Salivary tick protein that acts by scavenging histamine at the wound site, outcompeting histamine receptors for histamine, thereby overcoming host inflammatory responses (PubMed:10360182). Binds histamine with a high-affinity (Kd=18 nM) (PubMed:10360182). Contains two binding histamine sites (H and L), that appear to bind histamine with differing affinities (By similarity). In vivo, when tested on a mouse asthma model, shows a profound inhibitory effect on allergic asthma. Aerosol administration of this protein prevents airway hyperreactivity and abrogates peribronchial inflammation, eosinophil recruitment, mucus hypersecretion, and interleukins (IL-4 and IL-5) secretion (PubMed:16387687). In addition, when tested on a mouse model of acute respiratory distress syndrome (ARDS), it attenuates endotoxin-induced acute lung injury (PubMed:16387688). Monomer. Expressed by salivary glands. Early stage of adult feeding. Contains 2 sites/pockets that bind histamine with different affinities. Site H (high affinity) is indicated here as binding to histamine 1, and site L (low affinity) is indicated as binding to histamine 2. Is currently under preclinical trials by Akari therapeutics under the name Votucalis to act as an anti-histaminic to treat pruritus/itch and nociception. Belongs to the calycin superfamily. Histamine-binding salivary protein family.