Construction of a replicative expression vector based on the porcine circovirus 2 replicon / 生物工程学报

The antigen gene expression level of a DNA vaccine is the key factor influencing the efficacy of the DNA vaccine. Accordingly, one of the ways to improve the antigen gene expression level of a DNA vaccine is to utilize a plasmid vector that is replicable in eukaryotic cells. A replicative DNA vaccine vector pCMVori was constructed based on the non-replicative pcDNA3.1 and the replicon of porcine circovirus 2 (PCV2) in this study. An EGFP gene was cloned into pCMVori and the control plasmid pcDNA3.1. The two recombinant vectors were transfected into PK-15 cell, and the plasmid DNA and RNA were extracted from the transfected cells. Real-time PCR was used to determine the plasmid replication efficiency of the two plasmids using plasmid before and after Bcl Ⅰ digestion as templates, and the transcription level of the Rep gene in PCV2 replicon was detected by RT-PCR. The average fluorescence intensity of cells transfected with the two plasmids was analyzed with software Image J, and the transcription level of EGFP was determined by means of real-time RT-PCR. The results showed that the replication efficiency of pCMVori in PK-15 cells incubated for 48 h was 136%, and the transcriptions of Rep and Rep' were verified by RT-PCR. The average fluorescence intensity of the cells transfected with pCMVori-EGFP was 39.14% higher than that of pcDNA3.1-EGFP, and the transcription level of EGFP in the former was also 40% higher than that in the latter. In conclusion, the DNA vaccine vector pCMVori constructed in this study can independently replicate in eukaryotic cells. As a result, the expression level of cloned target gene was elevated, providing a basis for developing the pCMVori-based DNA vaccine.

Expression of recombinant PreS2-S protein from the hepatitis B virus surface antigen in Pichia pastoris

The aim of this work is the expression of the PreS2-S region of surface antigen of hepatitis B virus (HBV) in yeast Pichia pastoris. A cDNA fragment encoding the Pres2-S protein of HBV was cloned to yeast transfer vectors. Based on cloned new plasmids pPIC3.5-PreS2-S (8707 bp) and pPIC9-PreS2-S (8980 bp) the recombinant strains of P. pastoris producing the PreS2-S region of surface antigen of HBV were obtained. The PAGE electrophoresis and immunoblotting of obtained recombinant PreS2-S protein confirm the molecular weight (34 kDa) and high specificity to the HBV antibodies)AU)

El objetivo de este trabajo es la expresión de la región PreS2-S del antígeno de superficie del virus de la hepatitis B en la levadura Pichia pastoris. Se clonó un fragmento de ADNc que codifica la proteína PreS2-S del VHB en vectores de transferencia de levadura. A partir de los nuevos plásmidos clonados pPIC3.5-PreS2-S (8707 pb) y pPIC9-PreS2-S (8980 pb) se obtuvieron las cepas recombinantes de P. pastoris productoras de la región PreS2-S del antígeno de superficie del VHB. La electroforesis PAGE y la inmunotransferencia de la proteína PreS2-S recombinante obtenida confirman el peso molecular (34 kDa) y la alta especificidad a los anticuerpos contra el VHB(AU)

Respostas imunes induzidas por vacinas de DNA contra Zika e neuroadaptação de um isolado viral em camundongos para futuros testes de vacinas / Immune responses induced by DNA vaccines against Zika and neuroadaptation of a viral isolate in mice for future vaccine trials

Em geral, a doença causada pelo vírus Zika (ZIKV) é clinicamente semelhante às de outros arbovírus. No entanto, ocasionalmente ela é associada a síndromes neurológicas como a síndrome de Guillain-Barré. Além disso, durante a gravidez a infecção pode causar a síndrome congênita do zika, com danos cerebrais e sistêmicos no feto e/ou bebês, incluindo microcefalia. O genoma do ZIKV codifica três proteínas estruturais, capsídeo, pré-membrana/membrana e envelope (E), e sete proteínas não estruturais (NS1-5). As proteínas E e NS1 são indicadas como antígenos promissores, sendo consideradas alvos importantes no desenho de vacinas contra diversos flavivírus. Nosso grupo construiu dois plasmídeos recombinantes que codificam o ectodomínio da proteína E (pZKectoE) e a proteína NS1 (pZKNS1) do ZIKV. O objetivo deste trabalho foi investigar a capacidade desses plasmídeos de mediar a expressão de proteínas recombinantes e induzir respostas imunes. Células BHK-21 foram transfectadas com estes plasmídeos e a expressão das proteínas recombinantes foi avaliada. Como esperado, o pZKectoE e o pZKNS1 mediaram a expressão das proteínas recombinantes E e NS1, respectivamente. A ativação das respostas imunes humoral e celular em camundongos foi avaliada por ELISA e por ELISPOT. Ambos os plasmídeos induziram títulos de anticorpos específicos significativamente mais elevados do que o plasmídeo controle (pcTPA). Além disso,induziram respostas de células T com produção de IFN-γ após estimulação com duas bibliotecas de peptídeos derivadas de E e NS1. O mapeamento de peptídeos imunogênicos através de ensaios de ELISPOT identificou cinco epítopos imunodominantes na proteína E e três na proteína NS1. A maioria dos modelos murinos para estudos de ZIKV usa animais imunocomprometidos, que fornecem infecções robustas e letais, mas talvez não sejam ideais para testes de vacinas. Portanto, a fim de estabelecer um modelo murino imunocompetente suscetível à infecção pelo ZIKV, iniciamos experimentos de neuroadaptação de um vírus isolado de um paciente no Brasil, por sucessivas passagens no cérebro de camundongos recém-nascidos. Grupos de camundongos Swiss, com idades entre três e nove dias, foram infectados pela via intracerebral com ZIKV. No sétimo dia após a infecção, os animais foram eutanasiados e os cérebros foram coletados. As amostras foram tituladas por ensaio de plaques em células Vero. Em cada passagem, a amostra com o título viral mais alto foi usada para inoculação subsequente no cérebro de outros camundongos recém-nascidos. Nossos resultados mostraram uma alteração na morfologia do plaque produzido pela infecção com o vírus em comparação àquelas observadas com a amostra inicial de ZIKV. Em relação à carga viral, houve um aumento de 4 log durante as primeiras quatro passagens, seguido por uma ligeira redução e o sequenciamento do genoma viral revelou algumas mutações pontuais. De modo geral, as vacinas pZKEctoE e pZKNS1 foram capazes de mediar a expressão das proteínas recombinantes E ou NS1 com ativação das respostas imunes humoral e celular. Até o momento, não foi possível o estabelecimento de um modelo murino imunocompetente. Para obtenção do vírus neuroadaptado, com capacidade de causar sinais clínicos da infecção em animais adultos, deverão ser realizadas mais passagens em cérebros de camundogos Swiss. (AU)

Review of COVID­19 vaccine

Coronavirus disease 2019 (COVID­19) accounts for over 92 million confirmed cases worldwide, with over 2.06 million deaths. In the past year, more than 290 candidate vaccines have been tested; COVID-19 vaccine development was sped up, with shortened timeline, due to the urgent global need in the face of the pandemic. In addition, people with the highest risk of contracting the disease, such as health workers with a high risk of exposure, elderlies, and people with underlying comorbidities, were prioritized with vaccination rollout. The article narratively reviewed original and review articles available on PubMed and Google Scholar related to the theme to provide up­to­date information. The different templates developed and studied for COVID-19 vaccines include the whole-virus vaccine, viral vector vaccine, nucleic acid (deoxyribonucleic acid and ribonucleic acid), and protein subunit vaccine. Myths impede vaccine uptake in this part of the globe. Adopting these myths leads to sharing and spreading, which negatively impacts the prevention of COVID-19 and vaccine uptake. Adverse event following immunizations (AEFIs) is classified based on severity, from minor to severe. The minor ones are common events that pose no potential health risks to the receiver of the vaccine. The type determines the safety profile, severity, and frequency of AEFIs observed with the vaccine administration. Overall, this pandemic has heightened the global level of threat awareness; it has also provided motivation to prepare for future pandemics by developing new vaccines.

Enhanced epitope immunoreactivity of the dominant epitope of Toxoplasma gondii fused at the "N terminus" of HPV16L1 / 生物工程学报

For improving epitope immunogenicity and achieving the co-immunization, late protein 1 (L1) of HPV type 16 (HPV16L1) was selected as the vector to carry the dominant epitope of Toxoplasma gondii because of the shared common population between Toxoplasma gondii and human papillomavirus (HPV). RSepitope-HPV16L1 (RSepitope fused at the "N-terminus" of HPV16L1) and HPV16L1-RSepitope (RSepitope fused at the "C-terminus" of HPV16L1) chimeras were constructed. After transfection of COS-7 cells with the recombinants, Western blot, RT-PCR, and immunofluorescence experiments confirmed that RSepitope-HPV16L1 could successfully express the corresponding mRNA and protein of RSepitope and HPV16L1, but the HPV16L1-RSepitope construct could not. A "prime-boost" immunization program was applied in mice to further evaluate the immune response elicited by the constructs, and the RSepitope-HPV16L1 immunization group produced the most significantly increased humoral and cellular immune responses (the highest RSepitope-specific IgG antibody level and the highest IFN-γ production, respectively), in which both elevated Th1 and Th2 immune responses were obtained. Moreover, the advantage of HPV16L1 as an epitope carrier was remarkable for RSepitope-HPV16L1, which induced a more prominent immunological response than RSepitope alone (without fusion with HPV16L1). Our research indicated that the N-terminus of HPV16L1 could be a better insertion site for enhancing target epitope immunogenicity, and our study offers a design for epitope vaccine of reasonable combination.

DNA nanovaccines prepared using LemA antigen protect Golden Syrian hamsters against Leptospira lethal infection

BACKGROUND Nanoparticles (NPs) are viable candidates as carriers of exogenous materials into cells via transfection and can be used in the DNA vaccination strategy against leptospirosis. OBJECTIVES We evaluated the efficiency of halloysite clay nanotubes (HNTs) and amine-functionalised multi-walled carbon nanotubes (NH2-MWCNTs) in facilitating recombinant LemA antigen (rLemA) expression and protecting Golden Syrian hamsters (Mesocricetus auratus) against Leptospira interrogans lethal infection. METHODS An indirect immunofluorescent technique was used to investigate the potency of HNTs and NH2-MWCNTs in enhancing the transfection and expression efficiency of the DNA vaccine in Chinese hamster ovary (CHO) cells. Hamsters were immunised with two doses of vaccines HNT-pTARGET/lemA, NH2-MWCNTs-pTARGET/lemA, pTARGET/lemA, and empty pTARGET (control), and the efficacy was determined in terms of humoral immune response and protection against a lethal challenge. FINDINGS rLemA DNA vaccines carried by NPs were able to transfect CHO cells effectively, inducing IgG immune response in hamsters (p < 0.05), and did not exhibit cytotoxic effects. Furthermore, 83.3% of the hamsters immunised with NH2-MWCNTs-pTARGET/lemA were protected against the lethal challenge (p < 0.01), and 66.7% of hamsters immunised with HNT-pTARGET/lemA survived (p < 0.05). MAIN CONCLUSIONS NH2-MWCNTs and HNTs can act as antigen carriers for mammalian cells and are suitable for DNA nanovaccine delivery.

Biopolymer Xanthan: A New Adjuvant for DNA Vaccines

Abstract DNA vaccines have been evaluated as an option to prevent several diseases. In this study, the capacity of the xanthan biopolymer to improve the DNA vaccines immune response, administered intramuscularly, was evaluated. The experimental vaccines consisted of genes encoding fragments of the proteins LigA and LigB of Leptospira interrogans serogroup Icterohaemorrhagiae serovar Copenhageni strain Fiocruz L1-130. The humoral immune response was evaluated by indirect ELISA. Cytokine expression levels were determined by RT-qPCR. Compared to the control group, the IgG antibody levels of animals immunized with pTARGET/ligAni and pTARGET/ligBrep plasmids associated with xanthan biopolymer were significantly higher than the control group. Additionally, there was a significant increase in IL-17 expression in animals vaccinated with pTARGET/ligBrep and xanthan.

Avances en el desarrollo de una vacuna efectiva contra Cryptosporidium parvum: una revisión de la literatura / Advances in the development of an effective vaccine against Cryptosporidium parvum: An review of the literature / Avanços no desenvolvimento de uma vacina eficaz contra Cryptosporidium parvum: uma revisão da literatura

Introducción. Cryptosporidium parvum es un parásito zoonótico altamente prevalente, asociado a enfermedad diarreica en población inmunocomprometida, niños y terneros menores de 30 días. Esta infección puede ocasionar deshidratación, alteración del estado de conciencia, retraso en el desarrollo global y, en algunos casos, la muerte del paciente. A pesar de la alta prevalencia de C. parvum, no existen medicamentos completamente efectivos ni una vacuna aprobada para prevenir dicha enfermedad. Objetivo. Realizar una revisión de la literatura sobre candidatos vacunales contra C. parvum. Método. Revisión documental mediante la búsqueda de la literatura de los últimos 20 años, disponible en las bases de datos PubMed central, WEB OF SCIENCE, Embase, REDALYC y LILACS. Resultados. Las vacunas atenuadas, recombinantes, basadas en ADN, expresadas en vectores bacterianos y sintéticas han mostrado resultados prometedores en la inducción de inmunogenicidad contra los antígenos de C. parvum, siendo el antígeno de superficie de 15 kilodaltons de Cryptosporidium parvum (cp15), el antígeno inductor de una mejor respuesta inmune celular y humoral en el modelo murino estudiado. Conclusión. Se espera que la incorporación de nuevas técnicas para la selección de antígenos promisorios y la ejecución de una gran cantidad de ensayos in vivo, favorezcan el desarrollo de una vacuna totalmente efectiva contra C. parvum. Aunque el camino para lograr este objetivo será largo y difícil, se convierte en la mejor alternativa para controlar una de las enfermedades de interés en salud pública, con mayor impacto en la población inmunocomprometida.

Introduction. Cryptosporidium parvum is a highly prevalent zoonotic parasite, associated with diarrheal disease in immunocompromised population, children and calves under 30 days. This infection is associa- ted to dehydration, delayed global development and, in some cases, the death of the patient. Despite the high prevalence of C. parvum, there are no fully effective medications and an approved vaccine to prevent such disease. Objective. To conduct a thorough review of the literature on vaccine candidates against C. parvum. Method Documentary review by searching the literature of the last 20 years, available in the central PubMed, WEB OF SCIENCE, Embase, REDALYC and LILACS databases. Results. Attenuated, recombinant, DNA-based, expressed in bacterial vectors and synthetic vaccines have shown promising results in inducing immunogenicity against C. parvum, being the Cryptospori- dium parvum 15 kiloDalton surface antigen (cp15), the antigen inducer of a better cellular and humoral immune response in the murine model studied. Conclusion. It is expected that the incorporation of new techniques for the selection of promising antigens and the execution of a large number of in vivo assays will favor the development of a fully effective vaccine against C. parvum. Although the way to achieve this goal will be long and difficult, it will become the best alternative to control one of the diseases with the greatest impact on the immu- nocompromised population.

Introdução. O Cryptosporidium parvum é um parasita zoonótico de alta prevalência associado à doença diarreica em populações imunocomprometidas, crianças e bezerros com menos de 30 dias. Essa infecção pode causar desidratação, alteração do estado de consciência, atraso no desenvolvi- mento global e, em alguns casos, a morte do paciente. Apesar da alta prevalência de C. parvum, não existem medicamentos totalmente eficazes e uma vacina aprovada para prevenir a doença. Objetivo. Realizar uma revisão literária dos candidatos à vacina contra C. parvum. Método. Revisão documental, mediante pesquisa da literatura dos últimos 20 anos, disponível nas bases de dados PubMed central, WEB OF SCIENCE, Embase, REDALYC e LILACS. Resultados. Vacinas atenuadas, recombinantes e baseadas em DNA, expressas em vetores bacteria- nos e sintéticos, mostraram resultados promissores na indução de imunogenicidade contra antígenos de C. parvum, sendo o antígeno de superfície de 15 kilodaltons de Cryptosporidium parvum (cp15) o antígeno indutor de uma melhor resposta imune celular e humoral no modelo murino estudado. Conclusão. Se espera que a incorporação de novas técnicas para a seleção de antígenos promissores e a execução de um grande número de ensaios in vivo favoreçam o desenvolvimento de uma vacina totalmente eficaz contra C. parvum. Embora o caminho para alcançar este objetivo seja longo e difícil, torna-se a melhor alternativa para controlar uma das doenças de interesse na saúde pública com maior impacto na população imunocomprometida.

Rhoptry antigens as Toxoplasma gondii vaccine target

Toxoplasmosis is a cosmopolitan zoonotic infection, caused by a unicellular protozoan parasite known as Toxoplasma gondii that belongs to the phylum Apicomplexa. It is estimated that over one-third of the world's population has been exposed and are latently infected with the parasite. In humans, toxoplasmosis is predominantly asymptomatic in immunocompetent persons, while among immunocompromised individuals may be cause severe and progressive complications with poor prognosis. Moreover, seronegative pregnant mothers are other risk groups for acquiring the infection. The life cycle of T. gondii is very complex, indicating the presence of a plurality of antigenic epitopes. Despite of great advances, recognize and construct novel vaccines for prevent and control of toxoplasmosis in both humans and animals is still remains a great challenge for researchers to select potential protein sequences as the ideal antigens. Notably, in several past years, constant efforts of researchers have made considerable advances to elucidate the different aspects of the cell and molecular biology of T. gondii mainly on microneme antigens, dense granule antigens, surface antigens, and rhoptry proteins (ROP). These attempts thereby provided great impetus to the present focus on vaccine development, according to the defined subcellular components of the parasite. Although, currently there is no commercial vaccine for use in humans. Among the main identified T. gondii antigens, ROPs appear as a putative vaccine candidate that are vital for invasion procedure as well as survival within host cells. Overall, it is estimated that they occupy about 1%–30% of the total parasite cell volume. In this review, we have summarized the recent progress of ROP-based vaccine development through various strategies from DNA vaccines, epitope or multi epitope-based vaccines, recombinant protein vaccines to vaccines based on live-attenuated vectors and prime-boost strategies in different mouse models.

Application of lysis system in bacterial vector vaccines / 生物工程学报

Recombinant bacterial vector vaccines have been widely used as carriers for the delivery of protective antigens and nucleic acid vaccines to prevent certain infectious diseases because of their ability to induce mucosal immunity, humoral immunity and cellular immunity. However, protective antigens and nucleic acids recombined into bacterial vector vaccines are difficult to be released into host cells because of the presence of bacterial cell wall. Vaccine strains that are residual in animals or livestock products may also cause environmental contamination and spread of the vaccine strains. The effective solution for these problems is to construct an auto-lysis system that can regulate the vaccine strains to grow normally in vitro while lysis in vivo. The lysis systems that have been applied in germs mainly include: the lysis system based on regulated delayed peptidoglycan synthesis, the lysis system based on the regulation of bacteriophage lysis protein and the lysis system based on the toxin-antitoxin system. In addition, a potential lysis system based on bacterial Type Ⅵ Secretion System (T6SS) is also expected to be a new method for the construction of auto-lysis strains. This review will focus on the regulatory mechanisms of these bacterial lysis systems.

Recent progress in microneme-based vaccines development against Toxoplasma gondii

Toxoplasmosis is a cosmopolitan zoonotic disease, which infect several warm-blooded mammals. More than one-third of the human population are seropositive worldwide. Due to the high seroprevalence of Toxoplasma gondii infection worldwide, the resulting clinical, mental, and economical complications, as well as incapability of current drugs in the elimination of parasites within tissue cysts, the development of a vaccine against T. gondii would be critical. In the past decades, valuable advances have been achieved in order to identification of vaccine candidates against T. gondii infection. Microneme proteins (MICs) secreted by the micronemes play a critical role in the initial stages of host cell invasion by parasites. In this review, we have summarized the recent progress for MIC-based vaccines development, such as DNA vaccines, recombinant protein vaccines, vaccines based on live-attenuated vectors, and prime-boost strategy in different mouse models. In conclusion, the use of live-attenuated vectors as vehicles to deliver and express the target gene and prime-boost regimens showed excellent outcomes in the development of vaccines against toxoplasmosis, which need more attention in the future studies.

Purification and characterization of monoclonal IgG antibodies recognizing Ebola virus glycoprotein

PURPOSE: The goal of this study was to purify and characterize Ebola virus glycoprotein (GP)-specific IgG antibodies from hybridoma clones. MATERIALS AND METHODS: For hybridoma production, mice were injected by intramuscular-electroporation with GP DNA vaccines, and boosted with GP vaccines. The spleen cells were used for producing GP-specific hybridoma. Enzyme-linked immunosorbent assay, Western blot assay, flow cytometry, and virus-neutralizing assay were used to test the ability of monoclonal IgG antibodies to recognize GP and neutralize Ebola virus. RESULTS: Twelve hybridomas, the cell supernatants of which displayed GP-binding activity by enzyme-linked immunosorbent assay and the presence of both IgG heavy and light chains by Western blot assay, were chosen as a possible IgG producer. Among these, five clones (C36-1, D11-3, D12-1, D34-2, and E140-2) were identified to secrete monoclonal IgG antibodies. When the monoclonal IgG antibodies from the 5 clones were tested for their antigen specificity, they recognized GP in an antigen-specific and IgG dose-dependent manner. They remained reactive to GP at the lowest tested concentrations (1.953–7.8 ng/mL). In particular, IgG antibodies from clones D11-3, D12-1, and E140-2 recognized the native forms of GP expressed on the cell surface. These antibodies were identified as IgG1, IgG2a, or IgG2b kappa types and appeared to recognize the native forms of GP, but not the denatured forms of GP, as determined by Western blot assay. Despite their GP-binding activity, none of the IgG antibodies neutralized Ebola virus infection in vitro, suggesting that these antibodies are unable to neutralize Ebola virus infection. CONCLUSION: This study shows that the purified IgG antibodies from 5 clones (C36-1, D11-3, D12-1, D34-2, and E140-2) possess GP-binding activity but not Ebola virus-neutralizing activity.

Herpes Zoster DNA Vaccines with IL-7 and IL-33 Molecular Adjuvants Elicit Protective T Cell Immunity

Herpes zoster (HZ), or shingles, is caused by the reactivation of latent varicella-zoster virus (VZV) from the sensory ganglia when VZV-specific T-cell immunity is decreased because of aging or immunosuppression. In the present study, we developed HZ DNA vaccine candidates encoding VZV proteins and cytokine adjuvants, such as IL-7 and IL-33. We immunized C57BL/6 mice with DNA plasmids encoding VZV glycoprotein E (gE), immediate early (IE) 63, or IE62 proteins and found that robust VZV protein-specific T-cell responses were elicited by HZ DNA vaccination. Co-administration of DNA plasmids encoding IL-7 or IL-33 in HZ DNA vaccination significantly enhanced the magnitude of VZV protein-specific T-cell responses. Protective immunity elicited by HZ DNA vaccination was proven by challenge experiments with a surrogate virus, vaccinia virus expressing gE (VV-gE). A single dose of HZ DNA vaccine strongly boosted gE-specific T-cell responses in mice with a history of previous infection by VV-gE. Thus, HZ DNA vaccines with IL-7 and IL-33 adjuvants strongly elicit protective immunity.

Expression of MLAA34-HSP70 fusion gene constructed by SOE-PCR

To construct the pIRES2-MLAA34-HSP70 recombinant vector and express the MLAA34-HSP70 recombinant proteins in Escherichia coli [E. coli]. The MLAA34 and the HSP70 genes were extracted from U937 cells by RT-PCR, and then we amplified the fusion gene MLAA34-HSP70 by SOE-PCR and inserted it into the pIRES2-EGFP vector to construct the pIRES2-MLAA34-HSP70 recombinant vector. We amplified the fusion gene MLAA34-HSP70 successfully and identified the correctness of pIRES2-MLAA34-HSP70 recombinant vector by PCR and restriction endonuclease. Moreover, the MLAA34-HSP70 recombinant proteins expressed in E. coli were consistent with the expected molecular weight. We constructed the pIRES2-MLAA34-HSP70 recombinant vector successfully and the MLAA34-HSP70 recombinant proteins were successfully expressed by the induction of IPTG

DNA Vaccines Encoding Toxoplasma gondii Cathepsin C 1 Induce Protection against Toxoplasmosis in Mice

Toxoplasma gondii cathepsin C proteases (TgCPC1, 2, and 3) are important for the growth and survival of T. gondii. In the present study, B-cell and T-cell epitopes of TgCPC1 were predicted using DNAstar and the Immune Epitope Database. A TgCPC1 DNA vaccine was constructed, and its ability to induce protective immune responses against toxoplasmosis in BALB/c mice was evaluated in the presence or absence of the adjuvant α-GalCer. As results, TgCPC1 DNA vaccine with or without adjuvant α-GalCer showed higher levels of IgG and IgG2a in the serum, as well as IL-2 and IFN-γ in the spleen compared to controls (PBS, pEGFP-C1, and α-Galcer). Upon challenge infection with tachyzoites of T. gondii (RH), pCPC1/α-Galcer immunized mice showed the longest survival among all the groups. Mice vaccinated with DNA vaccine without adjuvant (pCPC1) showed better protective immunity compared to other controls (PBS, pEGFP-C1, and α-Galcer). These results indicate that a DNA vaccine encoding TgCPC1 is a potential vaccine candidate against toxoplasmosis.

Preferential production of IgM-secreting hybridomas by immunization with DNA vaccines coding for Ebola virus glycoprotein: use of protein boosting for IgG-secreting hybridoma production

PURPOSE: The goal of this study was to investigate the utility of DNA vaccines encoding Ebola virus glycoprotein (GP) as a vaccine type for the production of GP-specific hybridomas and antibodies. MATERIALS AND METHODS: DNA vaccines were constructed to express Ebola virus GP. Mice were injected with GP DNA vaccines and their splenocytes were used for hybridoma production. Enzyme-linked immunosorbent assays (ELISAs), limiting dilution subcloning, antibody purification methods, and Western blot assays were used to select GP-specific hybridomas and purify monoclonal antibodies (MAbs) from the hybridoma cells. RESULTS: Twelve hybridomas, the cell supernatants of which displayed GP-binding activity, were selected by ELISA. When purified MAbs from 12 hybridomas were tested for their reactivity to GP, 11 MAbs, except for 1 MAb (from the A6-9 hybridoma) displaying an IgG2a type, were identified as IgM isotypes. Those 11 MAbs failed to recognize GP. However, the MAb from A6-9 recognized the mucin-like region of GP and remained reactive to the antigen at the lowest tested concentration (1.95 ng/mL). This result suggests that IgM-secreting hybridomas are predominantly generated by DNA vaccination. However, boosting with GP resulted in greater production of IgG-secreting hybridomas than GP DNA vaccination alone. CONCLUSION: DNA vaccination may preferentially generate IgM-secreting hybridomas, but boosting with the protein antigen can reverse this propensity. Thus, this protein boosting approach may have implications for the production of IgG-specific hybridomas in the context of the DNA vaccination platform. In addition, the purified monoclonal IgG antibodies may be useful as therapeutic antibodies for controlling Ebola virus infection.

Development and trial of vaccines against Brucella

The search for ideal brucellosis vaccines remains active today. Currently, no licensed human or canine anti-brucellosis vaccines are available. In bovines, the most successful vaccine (S19) is only used in calves, as adult vaccination results in orchitis in male, prolonged infection, and possible abortion complications in pregnant female cattle. Another widely deployed vaccine (RB51) has a low protective efficacy. An ideal vaccine should exhibit a safe profile as well as enhance protective efficacy. However, currently available vaccines exhibit one or more major drawbacks. Smooth live attenuated vaccines suffer shortcomings such as residual virulence and serodiagnostic interference. Inactivated vaccines, in general, confer relatively low levels of protection. Recent developments to improve brucellosis vaccines include generation of knockout mutants by targeting genes involved in metabolism, virulence, and the lipopolysaccharide synthesis pathway, as well as generation of DNA vaccines, mucosal vaccines, and live vectored vaccines, have all produced varying degrees of success. Herein, we briefly review the bacteriology, pathogenesis, immunological implications, candidate vaccines, vaccinations, and models related to Brucella.

Construction of a fusion plasmid containing the PSCA gene and cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) and its anti-tumor effect in an animal model of prostate cancer

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is a negative regulator of T cell activation, which competes with CD28 for B7.1/B7.2 binding, and which has a greater affinity. Fusion of specific antigens to extracellular domain of CTLA4 represents a promising approach to increase the immunogenicity of DNA vaccines. In this study, we evaluated this interesting approach for CTLA4 enhancement on prostate stem cell antigen (PSCA)-specific immune responses and its anti-tumor effects in a prostate cancer mouse model. Consequently, we constructed a DNA vaccine containing the PSCA and the CTLA-4 gene. Vaccination with the CTLA4-fused DNA not only induced a much higher level of anti-PSCA antibody, but also increased PSCA-specific T cell response in mice. To evaluate the anti-tumor efficacy of the plasmids, murine models with PSCA-expressing tumors were generated. After injection of the tumor-bearing mouse model, the plasmid carrying the CTLA4 and PSCA fusion gene showed stronger inhibition of tumor growth than the plasmid expressing PSCA alone. These observations emphasize the potential of the CTLA4-fused DNA vaccine, which could represent a promising approach for tumor immunotherapy.