Nadia Storm

Lack of Marburg Virus Transmission From Experimentally Infected to Susceptible In-Contact Egyptian Fruit Bats

Egyptian fruit bats (Rousettus aegyptiacus) were inoculated subcutaneously (n = 22) with Marburg virus (MARV). No deaths, overt signs of morbidity, or gross lesions was identified, but microscopic pathological changes were seen in the liver of infected bats. The virus was detected in 15 different tissues and plasma but only sporadically in mucosal swab samples, urine, and fecal samples. Neither seroconversion nor viremia could be demonstrated in any of the in-contact susceptible bats (n = 14) up to 42 days after exposure to infected bats. In bats rechallenged (n = 4) on day 48 after infection, there was no viremia, and the virus could not be isolated from any of the tissues tested. This study confirmed that infection profiles are consistent with MARV replication in a reservoir host but failed to demonstrate MARV transmission through direct physical contact or indirectly via air. Bats develop strong protective immunity after infection with MARV.

Comparative Evaluation of the Diagnostic Performance of the Prototype Cepheid GeneXpert Ebola Assay

ABSTRACT The Ebola virus disease (EVD) outbreak in West Africa has highlighted an urgent need for point-of-care (POC) assays for the diagnosis of this devastating disease in resource-limited African countries. The diagnostic performance characteristics of a prototype Cepheid GeneXpert Ebola POC used to detect Ebola virus (EBOV) in stored serum and plasma samples collected from suspected EVD cases in Sierra Leone in 2014 and 2015 was evaluated. The GeneXpert Ebola POC is a self-contained single-cartridge automated system that targets the glycoprotein (GP) and nucleoprotein (NP) genes of EBOV and yields results within 90 min. Results from 281 patient samples were compared to the results of a TaqMan real-time reverse transcription-PCR (RT-PCR) targeting the polymerase gene and performed on two real-time PCR machines. Agreement between the three platforms was 100% at cycle threshold (CT ) values of ≤34.99, but discordant results were noted between CT values of 35 and 45.The diagnostic sensitivity of the three platforms was 100% in 91 patient samples that were confirmed to be infectious by virus isolation. All three molecular platforms detected viral EBOV RNA in additional samples that did not contain viable EBOV. The analytical sensitivity of the GeneXpert Ebola POC for the detection of NP was higher, and comparable to that of polymerase gene detection, than that for the detection of GP when using a titrated laboratory stock of EBOV. There was no detectable cross-reactivity with other hemorrhagic fever viruses or arboviruses. The GeneXpert Ebola POC offers an easy to operate and sensitive diagnostic tool that can be used for the rapid screening of suspected EVD cases in treatment or in holding centers during EVD outbreaks.

Human cases of Sindbis fever in South Africa, 2006–2010

Sindbis virus (SINV), the prototype positive-sense RNA alphavirus, causes febrile arthritis and is present throughout Afro-Eurasia. Little is known of the epidemiology of Sindbis fever due to insufficient surveillance in most endemic countries. The epidemiological features of Sindbis fever in humans in South Africa are described here based on a retrospective study of suspected arbovirus cases submitted for laboratory investigation from 2006 to 2010. Cases were detected annually mostly during the late summer/early autumn months and an increase in cases was noted for 2010, coinciding with an outbreak of Rift Valley fever. Cases were reported most often from the central plateau of South Africa and involved mostly males. No severe or fatal cases were reported and cases were associated with febrile arthralgia as commonly reported for SINV infection. Further surveillance is required to reveal the true extent of the morbidity of Sindbis fever in South Africa.

Prevalence of carbapenem resistance genes in Acinetobacter baumannii isolated from clinical specimens obtained from an academic hospital in South Africa

Acinetobacter baumannii is an important cause of hospital-acquired infections. The occurrence of carbapenem resistance that is caused by the carbapenem-hydrolysing class D β-lactamases and the metallo-β-lactamases (MBLs) limits the range of therapeutic alternatives in treating A. baumannii infections. In this study, two multiplex polymerase chain reactions were performed to screen for both carbapenem-hydrolysing class D β-lactamases and MBL genes in 97 clinical isolates of A. baumannii. Oxacillinase (OXA)-51 had a prevalence of 83% (81/97), and OXA-23 had a prevalence of 59% (57/97). One isolate was positive for an MBL [Verona integron-encoded metallo β-lactamases (VIM)]. Therefore, continuous surveillance and monitoring of A. baumannii is crucial because of the high prevalence of antibiotic resistance genes.

Taxonomy of the family Arenaviridae and the order Bunyavirales: update 2018

In 2018, the family Arenaviridae was expanded by inclusion of 1 new genus and 5 novel species. At the same time, the recently established order Bunyavirales was expanded by 3 species. This article presents the updated taxonomy of the family Arenaviridae and the order Bunyavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV) and summarizes additional taxonomic proposals that may affect the order in the near future.

Isolation of a novel orthobunyavirus from bat flies (Eucampsipoda africana)

The Bunyaviridae family comprises viruses causing diseases of public and veterinary health importance, including viral haemorrhagic and arboviral fevers. We report the isolation, identification and genome characterization of a novel orthobunyavirus, named Wolkberg virus (WBV), from wingless bat fly ectoparasites (Eucampsipoda africana) of Egyptian fruit bats (Rousettus aegyptiacus) in South Africa. Complete genome sequence data of WBV suggests it is most closely related to two bat viruses (Mojuí dos Campos and Kaeng Khoi viruses) and an arbovirus (Nyando virus) previously shown to infect humans. WBV replicates to high titres in VeroE6 and C6-36 cells, characteristic of mosquito-borne arboviruses. These findings expand our knowledge of the diversity of orthobunyaviruses and their insect vector host range.

Antibody Responses to Marburg Virus in Egyptian Rousette Bats and Their Role in Protection against Infection

Egyptian rousette bats (ERBs) are reservoir hosts for the Marburg virus (MARV). The immune dynamics and responses to MARV infection in ERBs are poorly understood, and limited information exists on the role of antibodies in protection of ERBs against MARV infection. Here, we determine the duration of maternal immunity to MARV in juvenile ERBs, and evaluate the duration of the antibody response to MARV in bats naturally or experimentally infected with the virus. We further explore whether antibodies in previously naturally exposed bats is fully protective against experimental reinfection with MARV. Maternal immunity was lost in juvenile ERBs by 5 months of age. Antibodies to MARV remained detectable in 67% of experimentally infected bats approximately 4 months post inoculation (p.i.), while antibodies to MARV remained present in 84% of naturally exposed bats at least 11 months after capture. Reinfection of seropositive ERBs with MARV produced an anamnestic response from day 5 p.i. Although PCR-defined viremia was present in 73.3% of reinfected ERBs, replicating virus was recovered from the serum of only one bat on day 3 p.i. The negative PCR results in the salivary glands, intestines, bladders and reproductive tracts of reinfected bats, and the apparent absence of MARV in the majority of swabs collected from these bats suggest that reinfection may only play a minor role in the transmission and maintenance of MARV amongst ERBs in nature.

A novel adenovirus isolated from the Egyptian fruit bat in South Africa is closely related to recent isolates from China

Recently a number of novel adenoviruses have been isolated from diverse bat species and from diverse geographical locations. We describe the isolation of a novel adenovirus (Family Adenoviridae, genus Mastadenovirus) from a pool of liver and spleen tissue of an apparently healthy wild-caught Egyptian fruit bat (Rousettus aegyptiacus) in South Africa. Genetically the virus is most closely related to four mastadenoviruses recently isolated in China, from Miniopterus schreibersi and Rousettus leschenaultii bats, which are highly divergent from previously identified bat adenoviruses. The length of the Rousettus aegyptiacus adenovirus-3085 (RaegAdV-3085) genome, at 29,342 bp is similar to its closest relatives, and contains 27 open reading frames. The RaegAdV-3085 genome has a low G + C content (36.4%) relative to other viruses in the genus (between 43.6 and 63.9%) but similar to its closest relatives. The inverted terminal repeat (ITR) of RaegAdV-3085 is only 40 bp compared to between 61 and 178 bp of its closest relatives. The discovery of RaegAdV-3085 expands the diversity of known adenoviruses in bats and might represent a member of a new mastadenovirus species in bats.

Analysis of Assembly and Budding of Lujo Virus

ABSTRACT The recently identified arenavirus Lujo virus (LUJV) causes fatal hemorrhagic fever in humans. We analyzed its mechanism of viral release driven by matrix protein Z and the cell surface glycoprotein precursor GPC. The L domains in Z are required for efficient virus-like particle release, but Tsg101, ALIX/AIP1, and Vps4A/B are unnecessary for budding. LUJV GPC is cleaved by site 1 protease (S1P) at the RKLM motif, and treatment with the S1P inhibitor PF-429242 reduced LUJV production.

Phylogeny of Sindbis virus isolates from South Africa

Sindbis virus (SINV), the prototype virus in the genus, Alphavirus, is an arbovirus with an extensive geographical distribution. Birds are the main vertebrate hosts for SINV, while Culex mosquitoes serve as vectors and occasionally transmit the virus to humans, causing a febrile illness with a maculopapular rash and arthritis. Currently, little information exists on the genetic diversity within SINV strains from South Africa. The E2 envelope glycoprotein gene was partially sequenced for a panel of 27 South African and African Sindbis virus isolates derived from a human case and from mosquito pools. A phylogenetic analysis was performed using these sequences, together with 65 partial E2 gene sequences from Sindbis virus isolates from elsewhere in the world. The resulting phylogenetic tree suggested five distinct Sindbis virus genotypes. The South African Sindbis virus isolates were grouped within genotype I, together with isolates from Sweden, Finland, Germany and Norway. The phylogeny of Sindbis virus reflects its geographical distribution and corresponds with the major migratory bird flyways, indicating that birds play a major role in Sindbis virus distribution.