The synergic and addictive activity of biogenic silver nanoparticle associated with meropenem against carbapenem-resistant Acinetobacter baumannii.

AIMS: Antibiotic management of infections caused by Acinetobacter baumannii often fails due to antibiotic resistance (especially to carbapenems) and biofilm-forming strains. Thus, the objective here was to evaluate in vitro the antibacterial and antibiofilm activity of biogenic silver nanoparticle (Bio-AgNP) combined with meropenem, against multidrug-resistant isolates of A. baumannii. METHODS AND RESULTS: In this study, A. baumannii ATCC® 19606™ and four carbapenem-resistant A. baumannii (Ab) strains were used. The antibacterial activity of Bio-AgNP and meropenem was evaluated through broth microdilution. The effect of the Bio-AgNP association with meropenem was determined by the checkboard method. Also, the time-kill assay and the integrity of the bacterial cell membrane were evaluated. Furthermore, the antibiofilm activity of Bio-AgNP and meropenem alone and in combination was determined. Bio-AgNP has antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration ranging from 0.46 to 1.87 µg ml-1. The combination of Bio-AgNP and meropenem showed a synergistic and additive effect against Ab strains, and Bio-AgNP was able to reduce the MIC of meropenem from 4- to 8-fold. Considering the time-kill of the cell, meropenem and Bio-AgNP when used in combination reduced bacterial load to undetectable levels within 10 min to 24 h after treatment. Protein leakage was observed in all treatments evaluated. When combined, meropenem/Bio-AgNP presents biofilm inhibition for Ab2 isolate and ATCC® 19606™, with 21% and 19%, and disrupts the biofilm from 22% to 50%, respectively. The increase in nonviable cells in the biofilm can be observed after treatment with Bio-AgNP and meropenem in carbapenem-resistant A. baumannii strains. CONCLUSIONS: The combination of Bio-AgNP with meropenem can be a therapeutic option in the treatment of infections caused by carbapenem-resistant A. baumannii.

Challenges and Strategies for Developing Recombinant Vaccines against Leptospirosis: Role of Expression Platforms and Adjuvants in Achieving Protective Efficacy.

The first leptospiral recombinant vaccine was developed in the late 1990s. Since then, progress in the fields of reverse vaccinology (RV) and structural vaccinology (SV) has significantly improved the identification of novel surface-exposed and conserved vaccine targets. However, developing recombinant vaccines for leptospirosis faces various challenges, including selecting the ideal expression platform or delivery system, assessing immunogenicity, selecting adjuvants, establishing vaccine formulation, demonstrating protective efficacy against lethal disease in homologous challenge, achieving full renal clearance using experimental models, and reproducibility of protective efficacy against heterologous challenge. In this review, we highlight the role of the expression/delivery system employed in studies based on the well-known LipL32 and leptospiral immunoglobulin-like (Lig) proteins, as well as the choice of adjuvants, as key factors to achieving the best vaccine performance in terms of protective efficacy against lethal infection and induction of sterile immunity.

Reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay as a rapid molecular diagnostic tool for COVID-19 in healthcare workers.

In December 2019, the Chinese Center for Disease Control (CDC of China) reported an outbreak of pneumonia in the city of Wuhan (Hubei province, China) that haunted the world, resulting in a global pandemic. This outbreak was caused by a betacoronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Several of these cases have been observed in healthcare professionals working in hospitals and providing care on the pandemic's frontline. In the present study, nasopharyngeal swab samples of healthcare workers were used to assess the performance of the reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay and subsequently compared with the real-time reverse-transcription quantitative PCR (RT-qPCR) method. Thus, in this study, we validated a method for detecting SARS-CoV-2 based on RT-LAMP that can be used to diagnose these workers. The methodology used was based on analyzing the sensitivity, specificity, evaluation of the detection limit, and cross-reaction with other respiratory viruses. The agreement was estimated using a dispersion diagram designed using the Bland-Altman method. A total of 100 clinical specimens of nasopharyngeal swabs were collected from symptomatic and asymptomatic healthcare workers in Pelotas, Brazil, during the SARS-CoV-2 outbreak. RT-LAMP assay, it was possible to detect SARS-CoV-2 in 96.7% of the healthcare professionals tested using the E gene and N gene primers approximately and 100% for the gene of human ß-actin. The observed agreement was considered excellent for the primer set of the E and N genes (k = 0.957 and k = 0.896), respectively. The sensitivity of the RT-LAMP assay was positive for the primer set of the E gene, detected to approximately 2 copies per reaction. For the primer set of the N gene, the assay was possible to verify an LoD of approximately 253 copies per reaction. After executing the RT-LAMP assay, no positive reactions were observed for any of the virus respiratory tested. Therefore, we conclude that RT-LAMP is effective for rapid molecular diagnosis during the COVID-19 outbreak period in healthcare professionals.

Surveillance of invasive meningococcal disease in southern Brazil: considerations of an immunization programme.

Invasive meningococcal disease (IMD) is a major cause of meningitis and septicaemia worldwide. Changes in serogroup predominance contribute to the unpredictable nature of the disease, with significant health impact. This study aimed to determine the epidemiological profile of IMD in Rio Grande do Sul, Santa Catarina and Paraná, three states in southern Brazil. We analysed 1024 IMD cases that had been confirmed by clinical and/or laboratory criteria and reported to the national information system for notifiable diseases between 2015 and 2019. Additionally, we calculated the proportions of serogroup and incidence by age. Of 1024 cases, 562 (55 %) were caused by serogroup C. Furthermore, serogroup W was responsible for almost half of the cases among children younger than 5 years between 2017 and 2018, with an overall incidence of 1.5 cases/100 000 infants. IMD remains a significant healthcare issue in southern Brazil despite reduced serogroup C incidence after the introduction of the meningococcal C conjugate vaccine into the childhood immunization programme. Changes in disease epidemiology were observed, and serogroup W was the most common serogroup among children younger than 5 years in 2017 and 2018. Although future cost-effectiveness studies are necessary, our results could have future implications for meningococcal vaccination programmes.

Auxotrophic Mycobacterium bovis BCG: Updates and Perspectives.

Mycobacterium bovis BCG has been used for a century as the only licensed vaccine against tuberculosis. Owing to its strong adjuvant properties, BCG has also been employed as an oncological immunotherapeutic as well as a live vaccine vector against other pathogens. However, BCG vaccination has limited efficacy in protecting against adult forms of tuberculosis (TB), raises concerns about its safety in immunocompromised populations, compromises the diagnosis of TB through the tuberculin test and lacks predictability for successful antigen expression and immune responses to heterologous antigens. Together, these factors propelled the construction and evaluation of auxotrophic BCG strains. Auxotrophs of BCG have been developed from mutations in the genes required for their growth using different approaches and have shown the potential to provide a model to study M. tuberculosis, a more stable, safe, and effective alternative to BCG and a vector for the development of recombinant live vaccines, especially against HIV infection. In this review, we provide an overview of the strategies for developing and using the auxotrophic BCG strains in different scenarios.

Development of Human Recombinant Leptospirosis Vaccines.

Leptospirosis is a bacterial zoonotic disease with significant impact on health all over the world. Currently, bacterins are the only vaccines available for prevention of this disease, despite several drawbacks. In an effort to develop a more effective vaccine against leptospirosis, reverse and structural vaccinology have been applied to design recombinant constructions composed of leptospiral surface-exposed antigens. Herein, we describe a protocol for design and development of Leptospirosis recombinant vaccines using immunoinformatic approaches.

Surveillance of invasive meningococcal disease in the south of Brazil: considerations of immunization programme.

Invasive meningococcal disease (IMD) is a major cause of meningitis and septicaemia worldwide. The switches in serogroup predominance contribute to the unpredictable nature of the disease with significant health impacts. The aim of this study was to determine the epidemiological profile of IMD in Rio Grande do Sul, Santa Catarina and Paraná, three states in the south of Brazil. All meningitis cases confirmed by clinical and/or laboratory criteria notified to the national information system for notifiable diseases between 2015 and 2019 were analysed. Proportions of serogroup and incidence by age were calculated. A total of 17 894 cases of IMD were reported during this period. Of these, 9029 cases (50 %) were due to serogroup C. Furthermore, serogroup W was responsible for almost half of the cases among children younger than 5 years old during 2017 and 2018, with an overall incidence of 33.3 cases per 100 000 infants. Despite the reduction in serogroup C after the introduction of meningococcal C conjugate vaccine into a childhood immunization programme in Brazil, it remains a significant healthcare issue in the south of the country. Changes in disease epidemiology were observed and serogroup W was the most common among children below 5 years of age in 2017 and 2018. Although future cost-effectiveness studies are necessary, our results could have future implications for meningococcal vaccination programmes.

Protection against leptospirosis conferred by Mycobacterium bovis BCG expressing antigens from Leptospira interrogans.

Leptospirosis is a zoonotic disease worldwide and caused by the pathogenic spirochetes of the genus Leptospira. Bacterins make up the vaccines used against leptospirosis, but they only succeed in providing short-term and serovar-specific protection. The use of Mycobacterium bovis BCG as a live vaccine vector expressing leptospiral antigens is a promising alternative, particularly due to its adjuvant properties. Four distinct portions P1 (lipL32), P2 (ligAni), P3 (lemA:ligAni) and P4 (lipL32:lemA) of a recombinant chimera composed of the lipL32, lemA and ligANI genes from Leptospira interrogans were cloned individually according to the BioBricks® strategy in the plasmid pUP500/PpAN. These constructs were individually transformed into a BCG Pasteur strain, and protein expression was detected by Western blot. For vaccination, 5 groups of 10 Golden Syrian hamsters were used, aged 4-6 weeks - group 1, rBCG (LipL32); group 2, rBCG (LigAni); group 3, rBCG (LemA:LigAni); group 4, (LipL32:LemA); group 5, wild-type BCG Pasteur (negative control). Two doses containing 106 CFU of rBCG were administered subcutaneously, the challenge was performed with 5 × LD50 of Leptospira interrogans serovar Copenhageni L1-130, and the animals were observed for a 30-day period until the endpoint was reached. Humoral immunity was assessed via indirect ELISA, while renal colonisation was assessed by culture and quantitative real-time PCR. All vaccinated groups were protected against lethal challenge and renal colonisation, in comparison with negative control group (P < 0.05). Recombinant vaccines were not effective at inducing significant humoral immunity, which suggests the induction of cellular immunity - a characteristic of M. bovis BCG. In conclusion, all formulations provide 100% significant protection against leptospirosis in hamsters with no renal colonisation. The use of rBCG as a vaccine vector represents a promising alternative for the control of animal leptospirosis, allowing for protection against clinical signs of leptospirosis and renal colonisation.

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.

Tetra-cationic platinum(II) porphyrins like a candidate photosensitizers to bind, selective and drug delivery for metastatic melanoma.

Photodynamic therapy (PDT) is an expanding treatment modality due to its minimally invasive localized activity and few adverse effects. This therapy requires photosensitive compounds, which have high sensitivity to light exposure. Thus, in this work, the in vitro antitumor activity of meso-tetra(3- and 4-pyridyl)porphyrins (3-TPyP and 4-TPyP) in metastatic melanoma cell (WM1366 line) and non-tumoral Ovarian lineage Chinese Hamister (CHO) was evaluated using photodynamic process. Cell viability tests, molecular docking, annexin V, confocal microscopy and qRT-PCR were performed. Our results show that both porphyrins inhibited the viability of metastatic melanoma cells when exposed to light and did not alter viability in the dark. In addition, they did not demonstrate cytotoxicity in non-tumor cells. Molecular coupling demonstrated platinum porphyrin affinity for the N-terminal region of APO B-100, LDL receptor, and therefore of the cells under study. Genes such as Caspase 3 and 9, P21, Bax / BCL2, MnSod and GSH showed increased expression. For meta isomer 3-PtTPyP treatment, caspase-9 and caspase-3 expression levels showed a 4.89 and 3.23-fold increase, respectively, while for the para isomer 4-PtTPyP, this change was 3.77 and 12.16-fold, respectively. We also observed an upregulated expression of p21, a protein well-known by its action in cell cycle arrest in a p53-dependent manner. Conclusion: 3-PtTPyP and 4-PtTPyP demonstrated antitumor effect on WM1366 cells, inducing apoptosis and significant alteration of cell cytoskeleton actin. Our work shows that platinum(II) porphyrins may be promising photosensitizers for the treatment of metastatic melanoma by PDT.

7-Chloroquinoline-1,2,3-triazoyl carboxamides induce cell cycle arrest and apoptosis in human bladder carcinoma cells.

In the present study, the antitumoral properties of a series of 7-chloroquinoline-1,2,3-triazoyl-carboxamides (QTCA) were investigated by analyzing their cytotoxic activities against human bladder cells (5637; grade II carcinoma). In addition, their effects on cell viability, cell cycle arrest mechanisms, apoptosis induction, in silico molecular docking, and detection of pro-apoptotic and anti-apoptotic proteins were evaluated. The cytotoxicity assay identified major dose- and time-dependent cytotoxic effects in 5637 cells after they were exposed to treatment with QTCA, only minimal effects were observed on normal cells. A live/dead assay confirmed that significant cell death, arrest in the G0/G1 phase and apoptosis were associated with treatment by 1-(7-Chloroquinolin-4-yl)-5-methyl-N-phenyl-1H-1,2,3-triazole-4-carboxamide (QTCA-1) and 1-(7-Chloroquinolin-4-yl)-N-(4-fluorophenyl)-5-methyl-1H-1,2,3-triazole-4-carboxamide (QTCA-4). The in silico results indicated that these compounds acted through different mechanisms for the induction of cell cycle arrest and apoptosis. Western blotting confirmed the binding of the QTCAs to pro- and anti-apoptotic proteins. In conclusion, QTCA-1 and QTCA-4 are promising candidates for inducing cytotoxicity, cell cycle arrest, and apoptosis in human bladder cancer cells.

A standardized BioBrick toolbox for the assembly of sequences in mycobacteria.

For more than 25 years, recombinant Mycobacterium bovis BCG has been genetically engineered for use as a vehicle for antigen expression and immunomodulation, typically through introducing or deleting a gene from BCG genome. However, BCG transformation efficacy is still unpredictable, and cloning and expression of sequences from mycobacteria is difficult to predict due to the lack of standardization. To overcome such limitations, we have employed the BioBrick format to construct a toolbox of several mycobacterial parts, including coding sequences, reporter genes, selective markers, promoters, and other regulatory sequences. Additionally, we have developed and characterized BioBrick-compatible episomal vectors that are able to replicate in M. bovis BCG to enable expression of heterologous antigens. The availability of a BCG Biobrick toolbox will enable any coding sequence to be optimally expressed in BCG. We believe that this mycobacterial toolbox represents a standardized and useful kit to enhance the efficacy and use of recombinant BCG.

Mycobacterium bovis BCG in metastatic melanoma therapy.

Melanoma is the most aggressive form of skin cancer, with a high mortality rate and with 96,480 new cases expected in 2019 in the USS. BRAFV600E, the most common driver mutation, is found in around 50% of melanomas, contributing to tumor growth, angiogenesis, and metastatic progression. Dacarbazine (DTIC), an alkylate agent, was the first chemotherapeutic agent approved by the US Food and Drug Administration (FDA) used as a standard treatment. Since then, immunotherapies have been approved for metastatic melanoma (MM) including ipilimumab and pembrolizumab checkpoint inhibitors that help decrease the risk of progression. Moreover, Mycobacterium bovis Bacillus Calmette-Guerin (BCG) serves as an adjuvant therapy that induces the recruitment of natural killer NK, CD4+, and CD8+ T cells and contributes to antitumor immunity. BCG can be administered in combination with chemotherapeutic and immunotherapeutic agents and can be genetically manipulated to produce recombinant BCG (rBCG) strains that express heterologous proteins or overexpress immunogenic proteins, increasing the immune response and improving patient survival. In this review, we highlight several studies utilizing rBCG immunotherapy for MM in combination with other therapeutic agents.

The Melding of Drug Screening Platforms for Melanoma.

The global incidence of cancer is rising rapidly and continues to be one of the leading causes of death in the world. Melanoma deserves special attention since it represents one of the fastest growing types of cancer, with advanced metastatic forms presenting high mortality rates due to the development of drug resistance. The aim of this review is to evaluate how the screening of drugs and compounds for melanoma has been performed over the last seven decades. Thus, we performed literature searches to identify melanoma drug screening methods commonly used by research groups during this timeframe. In vitro and in vivo tests are essential for the development of new drugs; however, incorporation of in silico analyses increases the possibility of finding more suitable candidates for subsequent tests. In silico techniques, such as molecular docking, represent an important and necessary first step in the screening process. However, these techniques have not been widely used by research groups to date. Our research has shown that the vast majority of research groups still perform in vitro and in vivo tests, with emphasis on the use of in vitro enzymatic tests on melanoma cell lines such as SKMEL and in vivo tests using the B16 mouse model. We believe that the union of these three approaches (in silico, in vitro, and in vivo) is essential for improving the discovery and development of new molecules with potential antimelanoma action. This workflow would provide greater confidence and safety for preclinical trials, which will translate to more successful clinical trials and improve the translatability of new melanoma treatments into clinical practice while minimizing the unnecessary use of laboratory animals under the principles of the 3R's.

The use of ErpY-like recombinant protein from Leptospira interrogans in the development of an immunodiagnostic test for swine leptospirosis.

Swine leptospirosis poses a major problem in the agricultural sector. The gold standard for serodiagnosis of leptospirosis is Microscopic Agglutination Test (MAT). However, the limitations of this technique make the search for alternative diagnostic methods inevitable. In the present study, ErpY-like recombinant protein (rErpY-like), produced in Escherichia coli and used as antigen in indirect enzyme-linked immunosorbent assay (ELISA), was evaluated for its efficacy as a novel diagnostic tool for swine leptospirosis. For the study, 72 samples of swine sera characterized by microscopic agglutination test (MAT), were evaluated by indirect ELISA. The sensitivity, specificity and accuracy values obtained from the analysis were 96.8%, 100%, and 99%, respectively, thereby suggesting that rErpY-like ELISA being a sensitive and specific method for antibodies detection in swine populations could be used as an alternative for diagnosis of swine leptospirosis.

Recombinant BCG strains expressing chimeric proteins derived from Leptospira protect hamsters against leptospirosis.

Leptospirosis is a zoonosis that is responsible for one million human cases per year. Fusing multiple immunogenic antigens represents a promising approach to delivering an effective vaccine against leptospirosis. Mycobacterium bovis bacillus Calmette-Guérin (BCG) is a potential vaccine vector due to its adjuvant properties and safety. Two chimeric genes based on genic sequences of ligANI, ligBrep, lipL32, and lemA, were individually cloned into five BioBrick vectors with different promoters (pAN, Hsp60, 18 kDa, Ag85B and Ag85B plus signal sequence) for antigen expression in BCG. Groups of ten hamsters were vaccinated with recombinant BCG (rBCG) strains in two doses of 106 CFU and challenged with 5 × LD50 of L. interrogans serovar Copenhageni. All rBCG vaccines expressing chimera 1, based on antigens LipL32, LigANI, and LemA, under the control of any promoter, protected 80-100% of the hamsters from challenge (P < 0.05) and four of them also protected from renal carrier status; for chimera 2, based on LigANI and LigBrep antigens, the only vaccine that afforded survival rates statistically different from the control was the vaccine that incorporated the pAN promoter (60% of survival). A single vaccine dose was sufficient to induce significant IgG levels by all vaccine compositions evaluated; however, humoral response was not related to protection. These findings suggest that the combination of potential vaccine candidates in chimeric antigens and the use of BCG as a live vector are promising strategies by which it is possible to obtain an effective and sterilizing vaccine against leptospirosis.

Revitalizing the AZT Through of the Selenium: An Approach in Human Triple Negative Breast Cancer Cell Line.

Triple-negative breast cancer represents about 15% of all cases of breast cancer, and still represents a therapeutic challenge. 3'-Azido-3'-deoxythymidine (AZT) is a nucleoside reverse transcriptase inhibitor with antitumor activity. Chalcogenides compounds, such as selenium, are very important intermediates applied in organic synthesis. Our objective was to investigate the effect and the underlying cell death mechanisms of AZT and its derivatives, in human breast cancer cell lines. The inhibitory effect of AZT and derivatives (1072, 1073, and 1079) was determined by MTT assay (0.1, 1, 10, 50, and 100 µM for concentrations and times 4, 24, 48, and 72 h) and Live/Dead in tumor cell lines MCF-7, MDA-MB 231 and also in non-tumor cell line CHO. Gene expression profiles related to apoptosis were investigated by qRT-PCR and induction of apoptosis was investigated by flow cytometry. MTT and Live/Dead assays showed that AZT derivatives decreased the rate of cell proliferation at concentrations of 50 and 100 µM in tumor cell lines MCF-7 and MDA-MB 231 while the commercial AZT presented a low antitumoral potential in all strains tested. In flow cytometry analysis we demonstrated that derivatives of AZT induced apoptosis, with an increase in both initial and late stages in both tumor cell lines evaluated, especially in MDA-MB 231. Our data show that the AZT derivative 1072 increased the expression of transcripts of the genes caspase 3 and 8 in MDA-MB 231 cell line when compared to control, suggesting that the extrinsic pathway of apoptosis was activated. In conclusion, derivatives of AZT, especially 1072, induce cytotoxicity in vitro in the triple negative breast cancer cell line through activation of the extrinsic pathway of apoptosis. These compounds containing selenium in its formulation are potential therapeutic agents for breast cancer.

LemA and Erp Y-like recombinant proteins from Leptospira interrogans protect hamsters from challenge using AddaVax™ as adjuvant.

BACKGROUND: Recombinant subunit vaccines have been extensively evaluated as promising alternatives against leptospirosis. Here, we evaluated two proteins in formulations containing the adjuvant AddaVax™ as vaccine candidates for prevention and control of leptospirosis. METHODS: Recombinant proteins rErp Y-like and rLemA were characterized by ELISA to assess their ability to bind extracellular matrix (ECM) components and fibrinogen. Groups of eight hamsters were immunized intramuscularly with rErp Y-like or rLemA mixed with a squalene-based adjuvant (AddaVax), and then vaccine efficacy was determined in terms of protection against a lethal challenge. The humoral immune response was determined by ELISA, and the evidence of sub-lethal infection was evaluated by histopathology and kidney culture. RESULTS: rLemA protein binds laminin, fibrinogen, and collagen type IV, while rErp Y-like interacts with fibrinogen. Significant protection was achieved for rLemA and rErp Y-like vaccines, which showed 87.5% and 62.5% survivals, respectively. On day 28, the humoral immune response was significantly greater in the vaccine groups as compared to that in the control group, and the response was predominantly based on IgG2/3. The surviving animals showed negative results in culture isolation but presented with tissue lesions in the lungs and kidneys. CONCLUSION: Cumulatively, our findings suggest that LemA and Erp Y-like proteins act as adhesins and are able to protect against mortality, but not against tissue lesions. Moreover, AddaVax is a novel adjuvant with potential for improving the immunogenicity of leptospiral vaccines.

DNA vaccines against leptospirosis: A literature review.

Leptospirosis is an infectious disease caused by pathogenic Leptospira species. The vaccines that are currently available for leptospirosis are composed of whole-cell preparations and suffer from limitations such as low efficacy, multiple side-effects, poor immunological memory and lack of cross-protection against different serovars of Leptospira spp. In light of the global prevalence of this disease, the development of a more effective vaccine against leptospirosis is of paramount importance. Genetic immunization is a promising alternative to conventional vaccine development. In the last 25years, several novel strategies have been developed for increasing the efficacy of DNA vaccines. Examples of such strategies include the introduction of novel plasmid vectors, adjuvants, alternate delivery routes, and prime-boost regimens. Herein we discuss the latest and most promising advances that have been made in developing DNA vaccines against leptospirosis. We also deliberate over the future directions that must be undertaken in order to improve results in this field.

Recombinant BCG vaccines: molecular features and their influence in the expression of foreign genes.

Recombinant Mycobacterium bovis BCG vaccines (rBCG) were first developed in the 1990s as a means of expressing antigens from multiple pathogens. This review examines the key structural factors of recombinant M. bovis that influence the expression of the heterologous antigens and the generation of genetic and functional stability in rBCG, which are crucial for inducing strong and lasting immune responses. The fundamental aim of this paper is to provide an overview of factors that affect the expression of recombinant proteins in BCG and the generation of the immune response against the target antigens, including mycobacterial promoters, location of foreign antigens, and stability of the vectors. The reporter systems that have been employed for evaluation of these molecular features in BCG are also reviewed here.