ABSTRACT
Background: Stenotrophomonas maltophilia is a non-fermentative gram-negativebacillus which is widely recognised as an important nosocomial pathogen causing pneumonia,blood-stream, wound and urinary tract infections, particularly in immunosuppressed patients. Theaim of this study was to evaluate a nosocomial outbreak of by S. maltophilia in an intensive careunit of a tertiary hospital and evaluate unexpected multiclonality.Methods: A total of 11 isolates from respiratory cultures in intensive care unit of a 24 bedtertiary hospital obtained over a one months period and one isolate obtained from the nebuliserduring environmental screening were investigated. The bacteria were identified by Phoenix 100system. The clonal relatedness was evaluated by PFGE and semi-automated repetitive sequencebasedPCR. Genotyping tests were repeated for 10 serial subcultures.Results: PFGE and DiversiLab yielded 10 genotypic profiles for 12 isolates. Four to eightdifferent genotypes were observed from 10 subcultures of the same isolate.Conclusion: We conclude that, high genetic diversity and supposed multiclonalappearance of the outbreak isolates may be due to changing profiles during subcultures mostprobably depending on hypermutation.
ABSTRACT
To identify the interchangeability of V(H) and V(L) framework region (FR) residues, we artificially introduced random mutations at all residue positions in a chicken monoclonal antibody, which has only one functional V(H) and Vλ gene. When we classified the amino acids into 5 groups by their physicochemical properties, all FR residues could be replaced by another group except L23 (C), H36 (W), H86 (D), H104 (G), and H106 (G). Eighty-two (50.9%), 48 (29.8%), 17 (10.6%), and 9 FR residues (5.6%) could be replaced by 4, 3, 2, and 1 group(s), individually, without significant loss of reactivity. We also confirmed a similar level of versatility with 2 different chicken antibodies. This high level of versatility on FR residues has not been predicted because it has not been observed in the 150 chicken antibodies that we previously generated or in the 1,269 naïve chicken V(H) sequences publically available. In conclusion, chicken antibody FR residues are highly interchangeable and this property can be applied for improving the physicochemical property of antibody including thermal stability, solubility and viscosity.
Subject(s)
Amino Acids , Antibodies , Chickens , Immunoglobulin Variable Region , Solubility , Somatic Hypermutation, Immunoglobulin , ViscosityABSTRACT
The hyper immunoglobulin M syndromes(HIGM) are a heterogeneous group of genetic disorders resulting in defects of immunoglobulin class switch recombination,with or without defects of somatic hypermutation.They can be classified as defects of signalling through CD40 causing combined immunodeficiency,or intrinsic defects in B cells of the mechanism of class switch recombination resulting in a pure humoral immunodeficiency.This review summarizes the molecular pathogenesis of HIGM.
ABSTRACT
Chronic lymphocytic leukaemia (CLL) is a haematological malignancy for which reliable prognostic markers are needed in view of its clinical heterogeneity. In approximately 50 percent of CLL patients, immunoglobulin (Ig) rearrangements are modified by somatic hypermutation (SHM), a process that represents a reliable prognostic indicator of favourable progression. In this study, we investigated SHM in 37 Brazilian CLL patients and identified the preferential involvement of specific immunoglobulin gene families and segments through PCR-amplified fragments or subcloned fragments. Forty-one rearrangements were observed and 37 of them were functional. A 98 percent homology cut-off with germinal sequences showed 18 patients (48.7 percent) with SHM. Unmutated cases showed a poorer clinical outcome. V H3 was the most frequent V H family, followed by V H4. The V H4-39 segment was the most frequently used, mainly in unmutated cases, while the V H3 family was predominant in mutated cases. The D3 and J H4/J H6 families were the most frequently observed.