# High-Avidity Anti-Filovirus IgG Elicited Using Protein Subunit Vaccines Does Not Correlate with Protection

## TL;DR

This study explores whether high-avidity antibodies from protein subunit vaccines correlate with protection against ebolaviruses, but finds no clear link.

## Contribution

The study investigates antibody avidity as a potential correlate of protection against ebolaviruses, revealing no direct correlation.

## Key findings

- High-avidity anti-Filovirus IgG does not correlate with protection against ebolaviruses.
- The role of antibody avidity in protective and nonprotective vaccine responses remains unclear.
- Current research lacks a full understanding of immune correlates for ebolavirus vaccines.

## Abstract

Zaire ebolavirus (EBOV) poses a significant threat to public health due to its high case fatality rate and epidemic potential. This is further complicated by the lack of precise immune correlates of protection and difficulties in conducting in vivo animal studies due to species specificity of Ebola virus disease (EVD) and classification as a biosafety level 4 pathogen. Related ebolaviruses have also contributed to the public health threat; Uganda recently experienced an outbreak of Sudan ebolavirus, which also had a high case fatality rate. Vaccination targeting EBOV has demonstrated significant efficacy; however, the protective cellular and humoral responses at play are still poorly understood. Vaccination for vulnerable populations such as pregnant women, young children, and immunocompromised individuals is still limited. Understanding vaccine correlates of protection (vCOP) is key to developing alternative vaccination strategies for these groups. Components of immunity such as neutralizing antibody and cell-mediated immunity are likely responsible for protective responses; however, existing research fails to fully define their roles in protection. Here we investigated vaccine-elicited antibody avidity as a potential correlate of protection and to further characterize the contribution of antibody avidity in protective and nonprotective vaccine responses.