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Order Martellivirales: Bromoviridae
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
To generate a vaccine against cat allergy, the recombinant Fel d 1 protein was coupled to the CuMVTT VLPs via a small Cys-containing linker. The Fel d 1 coupled to the CMVTT VLPs was highly immunogenic and induced a 10–100-fold-stronger antibody response than free Fel d 1 or Fel d 1 mixed with VLPs, demonstrating potent immunogenicity depended on the presentation by the CMVTT VLPs (Zeltins et al. 2017). Furthermore, Thoms et al. (2019) developed a new strategy to treat Fel d 1-induced allergy in human subjects by immunizing cats—but not allergic cat owners—against their own major allergen, Fel d 1. The CMVTT VLPs-based vaccine was well tolerated and had no overt toxic effect. All cats induced high-titer and long-lasting antibody responses. The antibodies were able to neutralize the allergen both in vitro and in vivo and led to the reduction of the endogenous allergen level and a reduced allergenicity of tear samples (Thoms et al. 2019). Thoms et al. (2020) reported the positive outcome of the first field trial with ten cat-allergic participants living together with their cats, where the cats were vaccinated with the Fel-CuMV vaccine termed HypoCatTM. It is noteworthy that a similar technique was developed earlier by the Bachmann team, when they displayed recombinant Fel d 1 on the surface of the VLPs of the previously mentioned RNA phage Qβ (Chapter 25). Remarkably, in both cases, the allergens displayed on the VLPs were more immunogenic than their free counterparts.
Environment and Lifestyle in Allergic Disease
Published in Pudupakkam K Vedanthan, Harold S Nelson, Shripad N Agashe, PA Mahesh, Rohit Katial, Textbook of Allergy for the Clinician, 2021
Anubha Tripathi, Thomas AE Platts-Mills
Cats and dogs are present in large numbers of homes and are an important cause of sensitization and allergic symptoms. However, there are major differences between cat exposure and mite exposure which may be relevant to the relationship of these allergens to disease (Platts-Mills et al. 2002). The aerodynamic sizes of particles carrying the cat allergen Fel d 1 are smaller (2–20 µm) than those of pollen grains (25–45 µm) or mite feces (20–40 µm). As a direct consequence of their smaller size, particles carrying cat allergen remain airborne in homes for a longer time, i.e., hours after disturbance and the overall quantities inhaled are much higher (Luczynska 1990). Indeed some estimates suggest that exposure in a home with a cat can be as high as one microgram per day. The particles carrying cat allergen carry Fel d 1 and endotoxin. Interestingly, while many cat proteins have major homology with the proteins of other mammals, this is not true of Fel d 1. This protein is present in all cats and has very little homology with other mammalian proteins. In addition, the DNA of cats is fully methylated and does not act as a TLR-9 agonist. Finally, although the cat particles remain airborne and have a smaller aerodynamic size, many of the particles take the form of a flake, which decreases their falling velocity and apparent size (Luczynska 1990).
Mammalian allergens
Published in Richard F. Lockey, Dennis K. Ledford, Allergens and Allergen Immunotherapy, 2020
Tuomas Virtanen, Marja Rytkönen-Nissinen
Genes encoding Fel d 1 chains are expressed in the cat salivary glands and skin [65]. Fel d 1 is found in hair roots and sebaceous glands; in dander, saliva, and lacrimal fluid; and, in high concentrations, in anal glands. The production of Fel d 1 is hormonally controlled, and male cats produce more than females. The biological function of Fel d 1 is unknown, but it may be related to the protection of epithelia [64], to ligand transport [66], or to chemical communication [67]. It is speculated that Fel d 1 has an intrinsic capacity to promote allergy by sequestering calcium ions from phospholipase A2 [66]. Fel d 1 does not have enzymatic activity [66]. Fel d 1 is also recognized by mannose receptor (MR), facilitating its internalization by antigen-presenting cells [31]. Further murine experiments suggest that the glycan component of Fel d 1 is involved in the Th2 immune deviation. A more recent study found that Fel d 1 enhanced LPS and lipoteichoic acid–induced TLR signaling (TLR4 and TLR2, respectively) in an experimental setting [28]. Interestingly, TLR4 signaling was independent of the glycosylation of Fel d 1 and thus MR activity. Moreover, Fel d 1 enhanced LPS-induced TNF-α production in primary human PBMCs.
Precision medicine in the allergy clinic: the application of component resolved diagnosis
Published in Expert Review of Clinical Immunology, 2022
Carmen Panaitescu, Laura Haidar, Maria Roxana Buzan, Manuela Grijincu, Daniela Elena Spanu, Catalina Cojanu, Alexandru Laculiceanu, Roxana Bumbacea, Ioana Agache
CRD can support the development of novel AIT methods. Several passive and active immunization protocols for cats against their own Fel d 1 antigen have been attempted. Commercially available cat food supplemented with anti-Fel d 1 IgY blocks the IgE binding sites in Fel d 1 from cat saliva [210]. Active immunization with a conjugate vaccine which stimulates B cells to secrete anti-Fel d 1 antibodies which bind the allergen, reduce its secretion in tears and reactogenicity may also result in reduced symptoms of allergic cat owners [211].
Component-resolved microarray analysis of IgE sensitization profiles to Felis catus major allergen molecules in Russian cat-allergic patients
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2018
Anna Sergeevna Dolgova, Anna Evgenevna Sudina, Anna Sergeevna Cherkashina, Olga Alekseevna Stukolova
Cat dander extract consists of several allergens. Fel d 1 is the major cat allergen [21]. Although Fel d 1 is responsible for the majority of IgE reactivity in cat-allergic patients, additional individual allergens should be used to increase the sensitivity of in vitro diagnostics. Moreover, cosensitization of different allergen molecules may serve as an indicator of asthma (Fel d 1 and Fel d 4) [22,23] or atopic dermatitis (Fel d 4 and/or Fel d 2) [24–26]. In the current study, we investigated the patients’ sensitization profiles to the three proteins of interest (Fel d 1; Fel d 2 and Fel d 4). The percentage of patients suffering from cat allergy that are sensitive to other cat proteins is considerably lower than the percentage of patients that are sensitive to these three. The total prevalence of sensitization was 92.5% for Fel d 1, 29.9% for Fel d 2, and 39.1% for Fel d 4 (Figure 1, Table 1). The average IgE reactivity to Fel d 1 and Fel d 2 was significantly higher than that to Fel d 4. However, there was no strong correlation between total IgE and sIgEs to Fel d 1, Fel d 2 and Fel d 4, in contrast to some other allergy types, such as house dust mite allergy [27]. There was absolutely no correlation between total IgE and sIgE towards Fel d 2 and a low positive correlation between Fel d 1 sIgE and total IgE (0.36; p < .0005). An interesting pattern was observed for the Fel d 4 protein. There was no obvious correlation between Fel d 4 sIgE and the total IgE level (0.25; p < .05), but the correlation increased to 0.36 when only males were considered (p < .05). The apparent correlation in males but not females is attributable not only to gender but also differences in age. The mean ages of the two groups differed significantly, with values of 14 years for males and 21 years for females (p = .0019), and the difference between the median values was even larger (7 and 23 years, respectively). The correlation between sIgE levels for each protein was also rather low. However, consistent with other component-resolving cat allergy studies, the best correlation was between Fel d 1 and Fel d 4 sIgE levels, with a correlation coefficient of 0.33 (p = .0005) (0.4 in [28]; 0.33 in [29] studies).