Distribution of Core Fragments from the Major Cat Allergen Fel d 1 Is Maintained among the Main Anatomical Sites of Production

Abstract

Background: Polymorphism of Fel d 1 has long been observed, but structural characterization of Fel d 1 variants among the various sites of production and animals is still missing. This study was aimed at elucidating the structural polymorphism of this protein as a function of the site of production and the resulting influence on the immunological behavior of the allergen. Methods: Fel d 1 was water-extracted from the 4 main sites of production, i.e. cheek zone, interdigital zone, anal sac (AS), and chest area and a panel of 10 cats. Fel d 1-like materials were immunoblotted, immunopurified and characterized by MALDI-TOF MS. Immunoreactivity was studied using ELISA dose-dependent curves at equilibrium. Results: In all areas, 4–10 isoforms ranging from 7 to 40 kDa were detected by MS. Essentially two truncated heterodimers of 13–14 and 16–17 kDa were identified together with intact Fel d 1 in all compartments and they were largely predominant in AS. These core fragments were found to contribute to a variable recognition by antibodies in a panel of ELISA. Conclusions: Our study identified truncated dimers of Fel d 1, probably resulting from proteolytic degradation of both chains and present in all cats. Core fragments are largely distributed among anatomical sites of production and especially well represented in AS. They are recognized as intact allergens by antibodies and may therefore introduce discrepancies in allergen measurement depending on the variable amount of intact and degraded Fel d 1 produced by the cat.

Keep the cat, change the care pathway: A transformational approach to managing Fel d 1, the major cat allergen

“…Fel d 1 is a four‐subunit (tetrameric) protein composed of two covalently linked heterodimers, each of which contains two distinct chains (Chain 1, a polypeptide, and Chain 2, a glycopeptide with N‐linked oligosaccharides) that are encoded by separate genes and linked with disulfide bridges . (Figure ) Despite variation in Fel d 1 due to differential gene expression for the two chains, core fragments are preserved and the structural variation in Fel d 1 has a low impact on its allergenicity …”

Another cat and mouse game: Deciphering the evolution of the SCGB superfamily and exploring the molecular similarity of major cat allergen Fel d 1 and mouse ABP using computational approaches

“…Fel d 1 is abundantly released into the environment by cats [ 29 ], [ 30 ]. The primary anatomical sites of Fel d 1 production are the facial area and anal sacs [ 17 ], [ 18 ], [ 31 ]. Interestingly, these areas are also involved in intraspecific chemical communication in cats through the release of pheromones [ 32 ], and Carayol et al (2000) hypothesized that Fel d 1 production at various anatomical sites are also involved in the binding of pheromones [ 18 ].…”

Sex Differences in Mouse Exploratory Behaviour to Fel d 1, a Cat ABP-Like Protein

“…In our study, Fel d 1 from both sexes of cats and different isoforms were used as olfactory stimuli. These isoforms can vary according to cat sex and behaviours as well as anatomical sites of production [ 25 , 42 ]. These results should therefore be framed as the response to Fel d 1 from a diverse cat population.…”

“…Second, cat rubbing marks showed a kairomone role in laboratory rodents [ 19 ]. Third, the anatomical areas involved in cat rubbing coincide with the main reservoir and production areas of Fel d 1 [ 12 , 25 ]. Fourth, Fel d 1 is closely related to ABPs, which are implied in sexual chemical communication [ 16 , 17 ].…”