Antimicrobial peptide from spider venom inhibits Chlamydia trachomatis infection at an early stage.

Antichlamydial activity of cyto-insectotoxin 1a (CIT 1a), representative of a unique class of antimicrobial peptides from the venom of the Central Asian spider Lachesana tarabaevi, was studied. A plasmid vector expressing the cit 1a gene controlled by a human cytomegalovirus tetracycline-dependent promoter was constructed. Impressive inhibition of Chlamydia trachomatis infection in HEK 293 cells transfected by the cit 1a-harboring vector was achieved. With the use of various schemes of cell infection and gene expression induction, it was shown for the first time that an antimicrobial peptide exerts its potent antichlamydial action at an early stage of the pathogen life cycle.

Cyto-Insectotoxin 1a from Lachesana tarabaevi Spider Venom Inhibits Chlamydia trachomatis Infection.

Venom of the ant spider Lachesana tarabaevi contains a wide variety of antimicrobial peptides. Among them, a special place belongs to cyto-insectotoxins, a class of cytolytic molecules showing equally potent antimicrobial and insecticidal effects. We tested one of them, CIT 1a, for ability to suppress Chlamydia trachomatis infection. HEK293 cells were transfected with plasmid vectors harboring the cit 1a gene. Controlled expression of the transgene led to a significant decrease in C. trachomatis viability inside the infected cells. Using proteomic and transcriptomic approaches, we found alterations in protein expression patterns and identified differentially expressed genes in transfected cells.

Spider venom peptides for gene therapy of Chlamydia infection.

Spider venoms are vast natural pharmacopoeias selected by evolution. The venom of the ant spider Lachesana tarabaevi contains a wide variety of antimicrobial peptides. We tested six of them (latarcins 1, 2a, 3a, 4b, 5, and cytoinsectotoxin 1a) for their ability to suppress Chlamydia trachomatis infection. HEK293 cells were transfected with plasmid vectors harboring the genes of the selected peptides. Controlled expression of the transgenes led to a significant decrease of C. trachomatis viability inside the infected cells.

The role of intracellular glutathione in the progression of Chlamydia trachomatis infection.

The productive internalization in the host cell of Chlamydia trachomatis elementary bodies and their infectivity depends on the degree of reduction of disulfide bonds in the outer envelope of the elementary body. We have hypothesized that the reducing agent may be intracellular glutathione (GSH). Three approaches were used to modulate the intracellular GSH concentration: (1) treatment of cells with buthionine sulfoximine, which causes irreversible inhibition of GSH biosynthesis; (2) hydrogen peroxide-induced oxidation of GSH by intracellular glutathione peroxidases; and (3) treatment of cells with N-acetyl-l-cysteine (NAC), a precursor of glutathione. In the first two cases, we observed a four- to sixfold inhibition of C. trachomatis infection, whereas in NAC-treated cells we detected an increase in the size of chlamydial inclusions. Using a proteomics approach, we showed that the inhibition of chlamydial infection does not combine with alterations in protein expression patterns after cell treatment. These results suggest that GSH plays a key role in the reduction of disulfide bonds in the C. trachomatis outer envelope at an initial stage of the infection.

Comparative evaluation of new typing schemes for urogenital Chlamydia trachomatis isolates.

Thirty urogenital Chlamydia trachomatis isolates collected in Moscow in 2005 were typed using newly developed molecular typing approaches: (1) multilocus sequence typing (MLST(7)) based on sequences of seven housekeeping genes (http://pubmlst.org/chlamydiales/), (2) MLST(5) based on the investigation of five target regions of the chlamydial genome and (3) ompA gene sequencing supplemented with three variable number tandem repeat (VNTR) loci of the genome. ompA typing divided all isolates into 11 groups with E serotype dominating, while MLST7, MLST5 and VNTR analysis divided them into eight, 20 and 18 groups, respectively. The discriminatory power of each method calculated using the Hunter-Gaston discriminatory index was found to be 0.83 for the ompA typing scheme, 0.82 for MLST(7) and 0.95 for MLST(5). A novel sequence type combining 13% of all strains was discovered, as well as new alleles of genes. This is the first study characterizing the genetic diversity of the urogenital C. trachomatis population in Central Russia using MLST. We conclude that the MLST(7) scheme is the best possible choice for global epidemiological purposes, whereas MLST(5) is more appropriate for tracing local outbreaks.

Induced expression of the antimicrobial peptide melittin inhibits experimental infection by Mycoplasma gallisepticum in chickens.

The in vivo action of the antimicrobial peptide melittin, expressed from a recombinant plasmid vector, on chickens experimentally infected with Mycoplasma gallisepticum was studied. The plasmid vector pBI/mel2/rtTA includes the melittin gene under the control of an inducible tetracycline-dependent human cytomegalovirus promoter and the gene coding for the trans-activation protein rtTA. Aerosol administration of the vector, followed by infecting the chickens with M. gallisepticum 1226, is shown to inhibit development of infection. The inhibitory action was confirmed by a complex of clinical, pathomorphological, histological and serological studies, and also by comparing the M. gallisepticum reisolation frequency from the respiratory tract and internal organs. The data suggest that plasmid vectors expressing genes of antimicrobial peptides can be considered as potential agents for the prevention and treatment of mycoplasma infections in poultry farming.