A Highly Divergent Coronavirus from the Asian House Shrew
Although shrews comprise one of the largest groups of mammals, little is known about their role in the evolution and transmission of coronaviruses (CoVs). Wang et al. (e00764-17) discovered a CoV, Wénchéng shrew virus (WESV), in Asian house shrews from China. WESV is most closely related to alphacoronaviruses but sufficiently divergent to be considered a new member of the genus Alphacorionavirus. The WESV genome contains a distinct S gene and a unique NS7 gene. These data suggest that shrews are natural reservoirs for CoV and have influenced CoV evolution.
Phylogenetic relationship between Wénchéng shrew virus and known CoVs.
Identification and Quantification of Hepatitis B Virus DNA Intermediate
Hepatitis B virus (HBV) persistence is maintained by its nuclear episome, a covalently closed circular (CCC) DNA, which is formed from a relaxed circular (RC) DNA. Luo et al. (e00539-17) identify an intermediate in RC to CCC DNA conversion, the closed minus-strand RC (cM-RC) DNA. Exonucleases that selectively degrade RC but not CCC DNA allowed identification of this intermediate and precise quantification of CCC DNA. Identifying cM-RC DNA as an intermediate elucidates CCC DNA formation pathways and mechanisms of HBV persistence.
Closed minus-strand intermediate in HBV RC to CCC DNA conversion.
Insights into Recognition of HIV Peptides by δ/αβ T Cell Receptors
The central interaction in T cell-mediated adaptive immunity is between the T cell receptor (TCR) and the antigen-presenting molecule loaded with a given antigen. Shi et al. (e00725-17) resolved the complex structures of two high-affinity δ/αβTCRs containing the same Vδ1 region bound to different locus-disparate class I major histocompatibility complex molecules loaded with HIV peptides. The δ/αβTCRs used a conserved CDR1δ loop to contact the ligands. The crystal structures and binding analyses illuminate TCR recognition and suggest ways to shape the δ/αβTCR repertoire to inhibit infection.
Conserved Vδ1 loop signature revealed by the top view of CDR loop footprints of the two δ/αβTCRs.
Dissecting Immune Response with an Anti-idiotypic Antibody
Anti-idiotypic antibodies can be employed as precise tools for analyzing immune responses and improving vaccines. Wong et al. (e00406-17) define the structural footprint of an anti-idiotype antibody, E1, which is specific for the HM14c10 antibody. E1 is a potent, fully human dengue virus serotype 1 (DENV1) envelope protein-specific antibody that can serve as a useful marker to follow anti-DENV1 immune responses and can be further engineered as an immunogen to elicit an anti-DENV immune response.
Structural mimicry of the flavivirus envelope E protein by the E1 anti-idiotypic antibody.
Vesicular Stomatitis Virus Pseudovirion Vaccine Protects against Ebola Virus
A recombinant, infectious vesicular stomatitis virus (VSV) encoding the Ebola virus glycoprotein effectively prevents Ebola virus-associated disease. A vaccine composed of VSV pseudovirions bearing Ebola virus glycoprotein may prove efficacious and have a better safety profile. Lennemann et al. (e00479-17) tested the efficacy of VSV pseudovirions containing Ebola virus glycoprotein and lacking the native G glycoprotein as a vaccine platform. The Ebola virus glycoprotein vaccine in the absence of an adjuvant provides robust protection of Ebola virus-challenged mice. Furthermore, removal of the N-linked glycans surrounding conserved regions of the glycoprotein does not alter vaccine efficacy.
VSV-based Ebola vaccine protects mice from mouse-adapted Ebola virus challenge.
- Copyright © 2017 American Society for Microbiology.
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- Article
- A Highly Divergent Coronavirus from the Asian House Shrew
- Identification and Quantification of Hepatitis B Virus DNA Intermediate
- Insights into Recognition of HIV Peptides by δ/αβ T Cell Receptors
- Dissecting Immune Response with an Anti-idiotypic Antibody
- Vesicular Stomatitis Virus Pseudovirion Vaccine Protects against Ebola Virus
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