{"id":"doi:10.1128/iai.00167-26","kind":"article","title":"Structure-guided design of <i>Anaplasma</i> P44 protein-based chimeric antigens for serodiagnosis of anaplasmosis in dogs","authors":["Cramer NA","Brangulis K","Mann SN","Herrera FM","Breitschwerdt EB","Carlyon JA","Marconi RT"],"author_count":7,"year":2026,"published":"2026-09-15","venue":"Infection and immunity","cited_by":0,"doi":"10.1128/iai.00167-26","arxiv_id":null,"nct_id":null,"source_url":"https://doi.org/10.1128/iai.00167-26","archive_url":"https://space-kitty.com/papers/doi:10.1128/iai.00167-26","updated":null,"pmid":"42742337","pmcid":null,"openalex_id":null,"pdf_url":null,"abstract":"Canine and human anaplasmosis are tick-borne diseases caused by the obligate intracellular bacteria, Anaplasma phagocytophilum and Anaplasma platys , respectively. In veterinary medicine, peptides derived from the immunodominant P44 protein are used to detect antibodies in serological point-of-care tests for anaplasmosis. To inform efforts to develop improved chimeric diagnostic proteins for anaplasmosis, the structure of the predicted surface-exposed domain (residues 151-308) of P44 was determined at a resolution of 1.65 Å. This domain comprises six α-helices and six short β-strands connected by loop regions. A structural similarity search of the P44 151-308 domain using the Distance Matrix Alignment server against the AlphaFold Database revealed that the domain represents a previously uncharacterized protein fold. The determined structure is consistent with AlphaFold v2 predictions, which further predict the core of P44 to be an eight-stranded β-barrel. Using P44 fragments, immunodominant epitopes were mapped within residues 151-308. Four chimeric genes (ADC1, ADC2, ADC3, and ADC4) were designed that incorporate the analogous immunodominant P44 domains from A. phagocytophilum and A. platys . The recombinant ADC chimerics were assessed for sensitivity and specificity by screening with serum from dogs diagnosed with anaplasmosis, Lyme disease, or ehrlichiosis, with sera from specific pathogen-free dogs serving as negative controls. Accuracy was further demonstrated by screening characterized serum samples from coyotes ( Canis latrans ; wild canids). The ADC1 chimeric provided 100% sensitivity and 98.04% specificity. The sensitivity and specificity of ADC1 support its potential use as a diagnostic Ag for anaplasmosis.","abstract_license":"CC-BY (article license as recorded by Europe PMC; abstract reproduced unmodified apart from markup removal)","license":"CC-BY","is_open_access":false,"retracted":false,"peer_reviewed":null,"categories":[],"details":null,"provenance":"europepmc","attribution":"Abstract of \"Structure-guided design of <i>Anaplasma</i> P44 protein-based chimeric antigens for serodiagnosis of anaplasmosis in dogs\" by Cramer NA, Brangulis K, Mann SN et al., https://doi.org/10.1128/iai.00167-26, used under its Creative Commons Attribution license (CC-BY); markup removed, otherwise unmodified.","topics":[{"slug":"protein-design","name":"AI Protein Design & Structure Prediction","domain_slug":"biotech"}],"cited_in_dossiers":[]}