Dimeric IgA is a specific biomarker of recent SARS-CoV-2 infection

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1. 

   ScreenIT

   Jul 3, 2021

   SciScore for 10.1101/2021.06.28.21259671: (What is this?)

   Please note, not all rigor criteria are appropriate for all manuscripts.

   Table 1: Rigor

   Ethics	IRB: Ethics: This study was conducted in concordance with the principles of the Declaration of Helsinki of the World Medical Association and approved by local human research ethics committees.
   Sex as a biological variable	not detected.
   Randomization	not detected.
   Blinding	not detected.
   Power Analysis	not detected.
   Cell Line Authentication	not detected.

   Table 2: Resources

   Antibodies
   Sentences	Resources
   Antibodies and proteins: Recombinant synthetic (GeneArt) chimeric IgA1 and IgA2 heavy chain sequences were constructed by joining the CB6 variable domain (amino acids 1-137) to the CH1 domain (amino acids 161-516) of IgA1 (J00220) or the CH1 domain (amino acids 161-501) of IgA2 (J00221) via a BspE1 …

   SciScore for 10.1101/2021.06.28.21259671: (What is this?)

   Please note, not all rigor criteria are appropriate for all manuscripts.

   Table 1: Rigor

   Ethics	IRB: Ethics: This study was conducted in concordance with the principles of the Declaration of Helsinki of the World Medical Association and approved by local human research ethics committees.
   Sex as a biological variable	not detected.
   Randomization	not detected.
   Blinding	not detected.
   Power Analysis	not detected.
   Cell Line Authentication	not detected.

   Table 2: Resources

   Antibodies
   Sentences	Resources
   Antibodies and proteins: Recombinant synthetic (GeneArt) chimeric IgA1 and IgA2 heavy chain sequences were constructed by joining the CB6 variable domain (amino acids 1-137) to the CH1 domain (amino acids 161-516) of IgA1 (J00220) or the CH1 domain (amino acids 161-501) of IgA2 (J00221) via a BspE1 restriction site and cloning into a pcDNA3 vector with an N-terminal TPA leader sequence.	CH1 domain (amino acids 161-516) of IgA1 suggested: None CH1 domain (amino acids 161-501) of IgA2 suggested: None J00221 suggested: None
   Nitrocellulose membranes (Sartorius, Germany) were striped with proteins in PBS (pH 7.4) to give two test lines, with test line 1 comprising 0.4 µl/cm of CSC (1 mg/ml) to capture dIgA, and test line 2 comprising 0.4 µl/cm of RBD (0.5 mg/ml) to capture total anti-RBD antibody, and a third procedural control line comprising 0.4 µl/cm of rabbit anti-chicken IgY (0.1 mg/ml) and dried at room temperature.	anti-RBD suggested: None anti-chicken IgY suggested: None
   Experimental Models: Cell Lines
   Sentences	Resources
   Protein Expression and purification: After transfection with RBD-encoding plasmid Expi293F or Expi293F BirA cells were incubated at 34°C whereas Expi293F cells transfected with CSC-encoding plasmid were incubated at 37°C.	Expi293F suggested: RRID:CVCL_D615)
   Recombinant DNA
   Sentences	Resources
   Vectors: The receptor binding domain (RBD) of the SARS CoV-2 spike protein (amino acids 332-532) and the chimeric secretory component (CSC) of the polymeric immunoglobulin receptor (650 amino acids protein synthesized by GenScript) were synthesized by ThermoFisher Scientific and subcloned into pcDNA3-based vectors under the control of the CMV promoter7.	pcDNA3-based suggested: None
   Protein Expression and purification: After transfection with RBD-encoding plasmid Expi293F or Expi293F BirA cells were incubated at 34°C whereas Expi293F cells transfected with CSC-encoding plasmid were incubated at 37°C.	CSC-encoding suggested: None
   For the expression of the J chain the mature protein sequence (DQ884395) amino acids 22-175 was synthesized (GeneArt) and cloned in frame with the tissue plasminogen activator (tpa) leader sequence into pcDNA3 based expression vector (Fig S1).	pcDNA3 suggested: RRID:Addgene_15475)
   Dimeric IgA1 and IgA2 were expressed by co-transfecting CB6 kappa light chain and CB6-IgA1 or CB6-IgA2 heavy chain sequence and pcDNA3-J using equivalent amounts of DNA.	pcDNA3-J suggested: RRID:Addgene_145146)
   Software and Algorithms
   Sentences	Resources
   Statistical methods: Data was analysed in Prism v9.02.	Prism suggested: (PRISM, RRID:SCR_005375)

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   Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

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   Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:

   However, IgM has many limitations in serology especially with low-prevalence infections 12, and none of these COVID-19 IgG/IgM tests have proven to be useful for determining the timing of recent or past infections in the absence of direct virus detection, severely limiting their utility in public health control measures. Our results suggest that SARS-CoV-2 specific dIgA may provide this missing tool for COVID-19 serology. Rapid antigen detection tests have received emergency authorization use under the FDA and have shown high specificity (>99%). However, the sensitivity of such tests is highly variable in symptomatic patients (63.7-79%) and have highest sensitivity (94.5%) where there is a high viral load (Ct values ≤25 or >106 genomic virus copies/mL) early in infection (<7 days) 13. The dIgA test performs at its best in the 2nd and 3rd week post symptom onset and a positive result by itself would indicate recent infection. The use of a rapid antigen test and the dIgA POC test in combination could allow rapid mass screening of individuals to identify active and recent past infections within at least the past 21 days, which would greatly enhance contact screening. For example, the dIgA LFA test could be used in backward contact tracing, including well-recognised super-spreader events. In these situations, where one or more individuals later become symptomatic and return a positive nucleic acid or antigen test result, there is often a missing link to the original source of inf...

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   Results from TrialIdentifier: No clinical trial numbers were referenced.

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   Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

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   Results from JetFighter: We did not find any issues relating to colormaps.

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   Results from rtransparent:

   • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
   • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
   • No protocol registration statement was detected.

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   Results from scite Reference Check: We found no unreliable references.

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   Version published to 10.1101/2021.06.28.21259671v1 on medRxiv

   Jul 1, 2021