{Reference Type}: Journal Article {Title}: Humoral anti-SARS-CoV-2 response in patients with different long COVID phenotypes. {Author}: Rzymski P;Niedziela J;Poniedziałek B;Rosińska J;Zarębska-Michaluk D;Sobala-Szczygieł B;Flisiak R;Gąsior M;Jaroszewicz J; {Journal}: Virology {Volume}: 596 {Issue}: 0 {Year}: 2024 Aug 23 {Factor}: 3.513 {DOI}: 10.1016/j.virol.2024.110118 {Abstract}: Long COVID (LC) is characterized by persistent symptoms following SARS-CoV-2 infection, with various mechanisms offered to explain its pathogenesis. This study explored whether adaptive humoral anti-SARS-CoV-2 responses differ in LC. Unvaccinated COVID-19 convalescents (n = 200) were enrolled, with 21.5% (n = 43) presenting LC three months post-infection. LC diagnosis was based on persistent symptom(s) and alterations in biochemical/clinical markers; three phenotypes were distinguished: cardiological, pulmonary, and psychiatric LC. All three phenotypes were characterized by significantly decreased seroprevalence of IgG antibodies against nucleocapsid (anti-NP). LC was associated with decreased odds of testing positive for anti-NP (OR = 0.35, 95%CI: 0.16-0.78, p = 0.001). Seropositive LC patients had lower anti-S1 and anti-S2 levels than individuals without LC, and those with pulmonary and psychological phenotypes also revealed decreased anti-RBD concentrations. The results indicate that LC can be characterized by diminished humoral response to SARS-CoV-2. The potential implication of this phenomenon in post-acute viral sequelae is discussed.