Identification of tumor antigens and immune subtypes of hepatocellular carcinoma for mRNA vaccine development

BACKGROUND mRNA vaccines have been investigated in multiple tumors,but limited studies have been conducted on their use for hepatocellular carcinoma(HCC).AIM To identify candidate mRNA vaccine antigens for HCC and suitable subpopu-lations for mRNA vaccination.METHODS Gene expression profiles and clinical information of HCC datasets were obtained from International Cancer Genome Consortium and The Cancer Genome Atlas.Genes with somatic mutations and copy number variations were identified by cBioPortal analysis.The differentially expressed genes with significant prognostic value were identified by Gene Expression Profiling Interactive Analysis 2 website analysis.The Tumor Immune Estimation Resource database was used to assess the correlation between candidate antigens and the abundance of antigen-presenting cells(APCs).Tumor-associated antigens were overexpressed in tumors and associated with prognosis,genomic alterations,and APC infiltration.A consensus cluster analysis was performed with the Consensus Cluster Plus package to identify the immune subtypes.The weighted gene coexpression network analysis(WGCNA)was used to determine the candidate biomarker molecules for appropriate populations for mRNA vaccines.immune subtypes showed distinct cellular and clinical characteristics.The IS1 and IS3 immune subtypes were immunologically“cold”.The IS2 and IS4 immune subtypes were immunologically“hot”,and the immune checkpoint genes and immunogenic cell death genes were upregulated in these subtypes.IS1-related modules were identified with the WGCNA algorithm.Ultimately,five hub genes(RBP4,KNG1,METTL7A,F12,and ABAT)were identified,and they might be potential biomarkers for mRNA vaccines.CONCLUSION AURKA,CCNB1,CDC25C,CDK1,TRIP13,PES1,MCM3,PPM1G,NEK2,KIF2C,PTTG1,KPNA2,and PRC1 have been identified as candidate HCC antigens for mRNA vaccine development.The IS1 and IS3 immune subtypes are suitable populations for mRNA vaccination.RBP4,KNG1,METTL7A,F12,and ABAT are potential biomarkers for mRNA vaccines.

Personalized pancreatic cancer therapy:from the perspective of mRNA vaccine

Pancreatic cancer is characterized by inter-tumoral and intra-tumoral heterogeneity,especially in genetic alteration and microenvironment.Conventional therapeutic strategies for pancreatic cancer usually suffer resistance,highlighting the necessity for personalized precise treatment.Cancer vaccines have become promising alternatives for pancreatic cancer treatment because of their multifaceted advantages including multiple targeting,minimal nonspecific effects,broad therapeutic window,low toxicity,and induction of persistent immunological memory.Multiple conventional vaccines based on the cells,microorganisms,exosomes,proteins,peptides,or DNA against pancreatic cancer have been developed;however,their overall efficacy remains unsatisfactory.Compared with these vaccine modalities,messager RNA(mRNA)-based vaccines offer technical and conceptional advances in personalized precise treatment,and thus represent a potentially cutting-edge option in novel therapeutic approaches for pancreatic cancer.This review summarizes the current progress on pancreatic cancer vaccines,highlights the superiority of mRNA vaccines over other conventional vaccines,and proposes the viable tactic for designing and applying personalized mRNA vaccines for the precise treatment of pancreatic cancer.

mRNA vaccine development for cholangiocarcinoma:a precise pipeline

Cholangiocarcinoma(CHOL)is one of the most aggressive tumors worldwide and cannot be effectively treated by conventional and novel treatments,including immune checkpoint blockade therapy.The mRNA vaccine-based immunotherapeutic strategy has attracted much attention for various diseases,however,its application in CHOL is limited due to the thoughtlessness in the integration of vaccine design and patient selection.A recent study established an integrated path for identifying potent CHOL antigens for mRNA vaccine development and a precise stratification for identifying CHOL patients who can benefit from the mRNA vaccines.In spite of a promising prospect,further investigations should identify immunogenic antigens and onco-immunological characteristics of CHOL to guide the clinical application of CHOL mRNA vaccines in the future.

mRNA vaccines: Past, present, future

mRNA vaccines have emerged as promising alternative platforms to conventional vaccines.Their ease of production,low cost,safety profile and high potency render them ideal candidates for prevention and treatment of infectious diseases,especially in the midst of pandemics.The challenges that face in vitro transcribed RNA were partially amended by addition of tethered adjuvants or co-delivery of naked mRNA with an adjuvanttethered RNA.However,it wasn’t until recently that the progress made in nanotechnology helped enhance mRNA stability and delivery by entrapment in novel delivery systems of which,lipid nanoparticles.The continuous advancement in the fields of nanotechnology and tissue engineering provided novel carriers for mRNA vaccines such as polymeric nanoparticles and scaffolds.Various studies have shown the advantages of adopting mRNA vaccines for viral diseases and cancer in animal and human studies.Self-amplifying mRNA is considered today the next generation of mRNA vaccines and current studies reveal promising outcomes.This review provides a comprehensive overview of mRNA vaccines used in past and present studies,and discusses future directions and challenges in advancing this vaccine platform to widespread clinical use.

Potential of mRNA vaccines to become versatile cancer vaccines

For centuries,therapeutic cancer vaccines have been developed and tried clinically.Way back in the late 19th century,the Father of Immunotherapy,William Coley had discovered that bacterial toxins were effective for inoperable sarcomas.In the 1970s,the Bacillus Calmette-Guérin(BCG)vaccine was repurposed,e.g.,for advanced melanomas.Then,therapeutic cancer vaccines based on tumorassociated antigens(found on the surfaces of cancer cells)were tried clinically but apparently have not made a really significant clinical impact.For repurposed pathogen vaccines,only the BCG vaccine was approved in 1989 for local application to treat nonmuscle-invading bladder cancers.Although the mildly toxic vaccine adjuvants deliberately added to conventional pathogen vaccines are appropriate for seasonal applications,when repurposed for continual oncology usage,toxicity may be problematic.In 2010,even with the approval of sipuleucel-T as the very first cancer vaccine(dendritic cell)developed for designated prostate cancers,it has also not made a really significant clinical impact.Perhaps more"user friendly"cancer vaccines should be explored.As from approximately 30 years ago,the safety and effectiveness of mRNA vaccination for oncology had already been studied,the current coronavirus disease 2019 pandemic,though disastrous,has given such progressively advancing technology a kickstart.For oncology,other virtues of mRNA vaccines seem advantageous,e.g.,rapid and versatile development,convenient modular design,and entirely cell-free synthesis,are being progressively recognized.Moreover,mRNAs encoding various oncology antigens for vaccination may also be tested with the combination of relatively non-toxic modalities of oncology treatments,e.g.,metformin or metronomic(low-dose,prolonged administration)chemotherapy.Admittedly,robust clinical data obtained through good quality clinical trials are mandatory.

Current state of knowledge on the excretion of mRNA and spike produced by anti-COVID-19 mRNA vaccines;possibility of contamination of the entourage of those vaccinated by these products

The massive COVID-19 vaccination campaign is the first time that mRNA vaccines have been used on a global scale.The mRNA vaccines correspond exactly to the definition of gene therapy of the American and European regulatory agencies.The regulations require excretion studies of these drugs and their products(the translated proteins).These studies have not been done for mRNA vaccines(nor for adenovirus vaccines).There are numerous reports of symptoms and pathologies identical to the adverse effects of mRNA vaccines in unvaccinated persons in contact with freshly vaccinated persons.It is therefore important to review the state of knowledge on the possible excretion of vaccine nanoparticles as well as mRNA and its product,the spike protein.Vaccine mRNA-carrying lipid nanoparticles spread after injection throughout the body according to available animal studies and vaccine mRNA(naked or in nanoparticles or in natural exosomes)is found in the bloodstream as well as vaccine spike in free form or encapsulated in exosomes(shown in human studies).Lipid nanoparticles(or their natural equivalent,exosomes or extracellular vesicles(EVs))have been shown to be able to be excreted through body fluids(sweat,sputum,breast milk)and to pass the transplacental barrier.These EVs are also able to penetrate by inhalation and through the skin(healthy or injured)as well as orally through breast milk(and why not during sexual intercourse through semen,as this has not been studied).It is urgent to enforce the legislation on gene therapy that applies to mRNA vaccines and to carry out studies on this subject while the generalization of mRNA vaccines is being considered.

A novel deep generative model for mRNA vaccine development: Designing 5′ UTRs with N1-methyl-pseudouridine modification

Efficient translation mediated by the 5'untranslated region(5'UTR)is essential for the robust efficacy of mRNA vaccines.However,the N1-methyl-pseudouridine(m1)modification of mRNA can impact the translation efficiency of the 5'UTR.We discovered that the optimal 5'UTR for m1y-modified mRNA(m1y-5'UTR)differs significantly from its unmodified counterpart,high-lighting the need for a specialized tool for designing mly-5'UTRs rather than directly utilizing high-expression endogenous gene 5'UTRs.In response,we developed a novel machine learning-based tool,Smart5UTR,which employs a deep generative model to identify superior m1y-5'UTRs in silico.The tailored loss function and network architecture enable Smart5UTR to overcome limitations inherent in existing models.As a result,Smart5UTR can successfully design superior 5'UTRs,greatly benefiting mRNA vaccine development.Notably,Smart5UTR-designed superior 5'UTRs significantly enhanced antibody titers induced by COVID-19 mRNA vaccines against the Delta and Omicron variants of SARS-CoV-2,surpassing the performance of vaccines using high-expression endogenous gene 5'UTRs.

A lipid nanoparticle platform incorporating trehalose glycolipid for exceptional mRNA vaccine safety

The rapid development of messenger RNA(mRNA)vaccines formulated with lipid nanoparticles(LNPs)has contributed to control of the COVID-19 pandemic.However,mRNA vaccines have raised concerns about their potential toxicity and clinical safety,including side effects,such as myocarditis,anaphylaxis,and pericarditis.In this study,we investigated the potential of trehalose glycolipids-containing LNP(LNP S050L)to reduce the risks associated with ionizable lipids.Trehalose glycolipids can form hydrogen bonds with polar biomolecules,allowing the formation of a stable LNP structure by replacing half of the ionizable lipids.The efficacy and safety of LNP S050L were evaluated by encapsulating the mRNA encoding the luciferase reporter gene and measuring gene expression and organ toxicity,respectively.Furthermore,mice immunized with an LNP S050L-formulated mRNA vaccine expressing influenza hemagglutinin exhibited a significant reduction in organ toxicity,including in the heart,spleen,and liver,while sustaining gene expression and immune efficiency,compared to conventional LNPs(Con-LNPs).Our findings suggest that LNP S050L,a trehalose glycolipid-based LNP,could facilitate the development of safe mRNA vaccines with improved clinical safety.

Safety,immunogenicity,and preliminary efficacy of a randomized clinical trial ofomicron XBB.1.5-containing bivalent mRNA vaccine

Periodically updating coronavirus disease 19(COVID-19)vaccines that offer broad-spectrum protection is needed giventhe strong immune evasion by the circulating omicron sublineages.The effectiveness of prototype and BA.4/5-containing bivalent mRNA vaccines is reduced when XBB subvariants predominate.We initiated an observer-blinded,threearms study in 376 patients in Chinese individuals aged from 18 to 55 years old who had previously received three dosesCOVID-19 vaccine.Immunogenicity in terms of neutralizing antibodies elicited by a 30-mg dose of XBB.1.5-containingbivalent vaccine(RQ3027),a 30-mg dose of BA.2/BA.5-Alpha/Beta bivalent vaccine(RQ3025)and their precedent 30-mg Alpha/Beta(combined mutations)monovalent mRNA vaccine(RQ3013)and safety are primary and secondary endpoints,respectively.We recorded prescribed COVID-19 cases to explore the preliminary efficacy of three vaccines.RQ3027 and RQ3025 boosters elicited superior neutralizing antibodies(NAbs)against XBB.1.5,XBB.1.16,XBB.1.9.1,and JN.1 compared to RQ3013 at day 14 in participants without SARS-CoV-2 infection.All study vaccines were welltolerated without serious adverse reactions identified.The incidence rates per 1000 person-years of COVID-19 casesduring the 2nd-19th week after randomization were lowest in RQ3027.Overall,our data show that XBB.1.5-containingbivalent booster generated superior immunogenicity and better protection against newer severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variants compared to BA.2/BA.5-containing bivalent and Alpha/Beta monovalentwith no new safety concerns.

Multi-valent mRNA vaccines against monkeypox enveloped or mature viron surface antigens demonstrate robust immune response and neutralizing activity

Monkeypox was declared a global health emergency by the World Health Organization,and as of March 2023,86,000 confirmed cases and 111 deaths across 110 countries have been reported.Its causal agent,monkeypox virus(MPV)belongs to a large family of double-stranded DNA viruses,Orthopoxviridae,that also includes vaccinia virus(VACV)and others.MPV produces two distinct forms of viral particles during its replication cycles:the enveloped viron(EV)that is released via exocytosis,and the mature viron(MV)that is discharged through lysis of host cells.This study was designed to develop multi-valent m RNA vaccines against monkeypox EV and MV surface proteins,and examine their efficacy and mechanism of action.Four m RNA vaccines were produced with different combinations of surface proteins from EV(A35R and B6R),MV(A29L,E8L,H3L and M1R),or EV and MV,and were administered in Balb/c mice to assess their immunogenicity potentials.A dynamic immune response was observed as soon as seven days after initial immunization,while a strong Ig G response to all immunogens was detected with ELISA after two vaccinations.The higher number of immunogens contributed to a more robust total Ig G response and correlating neutralizing activity against VACV,indicating the additive potential of each immunogen in generating immune response and nullifying VACV infection.Further,the m RNA vaccines elicited an antigen-specific CD4^(+)T cell response that is biased towards Th1.The m RNA vaccines with different combinations of EVand MV surface antigens protected a mouse model from a lethal dose VACV challenge,with the EV and MV antigens-combined vaccine offering the strongest protection.These findings provide insight into the protective mechanism of multi-valent m RNAvaccines against MPV,and also the foundation for further development of effective and safe m RNA vaccines for enhanced protection against monkeypox virus outbreak.

A lipid-based LMP2-mRNA vaccine to treat nasopharyngeal carcinoma

Nasopharyngeal carcinoma(NPC)is a serious and highly invasive epithelial malignancy that is closely associated with Epstein‒Barr virus(EBV).Due to the lack of therapeutic vaccines for NPC,we selected EBV latent membrane protein 2(LMP2)as a preferable targeting antigen to develop a lipid-based LMP2-mRNA(mLMP2)vaccine.Full-length mLMP2 expressing LMP2 was first synthesized using an in vitro transcription method and then encapsulated into(2,3-dioleacyl propyl)trimethylammonium chloride(DOTAP)-based cationic liposomes to obtain the mRNA vaccine(LPX-mLMP2).The cell assays showed that the antigenpresenting cells were capable of highly efficient uptake of LPX-mLMP2 and expression of LMP2.LMP2 could subsequently be presented to form the peptide-major histocompatibility complex(pMHC).Furthermore,LPX-mLMP2 could accumulate in the spleen,express antigens,promote the maturation of dendritic cells and stimulate antigen-specific T-cell responses in vivo.It dramatically inhibited the tumor growth of the LMP2-expressing tumor model after three doses of vaccination.Additionally,the proliferation of antigen-specific T cells in the tumor site made a good sign for the promise of mRNA vaccines in virus-induced cancer.Overall,we provided a newly developed antigen-encoding mRNA vaccine with advantages against NPC.We also demonstrated that mRNA vaccines are attractive candidates for cancer immunotherapy.

A novel heterologous receptor-binding domain dodecamer universal mRNA vaccine against SARS-CoV-2 variants

There are currently approximately 4000 mutations in the SARS-CoV-2 S protein gene and emerging SARS-CoV-2 variants continue to spread rapidly worldwide.Universal vaccines with high efficacy and safety urgently need to be developed to prevent SARS-CoV-2 variants pandemic.Here,we described a novel self-assembling universal mRNA vaccine containing a heterologous receptorbinding domain(HRBD)-based dodecamer(HRBD^(dodecamer))against SARS-CoV-2 variants,including Alpha(B.1.1.7),Beta(B.1.351),Gamma(B.1.1.28.1),Delta(B.1.617.2)and Omicron(B.1.1.529).HRBD containing four heterologous RBD(Delta,Beta,Gamma,and Wild-type)can form a stable dodecameric conformation under T4 trimerization tag(Flodon,FD).The HRBD^(dodecamer)-encoding mRNA was then encapsulated into the newly-constructed LNPs consisting of a novel ionizable lipid(4N4T).The obtained universal mRNA vaccine(4N4T-HRBD^(dodecamer))presented higher efficiency in mRNA transfection and expression than the approved ALC-0315 LNPs,initiating potent immune protection against the immune escape of SARS-CoV-2 caused by evolutionary mutation.These findings demonstrated the first evidence that structure-based antigen design and mRNA delivery carrier optimization may facilitate the development of effective universal mRNA vaccines to tackle SARS-CoV-2 variants pandemic.

Rapid evaluation of heterologous chimeric RBD-dimer mRNA vaccine for currently-epidemic Omicron sub-variants as booster shot after inactivated vaccine

With continuous mutations of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),the severe immune escape of Omicron sub-variants urges the development of next-generation broad-spectrum vaccines,especially as booster jabs after high-level vaccination coverage of inactivated vaccines in China and many other countries.Previously,we developed a coronavirus disease 2019(COVID-19)protein subunit vaccine ZF2001?based on the tandem homo-prototype receptor-binding domain(RBD)-dimer of the SARS-CoV-2 spike protein.We upgraded the antigen into a hetero-chimeric prototype(PT)-Beta or Delta-BA.1 RBD-dimer to broaden the cross-protection efficacy and prove its efficiency with protein subunit and mRNA vaccine platforms.Herein,we further explored the hetero-chimeric RBD-dimer mRNA vaccines and evaluated their broad-spectrum activities as booster jabs following two doses of inactivated vaccine(Ⅳ)in mice.Our data demonstrated that the chi-meric vaccines significantly boosted neutralizing antibody levels and specific T-cell responses against the vari-ants,and PT-Beta was superior to Delta-BA.1 RBD as a booster in mice,shedding light on the antigen design for the next-generation COVID-19 vaccines.

Safety and immunogenicity of a modified COVID-19 mRNA vaccine,SYS6006,as a fourth-dose booster following three doses of inactivated vaccines in healthy adults:an open-labeled Phase 1 trial

The continuous emergence of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variants led to a rapid decline in protection efficacy and neutralizing titers even after three doses of COVID-19 vaccines.Here,we report an open-labeled Phase I clinical trial of a modified mRNA vaccine(SYS6006)as a fourth-dose booster in healthy adults.Eighteen eligible participants,who had completed three doses of inactivated COVID-19 vaccines,received a fourth boosting dose of SYS6006-20μg.Eighteen convalescent COVID-19 patients were enrolled for the collection of serum samples as a comparator of immunogenicity.The primary endpoint of this trial was titers of anti-receptor binding domain of spike glycoprotein(RBD)antibodies of the Omicron strain(BA.2 and BA.4/5)in serum;titers of neutralizing antibodies against pseudovirus of the Omicron strain(BA.2 and BA.4/5).The secondary endpoint was the incidence of adverse events within 30 days after the boosting.The exploratory endpoint was the cellular immune responses(interferon gamma,IFN-γ).This trial was registered with the Chinese Clinical Trial Registry website.No serious adverse events were reported within 30 days after vaccination.No Grade 3 fever or serious adverse event was reported in the SYS6006 group.Notably,SYS6006 elicited higher titers and longer increases in anti-RBD antibodies and neutralizing antibodies(>90 days)compared with the convalescent group(P<0.0001)against Omicron strain(BA.2 and BA.4/5).Besides,higher positive spots of T-cell-secreting IFN-γwere observed in the SYS6006 group than those in the convalescent group(P<0.05).These data demonstrated that SYS6006 was well tolerated and highly immunogenic,generating a stronger and more durable immune response against different variants of SARS-CoV-2.

Protective efficacy of a universal influenza mRNA vaccine against the challenge of H1 and H5 influenza A viruses in mice

Current influenza vaccines need to be updated annually owing to constant antigenic drift in the globular head of the viral surface hemagglutinin(HA)glycoprotein.The immunogenic subdominant stem domain of HA is highly conserved and can be recognized by antibodies capable of binding multiple HA subtypes.Therefore,the HA stem antigen is a promising target for the design of universal influenza vaccines.On the basis of an established lipid nanoparticle-encapsulated mRNA vaccine platform,we designed and developed a novel universal influenza mRNA vaccine(mHAs)encoding the HA stem antigen of the influenza A(H1N1)virus.We tested the efficacy of the mHAs vaccine using a mouse model.The vaccine induced robust humoral and specific cellular immune responses against the stem region of HA.Importantly,two doses of the mHAs vaccine fully protected mice from lethal challenges of the heterologous H1N1 and heterosubtypic H5N8 influenza viruses.Vacci-nated mice had less pathological lung damage and lower viral titers than control mice.These results suggest that an mRNA vaccine using the conserved stem region of HA may provide effective protection against seasonal and other possible influenza variants.

Real-world effectiveness of mRNA COVID-19 vaccines in the elderly during the Delta and Omicron variants:Systematic review

BACKGROUND As of 31 December 2022,there were over 6.6 million coronavirus disease 2019(COVID-19)deaths and over 651 million cases across 200 countries worldwide.Despite the increase in vaccinations and booster shots,COVID-19 cases and deaths continue to remain high.While the effectiveness of these vaccines has already been established by different manufacturers,the fact remains that these vaccines were created quickly for global emergency use,tested under controlled clinical conditions from voluntary subjects and age groups whose general characteristics may differ from the actual general population.AIM To conduct a systematic review to determine the real-world effectiveness of mRNA COVID-19 vaccines in the elderly during the predominance of Delta and Omicron variants in preventing COVID-19 related infection,hospital,intensive care unit(ICU)admission and intubation,and death.METHODS A combination of Medical Subject Headings and non–Medical Subject Headings was carried out to identify all relevant research articles that meets the inclusion and exclusion criteria from PubMed,Cochrane,CINAHL,Scopus,ProQuest,EMBASE,Web of Science,and Google Scholar databases,as well as qualified research studies from pre–print servers using medRxiv and Research Square,published from January 1,2021-December 31,2022.RESULTS As per the inclusion and exclusion criteria,the effectiveness of Pfizer-BioNTech and Moderna vaccines were evaluated from an estimated total study population of 26535692 using infection,hospital,ICU admission and intubation,and death as outcome measures from studies published between 2021 and 2022,conducted in New York,Finland,Canada,Costa Rica,Qatar,Greece,and Brazil.The risk of bias was evaluated using risk of bias in nonrandomized studies of interventions(ROBINS-I)tool for cohort,case-control,and cross-sectional studies.While clinical trial data on Pfizer-BioNTech and Moderna vaccines demonstrated 94%vaccine effectiveness in the elderly,the results in this study showed that vaccine effectiveness in real-world settings is marginally lower against infection(40%-89%),hospitalization(92%),ICU admission and intubation(98%-85%),and death(77%-87%)with an indication of diminished effectiveness of vaccine over time.Furthermore,2 doses of mRNA vaccines are inadequate and only provides interim protection.CONCLUSION Because of the natural diminishing effectiveness of the vaccine,the need for booster dose to restore its efficacy is vital.From a research perspective,the use of highly heterogeneous outcome measures inhibits the comparison,contrast,and integration of the results which makes data pooling across different studies problematic.While pharmaceutical intervention like vaccination is important to fight an epidemic,utilizing common outcome measurements or carrying out studies with minimal heterogeneity in outcome measurements,is equally crucial to better understand and respond to an international health crisis.

A personalized mRNA vaccine has exhibited potential in the treatment of pancreatic cancer

This commentary discusses a ground-breaking study on the use of personalized mRNA cancer vaccines for treating pancreatic ductal adenocarcinoma(PDAC),a highly malignant form of cancer.The study,which capitalizes on lipid nanoparticles for mRNA vaccine delivery,aims to induce an immune response against patient-specific neoantigens and offers a potential ray of hope for improving patient prognosis.Initial results from a Phase 1 clinical trial indicated a significant T cell response in half of the subjects,opening new avenues for PDAC treatment.However,despite the promising nature of these findings,the commentary emphasizes the challenges that remain.These include the complexity of identifying suitable antigens,the possibility of tumor immune escape,and the requirement for extensive large-scale trials to confirm long-term safety and efficacy.This commentary underscores the transformative potential of mRNA technology in oncology while highlighting the hurdles that need to be overcome for its widespread adoption.

Development of mRNA vaccines and their prophylactic and therapeutic applications

Nucleic acid vaccines have attracted enormous attention for resolving the limitations of conventional vaccines using live attenuated viruses. Because nucleic acid vaccines can be produced rapidly in response to the emergence of new virus strains, they are more appropriate for the control of urgent epidemic and pandemic issues. In particular, messenger RNA （mRNA） vaccines have evolved as a new type of nucleic acid vaccines in accordance with their superior protein expression and a lack of mutagenesis as compared with DNA vaccines. Using mRNA vaccines, large amounts of target proteins can be expressed in immune cells for efficient immunization. For instance, antigen-specific vaccination is a feasible option involving the expression of specific antigens in antigen-presenting cells. Immunological reactions are modulated by expressing several proteins associated with stimulation or maturation of immune cells. In addition, mRNA vaccines can stimulate innate immunity through specific recognition by pattern recognition receptors. On the basis of these remarkable properties, mRNA vaccines have been used for prophylactic and therapeutic applications. This review highlights the role of mRNA vaccines as prophylactic vaccines for prevention of future infections and as therapeutic vaccines for cancer immunotherapy. In addition to the conventional type of mRNA vaccines, RNA replicons （self-amplifying mRNA vaccines） will be described.

An mRNA vaccine encoding Chikungunya virus E2-E1 protein elicits robust neutralizing antibody responses and CTL immune responses

Arthropod-borne chikungunya virus(CHIKV)infection can cause a debilitating arthritic disease in human.However,there are no specific antiviral drugs and effective licensed vaccines against CHIKV available for clinical use.Here,we developed an m RNA-lipid nanoparticle(m RNA-LNP)vaccine expressing CHIKV E2-E1 antigen,and compared its immunogenicity with soluble recombinant protein s E2-E1 antigen expressed in S2 cells.For comparison,we first showed that recombinant protein antigens mixed with aluminum adjuvant elicit strong antigenspecific humoral immune response and a moderate cellular immune response in C57BL/6 mice.Moreover,s E2-E1vaccine stimulated 12-23 folds more neutralizing antibodies than s E1 vaccine and s E2 vaccine.Significantly,when E2-E1 gene was delivered by an m RNA-LNP vaccine,not only the better magnitude of neutralizing antibody responses was induced,but also greater cellular immune responses were generated,especially for CD8+T cell responses.Moreover,E2-E1-LNP induced CD8~+T cells can perform cytotoxic effect in vivo.Considering its better immunogenicity and convenience of preparation,we suggest that more attention should be placed to develop CHIKV E2-E1-LNP m RNA vaccine.

Status epilepticus as a complication after COVID-19 mRNA-1273 vaccine:A case report

BACKGROUND We present a rare case of status epilepticus in a 56-year-old man which arose as a complication after vaccination with the coronavirus disease 2019(COVID-19)mRNA-1273 vaccine.The patient's history included well-compensated secondary epilepsy.The root cause of the situation was a fever which had developed as a side effect of the vaccination.CASE SUMMARY A 56-year-old man received the first dose of mRNA-1273 vaccine against the severe acute respiratory syndrome-coronavirus-2.The vaccine was administered intramuscularly(100 mg,0.5 mL).The next morning the man was found to be suffering from fever and headaches while at the same time experiencing general weakness.He lost consciousness suddenly and experienced generalized clonic seizures which turned into status epilepticus.When the Emergency Medical Service arrived the patient was unconscious with spontaneous breathing and generalized clonic seizures.It was necessary to administer diazepam repeatedly.It was also necessary to administer high doses of levetiracetam and temporary propofol.The status epilepticus was brought under control approximately 90 min after the patient’s transport to the Emergency Department.A follow-up electroencephalogram no longer revealed abnormal indications of epileptic fit.The patient was temporarily hospitalized in the Intensive Care Unit and after seven days care was discharged without any further apparent effects.CONCLUSION There is currently no specific treatment against COVID-19.Therefore,the benefits of COVID-19 vaccine protection outweigh the risks.