10 research outputs found
The Extracellular Domain of Myelin Oligodendrocyte Glycoprotein Elicits Atypical Experimental Autoimmune Encephalomyelitis in Rat and Species
Atypical models of experimental autoimmune encephalomyelitis (EAE) are advantageous in that the heterogeneity of clinical signs appears more reflective of those in multiple sclerosis (MS). Conversely, models of classical EAE feature stereotypic progression of an ascending flaccid paralysis that is not a characteristic of MS. The study of atypical EAE however has been limited due to the relative lack of suitable models that feature reliable disease incidence and severity, excepting mice deficient in gamma-interferon signaling pathways. In this study, atypical EAE was induced in Lewis rats, and a related approach was effective for induction of an unusual neurologic syndrome in a cynomolgus macaque. Lewis rats were immunized with the rat immunoglobulin variable (IgV)-related extracellular domain of myelin oligodendrocyte glycoprotein (IgV-MOG) in complete FreundĂąâŹâąs adjuvant (CFA) followed by one or more injections of rat IgV-MOG in incomplete FreundĂąâŹâąs adjuvant (IFA). The resulting disease was marked by torticollis, unilateral rigid paralysis, forelimb weakness, and high titers of anti-MOG antibody against conformational epitopes of MOG, as well as other signs of atypical EAE. A similar strategy elicited a distinct atypical form of EAE in a cynomolgus macaque. By day 36 in the monkey, titers of IgG against conformational epitopes of extracellular MOG were evident, and on day 201, the macaque had an abrupt onset of an unusual form of EAE that included a pronounced arousal-dependent, transient myotonia. The disease persisted for 6ĂąâŹâ7 weeks and was marked by a gradual, consistent improvement and an eventual full recovery without recurrence. These data indicate that one or more boosters of IgV-MOG in IFA represent a key variable for induction of atypical or unusual forms of EAE in rat and Macaca species. These studies also reveal a close correlation between humoral immunity against conformational epitopes of MOG, extended confluent demyelinating plaques in spinal cord and brainstem, and atypical disease induction
Structure and Function of the Genomically Encoded Fosfomycin Resistance Enzyme, FosB, from <i>Staphylococcus aureus</i>
The
Gram-positive pathogen <i>Staphylococcus aureus</i> is a
leading cause of global morbidity and mortality. Like many
multi-drug-resistant organisms, <i>S. aureus</i> contains
antibiotic-modifying enzymes that facilitate resistance to a multitude
of antimicrobial compounds. FosB is a Mn<sup>2+</sup>-dependent fosfomycin-inactivating
enzyme found in <i>S. aureus</i> that catalyzes nucleophilic
addition of either l-cysteine (l-Cys) or bacillithiol
(BSH) to the antibiotic, resulting in a modified compound with no
bactericidal properties. The three-dimensional X-ray crystal structure
of FosB from <i>S. aureus</i> (FosB<sup><i>Sa</i></sup>) has been determined to a resolution of 1.15 Ă
. Cocrystallization
of FosB<sup><i>Sa</i></sup> with either l-Cys or
BSH results in a disulfide bond between the exogenous thiol and the
active site Cys9 of the enzyme. An analysis of the structures suggests
that a highly conserved loop region of the FosB enzymes must change
conformation to bind fosfomycin. While two crystals of FosB<sup><i>Sa</i></sup> contain Zn<sup>2+</sup> in the active site, kinetic
analyses of FosB<sup><i>Sa</i></sup> indicated that the
enzyme is inhibited by Zn<sup>2+</sup> for l-Cys transferase
activity and only marginally active for BSH transferase activity.
Fosfomycin-treated disk diffusion assays involving <i>S. aureus</i> Newman and the USA300 JE2 methicillin-resistant <i>S. aureus</i> demonstrate a marked increase in the sensitivity of the organism
to the antibiotic in either the BSH or FosB null strains, indicating
that both are required for survival of the organism in the presence
of the antibiotic. This work identifies FosB as a primary fosfomycin-modifying
pathway of <i>S. aureus</i> and establishes the enzyme as
a potential therapeutic target for increased efficacy of fosfomycin
against the pathogen
Enhanced infection prophylaxis reduces mortality in severely immunosuppressed HIV-infected adults and older children initiating antiretroviral therapy in Kenya, Malawi, Uganda and Zimbabwe: the REALITY trial
Meeting abstract FRAB0101LB from 21st International AIDS Conference 18â22 July 2016, Durban, South Africa.
Introduction: Mortality from infections is high in the first 6 months of antiretroviral therapy (ART) among HIVâinfected adults and children with advanced disease in subâSaharan Africa. Whether an enhanced package of infection prophylaxis at ART initiation would reduce mortality is unknown.
Methods:
The REALITY 2Ă2Ă2 factorial openâlabel trial (ISRCTN43622374) randomized ARTânaĂŻve HIVâinfected adults and children >5 years with CD4 <100 cells/mm3. This randomization compared initiating ART with enhanced prophylaxis (continuous cotrimoxazole plus 12 weeks isoniazid/pyridoxine (antiâtuberculosis) and fluconazole (antiâcryptococcal/candida), 5 days azithromycin (antiâbacterial/protozoal) and singleâdose albendazole (antiâhelminth)), versus standardâofâcare cotrimoxazole. Isoniazid/pyridoxine/cotrimoxazole was formulated as a scored fixedâdose combination. Two other randomizations investigated 12âweek adjunctive raltegravir or supplementary food. The primary endpoint was 24âweek mortality.
Results:
1805 eligible adults (n = 1733; 96.0%) and children/adolescents (n = 72; 4.0%) (median 36 years; 53.2% male) were randomized to enhanced (n = 906) or standard prophylaxis (n = 899) and followed for 48 weeks (3.8% lossâtoâfollowâup). Median baseline CD4 was 36 cells/mm3 (IQR: 16â62) but 47.3% were WHO Stage 1/2. 80 (8.9%) enhanced versus 108(12.2%) standard prophylaxis died before 24 weeks (adjusted hazard ratio (aHR) = 0.73 (95% CI: 0.54â0.97) p = 0.03; Figure 1) and 98(11.0%) versus 127(14.4%) respectively died before 48 weeks (aHR = 0.75 (0.58â0.98) p = 0.04), with no evidence of interaction with the two other randomizations (p > 0.8). Enhanced prophylaxis significantly reduced incidence of tuberculosis (p = 0.02), cryptococcal disease (p = 0.01), oral/oesophageal candidiasis (p = 0.02), deaths of unknown cause (p = 0.02) and (marginally) hospitalisations (p = 0.06) but not presumed severe bacterial infections (p = 0.38). Serious and grade 4 adverse events were marginally less common with enhanced prophylaxis (p = 0.06). CD4 increases and VL suppression were similar between groups (p > 0.2).
Conclusions:
Enhanced infection prophylaxis at ART initiation reduces early mortality by 25% among HIVâinfected adults and children with advanced disease. The pill burden did not adversely affect VL suppression. Policy makers should consider adopting and implementing this lowâcost broad infection prevention package which could save 3.3 lives for every 100 individuals treated