as an emerging unconventional pet [1, 2]. Of note, domestic pig, also called “swine”, and wild boar belong to the same S. scrofa species, with the latter being hunted and in some cases farmed [3].
Clinical Relevance
Sensitization to serum albumins as food allergens may manifest as clinical reactions of variable intensity, from mild to severe [1].
The clinical relevance of serum albumins as a respiratory allergen is usually difficult to assess given its frequent association with major allergens from the same primary sensitizer and the infrequent finding of monosensitization to serum albumin, however, case reports of severe asthma caused by serum albumins from cat (Fel d 2) or horse (Equ c 3) are available [1].
Cross-reactive molecules
Sus s 1 IgE cross-reactivity, potentially extending to any serum albumin homologue, has been documented for Fel d 2 (cat serum albumin) and Gal d 5 (chicken serum albumin or alpha-livetin) [1, 5]. The degree of cross-reactivity between individual serum albumin may vary [5].
At the clinical level, Sus s 1 cross-reactivity may be relevant for cross-reactivity between pork (S. scrofa meat) and serum albumins from cat (Fel d 2, “pork-cat syndrome, which can also be caused by other cross-reactive allergens), cow (Bos d 6, bovine serum albumin present in cow’s milk and meat) and more generally meat and milk from other species [1, 5].
Diagnostics
Serum albumins including Sus s 1 are markers of cross-reactivity in most patients, with a very limited number of reports of monosensitization [1].
Cross-Reactivity
Sus s 1 is one of the allergen components involved in the pork-cat syndrome due to cross-reactivity with cat serum albumin Fel d 2 [1, 5]. The pork-cat syndrome denotes an allergic reaction to raw or underdone pork meat in a cat-allergic patient. Of note, clinically relevant cross-reactivity between Sus s 1 and the chicken serum albumin Gal d 5 (alpha-livetin) has been documented [5].
Sus s 1 cross-reactivity with other mammals’ serum albumins may contribute to meat and milk hypersensitivity reactions [1].
Exposure
The main route of exposure to Sus s 1 is through ingestion of pork meat.
References
- Matricardi, P.M., et al., EAACI Molecular Allergology User's Guide. Pediatr Allergy Immunol, 2016. 27 Suppl 23: p. 1-250.
- Curin, M. and C. Hilger, Allergy to pets and new allergies to uncommon pets. Allergol Select, 2017. 1(2): p. 214-221.
- Sales, J. and R. Kotrba, Meat from wild boar (Sus scrofa L.): a review. Meat Sci, 2013. 94(2): p. 187-201.
- Sigsgaard, T., et al., Respiratory diseases and allergy in farmers working with livestock: a EAACI position paper. Clin Transl Allergy, 2020. 10: p. 29.
- Hilger, C., et al., Occupational inhalant allergy to pork followed by food allergy to pork and chicken: sensitization to hemoglobin and serum albumin. Int Arch Allergy Immunol, 2010. 151(2): p. 173-8.
- UniProt. UniProt P08835 for Sus s 1. June 13 2022]; Available from: https://www.uniprot.org/uniprot/P08835.
- IUIS/WHO. IUIS/WHO Sus s 1. June 13 2022]; Available from: http://allergen.org/viewallergen.php?aid=854.