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Background: Cladribine is an effective immunotherapy for people with multiple sclerosis (pwMS). Whilst most pwMS do not require re-treatment following standard dosing (two treatment courses), disease activity re-emerges in others. The characteristics of pwMS developing re-emerging disease activity remain incompletely understood. Objectives: To explore whether clinical and/or paraclinical baseline characteristics, including the degree of lymphocyte reduction, drug dose and lesions on magnetic resonance imaging (MRI) are associated with re-emerging disease activity. Design: Service evaluation in pwMS undergoing subcutaneous cladribine (SClad) treatment. Methods: Demographics, clinical, laboratory and MRI data of pwMS receiving two courses of SClad were extracted from health records. To assess associations of predictor variables with re-emerging disease activity, a series of Cox proportional hazards models was fitted (one for each predictor variable). Results: Of n = 264 pwMS 236 received two courses of SClad and were included in the analysis. Median follow-up was 4.5 years (3.9, 5.3) from the first, and 3.5 years (2.9, 4.3) from the last SClad administration. Re-emerging disease activity occurred in 57/236 pwMS (24%); 22/236 received further cladribine doses (SClad or cladribine tablets) at 36.7 months [median; interquartile range (IQR): 31.7, 42.1], and 22/236 other immunotherapies 18.9 months (13.0, 30.2) after their second course of SClad, respectively. Eligibility was based on MRI activity in 29, relapse in 5, both in 13, elevated cerebrospinal fluid neurofilament light chain level in 3, deterioration unrelated to relapse in 4 and other in 3. Only 36/57 of those eligible for additional immunotherapy had received a reduced dose of SClad for their second treatment course. Association was detected between re-emerging disease activity and (i) high baseline MRI activity and (ii) low second dose of SClad. Conclusion: Re-emerging disease activity was associated with baseline MRI activity and low dose second course of SClad. [ABSTRACT FROM AUTHOR]

Intracellular replication of Salmonella enterica serovar Typhimurium within membrane-bound compartments, called Salmonella-containing vacuoles, depends on the activities of several effector proteins translocated by the Salmonella pathogenicity island 2 (SPI-2)-encoded type III secretion system. The SPI-2 effector protein SseJ shows similarity at the amino acid level to several GDSL lipases with glycerophospholipid : cholesterol acyltransferase (GCAT) activity. In this study, we show that catalytic serine-dependent phospholipase A (PLA) and GCAT activity of recombinant SseJ is potentiated by factor(s) present in HeLa cells, RAW macrophages and Saccharomyces cerevisiae. SseJ activity was enhanced with increasing amounts of, or preincubation with, eukaryotic cell extracts. Analysis of the activating factor(s) shows that it is soluble and heat- and protease-sensitive. We conclude that PLA and GCAT activities of SseJ are potentiated by proteinaceous eukaryotic factor(s).

Passage through the digestive tract exposes Salmonella enterica to high concentrations of bile salts, powerful detergents that disrupt biological membranes. Mutations in the wecD or wecA gene, both of which are involved in the synthesis of enterobacterial common antigen (ECA), render S. enterica serovar Typhimurium sensitive to the bile salt deoxycholate. Competitive infectivity analysis of wecD and wecA mutants in the mouse model indicates that ECA is an important virulence factor for oral infection. In contrast, lack of ECA causes only a slight decrease in Salmonella virulence during intraperitoneal infection. A tentative interpretation is that ECA may contribute to Salmonella virulence by protecting the pathogen from bile salts.

The type III secretion system (TTSS) encoded by Salmonella typhimurium pathogenicity island 2(SPI-2) is expressed after bacterial entry into host cells. The SPI-2 TTSS secretes the translocon components SseBCD, which translocate across the vacuolar membrane a number of effector proteins whose action is required for intracellular bacterial replication. Several of these effectors, including SifA and SifB, are encoded outside SPI-2. The two-component regulatory system SsrA--SsrB, encoded within SPI-2, controls the expression of components of the SPI-2 TTSS apparatus as well as its translocated effectors. The expression of SsrA--B is in turn regulated by the OmpR--EnvZ two-component system, by direct binding of OmpR to the ssrAB promoter. Several environmental signals have been shown to induce in vitro expression of genes regulated by the SsrA--B or OmpR--EnvZ systems. In this work, immunoblotting and flow cytometry were used to analyse the roles of SsrA--B and OmpR--EnvZ in coupling different environmental signals to changes in expression of a SPI-2 TTSS translocon component (SseB) and two effector genes (sifA and sifB). Using single and double mutant strains the relative contribution of each regulatory system to the response generated by low osmolarity, acidic pH or the absence of [Ca.sup.2=] was determined. SsrA--B was found to be essential for the induction of SPI-2 gene expression in response to each of these individual signals. OmpR--EnvZ was found to play a minor role in sensing these signals and to require a functional SsrA--B system to mediate their effect on SPI-2 TTSS gene expression.

Research has been conducted on Staphylococcus aureus gene svrA. Results indicate that this gene is required for accessory gene regulator and RNAIII transcripts expression and is an accessory gene regulator's regulatory network component which controlls virulence gene expression in S. aureus.

Research has been conducted on the intracellular pathogens. Results demonstrate that bacterial replication is inhibited if bacteria are released into cytosol or macrophages.

The structure of the boundaries of the Salmonella pathogenicity island two (SPI2) was analyzed to determine their relation to the corresponding region of the Escherichia coli K-12 genome. SPI2 was located near the transfer RNA VAL gene of Escherichia coli chromosome which contained a nine kb DNA at the insertion site of SPI2. Analysis of Salmonella isolates also indicated the presence of SPI2 in all strains except Salmonella bongori.

The genes that determine the pathogenicity and virulence of pathogens are identified by various molecular genetic selection and screening methods. The screening methods include forming cDNA from the RNA of pathogens, gene fusion, gene transfer, and comparing the genomes of non-pathogenic and pathogenic microorganisms. Directed and random mutagenesis and transposon mutagenesis are also used. Signature-tagged mutagenesis allows the study of different mutants in one host. An alternative to studying some pathogens in animals is to study them in plants.