The development of COVID-19 vaccines is critical in controlling global health issues under the COVID-19 pandemic. The subunit vaccines are the safest and most widely used vaccine platform and highly effective against a multitude of infectious diseases. An adjuvant is essential for subunit vaccines to enhance the magnitude and durability of immune responses. In this study, we determined whether a combination of toll-like receptor (TLR)1/2 and TLR3 agonists (L-pampo) can be a potent adjuvant for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) subunit vaccine. We measured a neutralizing antibody (nAb) and an angiotensin-converting enzyme 2 (ACE2) receptor-blocking antibody against SARS-CoV-2 receptor-binding domain (RBD). We also detected interferon-gamma (IFN-γ) production by using ELISPOT and ELISA assays. By employing a ferret model, we detected nAbs and IFN-γ producing cells and measured viral load in nasal wash after the challenge of SARS-CoV-2. We found that SARS-CoV-2 antigens with L-pampo stimulated robust humoral and cellular immune responses. The efficacy of L-pampo was higher than the other adjuvants. Furthermore, in the ferret model, SARS-CoV-2 antigens with L-pampo elicited nAb response and antigen-specific cellular immune response against SARS-CoV-2, resulting in substantially decreased viral load in their nasal wash. Our study suggests that SARS-CoV-2 antigens formulated with TLR agonists, L-pampo, can be a potent subunit vaccine to promote sufficient protective immunity against SARS-CoV-2.

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Formulas are presented for the optimum design of the H‐plane septum power divider in a rectangular waveguide. Optimum values of the septum offset are given in terms of the frequency and power‐divide ratio. Corresponding values of the septum length and iris width are given in terms of the frequency and septum offset. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 390–393, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10927

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A simple transition between a circular waveguide and a coaxial cable having mode-free operation over more than an octave bandwidth is presented. The transition consists of a conical coaxial probe, a rectangular waveguide section and a linearly tapered transformer from the rectangular to circular waveguide. The transition shows a reflection coefficient of <-20 dB, a transmission coefficient of >-0.57 dB and a higher-order mode level of < −25 dB over a frequency range 1.04-2.53 times the TE 11 mode cutoff frequency.