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Calboxyvinyl polymer adjuvant enhances respiratory iga responses through mucosal and systemic administration

Adjuvants play a crucial role in enhancing vaccine efficacy. Although several adjuvants have been approved, there remains a demand for safer and more effective adjuvants for nasal vaccines. Here, we identified calboxyvinyl polymer (CVP) as a superior mucosal vaccine adjuvant from pharmaceutical base materials using our screening systems; single nasal vaccination of the CVP-combined influenza split vaccine-induced antigen-specific IgA and IgG antibodies and provided protection against lethal influenza virus infection. Furthermore, nasal vaccination with CVP-combined severe acute respiratory syndrome coronavirus 2 antigen protected against the virus and stimulated the production of highly cross-reactive IgG antibodies against variants XBB1.5 and JN.1. Intriguingly, intramuscular vaccination of the CVP-combined vaccine also elicited the production of IgA antibodies in both nasal wash and bronchoalveolar lavage fluid in mice and cynomolgus monkeys. CVP therefore offers superior adjuvanticity to existing adjuvants and is anticipated to be a safe and effective adjuvant for mucosal vaccines.

Identifying falsified COVID-19 vaccines by analysing vaccine vial label and excipient profiles using MALDI-ToF mass spectrometry

The rapid development and worldwide distribution of COVID-19 vaccines is a remarkable achievement of biomedical research and logistical implementation. However, these developments are associated with the risk of a surge of substandard and falsified (SF) vaccines, as illustrated by the 184 incidents with SF and diverted COVID-19 vaccines which have been reported during the pandemic in 48 countries, with a paucity of methods for their detection in supply chains. In this context, matrix-assisted laser desorption ionisation-time of flight (MALDI-ToF) mass spectrometry (MS) is globally available for fast and accurate analysis of bacteria in patient samples, offering a potentially accessible solution to identify SF vaccines. We analysed the COVISHIELD™ COVID-19 vaccine; falsified versions of which were found in India, Myanmar and Uganda. We demonstrate for the first time that analysis of spectra from the vaccine vial label and its adhesive could be used as a novel approach to detect falsified vaccines. Vials tested by this approach could be retained in the supply chain since it is non-invasive. We also assessed whether MALDI-ToF MS could be used to distinguish the COVISHIELD™ vaccine from surrogates of falsified vaccines and the effect of temperature on vaccine stability. Both polysorbate 80 and L-histidine excipients of the genuine vaccine could be detected by the presence of a unique combination of MALDI-ToF MS peaks which allowed us to distinguish between the genuine vaccines and falsified vaccine surrogates. Furthermore, even if a falsified product contained polysorbate 80 at the same concentration as used in the genuine vaccine, the characteristic spectral profile of polysorbate 80 used in genuine products is a reliable internal marker for vaccine authenticity. Our findings demonstrate that MALDI-ToF MS analysis of extracts from vial labels and the vaccine excipients themselves can be used independently to detect falsified vaccines. This approach has the potential to be integrated into the national regulatory standards and WHO’s Prevent, Detect, and Respond strategy as a novel effective tool for detecting falsified vaccines.

Optimizing rabies mRNA vaccine efficacy via RABV-G structural domain screening and heterologous prime-boost immunization

mRNA vaccine has become a promising technology platform for rabies prevention. This study explores the roles of different structural domains of rabies virus glycoprotein (RABV-G) and heterologous prime-boost strategies for enhanced immune responses and protection. The results suggested that mRNA vaccines encoding full-length RABV-G (RABV-Full) and RABV-R333Q induced strong immune responses and provided full protection against rabies, while mRNA vaccines encoding ectodomain/transmembrane domain (RABV-TE) and ectodomain (RABV-E) were less effective. Heterologous immunization results revealed that mRNA-primed strategies yielded higher long-lasting VNTs, but lower early VNTs than inactivated rabies virus (IRV)-primed strategies. 2×RABV-Full and IRV > RABV-Full provided 100% protection, while that of RABV-Full>IRV was 90%. Transcriptome analysis showed that rabies mRNA vaccine induced both MHCI and MHCII antigen presentation, as well as B/T cell activation. In conclusion, full-length RABV-G mRNA vaccines, particularly with an ‘IRV prime and RABV-Full boost’ strategy, hold great potential for rabies prevention.

Toll-like receptor response to Zika virus infection: progress toward infection control

Infection with the Zika virus (ZIKV) poses a threat to human health. An improved understanding of the host Toll-like receptor response, disease onset, and viral clearance in vivo and in vitro may lead to the development of therapeutic or prophylactic interventions against viral infections. Currently, no clinically approved ZIKV vaccine is available, highlighting the need for its development. In this study, we discuss the progress in the Zika vaccine, including advances in the use of Toll-like receptor agonists as vaccine adjuvants to enhance vaccine efficacy.

Identifying vaccine-hesitant subgroups in the Western Pacific using latent class analysis

Vaccine hesitancy seriously compromised the COVID-19 vaccine roll-out across the Western Pacific with limited evidence-based recommendations for diverse populations across the region. This study investigates the profile of the vaccine-hesitant populations by using fixed-effect latent class analysis and multi-country survey data collected in 12 countries in 2021 and 2022: Cambodia, Viet Nam, Lao PDR, Japan, Republic of Korea, Malaysia, Philippines, Mongolia, Fiji, Solomon Islands, Tonga and Vanuatu. The analysis identified 9 latent classes: Stay-at-home mothers, High-school-educated employees, High-school-educated older adults, High-school-educated young adults, University-educated employees, University-educated older adults, University-educated young adults, Unemployed, Non-compliant employees. The probabilities of COVID-19 vaccine acceptance and booster uptake were significantly lower in most of these latent classes, compared to University-educated older adults, as the reference group. While each country had unique compositions of latent classes among vaccine-hesitant people, there were also some shared risk groups, such as High-school-educated employees and High-school-educated young adults, across the countries. The study findings demonstrate the benefits of subgroup analysis in unpacking the complex interplay of characteristics within vaccine-hesitant populations, highlighting the need for customised strategies tailored to each country’s unique profile of vaccine hesitancy.

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