Influenza viruses cause annual seasonal epidemics and occasional pandemics of human respiratory disease. Influenza virus infections represent a serious public health and economic problem, which are ...most effectively prevented through vaccination. However, influenza viruses undergo continual antigenic variation, which requires either the annual reformulation of seasonal influenza vaccines or the rapid generation of vaccines against potential pandemic virus strains. The segmented nature of influenza virus allows for the reassortment between two or more viruses within a co-infected cell, and this characteristic has also been harnessed in the laboratory to generate reassortant viruses for their use as either inactivated or live-attenuated influenza vaccines. With the implementation of plasmid-based reverse genetics techniques, it is now possible to engineer recombinant influenza viruses entirely from full-length complementary DNA copies of the viral genome by transfection of susceptible cells. These reverse genetics systems have provided investigators with novel and powerful approaches to answer important questions about the biology of influenza viruses, including the function of viral proteins, their interaction with cellular host factors and the mechanisms of influenza virus transmission and pathogenesis. In addition, reverse genetics techniques have allowed the generation of recombinant influenza viruses, providing a powerful technology to develop both inactivated and live-attenuated influenza vaccines. In this review, we will summarize the current knowledge of state-of-the-art, plasmid-based, influenza reverse genetics approaches and their implementation to provide rapid, convenient, safe and more effective influenza inactivated or live-attenuated vaccines.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The receptor‐binding domain (RBD) of the SARS‐CoV‐2 spike protein is a candidate vaccine antigen that binds angiotensin‐converting enzyme 2 (ACE2), leading to virus entry. Here, it is shown that ...rapid conversion of recombinant RBD into particulate form via admixing with liposomes containing cobalt‐porphyrin‐phospholipid (CoPoP) potently enhances the functional antibody response. Antigen binding via His‐tag insertion into the CoPoP bilayer results in a serum‐stable and conformationally intact display of the RBD on the liposome surface. Compared to other vaccine formulations, immunization using CoPoP liposomes admixed with recombinant RBD induces multiple orders of magnitude higher levels of antibody titers in mice that neutralize pseudovirus cell entry, block RBD interaction with ACE2, and inhibit live virus replication. Enhanced immunogenicity can be accounted for by greater RBD uptake into antigen‐presenting cells in particulate form and improved immune cell infiltration in draining lymph nodes. QS‐21 inclusion in the liposomes results in an enhanced antigen‐specific polyfunctional T cell response. In mice, high dose immunization results in minimal local reactogenicity, is well‐tolerated, and does not elevate serum cobalt levels. Taken together, these results confirm that particulate presentation strategies for the RBD immunogen should be considered for inducing strongly neutralizing antibody responses against SARS‐CoV‐2.
The receptor‐binding domain (RBD) of SARS‐CoV‐2 is a target for COVID‐19 vaccine development. Using a next‐generation vaccine adjuvant system that rapidly converts soluble antigens into stable particles, the neutralizing antibody response induced by the RBD is greatly enhanced, demonstrating merit for particle‐based approaches toward RBD‐based vaccines.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The ongoing coronavirus disease 2019 (COVID‐19) pandemic, caused by severe acute respiratory coronavirus 2 (SARS‐CoV‐2), has killed untold millions worldwide and has hurtled vaccines into the ...spotlight as a go‐to approach to mitigate it. Advances in virology, genomics, structural biology, and vaccine technologies have enabled a rapid and unprecedented rollout of COVID‐19 vaccines, although much of the developing world remains unvaccinated. Several new vaccine platforms have been developed or deployed against SARS‐CoV‐2, with most targeting the large viral Spike immunogen. Those that safely induce strong and durable antibody responses at low dosages are advantageous, as well are those that can be rapidly produced at a large scale. Virtually all COVID‐19 vaccines and adjuvants possess nanoscale or microscale dimensions and represent diverse and unique biomaterials. Viral vector vaccine platforms, lipid nanoparticle mRNA vaccines and multimeric display technologies for subunit vaccines have received much attention. Nanoscale vaccine adjuvants have also been used in combination with other vaccines. To deal with the ongoing pandemic, and to be ready for potential future ones, advanced vaccine technologies will continue to be developed in the near future. Herein, the recent use of advanced materials used for developing COVID‐19 vaccines is summarized.
Vaccines have been a major focus of the global SARS‐CoV‐2 response. Advanced materials have played a role in enabling the current generation of effective vaccines that have been deployed, and also they have shown promise in next‐generation vaccines that are being developed in response to the pandemic.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Accumulating evidence shows a progressive decline in the efficacy of coronavirus disease 2019 (COVID‐19) (severe acute respiratory syndrome coronavirus 2 SARS‐CoV‐2) messenger RNA (mRNA) vaccines ...such as Pfizer‐BioNTech (mRNA BNT161b2) and Moderna (mRNA‐1273) in preventing breakthrough infections due to diminishing humoral immunity over time. Thus, this review characterizes the kinetics of anti‐SARS‐CoV‐2 antibodies after the second dose of a primary cycle of COVID‐19 mRNA vaccination. A systematic search of the literature was performed and a total of 18 articles (N = 15 980 participants) were identified and reviewed. The percent difference of means of reported antibody titers was then calculated to determine the decline in humoral response after the peak levels postvaccination. Findings revealed that the peak humoral response was reached at 21–28 days after the second dose, after which serum levels progressively diminished at 4–6‐month postvaccination. Additionally, results showed that regardless of age, sex, serostatus, and presence of comorbidities, longitudinal data reporting antibody measurement exhibited a decline of both anti‐receptor binding domain immunoglobulin G (IgG) and anti‐spike IgG, ranging from 94% to 95% at 90–180 days and 55%–85% at 140–160 days, respectively, after the peak antibody response. This suggests that the rate of antibody decline may be independent of patient‐related factors and peak antibody titers but mainly a function of time and antibody class/molecular target. Hence, this study highlights the necessity of more efficient vaccination strategies to provide booster administration in attenuating the effects of waning immunity, especially in the appearance of new variants of concerns.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Studying influenza A virus (IAV) requires the use of secondary approaches to detect the presence of virus in infected cells. To overcome this problem, we and others have generated recombinant IAV ...expressing fluorescent or luciferase reporter genes. These foreign reporter genes can be used as valid surrogates to track the presence of virus. However, the limited capacity for incorporating foreign sequences in the viral genome forced researchers to select a fluorescent or a luciferase reporter gene, depending on the type of study. To circumvent this limitation, we engineered a novel recombinant replication-competent bireporter IAV (BIRFLU) expressing both fluorescent and luciferase reporter genes. In cultured cells, BIRFLU displayed growth kinetics comparable to those of wild-type (WT) virus and was used to screen neutralizing antibodies or compounds with antiviral activity. The expression of two reporter genes allows monitoring of viral inhibition by fluorescence or bioluminescence, overcoming the limitations associated with the use of one reporter gene as a readout.
, BIRFLU effectively infected mice, and both reporter genes were detected using
imaging systems (IVIS). The ability to generate recombinant IAV harboring multiple foreign genes opens unique possibilities for studying virus-host interactions and for using IAV in high-throughput screenings (HTS) to identify novel antivirals that can be incorporated into the therapeutic armamentarium to control IAV infections. Moreover, the ability to genetically manipulate the viral genome to express two foreign genes offers the possibility of developing novel influenza vaccines and the feasibility for using recombinant IAV as vaccine vectors to treat other pathogen infections.
Influenza A virus (IAV) causes a human respiratory disease that is associated with significant health and economic consequences. In recent years, the use of replication-competent IAV expressing an easily traceable fluorescent or luciferase reporter protein has significantly contributed to progress in influenza research. However, researchers have been forced to select a fluorescent or a luciferase reporter gene due to the restricted capacity of the influenza viral genome for including foreign sequences. To overcome this limitation, we generated, for the first time, a recombinant replication-competent bireporter IAV (BIRFLU) that stably expresses two reporter genes (one fluorescent and one luciferase) to track IAV infections
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The combination of cutting-edge techniques from molecular biology, animal research, and imaging technologies brings researchers the unique opportunity to use this new generation of reporter-expressing IAV to study viral infection dynamics in both cultured cells and animal models of viral infection.
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