The spread of chikungunya virus (CHIKV) is reaching pandemic levels, and vaccines and antivirals to control CHIKV infection have yet to be approved. Virus-like particles (VLPs), a self-assembled native multi-subunit protein structure, could potentially be used as an antigen for serological detection and vaccine development. In the current study, we describe the production of novel CHIKV VLPs from mosquitoes using a Baculovirus/Mosquito (BacMos) system in a simple Biosafety Level‐2 laboratory. Substantial envelope and capsid protein secretions were detected in culture medium. Co-fractionation of CHIKV E2, E1, and capsid proteins via sucrose gradient ultracentrifugation provided evidence of VLP formation. Transmission electron microscopy and dynamic light scattering analysis revealed the formation of VLPs in the form of spherical particles with a diameter of roughly 40 nm in transduced cells and culture medium. VLP-based IgM capture ELISA in CHIKV patient sera revealed native epitopes on the VLPs. These non-purified VLPs were shown to act as an antigen in CHIKV-specific IgM capture ELISA. The immunization of CHIKV-VLPs alone in mice induced a balance CHIKV-specific IgG2a/IgG1 antibodies and neutralized antibody responses. The study provides support for the hypothesis that mosquito cell-derived CHIKV VLPs could serve as a novel antigen for serological detection and the development of vaccines against CHIKV infection. Key points • CHIKV VLPs secreted from BacMos-CHIKV 26S-transduced mosquito cell. • This CHIKV VLPs potentially serve as an alternative capture antigen for MAC-ELISA. • Unadjuvanted CHIK VLPs induce CHIKV-specific IgG and NT responses in mice.

Reverse genetics is an important tool in the elucidation of viral replication and the development of countermeasures; however, these methods are impeded by laborious and inefficient replicon delivery methods. This paper demonstrates the use of a baculovirus to facilitate the efficient delivery of autonomous CHIKV replicons into mosquito and mammalian cells in vitro as well as adult mosquitoes in vivo. The efficacy of this approach was verified via co-localization among an eGFP reporter, nsP1, and dsRNA as well as through the inhibition of an RNA-dependent RNA polymerase (RdRp) null mutation (DDAA) in nsP4, or the treatment of a known antiviral compound (6-azauridine). We also investigated the correlation between CHIKV replicon-launched eGFP expression and the effectiveness of CHIKV replicon variants in inducing IFN-β expression in human cell lines. This delivery method based on a single vector is applicable to mosquito and mammalian cells in seeking to decipher the mechanisms underlying CHIKV replication, elucidate virus–host interactions, and develop antivirals. This study presents an effective alternative to overcome many of the technological issues related to the study and utilization of autonomous arbovirus replicons.

This study proposes a transfection-free system that enables the safe packaging of CHIK VRPs with all necessary components via baculovirus transduction. Those mosquito cell-derived CHIK VRP (mos-CHIK VRPs) were shown to recapitulate viral replication and subgenomic dual reporter (enhanced green fluorescent protein [eGFP] and luciferase) expression in infected host cells.

Background: Because of the low sensitivity of commercial products, development of a facile method to rapidly identify plague on-site remains highly attractive. Line arrays of poly(methacrylic acid) (PMAA) brushes were grafted using a photoresist template to fabricate one-dimensional diffraction gratings (DGs). The as-prepared samples first bound protein G to immobilize and orient the tails of the antibody of Yersinia pestis (abY). A laser beam was employed to analyze the 2D and 3D reflective signals of DGs at an incident angle of 45°. The abY-tailed PMAA DG possessed an optical feature with a characteristic diffraction effect along the SII, in which the projection of the laser beam on the plane of the DG chip was parallel to the strips, and ST configurations, in which they were perpendicular. A fluidic diffraction chip based on the abY-tailed PMMA DG was fabricated to examine the ability to detect Yersinia pestis along the ST configuration. Results: Upon flowing through the chip, Yersinia pestis was attached to the abY-tailed PMMA DG, which changed the diffraction intensity. The degree of the diffraction intensity exhibited a linear response to Yersinia pestis at concentrations from 102 to 107 CFU mL−1, and the limit of detection was 75 CFU mL−1, 1000 times lower than a commercial product (Alexter Bio-Detect Test). The diffractive sensor could selectively detect Yersinia pestis in spiked serum samples, with excellent standard deviation and recovery. Conclusion: Our platform provides a simple, label-free method for on-site plague diagnosis to prevent the highly rapid transmission of plague.