Predominant Th1 Immune Response Research Articles

Inserting Omp22 into the flagellin protein, replacing its hypervariable region, results in stronger protection against lethal Acinetobacter baumannii infection.

Acinetobacter baumannii, a common nosocomial pathogen, is known for its rapid acquisition of antimicrobial resistance, underscoring the urgent need to develop an effective vaccine against this pathogen. Outer membrane protein 22 (Omp22) regulates the biogenesis of outer membrane vesicles to transport virulence-promoting factors into the host cells and facilitates the progression of A. baumannii infection. In this study, we used a mouse model to assess a vaccine's immunogenicity and protective efficacy using recombinant Omp22 protein within the hypervariable region of flagellin (FliC-Omp22). FliC-Omp22 demonstrated superior protection following challenge with a lethal dose of multidrug-resistant (MDR) A. baumannii strain 58ST compared to Omp22 alone. In addition, it elicited increased IgG1/IgG2a and IL-4/IFN-γ ratios, indicating a predominant Th2 immune response. Furthermore, the FliC-Omp22 vaccination elicited strong specific antibodies that inhibited the adhesion and invasion of A. baumannii 58ST and enhanced the opsonic killing activity against the pathogen. FliC-Omp22 immunization significantly reduced bacterial loads in infected mice's spleen, lungs, and liver, thereby improving their survival against the lethal infection caused by MDR A. baumannii 58ST. This study suggests that integrating Omp22 into the hypervariable domain of flagellin holds promise for developing an effective vaccine against A. baumannii infections.

SMART-lipid nanoparticles enabled mRNA vaccine elicits cross-reactive humoral responses against the omicron sub-variants

The continual emergence of SARS-CoV-2 variants has necessitated the development of broad cross-reactive vaccines. Recent findings suggest that enhanced antigen presentation could lead to cross-reactive humoral responses against the emerging variants. Towards enhancing the antigen presentation to dendritic cells (DCs), we developed a novel shikimoylated mannose receptor targeting lipid nanoparticle system (SMART-LNPs) that could effectively deliver mRNAs into DCs. To improve the translation of mRNA, we developed spike domain-based trimeric-S1 (TS1) mRNA with optimized codon sequence, base modification, and engineered 5’&3’ UTRs. In a mouse model, SMART-LNPs-TS1 vaccine could elicit robust broad cross-reactive IgGs against Omicron sub-variants, and induced IFNγ producing T-cells against SARS-CoV-2 virus compared to non-targeted LNPs-TS1 vaccine. Further, T-cells analysis revealed that SMART-LNPs-TS1 vaccine induced long-lived memory T-cell subsets, Th1-dominant and cytotoxic T-cells immune responses against SARS-CoV-2 virus. Importantly, SMART-LNPs-TS1 vaccine produced strong Th1-predominant humoral and cellular immune responses. Overall, SMART-LNPs can be explored for precise antigenic mRNA delivery and robust immune responses. This platform technology can be explored further as a next-gen delivery system for mRNA-based immune therapies.

Insights on the Pathophysiology of the Progression to Decompensated Hepato-Splenic Schistosomiasis

Hepato-splenic schistosomiasis is the most important etiology of non-cirrhotic portal hypertension. It represents a particular type of chronic liver disease, which presents unique characteristics that differentiate it from those found in cirrhosis. The relative preservation of liver parenchyma despite portal fibrosis was thought to yield a more benign course of hepato-splenic schistosomiasis in terms of synthetic dysfunction and late decompensations. However, a wide range of immunologic and vascular modifications is responsible for an otherwise progressive liver disease resulting in decompensated condition frequently undistinguished from hepatic cirrhosis. A predominant Th2 immune response type, in which a fibrogenic profile of cytokines and interleukins such as IL-13, provides an immune-inflammatory background that favors fibrosis and its progression. Intra-hepatic vascular changes with portal vein branch derangement and abnormal vascular proliferation also contribute to continued disarray of the liver architecture resulting in decompensated disease frequently undistinguished from hepatic cirrhosis. This article will review immunologic and pathophysiological aspects of hepato-splenic schistosomiasis that might explain disease progression and severity.

Xenograft cancer vaccines prepared from immunodeficient mice increase tumor antigen diversity and host T cell efficiency against colorectal cancers.

Autologous cancer vaccines (ACVs) are a desirable approach for personalized medicine, but the efficiency of ACVs remains unsatisfactory due to their low immunogenicity. This study developed a platform that can enhance the immunogenicity of ACVs by transplanting the tumors into immunodeficient mice. The CT26cell line was inoculated into severe combined immunodeficient mice (SCID) for vaccine preparation where escalates tumor development, subsequently diversifying the tumor antigenic topology. CT26/SCID cancer vaccines significantly inhibited tumor growth, increased the amount of tumor infiltrating lymphocytes, and triggered Th-1 predominant immune responses. Tumor antigenic profiles of CT26/SCID cells were further analyzed by liquid chromatography-tandem mass spectrometry. Compared to CT26 parental cells, a total of 428 differentially expressed proteins (DEPs) were detected. These DEPs revealed that CT26/SCID cells overexpressed several novel therapeutic targets, including KNG1, apoA-I and, β2-GPI, which can trigger cytotoxic T cells towards Th-1 predominant immune responses and directly suppress proliferation in tumors. CT26/SCID cancer vaccines can be easily manufactured, while traits of triggering stronger antigen-specific Th-1 immune activity against tumors, are retained. Results of this study provide an effective proof-of-concept of an ACV for personalized cancer immunotherapy.

An Early Th1 Response Is a Key Factor for a Favorable COVID-19 Evolution.

The Th1/Th2 balance plays a crucial role in the progression of different pathologies and is a determining factor in the evolution of infectious diseases. This work has aimed to evaluate the early, or on diagnosis, T-cell compartment response, T-helper subsets and anti-SARS-CoV-2 antibody specificity in COVID-19 patients and to classify them according to evolution based on infection severity. A unicenter, randomized group of 146 COVID-19 patients was divided into four groups in accordance with the most critical events during the course of disease. The immunophenotype and T-helper subsets were analyzed by flow cytometry. Asymptomatic SARS-CoV-2 infected individuals showed a potent and robust Th1 immunity, with a lower Th17 and less activated T-cells at the time of sample acquisition compared not only with symptomatic patients, but also with healthy controls. Conversely, severe COVID-19 patients presented with Th17-skewed immunity, fewer Th1 responses and more activated T-cells. The multivariate analysis of the immunological and inflammatory parameters, together with the comorbidities, showed that the Th1 response was an independent protective factor for the prevention of hospitalization (OR 0.17, 95% CI 0.03–0.81), with an AUC of 0.844. Likewise, the Th1 response was found to be an independent protective factor for severe forms of the disease (OR 0.09, 95% CI: 0.01–0.63, p = 0.015, AUC: 0.873). In conclusion, a predominant Th1 immune response in the acute phase of the SARS-CoV-2 infection could be used as a tool to identify patients who might have a good disease evolution.

Flagella hook protein FlgE is a novel vaccine candidate of Pseudomonas aeruginosa identified by a genomic approach

Infections due to Pseudomonas aeruginosa (PA) are becoming a serious threat to patients in intensive care units. A PA vaccine is a practical and economical solution to solve the problems caused by PA infection successfully. In recent years, several antigen candidates have been tested in animal and human clinical trials, but none of them has been approved to date. An alternative strategy for antigen screening and protective antigens is in urgent demand. In this study, we generated a genome-wide library of PA protein fragments tagged with maltose-binding protein (MBP). Using sera from patients who recovered after PA infection, we identified a novel protective antigen, FlgE, which is the structural component of the flagella hook. Vaccination with recombinant FlgE (reFlgE) induced a Th2-predominant immune response and reduced bacterial load and inflammation in PA-infected mice. Anti-reFlgE antibodies recognized native FlgE on the bacterial membrane in vitro and conferred protection in mice, which may be due to the mediation of opsonophagocytic killing and inhibition of bacterial motility. In addition, the combination of reFlgE with rePcrVNH, an engineered antigen we reported previously, provided elevated protection against PA infection. Our data demonstrate that FlgE is a promising vaccine candidate for PA and provide a new strategy for the efficient screening of antigens of other pathogens.

Lipopolysaccharide-induced DC-SIGN/TLR4 crosstalk activates NLRP3 inflammasomes via MyD88-independent signaling in gastric epithelial cells

Abnormal pattern recognition receptor (PRR) signaling plays an important role in gastric mucosal damage caused by stomach microbiota; however, the underlying molecular mechanisms remain obscure. Here, we show that DC-SIGN, a surface phenotype marker of dendritic cells, is overexpressed in gastric epithelial cells facing LPS stimulation. NLRP3 expression in gastric epithelial cells are significantly increased and related to the degree of LPS stimulation. Furthermore, DC-SIGN could interact with TLR4, promote NLRP3 and related genes expression via MyD88-independent signaling pathway and regulate the secretion of IL-1β and IL-18 in gastric epithelial cells. The results of flow cytometry analysis show that DC-SIGN primarily mediates Th1 differentiation when co-cultured with gastric epithelial cells. These results reveal that LPS-induced DC-SIGN expression modulates NLRP3 inflammasomes formation via MyD88-independent TLR4 signaling in gastric epithelial cell, and induces a Th1-predominant host immune response,these findings may indicate a new function of DC-SIGN in non-immune cells, and elucidate the diversity role of gastric epithelial cells in mechanism of immune damage caused by microbial flora.

Simultaneous Immunization with Omp25 and L7/L12 Provides Protection against Brucellosis in Mice.

Currently used Brucella vaccines, Brucella abortus strain 19 and RB51, comprises of live attenuated Brucella strains and prevent infection in animals. However, these vaccines pose potential risks to recipient animals such as attenuation reversal and virulence in susceptible hosts on administration. In this context, recombinant subunit vaccines emerge as a safe and competent alternative in combating the disease. In this study, we formulated a divalent recombinant vaccine consisting of Omp25 and L7/L12 of B. abortus and evaluated vaccine potential individually as well as in combination. Sera obtained from divalent vaccine (Omp25+L7/L12) immunized mice group exhibited enhanced IgG titers against both components and indicated specificity upon immunoblotting reiterating its authenticity. Further, the IgG1/IgG2a ratio obtained against each antigen predicted a predominant Th2 immune response in the Omp25+L7/L12 immunized mice group. Upon infection with virulent B. abortus 544, Omp25+L7/L12 infected mice exhibited superior Log10 protection compared to individual vaccines. Consequently, this study recommends that simultaneous immunization of Omp25 and L7/L12 as a divalent vaccine complements and triggers a Th2 mediated immune response in mice competent of providing protection against brucellosis.

A combined subunit vaccine comprising BP26, Omp25 and L7/L12 against brucellosis.

The current vaccines against brucellosis, namely Brucella abortus strains 19 and RB51, prevent infection in animals but pose potential risks like virulence and attenuation reversal. In this milieu, although subunit vaccination using a single potent immunogen of B. abortus, e.g. BP26 or Omp25 or L7/L12 etc., appears as a safer alternative, nonetheless it confers inadequate protection against the zoonosis compared to attenuated vaccines. Hence, we have investigated the prophylactic potential of a combined subunit vaccine (CSV) comprising the BP26, Omp25 and L7/L12 antigens of B. abortus, in mice model. Sera obtained from CSV immunized mice groups showed heightened IgG titers against all the three components and exhibited specificity upon immunoblotting, reiterating their authenticity. Further, the IgG1/IgG2a ratio obtained against each antigen revealed a predominant Th2 immune response in CSV immunized mice group. However, on assessing the levels of Th1-dependent (IFN-γ and TNF-α) and Th2-dependent (IL-4 and IL-10) cytokines in different formulations, prominent IFN-γ levels were elicited in CSV immunized mice. Further, upon infection with virulent B. abortus 544, the combined subunit vaccinated mice displayed superior degree of protection (Log10 reduction) than the individual vaccines; however, B. abortus S19 showed the highest protection. Altogether, this study suggests that co-immunization of three B. abortus immunogens as a CSV complements and triggers a mixed Th1/Th2 immune response leading to superior degree of protection against pathogenic B. abortus 544 infection.

The association between asthma and Kawasaki disease

Kawasaki disease (KD) is a systemic vasculitis and the most common cause of acquired heart disease among preschool-aged chil dren. Asthma is one of the most common chronic illness of childhood. There is increasing interest in the potential link between in flammatory diseases and allergic diseases, and there is increasing epidemiologic evidence for an association of KD and allergic dis ease. In regards to asthma, 9 studies have been reported about its association with KD; 5 of them showed positive associations be tween these 2 diseases, while 4 of them showed no association. There are some possible underlying mechanisms for this associa tion. The serum IgE levels are found to be increased and there is a Th2-predominant immune response in KD. These are common findings of asthma. Human leukocyte antigen-G/regT cells and SMAD3/transforming growth factor-beta might also be involved in the pathogenesis of both diseases. Asthma may increase susceptibility to KD and tends to lead to immune dysregulation. Clinician’s recognition of the increased risks of KD and other asthma-related comorbidities among patients with asthma may enable early identification and intervention. The early identification and management of comorbidities may ultimately reduce the economic and social burden of these chronic conditions. (Allergy Asthma Respir Dis 2019;7:173-178)

Molecular characterization of a putative serine protease from Trichinella spiralis and its elicited immune protection

In our previous work, a Trichinella spiralis putative serine protease (TsSP) was identified from ES products of T. spiralis intestinal infective larvae (IIL) and adult worms (AW) by immunoproteomics: it was highly expressed in IIL compared with muscle larvae (ML). In this study, the TsSP biological characteristics in larval invasion and growth were identified and its potential as a vaccine target against Trichinella infection were investigated. Expression of TsSP at various developmental phases (newborn larvae, ML, IIL, and AW) was detected by qPCR, immunofluorescent test and Western blotting. The rTsSP could specifically bind to the intestinal epithelial cell (IEC) membrane and enter into the cytoplasm. Anti-rTsSP serum suppressed the larval invasion of enterocytes in a dose-dependent mode, and killed newborn and ML of T. spiralis, decreased larval infectivity and development in the host by an ADCC-mediated mechanism. Immunization of mice with rTsSP produced a Th2 predominant immune response, and resulted in a 52.70% reduction of adult worms at 5 days post-infection (dpi) and a 52.10% reduction of muscle larvae at 42 dpi. The results revealed there was an interaction between TsSP and the host’s IEC; TsSP might be a pivotal protein for the invading, growing and parasiting of this nematode in the host. Vaccination of mice with rTsSP elicited immune protection, and TsSP is a potential target molecule for vaccines against enteral Trichinella infection.

Vaccination with Live Attenuated L. Major and TLR4 Agonist Promotes a Th1 Immune Response and Induces Protection against L. Major Infection in BALB/c Mice.

Toll like receptors play a major role in immune responses against Leishmania parasites. To evaluate the efficacy of vaccination with live attenuated L. major and TLR4 agonist in protection against L. major infection. Attenuated L. major was prepared by continuous sub-culturing of the parasite. A total of 90 mice were assigned to 9 groups including 6 groups of BALB/c (G1-6) and 3 groups (G7-9) of C57BL/6 mice. Group 1 was the control groups, group 2 received the wild-type L. major promastigotes, group 3 the attenuated line, group 4 the TLR4 agonist, group 5 the wild-type L. major and TLR4 agonist, and group 6 the attenuated line along with TLR4 agonist. Group 7 was control, group 8 received wild-type L. major and group 9 the wild-type along with TLR4 agonist. Vaccinated mice were then challenged with wild-type of L. major. Lesion size, parasite burden, and the expression levels of IL-4, IFN-γ, IL-2, 1L-17A, IL-10, TGF-β and TLR4 were evaluated before the challenge while parasite burden and lesion size were evaluated. Vaccinated mice with a TLR4 agonist or attenuated L. major plus TLR4 agonist produced the highest levels of IFN-γ, IL-2, and IL-17A. Post-challenge analysis revealed that mice vaccinated with the attenuated line along with TLR4 agonist displayed the lowest lesion size and parasite load. These mice developed a predominant Th1 immune response. Vaccination with the attenuated L. major along with TLR4 agonist promotes a Th1-mediated immune response which leads to the protection of BALB/c mice against L. major infection.

Cloning, expression and characterisation of a cysteine protease from Trichinella spiralis.

Cysteine protease is a superfamily of widespread proteolytic enzymes and plays a major role in larval invasion, migration, exsheathing, survival and immune evasion in parasites. In the present study, the gene coding cysteine proteinase of the nematode Trichinella spiralis (Owen, 1835) was cloned into pQE-80L and subsequently expressed in E. coli JM109. The rTsCP was purified and its antigenicity was identified by Western blot and ELISA. Using anti-rTsCP serum the native TsCP was identified in muscle larval crude proteins. The results of quantitative real-time PCR and immunofluorescence test demonstrated that the TsCP was expressed in all stages of T. spiralis and located mainly in cuticle, stichosome and reproductive organs. The immunisation of mice with rTsCP elicited Th2-predominant immune responses. Anti-rTsCP antibodies could partially inhibit the in vitro larval invasion of intestinal epithelial cells and kill the newborn larvae by an antibody-dependent cell-mediated dose-dependent cytotoxicity. The vaccinated mice exhibited a 54% reduction of adults and a 33% reduction of muscle larvae following challenge infection. The results suggested that the TsCP might be an indispensable protein in Trichinella invasion, development and survival of T. spiralis in hosts, and could be a potential vaccine target against infection.

T-Helper 1 Immune Response in Metastatic Lymph Nodes of Pancreatic Ductal Adenocarcinoma: A Marker For Prolonged Survival.

Although lymph node (LN) metastases is considered a grave prognostic sign in pancreatic ductal adenocarcinoma (PDAC), patients with positive lymph nodes (PLN) constitute a heterogeneous group. Our purpose was to identify morphological and immune parameters in the primary tumor and in PLN of resected PDAC patients, which could further stratify these patients to different subgroups. We retrospectively evaluated histological and immunohistochemical characteristics of 66 patients with PDAC who were operated at our institution. These were subsequently correlated to clinical outcome. Mean patient age and number of LN harvested was 65.5±10.3 and 12.3±6.5years, respectively. Tumor size (T stage) and perineural invasion had no effect on clinical outcome. High-grade tumor was associated with decreased survival [overall survival (OS)=19.6±2.7months for poorly differentiated PDAC vs. 31.2±4 for well and moderately differentiated, p=0.03]. Patients with ≥8 PLN had significantly worse outcome (OS=7.3±0.8months for PLN≥8 vs. OS=30.1±3.2months for PLN<8, p<0.0001). T helper (Th) 1 immune response was measured both by its effector cells (CD8+) and expression of its main transcription factor, T-bet. CD8+ high patients had significantly increased OS compared with CD8+ low (OS=36.8±5.3months for CD8+high vs. OS=24.3±3.5 for CD8+low, p=0.03) Similarly, Th1 predominant immune response measured by T-bet expression was associated with improved OS compared with non-Th1 (OS=32.8±3.2 vs. OS=19.5±2.9, p<0.0001). Our data indicate an association between Th1-type immune response and increased survival. Future research is needed to exploit Th1 immune response as a biological marker for immunotherapy.

Cloning and expression of a Trichinella spiralis putative glutathione S-transferase and its elicited protective immunity against challenge infections

BackgroundGlutathione-S-transferase (GST) is a widespread multigene family of detoxification enzymes. The vaccination of mice with recombinant GST of 24 kDa from Trichinella spiralis elicited a low immune protection against challenge infection. The objective of this study was to characterize the T. spiralis putative GST gene (TspGST) encoding a 30.8 kDa protein and to evaluate its potential as a candidate antigen for anti-Trichinella vaccine.MethodsThe full-length cDNA sequence of TspGST from T. spiralis muscle larvae (ML) was expressed in E. coli. The enzymatic activity and antigenicity of the rTspGST were identified by spectrophotometry, Western blot, and ELISA. The expression of TspGST at T. spiralis various stages was investigated by RT-PCR and indirect immunofluorescent test (IIFT). Serum level of total IgG, IgG1, and IgG2a antibodies against rTspGST were measured by ELISA. The immune protection produced by vaccination with rTspGST against T. spiralis was evaluated.ResultsThe sequencing results showed that the cDNA of TspGST was 840 bp, and encoded a protein of 279 amino acids, which had a molecular size of 30.8 kDa and a pI of 5.21. Its amino acid sequence shares 37% similarity with TsGST. The rTspGST protein had enzymatic activity of GST. On Western blot and ELISA analysis, the native TspGST protein with 30.8 kDa in crude antigens derived from adult worms (AW), newborn larvae (NBL), infective intestinal larvae (IIL) and ML was recognized by anti-rTspGST sera, but the ML ES antigens could be not recognized by anti-rTspGST sera. Expression of TspGST was found in all of T. spiralis various stages (AW, NBL, ML, and IIL). An immunolocalization analysis identified TspGST in different stages (mainly in cuticles) of the nematode. The mice vaccinated with the rTspGST elicited Th2-predominant immune responses, showed a 34.38% reduction of adult worms and a 43.70% reduction of muscle larvae.ConclusionsImmunization with rTspGST produced a partial immune protection, and the rTspGST could be regarded as a potential candidate target for an anti-Trichinella vaccine.

Immunogenicity and therapeutic effects of recombinant Ag85AB fusion protein vaccines in mice infected with Mycobacterium tuberculosis

The immune function of tuberculosis (TB) patients is disordered. By using immune regulators to assist chemotherapy for TB the curative effect might be improved. In this study, a vaccine containing Mycobacterium tuberculosis (M. tuberculosis) recombinant Ag85AB fusion protein (rAg85AB) was constructed and evaluated. The mice were immunized intramuscularly three times at two-week intervals with Ag85AB fusion protein combined with Corynebacterium parvum adjuvant (rAg85AB+CP). In comparison to control mice that received either CP alone or saline, the mice that received rAg85AB+CP had significantly higher number of T cells secreting IFN-γ and higher levels of specific antibodies of IgG, IgG1 and IgG2a isotypes in sera. The specific antibodies also had higher ratios of IgG2a to IgG1, indicating a predominant Th1 immune response. To test for immunotherapy of TB, M. tuberculosis infected mice were given three intramuscular doses of 20μg, 40μg or 60μg of rAg85AB in rAg85AB+CP, or phosphate-buffered saline (PBS), or CP or Mycobacterium phlei (M. Phlei) F.U.36. Compared with the PBS group, 20µg, 40µg and 60µg rAg85AB+CP and M. phlei F.U.36 groups reduced the pulmonary bacterial loads by 0.13, 0.15, 0.42 and 0.40 log10, and the liver bacterial loads by 0.64, 0.64, 0.53 and 0.61 log10, respectively. Pathological changes of lungs were less, and the lesions were limited to a certain extent in 40µg and 60µg rAg85AB+CP and M. phlei F.U.36 groups. These results showed that rAg85AB+CP had immunotherapeutic effect on TB, significantly increasing the cellular immune response, and inhibiting the growth of M. tuberculosis.

Analysis of clinical data and T helper 1/T helper 2 responses in patients with different clinical forms of leprosy.

Currently, there are no laboratory tests or sensitive and specific molecular markers for the early diagnosis of leprosy. The aim of this study was to analyze the clinical characteristics of patients with leprosy and investigate their immunological profile, comparing this with the type of lesion and the presence or absence of a Bacillus Calmette-Guérin (BCG) vaccination scar. Statistical analyzes were performed by employing comparative tests (Pearson´s chi-square) to evaluate the variables in different clinical forms, considering significance at the 5% level. The study identified a predominance of lepromatous leprosy (26.9%) in patients aged between 34-53 years. Caucasians predominantly had borderline tuberculoid (BT) clinical forms (42%); a predominance of males with borderline lepromatous (19%) and lepromatous leprosy (26.9%) forms was observed; and the presence of BCG vaccination scars (27.5%) and lower limb nerves were more affected (38%) predominantly in the BT clinical form. Significant differences were identified, which included hypochromic lesions predominantly in the BT clinical form (24%); diffuse-type lesions predominantly in the tuberculoid (TT) clinical form (28%); ill-defined lesion border dominance in lepromatous leprosy (LL) clinical forms (30%); an irregular lesion limit predominantly in LL clinical forms (32%); and a predominant Th1 immune response in the BT clinical form (41.7%). The evaluation of the immunological profile in leprosy patients may contribute to the more detailed diagnosis and possibly better characterization of the prognosis for these individuals.

Protective immune response in mice induced by a suicidal DNA vaccine encoding NTPase-II gene of Toxoplasma gondii

DNA-based alphaviral RNA replicon vectors, also called suicidal DNA vectors, have been employed to alleviate biosafety concerns attribution to its ability to induce apoptotic cell death of the transfected cells. Toxoplasma gondii nucleoside triphosphate hydrolase-II (TgNTPase-II), which facilitates the parasite to salvage purines from the host cell for survival and replication, have been demonstrated to be a potential vaccine candidate for toxoplasmosis. Herein, we evaluated the immunogenic potential of a suicidal DNA vaccine encoding TgNTPase-II gene, pDREP-TgNTPase-II, delivered intramuscularly in combination with electroporation. Immunization of mice with pDREP-TgNTPase-II elicited specific humoral responses, with high IgG antibody titers and a mixed IgG1/IgG2a response. The cellular immune response was associated with high level production of IFN-γ, IL-2, IL-10 cytokines and low level IL-4 production as well as the increase of the percentage of CD8+ T cells, indicating that a Th1 predominant response was elicited. Furthermore, mice vaccinated with this suicidal DNA vaccine displayed partial protection against acute infection with the virulent RH strain as well as chronic infection with PRU cyst, which shows 77.7% and 71.4% reduction in brain cyst burden in comparison to PBS and pDREP-eGFP control group, respectively. Based on the cellular and antibody responses, the suicidal DNA vaccine elicited a Th1-predominant immune response against T. gondii challenge.

Ag85B synergizes with ESAT-6 to induce efficient and long-term immunity of C57BL/6 mice primed with recombinant Bacille Calmette-Guerin.

The latest probable scenario in vaccination strategies is to prime one live attenuated vaccine candidate followed by boost dose of second vaccine candidate. In the present study, we primed the mice with a recombinant Bacille Calmette-Guerin (BCG) comprising Ag85B and ESAT-6 followed by boost doses of Ag85B, ESAT-6 and Ag85B-ESAT-6 fusion protein in the DDA adjuvant, separately. After boost doses of 8 and 12 weeks, the levels of antigen-stimulated T cells secreting interferon (IFN)-γ, the content of the IFN-γ, tumor necrosis factor-α and interleukin-4 in the splenocytes in vitro culture supernatant, the antigen-specific immunoglobulin (Ig)G titer from mouse serum, IgG subclass and the population of antigen-specific CD4+ and CD8+ T cells were detected. The present study showed that recombinant BCG along with boost doses of Ag85B or ESAT-6 individually did not induce efficient T-helper (Th) 1-type immune response. On the other hand, recombinant BCG with boost doses of Ag85B-ESAT-6 fusion protein enhanced longer lasting predominant Th1 immune response. This result suggested that Ag85B might synergize with ESAT-6 protein in order to produce better as well as effective immune response. Thus, the present study concluded recombinant BCG with boost doses of Ag85B-ESAT-6 fusion protein could be a good strategy to improve the immune protective efficacy.

Immunogenicity and Therapeutic Effects of pVAX1-rv1419 DNA from Mycobacterium tuberculosis

Background The situation of tuberculosis (TB) is very severe in China. New therapeutic agents and regimens to treat TB are urgently needed. Objective In this study, a DNA vaccine expressing Mycobacterium tuberculosis (MTB) Rv1419 antigen was constructed and its immunogenicity and therapeutic effects were evaluated. Method Normal mice and TB model mice were immunized intramuscularly three times at two-week intervals with saline, plasmid vector pVAX1, M. vaccae vaccine, pVAX1- ag85a (rv3804c) DNA or pVAX1-rv1419 DNA, respectively. Results At three weeks after the last immunization, flow cytometry showed a higher proportion of CD4+ T cells expressing IFN-y (Th1) in response to Rv1419 protein in blood from the pVAX1- rv1419 DNA group compared with the saline and vector groups (P<0.05), suggesting a predominant Th1 immune response. Live bacterial loads in lungs and spleens were lower by 0.41 log10 in the pVAX1- rv1419 DNA group than in the saline controls. In addition, pathological changes in the lungs of the DNA vaccinated groups were less. These results suggest that pVAX1- rv1419 DNA could be effective for the treatment of TB, significantly increasing the Th1-type cellular immune response, and inhibiting the growth of MTB. Conclusion Therefore pVAX1- rv1419 DNA is a candidate for inclusion in a therapeutic combination DNA vaccine against TB.