Viral hemorrhagic fevers (VHF) describe a diverse group of often-fatal illnesses accompanied by severe bleeding. All known VHF are caused by viruses from four distinct families of lipid- enveloped viruses, including the filoviruses (ebolavius and marburgvirus), arenaviruses (e.g. Lassa virus), bunyaviruses, and flaviviruses. The rhabdovirus Bas-Congo virus (BASV) was first identified by deep sequencing of nucleic acids extracted from a serum sample obtained from a patient with hemorrhagic fever in the Democratic Republic of Congo (DRC). Prior to falling ill, the mentioned patient was a caregiver for two adolescents from the same village who succumbed to a severe disease with similar symptoms, including hemorrhage. A vesicular stomatitis virus (VSV)-based pseudotype system enables us to test serum samples for the presence of antibodies that neutralize pseudoviruses bearing the BASV glycoprotein (BASV-G). A serum sample obtained from the initial patient almost 3 years after recovering from the disease revealed strong neutralization activity specific for BASV-G pseudotypes. Surprisingly, an asymptomatic close contact of the patient tested positive for BASV-G neutralizing antibodies with even higher titers, whereas other health care workers from the village did not show signs of exposure to BASV. Testing of 50 sera from blood donors identified one individual with moderate neutralizing activity specific to BASV-G. A key step in estimating the level of human exposure to BASV will be the screening of large numbers of serum samples from the area and surrounding countries for the presence of antibodies to BASV. The pseudotype neutralization assay is suitable for high-throughput processing of large sample numbers. However, it will exclusively detect antibodies targeting the viral glycoprotein, thereby interfering with infection of target cells. Consequentially, we confirm positivity with additional assays for other viral proteins, such as M and N. We plan to screen over 8000 sera from a total of seven countries for serological evidence of BASV infection, as well as looking at the basal seroprevalence of three additional VHFs - ebolavirus, marburgvirus and Lassa virus, as well as an additional African rhabdovirus, Kotonkan that is believed to infect humans, but is not thought to be a VHF.

Public Health Relevance

In this project we will develop and optimize a number of serological assays for African viral hemorrhagic fever viruses, notably the novel human rhabdovirus, Bas-Congo virus (BASV), which has been linked to a small outbreak of hemorrhagic fever in the Democratic Republic of Congo (DRC). We will screen over 8000 plasma and serum samples from DRC and surrounding African countries for serological evidence of BASV, as well as Ebola virus, Marburg virus and Lassa virus in order to establish the seroprevalence of these viruses. From this work we hope to learn how prevalent BASV infection is and how commonly asymptomatic infection occurs for viral hemorrhagic fever viruses.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21AI107420-02
Application #
8917088
Study Section
Clinical Research and Field Studies of Infectious Diseases Study Section (CRFS)
Program Officer
Challberg, Mark D
Project Start
2014-09-01
Project End
2016-12-31
Budget Start
2015-09-01
Budget End
2016-12-31
Support Year
2
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Blood Systems Research Institute
Department
Type
DUNS #
006902498
City
San Francisco
State
CA
Country
United States
Zip Code
94118
Rimoin, Anne W; Lu, Kai; Bramble, Matthew S et al. (2018) Ebola Virus Neutralizing Antibodies Detectable in Survivors of theYambuku, Zaire Outbreak 40 Years after Infection. J Infect Dis 217:223-231
Hoff, Nicole A; Mukadi, Patrick; Doshi, Reena H et al. (2018) Serologic Markers for Ebolavirus Among Healthcare Workers in the Democratic Republic of the Congo. J Infect Dis :
Bramble, Matthew S; Hoff, Nicole; Gilchuk, Pavlo et al. (2018) Pan-Filovirus Serum Neutralizing Antibodies in a Subset of Congolese Ebolavirus Infection Survivors. J Infect Dis 218:1929-1936