Ebola Virus Persistence in Breast Milk After No Reported Illness: A Likely Source of Virus Transmission From Mother to Child.

A 9-month-old infant died from Ebola virus (EBOV) disease with unknown epidemiological link. While her parents did not report previous illness, laboratory investigations revealed persisting EBOV RNA in the mother's breast milk and the father's seminal fluid. Genomic analysis strongly suggests EBOV transmission to the child through breastfeeding.

Biological Characteristics and Patterns of Codon Usage Evolution for the African Genotype Zika Virus.

We investigated temporal trends of codon usage changes for different host species to determine their importance in Zika virus (ZIKV) evolution. Viral spillover resulting from the potential of codon adaptation to host genome was also assessed for the African genotype ZIKV in comparison to the Asian genotype. To improve our understanding on its zoonotic maintenance, we evaluated in vitro the biological properties of the African genotype ZIKV in vertebrate and mosquito cell lines. Analyses were performed in comparison to Yellow fever virus (YFV). Despite significantly lower codon adaptation index trends than YFV, ZIKV showed evident codon adaptation to vertebrate hosts, particularly for the green African monkey Chlorocebus aethiops. PCA and CAI analyses at the individual ZIKV gene level for both human and Aedes aegypti indicated a clear distinction between the two genotypes. African ZIKV isolates showed higher virulence in mosquito cells than in vertebrate cells. Their higher replication in mosquito cells than African YFV confirmed the role of mosquitoes in the natural maintenance of the African genotype ZIKV. An analysis of individual strain growth characteristics indicated that the widely used reference strain MR766 replicates poorly in comparison to African ZIKV isolates. The recombinant African Zika virus strain ArD128000*E/NS5 may be a good model to include in studies on the mechanism of host tropism, as it cannot replicate in the tested vertebrate cell line.

2018 Ebola virus disease outbreak in Équateur Province, Democratic Republic of the Congo: a retrospective genomic characterisation.

BACKGROUND: The 2018 Ebola virus disease (EVD) outbreak in Équateur Province, Democratic Republic of the Congo, began on May 8, and was declared over on July 24; it resulted in 54 documented cases and 33 deaths. We did a retrospective genomic characterisation of the outbreak and assessed potential therapeutic agents and vaccine (medical countermeasures). METHODS: We used target-enrichment sequencing to produce Ebola virus genomes from samples obtained in the 2018 Équateur Province outbreak. Combining these genomes with genomes associated with known outbreaks from GenBank, we constructed a maximum-likelihood phylogenetic tree. In-silico analyses were used to assess potential mismatches between the outbreak strain and the probes and primers of diagnostic assays and the antigenic sites of the experimental rVSVΔG-ZEBOV-GP vaccine and therapeutics. An in-vitro flow cytometry assay was used to assess the binding capability of the individual components of the monoclonal antibody cocktail ZMapp. FINDINGS: A targeted sequencing approach produced 16 near-complete genomes. Phylogenetic analysis of these genomes and 1011 genomes from GenBank revealed a distinct cluster, confirming a new Ebola virus variant, for which we propose the name "Tumba". This new variant appears to have evolved at a slower rate than other Ebola virus variants (0·69 × 10-3 substitutions per site per year with "Tumba" vs 1·06 × 10-3 substitutions per site per year without "Tumba"). We found few sequence mismatches in the assessed assay target regions and antigenic sites. We identified nine amino acid changes in the Ebola virus surface glycoprotein, of which one resulted in reduced binding of the 13C6 antibody within the ZMapp cocktail. INTERPRETATION: Retrospectively, we show the feasibility of using genomics to rapidly characterise a new Ebola virus variant within the timeframe of an outbreak. Phylogenetic analysis provides further indications that these variants are evolving at differing rates. Rapid in-silico analyses can direct in-vitro experiments to quickly assess medical countermeasures. FUNDING: Defense Biological Product Assurance Office.

One-step RT-PCR for detection of Zika virus.

BACKGROUND: Zika virus (ZIKV) is an emerging mosquito-borne flavivirus circulating in Asia and Africa. Human infection induces an influenza-like syndrome that is associated with retro-orbital pain, oedema, lymphadenopathy, or diarrhea. Diagnosis of Zika fever requires virus isolation and serology, which are time consuming or cross-reactive. OBJECTIVE: To develop a one-step RT-PCR assay to detect ZIKV in human serum. STUDY DESIGN: An assay targeting the envelope protein coding region was designed and evaluated for its specificity, detection limit, repeatability, and capacity to detect ZIKV isolates collected over a 40-year period from various African countries and hosts. RESULTS: The assay's detection limit and repeatability were respectively 7.7pfu/reaction and 100% in serum and L-15 medium; none of 19 other flaviviruses tested were detected. CONCLUSIONS: The assay is rapid, sensitive, and specific to detect ZIKV in cell culture or serum, but needs to be validated for diagnosis using clinical samples.