Development of rapid antigen test prototype for detection of SARS-CoV-2 in saliva samples

Agnija Kivrane, Viktorija Igumnova, Elza Elizabete Liepina, Dace Skrastina, Ainars Leonciks, Zanna Rudevica, Svjatoslavs Kistkins, Aigars Reinis, Anna Zilde, Andris Kazaks, Renate Ranka (Coresponding Author)

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
1 Downloads (Pure)


Background: The development of easy-to-perform diagnostic methods is highly important for detecting current coronavirus disease (COVID-19). This pilot study aimed at developing a lateral flow assay (LFA)- based test prototype to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus in saliva samples. Methods: Mice were immunized using the recombinant receptor-binding domain (rRBD) of SARS-CoV-2 virus spike protein. The combinations of the obtained mouse anti-receptor-binding domain (RBD) polyclonal antibodies (PAbs) and several commercial antibodies directed against the SARS-CoV-2 spike protein were used for enzyme-linked immunosorbent assay (ELISA) to select antibody pairs for LFA. The antibody pairs were tested in a LFA format using saliva samples from individuals with early SARS-CoV-2 infection (n = 9). The diagnostic performance of the developed LFA was evaluated using saliva samples from hospitalized COVID-19 patients (n = 111); the median time from the onset of symptoms to sample collection was 10 days (0-24 days, interquartile range (IQR): 7-13). The reverse transcription-polymerase chain reaction (rRT-PCR) was used as a reference method. Results: Based on ELISA and preliminary LFA results, a combination of mouse anti-RBD PAbs (capture antibody) and rabbit anti-spike PAbs (detection antibody) was chosen for clinical analysis of sample. When compared with rRT-PCR results, LFA exhibited 26.5% sensitivity, 58.1% specificity, 50.0% positive prediction value (PPV), 33.3% negative prediction value (NPV), and 38.7% diagnostic accuracy. However, there was a reasonable improvement in assay specificity (85.7%) and PPV (91.7%) when samples were stratified based on the sampling time. Conclusion: The developed LFA assay demonstrated a potential of SARS-CoV-2 detection in saliva samples. Further technical assay improvements should be made to enhance diagnostic performance followed by a validation study in a larger cohort of both asymptomatic and symptomatic patients in the early stage of infection.

Original languageEnglish
Article numbere8207
Number of pages9
JournalUpsala Journal of Medical Sciences
Issue number1
Publication statusPublished - 25 Feb 2022


  • antigen test
  • COVID-19
  • Lateral flow assay
  • point-of-care testing
  • polyclonal antibodies

Field of Science*

  • 3.1 Basic medicine
  • 3.2 Clinical medicine

Publication Type*

  • 1.1. Scientific article indexed in Web of Science and/or Scopus database


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