Wenjie Tan’s research while affiliated with State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences and other places

Mpox viruses (MPXV) has emerged as a formidable orthopoxvirus, posing an immense challenge to global public health. Understanding the regulatory mechanisms of MPXV infection, replication and immune evasion will benefit the development of novel antiviral strategies. Despite the involvement of G-quadruplexes (G4s) in modulating infection and replication processes of multiple viruses, their roles in MPXV life cycle remain largely unknown. Here, we found a highly conservative and stable G4 in MPXV, which acts as a positive regulatory element for viral immunodominant protein expression. Furthermore, by screening 42 optically pure chiral metal complexes, we identified the Λ enantiomer of a pair of chiral helical compounds can selectively target mRNA G4 and enhance expression of the 39-kDa core protein encoded by the MPXV A5L gene. Mechanistically, RNA G4-specific helicase DHX36 inhibits A5L protein expression by unwinding G4. In contrast, MH3 Λ enhanced mRNA stability by specifically targeting G4 structures and subsequently increased protein expression. Furthermore, given the pivotal role of the 39-kDa core protein in activating immune responses and facilitating virion maturation, modulation of MPXV G4 folding by MH3 Λ exhibited inhibitory effects on MPXV replication through enhancing immune response. Our findings underscore the critical involvement of G4 in MPXV life cycle and offer potential avenues for developing antiviral drugs targeting G4.

A global outbreak of monkeypox (mpox) caused by the mpox virus (MPXV) has posed a serious threat to public health worldwide, thus calling for the urgent development of antivirals and vaccines to curb its further spread. In this study, we screened 41 anhydride‐modified proteins and found that 3‐hydroxyphthalic anhydride‐modified β‐lactoglobulin (3HP‐β‐LG), a clinically used anti‐HPV agent, was highly effective in inhibiting infection of vaccinia virus Tiantan strain (VACV‐VTT) and MPXV. Mechanistic studies demonstrated that 3HP‐β‐LG bound to the virus, not the host cell, by targeting the early stage of virus entry, possibly through the interaction between the amino acids with negatively charges in 3HP‐β‐LG and the key amino acids with positive charges in the target region of A29L, a key surface protein of MPXV. A synergistic effect was observed when 3HP‐β‐LG was combined with tecovirimat, a small‐molecule antiviral drug approved by the United States Food and Drug Administration and the European Medicine Agency for the treatment of smallpox and mpox. Because of its clinically proven safety and stability, 3HP‐β‐LG shows promise for further development as a prophylactic agent to prevent the sexual transmission of MPXV.

The mpox outbreak since 2022 has caused over 97,208 infected cases with 186 deaths across 117 countries/territories/areas and was declared a public health emergency of international concern by the WHO. The causative pathogen, monkeypox virus (MPXV), is a zoonotic double-stranded DNA orthopoxvirus. To investigate the structures and replication mechanism of MPXV, the MPXV recombinant proteins and vaccinia virus (VACV) particles have been studied by cryo-EM, however, in situ structural insights into major structural proteins and assembly of the authentic MPXV particles are missing. Here, we optimized an MPXV propagation and purification workflow. Combining cryo-electron tomography (cryo-ET) and sub-tomogram averaging (STA), we determined the structures and assembly of palisade proteins and portal complexes to unveil the architecture of intact MPXV MVs. We also discovered irregularly-shaped MV particles with distorted core walls, which have not been reported before.

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract disease of infants and older people. There is an urgent need for safe and effective vaccines against RSV infection. In this study, we analyzed the effects of the immune response and protection with the RSV recombinant G protein extracellular domain (Gecto) combined with various adjuvants as novel subunit vaccines in mice. All groups receiving RSV Gecto combined with adjuvants exhibited robust humoral and cellular immunity compared to those receiving an adjuvant alone or inactivated RSV vaccine. The greatest effect was observed in mice receiving Gecto combined with a CpG ODN + Alum salt adjuvant, resulting in the highest production of neutralizing antibodies against both RSV A and B subtypes, G-specific IgG and IFN-γ production in splenocytes, and interleukin-2 and interferon-γ expression in CD4⁺ T cells. Significant humoral and cellular immune responses were observed in mice immunized with Gecto combined with AddaS03™ or cyclosporin A adjuvants. The vaccine containing the AddaS03™ adjuvant showed significantly high expression of interleukin-4 in CD4⁺ T cells. Cross-protection against a challenge with either RSV A or B subtypes was observed in the Gecto plus adjuvant groups, resulting in a significant decrease in viral load and reduced pathological damage in the mouse lungs. These findings offer valuable insights into the development and application of recombinant RSV G-subunit vaccines with adjuvants.