{"doi":"10.1128/jvi.02379-20","title":"A Competitive Hemagglutination Inhibition Assay for Dissecting Functional Antibody Activity against Influenza Virus","abstract":"The hemagglutination inhibition (HAI) assay is a well-established and reproducible method that quantifies functional antibody activity against influenza viruses and, in particular, the capability of an antibody formulation to inhibit the binding of hemagglutinin (HA) to sialic acid. However, the HAI assay does not provide full insights on the breadth and epitope recognition of the antibody formulation, especially in the context of polyclonal sera, where multiple antibody specificities contribute to the overall observed functional activity. In this report we introduce the use of Y98F point-mutated recombinant HA (HAΔSA) proteins, which lack sialic acid binding activity, in the context of the HAI assay as a means to absorb out certain HA-directed (i.e., strain-specific or cross-reactive) antibody populations. This modification to the classical HAI assay, referred to as the competitive HAI assay, represents a new tool to dissect the magnitude and breadth of polyclonal antibodies elicited through vaccination or natural infection.","journal":"Journal of Virology","year":2021,"id":198012,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":11,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9556,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":299104,"name":"Giuseppe A. Sautto","orcid":"0000-0002-0273-2235","position":1,"is_corresponding":false},{"id":773135,"name":"Robert A. Richardson","orcid":null,"position":2,"is_corresponding":false},{"id":300382,"name":"Jeffrey W. Ecker","orcid":null,"position":3,"is_corresponding":false},{"id":245069,"name":"Ted M. Ross","orcid":"0000-0003-1947-7469","position":4,"is_corresponding":false},{"id":299098,"name":"Greg A. Kirchenbaum","orcid":"0000-0001-6463-7623","position":0,"is_corresponding":true}],"reference_count":17,"raw_metadata":null,"created_at":"2026-07-18T23:50:27.616568Z","pmid":"34523961","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}