McCoy Cells Research Articles

Diagnosis of Chlamydia abortus by Isolation in Cell Culture and Real Time PCR in Aborted Sheep and Goats

Background: Ovine enzootic abortion (OEA) caused by Chlamyidia abortus is one of the most important abortive disease in small ruminants. Diagnosis of Ovine enzootic abortion depends on the isolation and detection of the agent or its nucleic acid. The aim of the present study was to detect Chlamydia abortus using both isolation method and real-time PCR in Brucella free flocks in Iran. Methods: Twenty-eight vaginal and conjunctival swab samples which were Chlamydia abortus seropositive, were selected from ewes and does with recent abortion. Then the samples were tested by real-time PCR and positive molecular samples were inoculated into McCoy cells. Results: Using real-time PCR, 18 samples (64.3%) were positive and 7 (25%) of them were isolated in cell culture. Conclusion: The present results indicate that Chlamydia can play a relatively significant role in the abortion in does and ewes in Iran. Although the isolation of Chlamydia abortus have 100% specificity, because of low sensitivity, time consuming, cost and high probability of contamination, it is not suitable for routine laboratory diagnosis. Therefore, applying real-time PCR which have high sensitivity and specificity is recommended.

A Distinct Genotype, D/Ep6, Detected in Korean Female Patients: Chlamydia trachomatis Characterization from 2017 - 2018.

The objective of this study lies in identifying the dominant genotype of C. trachomatis isolated in Republic of Korea (ROK) between 2017 and 2018. A total of 504 clinical cervicovaginal swabs from patients were collected and inoculated on McCoy cell monolayers to isolate Chlamydial agents. C. trachomatis isolates were analyzed by sequencing of its ompA gene. A total of 54 C. trachomatis isolates were obtained. The constructed phylogenetic tree revealed the genotypes of isolates are D/Ep6 (48, 88.89%), D/Ep6-like (5, 9.26%), and Ja (1, 1.85%). The C. trachomatis D/Ep6-like have one single nucleotide polymorphism (SNP) compared to C. trachomatis D/Ep6, leading to E870K amino acid change. Phylogenetic analysis demonstrated globally rare C. trachomatis D/Ep6 was dominant in the ROK from 2017 to 2018. Findings in this study act as a keystone, bridging past and present molecular epidemiology of C. trachomatis in context of ROK.

Enzyme Fueled Dissipative Self-assembly of Guanine Functionalized Molecules and Their Cellular Behaviour.

Generally, an esterase lipase enzyme can hydrolyze specific substrates called esters in an aqueous solution. Herein, we investigate how a G-quadruplex self-assembly affects the hydrolysis equilibrium in reverse. The biocatalyst, lipase, activates the individual building-blocks through fuel consumption, causing them to undergo a higher degree of self-organization into nanofibers within spheres. We have synthesized five peptide-lipid-conjugated guanine base functionalized molecules to explore how the equilibrium can be shifted through reverse hydrolysis. Among these, NAC5 self-assembled into a G-quadruplex structure which has been confirmed by various spectroscopic techniques. The wide-angle powder XRD, ThT dye binding assay and circular dichroism study is carried out to support the presence of the G-quadruplex structure. The biocatalytic formation of nanofibers enclosed spheres is analyzed using CLSM, FE-SEM and HR-TEM experiments. Additionally, we assess the biocompatibility of the enzyme fueled dissipative self-assembled fibers enclosed spheres, as they have potential applications as a biomaterial in protocells. MTT assay is performed to check the cytotoxicity of G-quadruplex hydrogel, using HEK 293 and McCoy cell lines for viability assessment. Finally, the utility of the novel NAC5 hydrogel as a wound repairing biomaterial is demonstrated by cell migration experiment in a scratch assay.

Modulation of Inflammation in McCoy Cells by Zinc Nanoparticles Conjugated With β-Chitosan.

This study investigated biosynthetically derived β-chitosan-derived zinc nanoparticles (β-Ch-Zn NPs) for their potential anti-inflammatory properties on McCoy cells.β-Ch-Zn NPs were synthesized usinga green chemistry approach, and their characterization confirmed successful synthesis, appropriate size, and morphology. The study aimed to evaluate the cytotoxicity ofβ-Ch-Zn NPs and their effects on inflammatory responses in McCoy cells stimulated with lipopolysaccharide (LPS). β-Ch-Zn NPs were synthesizedand characterized using Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis) spectroscopy, and X-ray diffraction (XRD) to confirm their structural and morphological properties. The cytotoxicity ofβ-Ch-Zn NPs was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay at various concentrations to determine safe doses for subsequent experiments. To induce inflammation, McCoy cells were pretreated with β-Ch-Zn NPs at different concentrations before LPS stimulations. Gene expression analysis using quantitative real-time polymerase chain reaction was performed to measure the messenger RNA (mRNA) levels of proinflammatory cytokine. FTIR, UV-Vis spectroscopy, and XRD confirmed the successful synthesis ofβ-Ch-Zn NPs with the desired size and morphology. The MTT assay demonstrated concentration-dependent cytotoxicity of β-Ch-Zn NPs, indicating safety for cellular studies. Pretreatment withβ-Ch-Zn NPs significantly downregulated the mRNA expression of proinflammatory cytokines. The nanoparticles effectively downregulate proinflammatory cytokines and promote anti-inflammatory pathways, as evidenced by the significant reduction in interleukin (IL)-2, IL-6, hypoxia-inducible factor, and nuclear factor kappa B expression in a dose-dependent manner. This study demonstrated that biosynthetically derivedβ-Ch-Zn NPs exhibit potent anti-inflammatory effects in McCoy cells. These findings underscore the therapeutic potential ofβ-Ch-Zn NPs for treating inflammatory conditions and support further investigation into their in vivo efficacy and safety.

Development of a lambda Red based system for gene deletion in Chlamydia.

The ability to efficiently target loci in the Chlamydia trachomatis genome for deletion remains a desirable goal in the field and new strategies need to be developed and refined. Here we describe the development and application of a lambda red recombineering system for Chlamydia. Using a non-replicative plasmid encoding key lambda Red components and targeting sequences, we demonstrate the efficient deletion of numerous gene targets in the model chlamydial strains C. trachomatis L2/434 and C. muridarum. For initial development of the system, we targeted the incA gene of C. trachomatis for deletion. Deletion mutants containing a chloramphenicol resistance marker were recovered within 3 rounds of selection, or 2 rounds of passaging, in McCoy cells and the resulting clones (CTΔincA) were verified by PCR-based genotyping and whole genome sequencing. Phenotypic assessment of host cells infected with CTΔincA was performed by immunofluorescence microscopy and confirmed the lack of IncA expression and the uniform presence of nonfusogenic vacuoles (inclusions) across CTΔincA-infected monolayers. To explore the utility of this system, we deleted 5 additional candidate virulence factors in C. trachomatis and C. muridarum, including deletions of single and multiple genes. We expect lambda Red recombineering to offer a powerful new strategy for making gene deletion and/or replacement mutants in Chlamydia.

Design and synthesis of a nucleobase functionalized peptide hydrogel: in vitro assessment of anti-inflammatory and wound healing effects.

Over the past several years, a significant increase in the expanding field of biomaterial sciences has been observed due to the development of biocompatible materials based on peptide derivatives that have intrinsic therapeutic potential. In this report, we synthesized nucleobase functionalized peptide derivatives (NPs). Hydrogelation in the synthesized NPs was induced by increasing their hydrophobicity with an aromatic moiety. The aggregation behavior of the NPs was analyzed by performing molecular dynamics simulations and DOSY NMR experiments. We performed circular dichroism (CD), thioflavin-T binding and PXRD to characterize the supramolecular aggregation in the NP1 hydrogel. The mechanical strength of the NP1 hydrogel was tested by performing rheological experiments. TEM and SEM experiments were performed to investigate the morphology of the NP1 hydrogel. The biocompatibility of the newly synthesized NP1 hydrogel was investigated using McCoy and A549 cell lines. The hemolytic activity of the NP1 hydrogel was examined in human blood cells. The stability of the newly formed NP1 hydrogel was examined using proteinase K and α-chymotrypsin. The NP1 hydrogel was used for in vitro wound healing. Western blotting, qRT-PCR and DCFDA assay were performed to determine the anti-inflammatory activity of the NP1 hydrogel. The synthesized NP1 hydrogel also exhibits antibacterial efficacy.

Vitamin D effects on Chlamydia trachomatis infection: a case-control and experimental study.

Vitamin D deficiency is the most common nutritional deficiency worldwide. Chronic vitamin D deficiency causes immune system dysfunction, which increases susceptibility to pathogens such as bacteria, especially intracellular parasites, and viruses. Chlamydia trachomatis (C. t) is an obligate intracellular parasitic bacterium that causes a variety of sequelae. We speculated that vitamin D might be associated with C. t infection. This study aimed to address this gap in knowledge by investigating the relationship between vitamin D and C. t infection using both in vitro and in vivo models. The addition of calcitriol to McCoy cell culture in vitro delayed and reduced the quantity and volume of inclusions compared to the control group. Macrophages of peritoneally lavaged mice co-cultured with McCoy decreased the infection rate and delayed the appearance of inclusions. In mice models of vitamin D deficiency, mice in the VD-group exhibited more severe genital tract inflammation and a longer duration of infection after inoculation with C. t in the genital tract. Supplementing these mice with vitamin D3 during treatment enhanced the therapeutic effect of antibiotics. We also conducted a case-control study involving 174C. t-positive patients (95 males and 79 females) and 380 healthy volunteers (211 males and 169 females) aged 20-49 from January 2016 to March 15, 2017. Serum 25-(OH)D concentration was measured by assessing morning fasting blood samples of healthy volunteers and C. t-positive patients 1 day before antibiotic treatment and the next day after one course of treatment. The patients were followed up for 1 month and evaluated for recovery. The results showed that vitamin D deficiency was a risk factor for C. t infection and treatment failure. In summary, findings from experimental and clinical studies indicate a close association between vitamin D levels and C. t infection and treatment outcomes. Given the affordability and safety of vitamin D, both healthy individuals and patients should focus on vitamin D intake. Vitamin D supplementation could enhance treatment success and should be used as an adjunctive therapy alongside antibiotic therapy for C. t infections, pending confirmation in larger, prospective, randomized controlled trials.

Vanadium oxide 3- methoxy salen, a synthetic biologically active complex against HeLa and McCoy cell lines

Background: Vanadium is an essential dietary microelement that plays a key role in metabolic pathways and has anti-neoplastic effects. In this regard, vanadium oxide 3-methoxy salen complex was produced and its anticancer effects were evaluated against HeLa and McCoy cell lines.
 Methods: Schiff bases produced from equivalents of Vanadyl acetylacetonate [VO(acac)2] in methanol were used to make a vanadium oxide 3-methoxy salen complex. Then, The antioxidant property of compound, cell viability and cytotoxicity assay, DNA fragmentation analysis and determination of the apoptosis pathway genes were evaluated.
 Results: The result showed that the compound with an RC50 value of 126.3 µM demonstrated considerable free radical scavenging activity. The combination strongly suppressed the viability and proliferation of HeLa and McCoy cell lines in a dose-dependent manner, with IC50 values of 213 µM and 175 µM, respectively. When the viability and cytotoxicity values of the treated cells were compared, it was discovered that the cells had died of apoptosis, which was validated by DNA fragmentation analysis. Capspase 3, Bcl2 antagonist/killer, and Bcl2 associated X protein (Bax) gene expression levels all increased significantly in a quantitative investigation of apoptotic pathway genes, with 2-CT values of 2.36, 2.63, and 3.18, respectively.
 Conclusion: In HeLa and McCoy malignant cell lines, lower quantities of the complex caused programmed cell death. This potential of complex can be used in cancer chemoprevention and cancer therapy.

Phenotypic and Genotypic Antimicrobial Susceptibility Testing of Chlamydia trachomatis Isolates from Patients with Persistent or Clinical Treatment Failure in Spain

The aim of this multicentre project (seven hospitals across the Spanish National Health Service) was to study the phenotypic and genotypic susceptibility of C. trachomatis to the main antimicrobials used (macrolides, doxycycline, and quinolones) in isolates from patients with clinical treatment failure in whom reinfection had been ruled out. During 2018–2019, 73 clinical isolates were selected. Sixty-nine clinical specimens were inoculated onto confluent McCoy cell monolayers for phenotypic susceptibility testing. The minimum inhibitory concentration for azithromycin and doxycycline was defined as the lowest concentration associated with an at least 95% reduction in inclusion-forming units after one passage in the presence of the antibiotic compared to the initial inoculum for each strain (control). Sequencing analysis was performed for the genotypic detection of resistance to macrolides, analysing mutations in the 23S rRNA gene (at positions 2057, 2058, 2059, and 2611), and quinolones, analysing a fragment of the gyrA gene, and searching for the G248T mutation (Ser83->Ile). For tetracyclines, in-house RT-PCR was used to test for the tet(C) gene. The phenotypic susceptibility testing was successful for 10 isolates. All the isolates had minimum inhibitory concentrations for azithromycin ≤ 0.125 mg/L and for doxycycline ≤ 0.064 mg/L and were considered sensitive. Of the 73 strains studied, no mutations were found at positions T2611C or G248T of the gyrA gene. We successfully sequenced 66 isolates. No macrolide resistance-associated mutations were found at positions 2057, 2058, 2059, or T2611C. None of the isolates carried the tet(C) gene. We found no evidence for genomic resistance in this large, clinically relevant dataset.

Synergistic Effect of Silk Sericin and Curcumin to Treat an Inflammatory Condition.

Inflammation-related diseases are recognized as the major cause of morbidity around the globe. In this study, the anti-inflammatory potential of sericin, curcumin, and their mixture was investigated in vivo and in vitro. Edema was induced via 1% carrageenan and then sericin (0.03, 0.06, 0.09 mg/ml), curcumin (1%, 2%, 3%), and their mixture doses were applied topically. The paw circumference and thickness were measured after 1-, 2-, 3-, 4-, 5-, and 6-hour post-carrageenan injection. The levels of IL-4 and IL-10 were measured from the serum. In mice fibroblast cells, sericin (20, 40, 60 μg/ml), curcumin (5, 10, 20 μM), and mixture concentrations were applied and then stimulated with lipopolysaccharide (LPS). Afterward, the cells were used for the analysis of gene expression, and the supernatant was collected for protein expression of IL-1β, IL-4, and IL-10. Our results demonstrated that sericin and curcumin caused a dose-dependent reduction in edema, whereas the mixture-treated group reduced the paw thickness and circumference most significantly (p = .0001). Furthermore, the mixture treatment of carrageenan-inflicted group increased the levels of anti-inflammatory cytokines, IL-4 (650.87 pg/ml) and IL-10 (183.14 pg/ml), in comparison to the carrageenan control. The in vitro data revealed that among all the treatment doses, the mixture-treated group has effectively reduced the gene (1.13-fold) and protein (51.9 pg/ml) expression of IL-1β in comparison to McCoy cells stimulated with LPS. Moreover, mixture treatment elevated the expression of IL-4 and IL-10 at genes (4.3-fold and 3.7-fold, respectively) and protein levels (169.33 and 141.83 pg/ml, respectively). The current study reports the enhanced anti-inflammatory effects of the mixture of curcumin and sericin through modulating expressions of interleukins in vitro and in vivo. Thus, natural products (curcumin and sericin)-based formulations have greater potential for clinical investigations.

Whole-genome sequencing of Chlamydia trachomatis isolates from persistently infected patients

Current understanding of the causes of treatment failure in Chlamydia trachomatis is poor and antimicrobial susceptibility data are lacking. We used genome sequencing to seek evidence of antimicrobial resistance in isolates sourced from patients who were persistently infected. Genomic DNA was extracted from C. trachomatis isolates cultured in McCoy cell monolayers. Sequencing libraries were prepared using the SureSelectXT Illumina paired-end protocol. Paired reads were mapped against a reference genome and single nucleotide variants (SNVs) were identified. Seven isolates from persistently infected patients and five isolates from successfully treated patients were sequenced. No previously reported SNVs associated with antimicrobial resistance were found. A unique SNV was identified in the gyrA gene of one treatment failure isolate but was located outside of the quinolone resistance determining region; this SNV has been previously reported in other members of the Chlamydiaceae family. No genomic evidence was found to explain the differences in clinical outcome for our two groups of patients. A mutation unrelated to antimicrobial susceptibility was found in an isolate from a persistently infected patient. The cause of these persistent infections with C. trachomatis remains unclear.

In vitro transmission of Chlamydia using naturally infected koala (Phascolarctos cinereus) semen.

Transmission of Chlamydia pecorum infection has generally been assumed to be via the urogenital route and in an attempt to confirm this we investigated an in vitro method of Chlamydia infection using naturally infected koala semen to inoculate a cell line and attempt to estimate C. pecorum infectious load. A total of 57% of 122 koala semen samples had low C. pecorum copy number or no burden, while 18% of semen samples contained >10000 inclusion-forming units/mL, as determined by quantitative polymerase chain reaction. In vitro inoculation of a McCoy cell line resulted in successful infection from 4% of semen samples where C. pecorum burden was >105 inclusion-forming units/mL. Our preliminary study suggests that transmission of C. pecorum infectious dose may be restricted to peak bacterial shedding in semen associated with recent infection. Here, we report venereal transmission of C. pecorum in koala semen is possible; however, we speculate that antimicrobial factors and innate immune function receptors associated with semen may inhibit chlamydial growth. These mechanisms have yet to be reported in marsupial semen.

Transferrins Reduce Replication of Chlamydia suis in McCoy Cells.

Chlamydia suis (C. suis) resides in the intestines of pigs and tetracycline-resistant strains are emerging worldwide. Intestinal infections are often subclinical. However, the gut is regarded as a C. suis reservoir and clinical infections have been associated with enteritis, conjunctivitis, pneumonia and reproductive failure. C. suis was found in boar semen and venereal transmission occurred. We studied the anti-Chlamydia suis activity of ovotransferrin (ovoTF) and bovine lactoferrin (bLF). Pre-incubation of C. suis with bLF or ovoTF had no significant effect on overall chlamydia replication (mean fluorescence area) in McCoy cells. The addition of ovoTF to the culture medium had no effect on bacterial replication, but the addition of 0.5 or 5 mg/mL of bLF significantly reduced the inclusion size by 17% and 15% respectively. Egg components are used for cryopreservation of boar semen. When inoculating an ovoTF-containing and Chlamydia suis-spiked semen sample in McCoy cells, a significant reduction in inclusion number (by 7%) and overall replication (by 11%) was observed. Thus, we showed that transferrins possess anti-chlamydial activity. Moreover, ovoTF addition to semen extenders might reduce C. suis venereal transmission. Further research is needed to unravel the mechanisms behind the observations and to enhance the effect of transferrins on C. suis.

A new species of Chlamydia isolated from Siamese crocodiles (Crocodylus siamensis).

Chlamydia is a known pathogen in both saltwater and freshwater crocodiles. However, the exact species/strain has not been clearly identified. In this study, we successfully cultivated Siamese crocodile Chlamydia in McCoy cells at a temperature of 30°C. Electron microscopy; phylogeny based on nine conserved taxonomically informative markers, on ompA, or on seven housekeeping genes; and whole-genome sequencing and analysis of the isolate confirmed the identity of the isolate as a new member of the genus Chlamydia, a new species that we name Chlamydia crocodili.

Microscopy of Eugenia involucrata, Chemical Composition and Biological Activities of the Volatile Oil

This paper studied the chemical profile, cytotoxicity, and insecticidal activity of the volatile oil, as well as provided a detailed anatomy of the leaves and stems from Eugenia involucrata DC., Myrtaceae. Its volatile oil was identified by gas chromatography coupled with mass spectrometry. The insecticidal activity was performed using the volatile oil against two strains of Cimex lectularius L., using topical, residual, and fumigant methods. Cytotoxicity was verified against B16F10, MCF7, and McCoy cell lines. The cytotoxic mechanism was studied by the morphology feature changes. The microscopic analysis was performed by usual microscopy techniques. The main volatile compounds of E. involucrata were germacrene B (22.17%), bicyclogermacrene (19.76%), and β-elemene (10.86%). Volatile oil demonstrated low toxicity against two strains of the bed bug in the topical test and did not present toxicity in fumigation and residual methods. Cytotoxicity for the B16F10 murine melanoma cells was demonstrated. Moreover, the volatile oil induces morphological characteristic changes of the cell death process of apoptosis. The microscopic data of the leaf and stem provided information to support the identification of E. involucrata.

Covalently Bonded N-Acetylcysteine-polyester Loaded in PCL Scaffolds for Enhanced Interactions with Fibroblasts.

Poly(ε-caprolactone) (PCL) is commonly used in devices for tissue reconstruction due to its biocompatibility and suitable mechanical properties. However, its high crystallinity and hydrophobicity do not favor cell adhesion and difficult polymer bioresorption. To improve these characteristics, the development of engineered scaffolds for tissue regeneration, based on poly(globalide-co-ε-caprolactone) (PGlCL) covalently bonded with N-acetylcysteine (PGlCL-NAC) was proposed. The scaffolds were obtained from polymer blends of PCL and PGlCL-NAC, using the electrospinning technique. The use of PGlCL-NAC allowed for the modification of the physical and chemical properties of PCL electrospun scaffolds, including an expressive reduction in the fiber's diameter, hydrophobicity, and crystallinity. All electrospun scaffolds showed no cytotoxicity against fibroblasts (McCoy cells). In vitro biocompatibility assays showed that all tested scaffolds provided high cell viability and proliferation in short-term (NRU, MTT, and nuclear morphology assays) and long-term (clonogenic assay) assays. Nevertheless, PGlCL-NAC based scaffolds have favored the survival and proliferation of the cells in comparison to PCL scaffolds. Cell adhesion on the scaffolds assessed by electronic microscopy images confirmed this behavior. These results suggest that the incorporation of PGlCL-NAC in scaffolds for tissue regeneration could be a promising strategy to improve cell-surface interactions and contribute to the development of more efficiently engineered biomedical devices.

Liposomes-In-Hydrogel Delivery System Enhances the Potential of Resveratrol in Combating Vaginal Chlamydia Infection.

Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infections and causes serious reproductive tract complications among women. The limitations of existing oral antibiotics and treatment of antimicrobial resistance require alternative treatment options. We are proposing, for the first time, the natural polyphenol resveratrol (RES) in an advanced delivery system comprising liposomes incorporated in chitosan hydrogel, for the localized treatment of C. trachomatis infection. Both free RES and RES liposomes-in-hydrogel inhibited the propagation of C. trachomatis in a concentration-dependent manner, assessed by the commonly used in vitro model comprising McCoy cells. However, for lower concentrations, the anti-chlamydial effect of RES was enhanced when incorporated into a liposomes-in-hydrogel delivery system, with inhibition of 78% and 94% for 1.5 and 3 µg/mL RES, respectively for RES liposomes-in-hydrogel, compared to 43% and 72%, respectively, for free RES. Furthermore, RES liposomes-in-hydrogel exhibited strong anti-inflammatory activity in vitro, in a concentration-dependent inhibition of nitric oxide production in the LPS-induced macrophages (RAW 264.7). The combination of a natural substance exhibiting multi-targeted pharmacological properties, and a delivery system that provides enhanced activity as well as applicability for vaginal administration, could be a promising option for the localized treatment of C. trachomatis infection.

Lipofectamine enhances Chlamydia infectivity in cell culture

Cultivation of Chlamydia species in cell lines requires centrifugation of the inoculum onto diethylaminoethyl-dextran-pretreated cell monolayers to improve the infection efficiency. Here we report that the addition of DNA transfection reagent Lipofectamine in the inoculum significantly enhances the infectivity of Chlamydia abortus in mouse fibroblast McCoy cells, with an infection efficiency equivalent to that of the centrifugation method. Similar enhancement effects of Lipofectamine on the infectivity of C. psittaci and C. trachomatis were also observed. This study provides an alternative and convenient method for the cultivation of Chlamydia species in vitro in the absence of centrifugation.

Inhibition of the Extracellular Signal–Regulated Kinase/Ribosomal S6 Kinase Cascade Limits Chlamydia trachomatis Infection

Chlamydiatrachomatis is the cause of the most common bacterial sexually transmitted infection worldwide. Azithromycin is effective in treating chlamydial infection; however, resistance to this antibiotic is increasing, and it is important that new therapeutic strategies are developed. In this study, we demonstrated that inhibitors targeting each kinase in the extracellular signal-regulated kinase/ribosomal S6 kinase cascade significantly decreased the size and number of inclusions as well as the number of infectious progeny. The suppressive effects of the inhibitors were observed across the Chlamydia serotypes D, E, F, and L1 and across HeLa, McCoy, and Vero host cells. When combined with azithromycin, all the inhibitors exerted a synergistic suppressive effect on chlamydial infection. Knockdown experiments using small interfering RNA demonstrated that extracellular signal-regulated kinase 1/2 and ribosomal S6 kinase 1 were crucial for chlamydial infection. Moreover, BVD-523, a first-in-class extracellular signal-regulated kinase 1/2 inhibitor currently undergoing a phase II clinical trial, suppressed chlamydial infection both in cell culture and in a mouse model. These observations demonstrated not only that the extracellular signal-regulated kinase/ribosomal S6 kinase pathway plays a critical role in chlamydial infection but also that these kinases have potential as targets for host-directed therapy against C.trachomatis.

Survival of Lawsonia intracellularis in porcine peripheral blood monocyte-derived macrophages.

Lawsonia intracellularis, an obligately intracellular enteric bacterium, infects intestinal epithelial cells, but may also be found within macrophages in the intestinal lamina propria of affected pigs. Macrophages play an important role in host defense against infectious agents, but the role of this cell in L. intracellularis infection is not well understood. The aim of this study was to evaluate the permissibility of macrophages to L. intracellularis infection in vitro. Pure culture of L. intracellularis was added to swine peripheral blood monocyte-derived macrophages. Viability of intracytoplasmic L. intracellularis was evaluated at different time points by transmission electron microscopy (TEM). Potential replication of L. intracellularis in macrophages was also evaluated by qPCR. By TEM, phagocytosis L. intracellularis within of phagolysosomes were observed 1-hour post-infection (hpi) and bacterial structures in binary fission at 48 hpi. The number of intracellular bacteria was determined at 1, 4, 24, 48, and 72 hpi by qPCR in infected macrophages and compared to the number of intracellular bacteria from culture in McCoy cells. In both cell lines, the amount of L. intracellularis was decreased at 4 hpiand increased at 24 hpi. The number of intracellular bacteria continued to increase in McCoy cells over time. This is the first study showing interaction, survival and propagation of L. intracellularis in macrophages. These findings are critical to establish an experimental model for future studies of the pathogenesis of porcine proliferative enteropathy and the potential persistence of L. intracellularis in macrophages during chronic infections.