Infectious Disorders - Drug Targets (Formerly Current Drug Targets - Infectious Disorders) - Volume 14, Issue 1, 2014

Periodontal disease, is the most prevalent inflammatory affliction characterized by the loss of supporting structures of the teeth. Although bacteria are identified as prime agents initiating the disease, but major part of tissue destruction is driven by the host immune response to infecting agent and is responsible for the clinical presentation of the disease. Porphyromonas gingivalis (P. gingivalis) has been identified as main microbial factor for causation and progression of periodontal disease. Three emerging concepts of periodontal disease viz wide prevalence, polymicrobial nature and their role in perpetuation of systemic diseases bear critical significance on the development of novel therapeutic approaches to eradicate or alleviate the disease burden. Therefore, development of preventive approaches such as periodontal vaccine appears as an exciting modality which can prove as a significant adjunct to current periodontal therapies. The new generation diagnostics including microbial genome sequencing and bioinformatics analysis are available now to detect and analyze the whole genomic and proteomic data regarding almost all human pathogens for exploring these as novel drug targets for vaccine development. The current review, aims to provide an update of wide-ranging virulence factors of P. gingivalis as potential antigenic targets for periodontal vaccine developement.

Objectives: Investigation of osteoblastic responses to oxidative stress, induced by C-reactive protein (CRP) and IL-6 and ameliorating effects of doxycycline (Dox); using assays for 5-alpha dihydrotestosterone (DHT) as an antioxidant marker of healing. IL-6 and CRP are risk markers of periodontitis and prevalent comorbidities in periodontitis subjects. Methods: Confluent monolayer cultures of osteoblasts were incubated with radiolabelled testosterone (14C-T) as substrate, in the presence or absence (Control) of pre-determined optimal concentrations of CRP, IL-6, Dox; alone and in combination (n=8) for 24h in MEM. The eluent was solvent-extracted for steroid metabolites. They were separated using TLC in a benzene/ acetone solvent system 4:1 v/v; and quantified using radioisotope scanning. The identity of formed metabolites was confirmed using the mobility of cold standards added to the samples and disclosed in iodine. Further confirmation of the authenticity of DHT was carried out by combined gas chromatrography-mass spectrometry, after derivatization to pentafluorobenzyloxime trimethyl silyl ether. Results: The yields of DHT from 14C-testosterone showed 2-fold and 1.8-fold- inhibition in response to IL-6 and CRP respectively and 28% stimulation in response to Dox, via the 5-alpha reductase pathway. The combination of IL-6 + CRP showed a 2-fold reduction in the yields of DHT, elevated to control values when combined with Dox (n=8; p<0.001). Yields of 4-androstenedione showed an inverse relationship to those of DHT, in response to the agents tested, in keeping with the 17-beta hydroxysteroid dehydrogenase pathway. Conclusions: Inhibition of DHT synthesis in osteoblasts by IL-6 and CRP was overcome by doxycycline. Oxidative actions of IL-6 and CRP; and antioxidant actions of Dox are reinforced by the metabolic yields of DHT in response to agents tested. Using a novel metabolically active model allows closer extrapolation to in vivo conditions; in the context of adjunctive therapeutic applications for periodontitis and prevalent comorbidities.

Giardia lamblia mitosomes are believed to be vestigial mitochondria which lack a genome. Similar to higher eukaryotes, mitosomal proteins possess either N-terminal or internal mitosomal targeting sequences. To date, some components of the higher eukaryote archetypal mitochondrial protein import apparatus have been identified and characterized in Giardia mitosomes; therefore, it is expected that mitochondrial signals will be recognized by the mitosomal protein import system. To further determine the level of conservation of the Giardia mitosome protein import apparatus, we expressed mitochondrial proteins from higher eukaryotes in Giardia. These recombinant proteins include Tom20 and Tom22; two components of the mitochondrial protein import machinery. Our results indicate that N-terminal mitochondrial targeting sequence is recognized by the mitosomal protein import machinery; however, interestingly the internal mitochondrial targeting sequences of higher eukaryotes are not recognized by the mitosome. Our results indicate that Giardia mitosome protein transport machinery shows differential recognition of higher eukaryotic mitochondria transfer signals, suggesting a divergence of the transport system in G. lamblia. Therefore, our data support the hypothesis that the protein import machinery in Giardia lamblia mitosome is an incomplete vestigial derivative of mitochondria components.

Trypanosomatids parasites have complex life cycles which involve a wide diversity of milieus with very different physicochemical properties. Arginine kinase is one of the key enzymes, responsible for the parasites’ metabolic plasticity, which maintains the cell energy homeostasis during environment changes. Arginine kinase catalyzes the reversible phosphorylation between phosphoarginine and ADP. The phosphagen phosphoarginine sustains high levels of cellular activity until metabolic events, such as glycolysis and oxidative phosphorylation, are switched on. In different unicellular and multicellular organisms including trypanosomatids, it was demonstrated that arginine kinase is an important component in resistance mechanisms to different stress factors, such as reactive oxygen species, trypanocidal drugs, pH and starvation. In addition, few arginine kinase inhibitors were identified during the lasts years, some of them with trypanocidal activity, such as polyphenolic compounds. All these unique features, in addition to the fact that arginine kinase is completely absent in mammals, make this pathway a favorable start point for rational drug design for the treatment of human trypanosomamiases.

A novel coronavirus (MERS-CoV) related to SARS-CoV recently emerged in the Middle East causing more than 400 deaths with a mortality rate of about 30%, much higher than SARS-CoV. Both viruses target epithelial cells in the respiratory tract, although utilizing different cellular receptors. Because of the sporadic nature of the MERS outbreak and difficulty in collecting randomized, controlled clinical data, the objective of this review was to focus on published in vitro and in vivo drug sensitivity data using both cell lines and available animal models of SARS/MERS CoV infection. Determination of drug activity was based on achievable serum levels in humans relative to in vitro IC50 (50% inhibitory concentration) or EC50 (50% effective concentration) drug concentrations. The most active drugs against SARS/MERS CoV at clinically achievable serum levels were type I interferons and a TLR3 agonist, interferon inducer/activator.

This is a case series describing an outbreak of VRSA/VISA associated infections in orthopedic related procedures that occurred on a medical mission trip in Antigua, Guatemala. The paper describes the clinical features, microbiology and treatment options available to treat such infections in a Third World country. It also highlights the difficulty in making an accurate diagnosis with suboptimal microbiological support.

Viperidae snakes venoms represent a source of efficient bioactive components that have already led to the development of several new drugs. In this work, we analyzed the protein content of the Montivipera bornmuelleri crude venom using LC-ESI-MS, sephadex G-75 gel filtration and SDS-PAGE and demonstrated the presence of proteins with molecular masses corresponding to metalloprotease III, serine-protease and PLA2 in three fractions collected after gel filtration. Equally, we examined the antimicrobial effect of the venom that showed an important potency, as bactericidal agent, based on MBC and MIC values obtained, against Staphylococcus aureus and Morganella morganii bacteria. However, no activity was registered against Enterococcus faecalis, being the most resistant bacteria, neither against Aspergillus flavus and Penicillium digitatum fungal. Furthermore, on eleven other bacterial strains and the Candida albicans fungus, the venom has shown an intermediate efficacy by slightly reducing the growth. Our data concerning the Montivipera bornmuelleri venom give evidence of a rich and complex content aiding the exploration of new bioactive molecules for biopharmaceuticals purposes.

Leishmaniasis is a complex protozoan disease comprising a wide range of clinical manifestations that is usually divided into visceral leishmaniasis, cutaneous leishmaniasis, and muco-cutaneous leishmaniasis depending on leishmania parasite species and host's immune system responses. Most of the drugs produced for the treatment of leishmaniasis, from the first used to the most recently accepted, are toxic, resistance issues and poorly tolerated. The purpose of this study is to evaluate the effectiveness of saffron (Crocus sativus) and its apoptotic activity against Leishmania major (MRHO/IR/ 75/ER) promastigotes. MTT assay was used to find viability of L. major promastigotes and the achieved results were explicated as IC50 (50% inhibitory concentration). ED50 (50% effective doses) for L. major amastigotes were also analyzed. Annexin-V FLUOS staining was performed to study the cell death properties of saffron by using FACS analysis. Qualitative analysis of the DNA fragmentations was accomplished by agarose gel electrophoresis and light microscopy was used to observe morphological changes of promastigotes. Our results revealed that L. major promastigotes and amastigotes are sensitive to saffron at different concentrations and time dependent manner with apoptotic features including DNA laddering, cytoplasmic shrinkage, and externalization of phosphatidylserine. IC50 and ED50 of this extract after 48 h of incubation was 0.7mg/ml and 0.5 mg/ml respectively. Finally, C. sativus has shown anti-leishmanial activity against L. major promastigote and amastigote and may induce apoptosis.

Viral disease is a calamity which absolutely can not be ignored for human health. The emergence of drug resistance and spread of new virus will be the new challenge against viral disease. To find and develop new antivirus agents with properties of safety, significant effect and low toxicity is the pressing question facing humans today. Because of its advantages, including rich resources, low price, less adverse effect, Traditional Chinese medicine (TCM) have become the research focus in antiviral treatment. In recent years, there are numerous articles about the studies from separation of active ingredients to the antiviral mechanism. In this paper, the progress in experimental study was illustrated on the basis of active ingredients, species of virus, mechanism, clinical application. Obviously, TCM have obvious advantages in the treatment of virus infectious disease and has a broad prospect of application.