Ebola vaccine induces T cell cross-reactivity against Bundibugyo virus in humans
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The current Bundibugyo Ebola virus (BDBV) outbreak in the Democratic Republic of the Congo is the second largest Ebola outbreak worldwide, with over 6,000 confirmed cases and a 48% fatality rate. There is currently no approved BDBV vaccine.
The VSV-EBOV (Ervebo) vaccine, which was developed to combat the related Ebola virus (EBOV), has shown partial cross-protection in non-human primates and has induced BDBV-reactive antibodies in humans.
A DZIF research team led by Dr. Leonie Mayer and Professor Marylyn Addo from the Institute for Infection Research and Vaccine Development at the University Medical Center Hamburg-Eppendorf and Professor Christof Geldmacher and Dr. Rolanda Londt from the Institute of Infectious Diseases and Tropical Medicine at the LMU University Hospital Munich analyzed and mapped T-cell responses against EBOV, BDBV and Sudan virus (SUDV) in VSV-EBOV-vaccinated individuals.
The work is published in The Lancet Infectious Diseases journal.
T-cell responses contribute to viral control and protection against severe disease for diverse types of viruses. Because T cells can recognize conserved viral epitopes, they may cross-react between related viruses. However, whether VSV-EBOV vaccination also induces T cells that recognize BDBV in humans has remained unknown.
Mapping conserved viral sequences
The glycoproteins of the three viruses are phylogenetically distant, with EBOV and BDBV sharing 66.3% amino acid identity, compared with 56.3% between EBOV and SUDV.
"Using multiple sequence alignments—the parallel comparison of multiple amino acid sequences—we identified several sequences that are highly conserved among the glycoproteins of EBOV, BDBV and SUDV, and tested these regions for their interactions with the immune systems of vaccine recipients," says first author Mayer.
Cross-reactive responses after one vaccination
The researchers then assessed cross-reactive T-cell responses in 20 vaccine recipients on day 28 after VSV-EBOV vaccination. Of these vaccine recipients, 16 showed EBOV-glycoprotein-specific T-cell responses, 13 showed BDBV-glycoprotein-reactive T-cell responses and seven showed SUDV-glycoprotein-reactive T-cell responses on day 28 after vaccination. Most vaccine recipients with a positive EBOV-glycoprotein response also had BDBV-reactive T cells.
The study demonstrates that a single immunization with the available, licensed EBOV vaccine can induce T-cell cross-reactivity against BDBV and—to a lesser extent—against SUDV. While it is not known whether these T cells can contribute to improved clinical outcomes upon infection with BDBV, preclinical studies in nonhuman primates suggest that T-cell responses are required for vaccine-mediated protection.
"Our findings provide the first evidence that VSV-EBOV vaccination against ebolavirus induces BDBV-cross-reactive T-cell responses," says Geldmacher. "While the study has limitations due to its small sample size, in the absence of a BDBV-specific vaccine, the study supports the systematic evaluation of the EBOV vaccine within clinical trials during the current BDBV outbreak," he concludes.
Publication details
Leonie Mayer et al., Cross-reactive T-cell responses against BDBV in humans after rVSVΔG-ZEBOV-GP vaccination, The Lancet Infectious Diseases (2026). DOI: 10.1016/s1473-3099(26)00529-3
Journal information: Lancet Infectious Diseases
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Sadie Harley
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Citation: Ebola vaccine induces T cell cross-reactivity against Bundibugyo virus in humans (2026, October 14) retrieved 15 October 2026 from https://medicalxpress.com/news/2026-10-ebola-vaccine-cell-reactivity-bundibugyo.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.