A time-resolved immunoassay to measure serum antibodies to the rotavirus VP6 capsid protein
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Published on: January 28, 2019
Owen Kavanagh1, Xi-Lei Zeng, Sasirekha Ramani
1Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA.
Insights
This study produced rotavirus (RV) VP6 recombinant proteins to measure RV-specific antibodies. The new assay effectively detects immune responses, proving useful for future vaccine and infection studies.
Area of Science:
- Immunology
- Virology
- Vaccinology
Background:
- Rotavirus (RV) inner capsid protein VP6 is crucial for assessing immune responses to natural infection and vaccines.
- Previous methods for evaluating RV immunity have limitations.
- Recombinant VP6 proteins offer a standardized approach for immune response measurement.
Purpose of the Study:
- To produce recombinant VP6 proteins from prevalent Indian rotavirus strains (SGII [G1P[8]] and SGI [G10P[11]]).
- To validate a Dissociation-Enhanced Lanthanide Fluorometric Immunoassay (DELFIA) for detecting VP6-specific IgG antibodies.
- To compare the DELFIA assay's performance against a gold standard virus-capture ELISA.
Main Methods:
- Production of purified recombinant VP6 proteins from specific rotavirus strains.
- Utilizing DELFIA to quantify VP6-specific IgG antibody levels in serum samples.
- Comparing DELFIA results with a virus-capture ELISA using longitudinal study samples.
Main Results:
- A strong association (p<0.001) was found between the DELFIA assay and the gold standard ELISA.
- The DELFIA assay demonstrated consistent performance regardless of RV RNA detection timing relative to antibody rise.
- The assay effectively detected a ≥2 fold rise in IgG levels.
Conclusions:
- Recombinant VP6 proteins are suitable for measuring anti-rotavirus immune responses.
- The DELFIA assay provides a reliable method for evaluating VP6-specific antibody levels.
- This study establishes a proof of principle for using recombinant proteins to identify correlates of protection against rotavirus.
Abstract:
The rotavirus (RV) inner capsid protein VP6 is widely used to evaluate immune response during natural infection and in vaccine studies. Recombinant VP6 from the most prevalent circulating rotavirus strains in each subgroup (SG) identified in a birth cohort of children in southern India [SGII (G1P[8]) and SGI (G10P[11])] were produced. The purified proteins were used to measure VP6-specific antibodies in a Dissociation-Enhanced Lanthanide Fluorometric Immunoassay (DELFIA). The ability of the assay to detect a ≥2 fold rise in IgG level in a panel of serum samples from a longitudinal study was compared to a gold standard virus-capture ELISA. A strong association was observed between the assays (p<0.001; chi-squared test) with assay performances remaining similar when the samples were subdivided as having a fold change increase in VP6 antibody levels (a) within 90 days of RV RNA detection in stool or (b) if no RV RNA was detected within that time period. This study demonstrates the suitability of using recombinant proteins to measure anti-RV immune responses and serves as a "proof of principle" to examine the antibody responses generated to other recombinant RV proteins and thereby possibly identify a correlate of protection.
