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An Improved and High Throughput Respiratory Syncytial Virus RSV Micro-neutralization Assay
Published on: January 26, 2019
Development of a Kinetic ELISA and Reactive B Cell Frequency Assay to Detect Respiratory Syncytial Virus Pre-Fusion F
Stephanie L Rolsma1, Sandra M Yoder1, Rachel S Nargi2
1Vanderbilt Vaccine Research Program and Division of Pediatric Infectious Diseases, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Insights
New assays can distinguish between maternal antibodies and infant immune responses to respiratory syncytial virus (RSV) pre-fusion (F) protein. This helps determine eligibility for infant RSV vaccine trials by accurately assessing prior RSV infection.
Area of Science:
- Immunology
- Virology
- Pediatrics
Background:
- Respiratory syncytial virus (RSV) poses a significant threat to infants, driving interest in vaccination.
- Previous vaccine trials faced challenges due to vaccine-enhanced disease in RSV-naive children.
- Maternally transferred antibodies complicate the assessment of infant immune responses to RSV.
Purpose of the Study:
- To develop assays capable of differentiating between maternal and infant immune responses to the RSV pre-fusion (F) protein.
- To aid in determining infant eligibility for future RSV vaccine trials by accurately assessing prior infection.
Main Methods:
- Developed a kinetic enzyme-linked immunosorbent assay (kELISA) targeting RSV pre-F epitopes.
- Developed a reactive B cell frequency (RBF) assay targeting RSV F-specific B cells.
- Measured RSV-specific responses in infants <3 years, including RSV-infected and RSV-uninfected groups.
Main Results:
- Two distinct patterns were observed in RSV-uninfected infants: declining kELISA with no reactive B cells (maternal antibodies) and persistently positive kELISA with reactive B cells (undiagnosed asymptomatic infection).
- RSV-infected infants generally showed positive kELISA and RBF results during the study.
- The assays demonstrated potential in distinguishing antibody sources.
Conclusions:
- A kELISA targeting RSV pre-F epitopes and an RBF assay for RSV F-specific B cells can generally differentiate between maternal and infant-derived antibodies.
- These assays are valuable tools for assessing infant immune status regarding RSV.
- Accurate assessment is crucial for the safe and effective development of infant RSV vaccines.
Background:
Respiratory syncytial virus (RSV) is a major cause of respiratory disease in infants, making vaccination an attractive preventive strategy. Due to earlier reports of vaccine-enhanced disease in RSV-naive children, assessing prior RSV infection is critical for determining eligibility for future infant vaccine trials. However, this is complicated by the presence of maternally transferred maternal antibodies. We sought to develop assays that measure immune responses to RSV pre-fusion (F) protein that discriminates between maternal and infant responses.
Methods:
We measured RSV-specific responses in two groups of children <3 years of age; those with laboratory-confirmed RSV (RSV-infected) and those enrolled prior to their first RSV season (RSV-uninfected). Serial blood samples were obtained and recent infections with RSV and other respiratory viruses were assessed during follow-up. An RSV pre-F-specific kinetic enzyme-linked immunosorbent assay (kELISA) and an F-specific reactive B cell frequency (RBF) assay were developed.
Results:
One hundred two young children were enrolled between July 2015 and April 2017; 74 were in the RSV-uninfected group and 28 were in the RSV-infected group. Participants were asked to provide sequential blood samples over time, but only 53 participants in the RSV-uninfected group and 22 participants in the RSV-infected groups provided multiple samples. In the RSV-infected group, most had positive kELISA and RBF during the study. In the RSV-uninfected group, two patterns emerged: declining kELISA values without reactive B cells, due to maternal transplacental antibody transfer, and persistently positive kELISA with reactive B cells, due to asymptomatic undiagnosed RSV infection.
Conclusions:
A kELISA targeting RSV pre-F epitopes and an RBF assay targeting RSV F-specific B cells generally allow discrimination between maternally and infant-derived antibodies.
