Scroll through the 5 CERID publications from CERID labs, PIs, and lab technicians publications that have hit the PubMed stands since the end of August! The scope of the individual publications is wide, covering a number of important pathogens and viruses from Shigella flexneri to neuropathological West Nile virus infections. Read on for highlights from the abstract and the diseases studied in this month’s publication round up by following the links! Publications are listed by the date published. All descriptions of the work have been paraphrased from the publications' respective abstracts and are cited as such.
Neurotropic viral infection can result in complications underscored by persistent T cell presence in the brain linked with cognitive decline. A recent study by Garber et al. showed that sustained T cell production of interferon (IFN)-γ mediating microglia activation triggers cognitive decline during recovery from Zika virus (ZIKV) or West Nile virus (WNV) infection. Read the full paper here!
Functional genetic analysis of Chlamydia has been a challenge due to the historical genetic intractability of Chlamydia, although recent advances in chlamydial genetic manipulation have begun to remove these barriers. Herein, we report the development of the Himar C9 transposon system for C. muridarum, a mouse-adapted Chlamydia species that is widely used in Chlamydia infection models. We demonstrate the generation and characterization of an initial library of 33 chloramphenicol (cam) resistant, GFP-expressing C. muridarum transposon mutants. The majority of mutants contained single transposon insertions spread throughout the entire C. muridarum chromosome. In all, the library contained 31 transposon insertions in coding open reading frames (ORFs) and 7 insertions in intergenic regions. Whole genome sequencing analysis of 17 mutant clones confirmed the chromosomal locations of insertions. Four mutants with transposon insertions in glgB, pmpI, pmpA, and pmpD, were investigated further for in vitro and in vivo phenotypes, including growth, inclusion morphology, and attachment to host cells. The glgB mutant was shown to be incapable of complete glycogen biosynthesis and accumulation in the lumen of mutant inclusions. Of the 3 pmp mutants, pmpI was shown to have the most pronounced growth attenuation defect. This initial library demonstrates the utility and efficacy of stable, isogenic transposon mutants for C. muridarum. The generation of a complete library of C. muridarum mutants will ultimately enable a comprehensive identification of the functional genetic requirements for Chlamydia infection in vivo. Read the full abstract and paper here!
Lateral gene transfer (LGT) among C. trachomatis strains is common, both in isolates generated in the laboratory and those examined directly from patients. In contrast, there are very few examples of recent acquisition of DNA by any Chlamydia spp. from any other species. Interspecies LGT in this system was analyzed using crosses of tetracycline (Tc)-resistant Chlamydia trachomatis L2/434 and chloramphenicol (Cam)-resistant C. muridarum VR-123. Parental C. muridarum strains were created using a plasmid-based Himar transposition system, which led to integration of the CamR marker randomly across the chromosome. Fragments encompassing 79% of the C. muridarum chromosome were introduced into a C. trachomatis background, with the total coverage contained on 142 independent recombinant clones. Genome sequence analysis of progeny strains identified candidate recombination hotspots, a property not consistent with in vitro C. trachomatis × C. trachomatis (intraspecies) crosses. In both interspecies and intraspecies crosses there were examples of duplications, mosaic recombination endpoints, and recombined sequences that were not linked to the selection marker. Quantitative analysis of the distribution and constituency of inserted sequences indicated that there are different constraints on interspecies LGT as compared to intraspecies crosses. These constraints may help explain why there is so little evidence of interspecies genetic exchange in this system, which is in contrast to very widespread intraspecies exchange in C. trachomatis. Read the full abstract and paper here!
Shigella spp., the bacteria responsible for shigellosis, are one of the leading causes of diarrheal morbidity and mortality amongst children. There is a pressing need for the development of novel therapeutics, as resistance of Shigella to many currently used antibiotics is rapidly emerging. This paper describes the development of robust in vitro and in vivo tools to study antibiotic efficacy against Shigella flexneri. A novel bioluminescent S. flexneri strain (S. flexneri lux1) was generated, which can be used in a mammalian epithelial cell co-culture assay to evaluate antibiotic intracellular and extracellular efficacy. In addition, the S. flexneri lux1 strain was used with an intraperitoneal (IP) murine model of shigellosis to test the efficacy of ciprofloxacin and ampicillin. Both antibiotics significantly reduced the observed radiance from the gastrointestinal tissue of infected mice compared to vehicle control. Furthermore, plated gastrointestinal tissue homogenate confirmed antibiotic treatment significantly reduced the S. flexneri infection. However, in contrast to the results generated with tissue homogenate, the radiance data was not able to distinguish between the efficacy of ampicillin and ciprofloxacin. Compared to traditional methods, these models can be utilized for efficient screening of novel antibiotics aiding in the discovery of new treatments against shigellosis. Read the full paper here!
Salivary gland tumor comprises of approximately 3 to 10% of neoplasms of the head and neck region. Parotid gland is the most commonly involved salivary gland with an incidence of 62% followed by submandibular gland and other minor salivary gland tumors. However clinical course of benign and malignant tumors resemble each other in clinical findings, we require histopatholocal or cytological diagnosis for planning of management. To analyze parotid tumors retrospectively with following objectives. (1) Demographic distribution of parotid tumors. (2) To evaluate cytological and histopathological findings of parotid tumors. (3) Correlation of cytological and histopathological findings of parotid tumors. It was a retrospective observational study involving 31 patients who presented with parotid region swelling. Pre operative FNAC (fine needle aspiration cytology) and post operative histopathology were correlated. Surgical management depended on nature of disease. Correlation of FNAC and Histopathology: among 27 cases pre operative FNAC and post operative histopathology was same and in only 3 cases reports differed. One FNAC was inconclusive. In present study, Sensitivity of FNAC is 81.81%, Specificity is 94.73% and accuracy is 90%. FNAC is usually the first investigative modality, as it is a minimally invasive, cheap, OPD procedure that can differentiate benign from malignant tumors. Knowing preoperative pathological nature of disease can help in planning of surgical process. Read the full paper here!