Protective Immunity of the Primary SARS-CoV-2 Infection Reduces Disease Severity Post Re-Infection with Delta Variants in Syrian Hamsters

  1. Sreelekshmy Mohandas
  2. Pragya D. Yadav
  3. Anita Shete
  4. Dimpal Nyayanit
  5. Rajlaxmi Jain
  6. Gajanan Sapkal
  7. Chandrashekhar Mote

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Abstract

The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Delta variant has evolved to become the dominant SARS-CoV-2 lineage with multiple sub-lineages and there are also reports of re-infections caused by this variant. We studied the disease characteristics induced by the Delta AY.1 variant and compared it with the Delta and B.1 variants in Syrian hamsters. We also assessed the potential of re-infection by these variants in Coronavirus disease 2019 recovered hamsters 3 months after initial infection. The variants produced disease characterized by high viral load in the respiratory tract and interstitial pneumonia. The Delta AY.1 variant produced mild disease in the hamster model and did not show any evidence of neutralization resistance due to the presence of the K417N mutation, as speculated. Re-infection with a high virus dose of the Delta and B.1 variants 3 months after B.1 variant infection resulted in reduced virus shedding, disease severity and increased neutralizing antibody levels in the re-infected hamsters. The reduction in viral load and lung disease after re-infection with the Delta AY.1 variant was not marked. Upper respiratory tract viral RNA loads remained similar after re-infection in all the groups. The present findings show that prior infection could not produce sterilizing immunity but that it can broaden the neutralizing response and reduce disease severity in case of reinfection.

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  1. Version published to 10.3390/v14030596
  2. ScreenIT

    SciScore for 10.1101/2021.11.28.470293: (What is this?)

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

    Table 1: Rigor

    EthicsIACUC: Ethics statement: The ethical approval for the study was received from Institutional Animal Ethics Committee (Approval no: NIV/IAEC/2021/ MCL/01), ICMR-National Institute of Virology, Pune and all the animal experiments were performed in adherence with the guidelines of the Committee for the Purpose of Control and Supervision of Experiments on Animals, Government of India.
    Sex as a biological variableFor the re-infection study, 12 female hamsters, 16-18 weeks old which were previously infected with B.1 variant of SARS-CoV-2 (with an infectious dose of 104,5 TCID50) after 3 months of initial infection were used (Figure 1a).
    RandomizationIgG response and neutralizing antibody levels were checked and animals were divided into 3 groups randomly.
    BlindingThe samples were coded and were blindly scored.
    Power Analysisnot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    1 Anti-SARS-CoV-2 IgG detection: The serum samples were tested for IgG antibodies by an in-house developed ELISA22.
    Anti-SARS-CoV-2 IgG
    suggested: None
    IgG
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Briefly, inactivated SARS-CoV-2 antigen/ Vero CCL81 cell lysate coated microtiter plates were blocked with liquid plate sealer.
    Vero CCL81
    suggested: None
    Software and Algorithms
    SentencesResources
    Data analysis: Graph pad Prism version 9.2.0 software was used for the descriptive statistics and statistical analysis.
    Graph pad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    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).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Our study had limitation of small sample size too. In conclusion, the present study shows re-infection with Delta variants or B. 1 variant post 3 months of prior B.1 variant infection could reduce the SARS-CoV-2 virus shedding and reduce disease severity. Delta AY.1 variant produced mild disease and generated cross neutralising antibodies against B.1, Delta and Beta variants. The findings indicate that primary infection can produce protective immunity against a further infection for at least 3 months and can reduce severity of infection in hamsters.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

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

    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.

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

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2021.11.28.470293v1 on bioRxiv