Characteristics of Ebola Virus Disease Survivor Blood and Semen in Liberia: Serology and RT-PCR.

INTRODUCTION: Ebola virus (EBOV), species Zaire ebolavirus, may persist in the semen of male survivors of Ebola Virus Disease (EVD). We conducted a study of male survivors of the 2014-2016 EVD outbreak in Liberia and evaluated their immune responses to EBOV. We report here findings from the serologic testing of blood for EBOV-specific antibodies, molecular testing for EBOV in blood and semen, and serologic testing of peripheral blood mononuclear cells (PBMCs) in a subset of study participants.

METHODS: We tested for EBOV RNA in blood by qRT-PCR, and for anti-EBOV-specific IgM and IgG antibodies by enzyme-linked immunosorbent assay (ELISA) for 126 study participants. We performed peripheral blood mononuclear cell (PBMC) analysis on a subgroup of 26 IgG-negative participants.

RESULTS: All 126 participants tested negative for EBOV RNA in blood by qRT-PCR. The blood of 26 participants tested negative for EBOV-specific IgG antibodies by ELISA. PBMCs were collected from 23/26 EBOV IgG-negative participants. Of these, 1/23 participants had PBMCs which produced anti-EBOV-specific IgG antibodies upon stimulation with EBOV-specific GP and NP antigens.

DISCUSSION: The blood of EVD survivors, collected when they did not have symptoms meeting the case definition for acute or relapsed EVD, is unlikely to pose a risk for EBOV transmission. We identified one IgM/IgG negative participant who had PBMCs which produced anti-EBOV-specific antibodies upon stimulation. Immunogenicity following acute EBOV infection may exist along a spectrum and absence of antibody response should not be exclusionary in determining an individual's status as a survivor of EVD.