Cross-Protection Induced by Virus-like Particles Derived from the Influenza B Virus

Advancements in the application and research of baculovirus vector vaccines for respiratory diseases in human

The rapid spread of respiratory diseases, such as influenza, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and Respiratory Syncytial Virus (RSV), poses significant challenges to global public health systems. Vaccination remains the most effective strategy to mitigate these threats. Baculovirus Expression Vector Systems (BEVS) have emerged as a promising platform for vaccine development, addressing key limitations of traditional methods, including complex production processes, lengthy timelines, and high costs. BEVS offers distinct advantages, such as enhanced efficacy, safety, cost-effectiveness, and scalability for large-scale manufacturing. This review highlights the application of BEVS in combating respiratory diseases by analyzing preclinical studies, clinical trials, and approved vaccines targeting these pathogens. It also examines recent advancements in BEVS technology, emphasizing its capacity to accelerate vaccine development and respond to emerging respiratory threats. By focusing on the synergy between BEVS and respiratory disease prevention, this review provides valuable insights to guide global vaccine innovation.

Vaccine efficacy induced by 2020-2021 seasonal influenza-derived H3N1 virus-like particles co-expressing M2e5x or N2

Influenza A matrix protein 2 (M2e) and neuraminidase (NA) antigens are known to play important roles in mounting a broad range of protection. Nonetheless, the protective efficacy of the VLP vaccines co-expressing both M2e and NA antigens has not been explored. In this study, we generated 2020/2021 seasonal influenza H3N1 VLPs that co-expressed either M2e5x (H3N1M2e5x) or N2 (H3N1N2 VLP) antigens. The protective efficacy of these VLPs was assessed by challenge infection with heterologous H3N2 and heterosubtypic H1N1 and H5N1 viruses in mice. Both VLP formulations induced cross-protection against distinct viruses, H3N1M2e5x VLPs elicited higher levels of cross-reactive IgG in sera against H1N1 and H5N1 viruses than H3N1N2 VLPs. Compared to H3N1N2 VLPs, H3N1M2e5x VLPs also induced substantially enhanced germinal center B cell responses while inhibiting IFN-γ production in the lungs. Importantly, H3N1M2e5x VLPs significantly reduced the lung virus titers upon H1N1, H3N2, and H5N1 challenge infections. These results indicated that VLPs comprising the M2e5x antigen are a promising vaccine design strategy that could aid in the pursuit of a universal influenza vaccine.

Viral vector- and virus-like particle-based vaccines against infectious diseases: A minireview

To overcome the limitations of conventional vaccines, new platforms for vaccine design have emerged such as those based on viral vectors and virus-like particles (VLPs). Viral vector vaccines are highly efficient and the onset of protection is quick. Many recombinant vaccine candidates for humans are based on viruses belonging to different families such as Adenoviridae, Retroviridae, Paramyxoviridae, Rhabdoviridae, and Parvoviridae. Also, the first viral vector vaccine licensed for human vaccination was the Japanese encephalitis virus vaccine. Since then, several viral vectors have been approved for vaccination against the viruses of Lassa fever, Ebola, hepatitis B, hepatitis E, SARS-CoV-2, and malaria. VLPs are nanoparticles that mimic viral particles formed from the self-assembly of structural proteins and VLP-based vaccines against hepatitis B and E viruses, human papillomavirus, and malaria have been commercialized. As evidenced by the accelerated production of vaccines against COVID-19, these new approaches are important tools for vaccinology and for generating rapid responses against pathogens and emerging pandemic threats.

Crossprotection induced by virus-like particles containing influenza dual-hemagglutinin and M2 ectodomain

Aims: To develop an effective universal vaccine against antigenically different influenza viruses. Materials & methods: We generated influenza virus-like particles (VLPs) expressing the H1 and H3 antigens with or without M2e5x. VLP-induced immune responses and crossprotection against H1N1, H3N2 or H5N1 viruses were assessed to evaluate their protective efficacy. Results: H1H3M2e5x immunization elicited higher crossreactive IgG antibodies than H1H3 VLPs. Upon challenge, both VLPs enhanced lung IgG, IgA and germinal center B-cell responses compared with control. While these VLPs conferred protection, H1H3M2e5x showed greater lung viral load reduction than H1H3 VLPs with minimal body weight loss. Conclusion: Utilizing VLPs containing dual-hemagglutinin, along with M2e5x, can be a vaccination strategy for inducing crossprotection against influenza A viruses.

Immunogenicity risk assessment of synthetic peptide drugs and their impurities

Peptide drugs play an important part in medicine owing to their many therapeutic applications. Of the 80 peptide drugs approved for use in humans, at least five are now off-patent and are consequently being developed as generic alternatives to the originator products. To accelerate access to generic products, the FDA has proposed new regulatory pathways that do not require direct comparisons of generics to originators in clinical trials. The 'Abbreviated New Drug Application' (ANDA) pathway recommends that sponsors provide information on any new impurities in the generic drug, compared with the originator product, because the impurities can have potential to elicit unwanted immune responses owing to the introduction of T-cell epitopes. This review describes how peptide drug impurities can elicit unexpected immunogenicity and describes a framework for performing immunogenicity risk assessment of all types of bioactive peptide products. Although this report primarily focuses on generic peptides and their impurities, the approach might also be of interest for developers of novel peptide drugs who are preparing their products for an initial regulatory review.

Respiratory Viruses and Virus-like Particle Vaccine Development: How Far Have We Advanced?

With technological advancements enabling globalization, the intercontinental transmission of pathogens has become much easier. Respiratory viruses are one such group of pathogens that require constant monitoring since their outbreak leads to massive public health crises, as exemplified by the influenza virus, respiratory syncytial virus (RSV), and the recent coronavirus disease 2019 (COVID-19) outbreak caused by the SARS-CoV-2. To prevent the transmission of these highly contagious viruses, developing prophylactic tools, such as vaccines, is of considerable interest to the scientific community. Virus-like particles (VLPs) are highly sought after as vaccine platforms for their safety and immunogenicity profiles. Although several VLP-based vaccines against hepatitis B and human papillomavirus have been approved for clinical use by the United States Food and Drug Administration, VLP vaccines against the three aforementioned respiratory viruses are lacking. Here, we summarize the most recent progress in pre-clinical and clinical VLP vaccine development. We also outline various strategies that contributed to improving the efficacy of vaccines against each virus and briefly discuss the stability aspect of VLPs that makes it a highly desired vaccine platform.

Analysis of Viral and Host Factors on Immunogenicity of 2018, 2019, and 2020 Southern Hemisphere Seasonal Trivalent Inactivated Influenza Vaccine in Adults in Brazil

Annual vaccination against influenza is the best tool to prevent deaths and hospitalizations. Regular updates of trivalent inactivated influenza vaccines (TIV) are necessary due to high mutation rates in influenza viruses. TIV effectiveness is affected by antigenic mismatches, age, previous immunity, and other host factors. Studying TIV effectiveness annually in different populations is critical. The serological responses to Southern-Hemisphere TIV and circulating influenza strains were evaluated in 2018−2020 among Brazilian volunteers, using hemagglutination inhibition (HI) assays. Post-vaccination titers were corrected to account for pre-vaccination titers. Our population achieved >83% post-vaccination seroprotection levels, whereas seroconversion rates ranged from 10% to 46%. TIV significantly enhanced antibody titers and seroprotection against all prior and contemporary vaccine and circulating strains tested. Strong cross-reactive responses were detected, especially between H1N1 subtypes. A/Singapore/INFIMH-16-0019/2016, included in the 2018 TIV, induced the poorest response. Significant titer and seroprotection reductions were observed 6 and 12 months after vaccination. Age had a slight effect on TIV response, whereas previous vaccination was associated with lower seroconversion rates and titers. Despite this, TIV induced high seroprotection for all strains, in all groups. Regular TIV evaluations, based on regional influenza strain circulation, should be conducted and the factors affecting response studied.