Singleplex gold-standard FANG ELISA versus Pan-filovirus Multiplex Immuno Assay analysis of EBOV GP IgG antibody reactivity in rVSV-EBOV-GP Vaccinated individuals in Beni, Democratic Republic of Congo

Abstract

Between 2018 and 2020, the Democratic Republic of Congo (DRC) experienced an Ebola virus Disease (EVD) outbreak during which, the rVSV-ZEBOV vaccine was first used as an intervention strategy. However, no studies have been conducted on the duration of vaccineinduced antibodies (Ab). Again Ebola virus (EBOV) is a highly infectious pathogen, and its long-term consequences continue to be investigated. With its high fatality rate and potential for reinfection or latent infection, continued development of research tools is of utmost importance since not all immunoassays have been shown to detect a vaccine-induced immune response, and previous EBOV serosurveillance has been primarily conducted with singleplex technology, meanwhile MIA is an additional resource. We therefore aim to compare the gold-standard FANG ELISA and the pan-filovirus MIA in determining EBOV GP IgG antibody reactivity in rVSV-EBOV-GP Vaccinated individuals in Beni, DRC. 617 vaccine recipients were recruited from August 2018 to February 2019.A questionnaire was used to collect socio-demographic data and likely determinants of EVD exposure for each recruited individual. Subsequently, 6ml of blood was collected in dry tubes for Ebola glycoprotein IgG Ab testing. 9 had Ebola IgG antibodies at baseline. Follow-up visits at 21 days and 6 months after vaccination included 608 participants without anti-Ebola Ab at baseline. These samples collected were heat-inactivated and analyzed separately with the gold-standard FANG ELISA and Pan-filovirus MIA. In a total of 9 of 617 participants (1.5%), baseline Ebola Ab was elevated. Also, of the 608 participants expected at the time of the appointments, 90% (n=548) of the participants had responded by D21 after vaccination.71.4% (n=434) of the participants responded at the 6-month post-vaccination visit. Of these, 95.6% of the vaccinated participants had IgG anti-Ebola virus antibodies with significantly elevated geometric mean antibody concentrations of 1231 (1145 - 1324) EU/mL. Moreover, of the samples used for both FANG and MIA, 68% were MIA seroreactive and FANG non-seroreactive. This study shows that MIA could be an appropriate alternative to the singleplex FANG in assessing immunological responses to EBOV GP across a geographical area, especially in a low resource setting. In addition, this result shows that one dose of this vaccine can protect against EVD 6 months after use. However, further studies are recommended to understand and complement the data from this study