SARS-CoV-2 antibody response and serum neutralizing capacity of early unvaccinated COVID-19 patients in the Philippines
Year: 2025
Type: article
Study design: Observational Study
Abstract: BackgroundSerological studies on the association between disease severity and humoral immunity against SARS-CoV-2 during the first wave of the COVID-19 pandemic remains inconclusive. This study focused on humoral immune responses of antigen-specific and isotypespecific antibodies from SARS-CoV-2 infected patients with different disease severity prior to the implementation of the national COVID-19 vaccination program in the Philippines.MethodsThis study analyzed 177 biobank serum samples from 67 hospitalized adult patients with RT-PCR-confirmed COVID-19 during the first wave of the pandemic. Immunoglobulin (Ig) G, IgM, and IgA antibodies against SARS-CoV-2 S1, S2, RBD, and N proteins, as well as IgG antibodies against human ACE2, were determined by enzyme-linked immunosorbent assay (ELISA). Serum neutralization capacity was determined by 1) ACE2-RBD binding inhibition assay and 2) pseudovirus neutralization assay. The relationship of the binding antibodies with various clinical parameters was determined.FindingsIgG, IgM, and IgA antibody responses were associated with disease severity within two weeks after symptom onset. IgM response positively correlated with inflammatory markers ferritin and C-reactive protein. IgM-N in particular was shown to predict in-hospital mortality. However, the patient sera lacked neutralizing activity to the SARS-CoV-2 Wuhan strain. On the other hand, anti-ACE2 IgG was detected in the patient cohort, and levels were not associated with disease severity or inflammatory markers.InterpretationMost patients early in the pandemic had high binding antibodies against SARSCoV-2 but had low serum neutralizing capacity. Moreover, the role and clinical implications ofdetectable IgG against ACE2 in COVID-19 patients need further investigation.
Language: English
Subfield: Infectious Diseases
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,320
OpenAlex ID: W4410586389