Protein Nanoparticles as Vaccine Platforms for Human and Zoonotic Viruses.

Vaccines are one of the most effective medical interventions, playing a pivotal role in treating infectious diseases. Although traditional vaccines comprise killed, inactivated, or live-attenuated pathogens that have resulted in protective immune responses, the negative consequences of their administration have been well appreciated. Modern vaccines have evolved to contain purified antigenic subunits, epitopes, or antigen-encoding mRNAs, rendering them relatively safe. However, reduced humoral and cellular responses pose major challenges to these subunit vaccines. Protein nanoparticle (PNP)-based vaccines have garnered substantial interest in recent years for their ability to present a repetitive array of antigens for improving immunogenicity and enhancing protective responses. Discovery and characterisation of naturally occurring PNPs from various living organisms such as bacteria, archaea, viruses, insects, and eukaryotes, as well as computationally designed structures and approaches to link antigens to the PNPs, have paved the way for unprecedented advances in the field of vaccine technology. In this review, we focus on some of the widely used naturally occurring and optimally designed PNPs for their suitability as promising vaccine platforms for displaying native-like antigens from human viral pathogens for protective immune responses. Such platforms hold great promise in combating emerging and re-emerging infectious viral diseases and enhancing vaccine efficacy and safety.

Multi-Gene Recombinant Baculovirus Expression Systems: From Inception to Contemporary Applications.

Many protein expression systems are primarily utilised to produce a single, specific recombinant protein. In contrast, most biological processes such as virus assembly rely upon a complex of several interacting proteins rather than the activity of a sole protein. The high complexity of the baculovirus genome, coupled with a multiphase replication cycle incorporating distinct transcriptional steps, made it the ideal system to manipulate for high-level expression of a single, or co-expression of multiple, foreign proteins within a single cell. We have developed and utilised a series of recombinant baculovirus systems to unravel the sequential assembly process of a complex non-enveloped model virus, bluetongue virus (BTV). The high protein yields expressed by the baculovirus system not only facilitated structure-function analysis of each viral protein but were also advantageous to crystallography studies and supported the first atomic-level resolution of a recombinant viral protein, the major BTV capsid protein. Further, the formation of recombinant double-shelled virus-like particles (VLPs) provided insights into the structure-function relationships among the four major structural proteins of the BTV whilst also representing a potential candidate for a viral vaccine. The baculovirus multi-gene expression system facilitated the study of structurally complex viruses (both non-enveloped and enveloped viruses) and heralded a new generation of viral vaccines.

Vacinas passado e futuro ­ Reflexões para discussão / The past and future of vaccines ­ Reflections for discussion

Neste artigo de opinião, apresento uma breve história do desenvolvimento de vacinas, comentando sobre as formas clássicas de produção de vacinas utilizando o próprio agente infeccioso. Em seguida, abordo as vacinas virais, discutindo seus benefícios e dificuldades e a questão dos sorotipos virais, bem como as vacinas bacterianas e seu relativo sucesso. Apresento nossos estudos sobre doença cardíaca reumática e o desenvolvimento de uma vacina contra infecções estreptocócicas. Também discuto plataformas vacinais, especialmente os sucessos alcançados com vacinas de vetores virais não replicantes e, acima de tudo, o grande êxito das vacinas de RNA mensageiro (mRNA). As vacinas de mRNA tornaram-se possíveis somente após os avanços obtidos com a substituição de nucleotídeos que reduziam a ação da imunidade inata. Serão todas as vacinas desenvolvidas a partir de mRNA no futuro? Em seguida, abordo a questão das vias de administração de vacinas, seja por via subcutânea, intradérmica, intramuscular ou nasal. Exponho dados do meu laboratório sobre o desenvolvimento de uma vacina de instilação nasal que induziu uma resposta de proteção da mucosa, prevenindo a infecção e, consequentemente, a transmissão do SARS-CoV-2. Posteriormente, discuto quais vacinas futuras poderiam ser desenvolvidas para além das doenças infecciosas agudas. Por fim, discuto as vantagens do desenvolvimento de vacinas seguras, eficazes e de uso múltiplo, bem como a forma de torná-las acessíveis à população mundial, promovendo a equidade em saúde.

In this opinion article, I provide a brief history of vaccine development, commenting on the classic ways of producing vaccines using the infectious agent itself. I address viral vaccines, discussing their benefits and challenges and the issue of viral serotypes, as well as bacterial vaccines and their relative success. I present our studies on rheumatic heart disease and the development of a vaccine against streptococcal infection. I also discuss vaccine platforms, highlighting the success achieved with non-replicating viral vector-based vaccines and, especially, with messenger RNA (mRNA) vaccines. mRNA vaccines only became possible after the advances provided by the replacement of nucleotides that reduced the action of the innate immune system. Will all vaccines be made from mRNA in the future? Then, I address the issue of vaccine administration routes, whether subcutaneously, intradermally, intramuscularly, or intranasal. I present data from my laboratory on the development of an intranasal vaccine that induced a protective mucosal response, preventing infection and, consequently, the transmission of SARSCoV- 2. I discuss which future vaccines could be developed beyond acute infectious diseases. Finally, I discuss the advantages of developing safe, effective, multiple-use vaccines and how to make them accessible worldwide by promoting health equity.

Transgene expression knock-down in recombinant Modified Vaccinia virus Ankara vectors improves genetic stability and sustained transgene maintenance across multiple passages.

Modified vaccinia virus Ankara is a versatile vaccine vector, well suited for transgene delivery, with an excellent safety profile. However, certain transgenes render recombinant MVA (rMVA) genetically unstable, leading to the accumulation of mutated rMVA with impaired transgene expression. This represents a major challenge for upscaling and manufacturing of rMVA vaccines. To prevent transgene-mediated negative selection, the continuous avian cell line AGE1.CR pIX (CR pIX) was modified to suppress transgene expression during rMVA generation and amplification. This was achieved by constitutively expressing a tetracycline repressor (TetR) together with a rat-derived shRNA in engineered CR pIX PRO suppressor cells targeting an operator element (tetO) and 3' untranslated sequence motif on a chimeric poxviral promoter and the transgene mRNA, respectively. This cell line was instrumental in generating two rMVA (isolate CR19) expressing a Macaca fascicularis papillomavirus type 3 (MfPV3) E1E2E6E7 artificially-fused polyprotein following recombination-mediated integration of the coding sequences into the DelIII (CR19 M-DelIII) or TK locus (CR19 M-TK), respectively. Characterization of rMVA on parental CR pIX or engineered CR pIX PRO suppressor cells revealed enhanced replication kinetics, higher virus titers and a focus morphology equaling wild-type MVA, when transgene expression was suppressed. Serially passaging both rMVA ten times on parental CR pIX cells and tracking E1E2E6E7 expression by flow cytometry revealed a rapid loss of transgene product after only few passages. PCR analysis and next-generation sequencing demonstrated that rMVA accumulated mutations within the E1E2E6E7 open reading frame (CR19 M-TK) or deletions of the whole transgene cassette (CR19 M-DelIII). In contrast, CR pIX PRO suppressor cells preserved robust transgene expression for up to 10 passages, however, rMVAs were more stable when E1E2E6E7 was integrated into the TK as compared to the DelIII locus. In conclusion, sustained knock-down of transgene expression in CR pIX PRO suppressor cells facilitates the generation, propagation and large-scale manufacturing of rMVA with transgenes hampering viral replication.

Vacunas contra el virus chikungunya: avances y perspectivas

El virus chikungunya (CHIKV) es un alfavirus cuya infección provoca una enfermedad caracterizada principalmente por fiebre y dolores articulares/musculares. Entre 25-50% de las infecciones se presentan con enfermedad crónica que puede durar de meses a años. El primer brote de CHIKV en Paraguay corresponde al año 2015, siendo el último en el año 2022/2023. Diversos candidatos vacunales contra CHIKV se encuentran en diferentes etapas de desarrollo, e incluso recientemente (noviembre/2023) fue aprobada la primera vacuna contra CHIKV llamada VLA1553 (Ixchiq). Adicionalmente, al menos 30 candidatos vacunales se encuentran en ensayos preclínicos/clínicos. Con la aprobación de la primera vacuna contra CHIKV y la posibilidad de otras que lleguen al mercado prontamente, debido al estado avanzado de otros candidatos vacunales, se abrirá un nuevo escenario en esta enfermedad. Se espera que la introducción de vacunas efectivas genere un avance importante para la prevención de esta enfermedad, disminuyendo los casos agudos y los efectos crónicos de la infección por el virus. En este trabajo de revisión se analiza el avance de las vacunas contra CHIKV, además de examinar los desafíos de vigilancia epidemiológica que plantean la introducción de estas vacunas.

Chikungunya virus (CHIKV) is an alphavirus that causes an illness characterized mainly by fever and joint/muscle pain. Between 25-50% of infections present with chronic diseases that can last from months to years. The first outbreak of CHIKV in Paraguay occurred in 2015, with the last outbreak occurring in 2022/2023. Several vaccine candidates against CHIKV are in different stages of development, and even recently (November/2023), the first vaccine against CHIKV, called VLA1553 (Ixchiq), was approved. In addition, at least 30 vaccine candidates are available for preclinical and clinical trials. With the approval of the first vaccine against CHIKV and the possibility of others coming to the market soon, due to the advanced status of other vaccine candidates, a new scenario will open for this disease. The introduction of effective vaccines is expected to generate an important advance in the prevention of this disease, reducing acute cases and the chronic effects of viral infection. This review analyzes the progress of CHIKV vaccines and examines the epidemiological surveillance challenges posed by the introduction of these vaccines.

COVID-19 vaccine-induced immune thrombotic thrombocytopenia: a review.

Rare but serious thrombotic incidents in relation to thrombocytopenia, termed vaccine-induced immune thrombotic thrombocytopenia (VITT), have been observed since the vaccine rollout, particularly among replication-defective adenoviral vector-based severe acute respiratory syndrome coronavirus 2 vaccine recipients. Herein, we comprehensively reviewed and summarized reported studies of VITT following the coronavirus disease 2019 (COVID-19) vaccination to determine its prevalence, clinical characteristics, as well as its management. A literature search up to October 1, 2021 using PubMed and SCOPUS identified a combined total of 720 articles. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline, after screening the titles and abstracts based on the eligibility criteria, the remaining 47 full-text articles were assessed for eligibility and 29 studies were included. Findings revealed that VITT cases are strongly related to viral vector-based vaccines, which are the AstraZeneca COVID-19 vaccine (95%) and the Janssen COVID-19 vaccine (4%), with much rarer reports involving messenger RNA-based vaccines such as the Moderna COVID-19 vaccine (0.2%) and the Pfizer COVID-19 vaccine (0.2%). The most severe manifestation of VITT is cerebral venous sinus thrombosis with 317 cases (70.4%) and the earliest primary symptom in the majority of cases is headache. Intravenous immunoglobulin and non-heparin anticoagulant are the main therapeutic options for managing immune responses and thrombosis, respectively. As there is emerging knowledge on and refinement of the published guidelines regarding VITT, this review may assist the medical communities in early VITT recognition, understanding the clinical presentations, diagnostic criteria as well as its management, offering a window of opportunity to VITT patients. Further larger sample size trials could further elucidate the link and safety profile.

Continuous multi-membrane chromatography of large viral particles.

Continuous multi-column chromatography (CMCC) has been successfully implemented to address biopharmaceutical biomolecule instability, to improve process efficiency, and to reduce facility footprint and capital cost. This paper explores the implementation of a continuous multi-membrane chromatography (CMMC) process, using four membrane units, for a large viral particle in just few weeks. CMMC improves the efficiency of the chromatography step by enabling higher loads with smaller membranes for multiple cycles of column use and enables steady-state continuous bioprocessing. The separation performance of CMMC was compared to a conventional batch chromatographic capture step used at full manufacturing scale. The product step yield was 80% using CMMC versus 65% in batch mode while increasing slightly the relative purity. Furthermore, the total amount of membrane area required for the CMMC approach was approximately 10% of the area needed for batch operation, while realizing similar processing times. Since CMMC uses smaller membrane sizes, it can take advantage of the high flow rates achievable for membrane chromatography that are not typically possible at larger membrane scales due to skid flow rate limitations. As such, CMMC offers the potential for more efficient and cost-effective purification trains.

Inactivated influenza virions are a flexible vaccine platform for eliciting protective antibody responses against neuraminidase.

Most seasonal influenza vaccines are produced using hemagglutinin (HA) surface antigens from inactivated virions. However, virions are thought to be a suboptimal source for the less abundant neuraminidase (NA) surface antigen, which is also protective against severe disease. Here, we demonstrate that inactivated influenza virions are compatible with two modern approaches for improving protective antibody responses against NA. Using a DBA/2J mouse model, we show that the strong infection-induced NA inhibitory (NAI) antibody responses are only achieved by high dose immunizations of inactivated virions, likely due to the low viral NA content. Based on this observation, we first produced virions with higher NA content by using reverse genetics to exchange the viral internal gene segments. Single immunizations with these inactivated virions showed enhanced NAI antibody responses and improved NA-based protection from a lethal viral challenge while also allowing for the development of natural immunity to the heterotypic challenge virus HA. Second, we combined inactivated virions with recombinant NA protein antigens. These combination vaccines increased NA-based protection following viral challenge and elicited stronger antibody responses against NA than either component alone, especially when the NAs possessed similar antigenicity. Together, these results indicate that inactivated virions are a flexible platform that can be easily combined with protein-based vaccines to improve protective antibody responses against influenza antigens.

Response to Bovine Viral Diarrhea Virus in Heifers Vaccinated with a Combination of Multivalent Modified Live and Inactivated Viral Vaccines.

Bovine viral vaccines contain both live or inactivated/killed formulations, but few studies have evaluated the impact of vaccinating with either live or killed antigens and re-vaccinating with the reciprocal. Commercial dairy heifers were utilized for the study and randomly assigned to three treatment groups. Treatment groups received a commercially available modified-live viral (MLV) vaccine containing BVDV and were revaccinated with a commercially available killed viral (KV) vaccine containing BVDV, another group received the same KV vaccine and was revaccinated with the same MLV vaccine, and yet another group served as negative controls and did not receive any viral vaccines. Heifers in KV/MLV had higher virus neutralizing titers (VNT) at the end of the vaccination period than heifers in MLV/KV and control groups. The frequency of IFN-γ mRNA positive CD4+, CD8+, and CD335+ populations, as well as increased mean fluorescent intensity of CD25+ cells was increased for the MLV/KV heifers as compared to KV/MLV and controls. The data from this study would suggest that differences in initial antigen presentation such as live versus killed could augment CMI and humoral responses and could be useful in determining vaccination programs for optimizing protective responses, which is critical for promoting lifetime immunity.

Improved DNA Vaccine Delivery with Needle-Free Injection Systems.

DNA vaccines have inherent advantages compared to other vaccine types, including safety, rapid design and construction, ease and speed to manufacture, and thermostability. However, a major drawback of candidate DNA vaccines delivered by needle and syringe is the poor immunogenicity associated with inefficient cellular uptake of the DNA. This uptake is essential because the target vaccine antigen is produced within cells and then presented to the immune system. Multiple techniques have been employed to boost the immunogenicity and protective efficacy of DNA vaccines, including physical delivery methods, molecular and traditional adjuvants, and genetic sequence enhancements. Needle-free injection systems (NFIS) are an attractive alternative due to the induction of potent immunogenicity, enhanced protective efficacy, and elimination of needles. These advantages led to a milestone achievement in the field with the approval for Restricted Use in Emergency Situation of a DNA vaccine against COVID-19, delivered exclusively with NFIS. In this review, we discuss physical delivery methods for DNA vaccines with an emphasis on commercially available NFIS and their resulting safety, immunogenic effectiveness, and protective efficacy. As is discussed, prophylactic DNA vaccines delivered by NFIS tend to induce non-inferior immunogenicity to electroporation and enhanced responses compared to needle and syringe.

Leishmania tarentolae: a vaccine platform to target dendritic cells and a surrogate pathogen for next generation vaccine research in leishmaniases and viral infections.

Parasites of the genus Leishmania are unusual unicellular microorganisms in that they are characterized by the capability to subvert in their favor the immune response of mammalian phagocytes, including dendritic cells. Thus, in overt leishmaniasis, dendritic cells and macrophages are converted into a niche for Leishmania spp. in which the parasite, rather than being inactivated and disassembled, survives and replicates. In addition, Leishmania parasites hitchhike onto phagocytic cells, exploiting them as a mode of transport to lymphoid tissues where other phagocytic cells are potentially amenable to parasite colonization. This propensity of Leishmania spp. to target dendritic cells has led some researchers to consider the possibility that the non-pathogenic, reptile-associated Leishmania tarentolae could be exploited as a vaccine platform and vehicle for the production of antigens from different viruses and for the delivery of the antigens to dendritic cells and lymph nodes. In addition, as L. tarentolae can also be regarded as a surrogate of pathogenic Leishmania parasites, this parasite of reptiles could possibly be developed into a vaccine against human and canine leishmaniases, exploiting its immunological cross-reactivity with other Leishmania species, or, after its engineering, for the expression of antigens from pathogenic species. In this article we review published studies on the use of L. tarentolae as a vaccine platform and vehicle, mainly in the areas of leishmaniases and viral infections. In addition, a short summary of available knowledge on the biology of L. tarentolae is presented, together with information on the use of this microorganism as a micro-factory to produce antigens suitable for the serodiagnosis of viral and parasitic infections.

COVID-19 vaccination status and its impact on psoriatic lesions in patients with psoriasis treated with biologics: a single-center cross-sectional study / 中华皮肤科杂志

Objective:To investigate COVID-19 vaccination status and relevant adverse reactions in patients with psoriasis treated with biological agents, and to explore the effect of COVID-19 vaccination on psoriatic lesions.Methods:Clinical data were collected from 572 psoriasis patients aged 18 - 60 years, who were registered in the management system of psoriasis patients treated with biological agents in the University of Hong Kong-Shenzhen Hospital from May 2019 to June 2021. The COVID-19 vaccination status was investigated by telephone interviews, and the vaccination-related information was obtained by fixed healthcare workers during a fixed time period according to a predesigned questionnaire. Measurement data were compared between two groups by using t test, and enumeration data were compared by using chi-square test or Fisher′s exact test. Results:The COVID-19 vaccination coverage rate was 43.13% (226 cases) among the 524 patients who completed the telephone interview, and was significantly lower in the biological agent treatment group (30.79%, 105/341) than in the traditional drug treatment group (66.12%, 121/183; χ2 = 60.60, P < 0.001) . The main reason for not being vaccinated was patients′ fear of vaccine safety (49.66%, 148/298) , followed by doctors′ not recommending (26.51%, 79/298) . In the biological agent treatment group after vaccination, the exacerbation of psoriatic lesions was more common in patients receiving prolonged-interval treatment (42.86%, 6/14) compared with those receiving regular treatment (4.40%, 4/91; Fisher′s exact test, P < 0.001) . Skin lesions were severely aggravated in two patients after COVID-19 vaccination, who ever experienced allergic reactions and whose skin lesions did not completely subside after the treatment with biological agents. Conclusions:The COVID-19 vaccination coverage rate was relatively low in the psoriasis patients treated with biological agents, and no serious adverse reaction was observed after vaccination. Prolonged-interval treatment due to COVID-19 vaccination ran the risk of exacerbation of skin lesions.

Acute myocarditis after COVID-19 vaccination.

Heart muscle inflammations were reported following SARS-CoV-2 messenger ribonucleic acid (RNA) vaccination by the Disease Control Centers in America, and cases of these inflammations reported as adverse effects of this COVID-19 vaccine application increased 1000 times since April 2021. A male individual, 18-year-old received vaccination with mRNA-1273 vaccine, and after a while attended the Emergency Department at King Abdulaziz University Hospital, Jeddah, Saudi Arabia. Upon presentation, the patient complained of a history of chest pain, and he had a high troponin level along with new-onset electrocardiogram changes. During his stay in hospital the patient's blood circulation status remained stable, and no evidence of another infectious or immune cases was found. Although these vaccines are a must and very advantageous in fighting COVID-19 and their benefits are far beyond their risks, although it seems that there is a risk of myopericarditis cases. Under such conditions it is essential to rely on early diagnosis for control and deal with the possible cases of morbidity and mortality associated with these conditions.

The Second Human Pegivirus, a Non-Pathogenic RNA Virus with Low Prevalence and Minimal Genetic Diversity.

The second human pegivirus (HPgV-2) is a virus discovered in the plasma of a hepatitis C virus (HCV)-infected patient in 2015 belonging to the pegiviruses of the family Flaviviridae. HPgV-2 has been proved to be epidemiologically associated with and structurally similar to HCV but unrelated to HCV disease and non-pathogenic, but its natural history and tissue tropism remain unclear. HPgV-2 is a unique RNA virus sharing the features of HCV and the first human pegivirus (HPgV-1 or GBV-C). Moreover, distinct from most RNA viruses such as HCV, HPgV-1 and human immunodeficiency virus (HIV), HPgV-2 exhibits much lower genomic diversity, with a high global sequence identity ranging from 93.5 to 97.5% and significantly lower intra-host variation than HCV. The mechanisms underlying the conservation of the HPgV-2 genome are not clear but may include efficient innate immune responses, low immune selection pressure and, possibly, the unique features of the viral RNA-dependent RNA polymerase (RdRP). In this review, we summarize the prevalence, pathogenicity and genetic diversity of HPgV-2 and discuss the possible reasons for the uniformity of its genome sequence, which should elucidate the implications of RNA virus fidelity for attenuated viral vaccines.

Breakthrough SARS-CoV-2 infections after COVID-19 immunization.

As no vaccines are 100% effective at preventing illness, COVID-19 vaccine breakthrough cases are expected. We here aim to review the most recent literature on COVID-19 vaccine breakthrough infections. SARS-CoV-2 breakthrough infections are, in general, rare. Age may still be a factor in SARS-CoV-2 infections in immunized individuals.

Impact of Vaccine and Immunity Passports in the Context of COVID-19: A Time Series Analysis in Overseas France.

(1) Background: By summer 2021, overseas France turned COVID-19 vaccine and immunity certificates into passports to open travel bubbles. Subsequently, its territories set French records for both COVID-19 and 6-month excess all-cause mortality. (2) Methods: Official time series were collected to compare time correlations between air traffic and COVID-19 transmission and mortality in overseas France, before and after the implementation of immunity passports. (3) Results: Air traffic initially had a reversed relationship with COVID-19, which transitioned into a leader-follower relationship with the introduction of immunity passports. Essentially, air traffic increased 16 days before COVID-19 cases increased (r = 0.61) and 26 days before deaths increased (r = 0.31) in Martinique, 26 days (r = 0.72) and 40 days (r = 0.82) before in Guadeloupe, and 29 days (r = 0.60) and 31 days (r = 0.41) before in Réunion upon introduction of immunity passports. Moreover, air traffic became as correlated as community transmission to COVID-19 mortality in Guadeloupe. (4) Conclusions: Since the introduction of immunity passports, air traffic has been pacesetting COVID-19 within one month for transmission, and within an additional two weeks for mortality in overseas France. Responding to WHO's call for real-world evidence, this study suggests that COVID-19 passports are not commensurate with health system goals.

Vaccines against Major Poultry Viral Diseases: Strategies to Improve the Breadth and Protective Efficacy.

The poultry industry is the largest source of meat and eggs for human consumption worldwide. However, viral outbreaks in farmed stock are a common occurrence and a major source of concern for the industry. Mortality and morbidity resulting from an outbreak can cause significant economic losses with subsequent detrimental impacts on the global food supply chain. Mass vaccination is one of the main strategies for controlling and preventing viral infection in poultry. The development of broadly protective vaccines against avian viral diseases will alleviate selection pressure on field virus strains and simplify vaccination regimens for commercial farms with overall savings in husbandry costs. With the increasing number of emerging and re-emerging viral infectious diseases in the poultry industry, there is an urgent need to understand the strategies for broadening the protective efficacy of the vaccines against distinct viral strains. The current review provides an overview of viral vaccines and vaccination regimens available for common avian viral infections, and strategies for developing safer and more efficacious viral vaccines for poultry.