40 research outputs found
Live Recombinant Salmonella Typhi Vaccines Constructed to Investigate the Role of rpoS in Eliciting Immunity to a Heterologous Antigen
We hypothesized that the immunogenicity of live Salmonella enterica serovar Typhi vaccines expressing heterologous antigens depends, at least in part, on its rpoS status. As part of our project to develop a recombinant attenuated S. Typhi vaccine (RASTyV) to prevent pneumococcal diseases in infants and children, we constructed three RASTyV strains synthesizing the Streptococcus pneumoniae surface protein PspA to test this hypothesis. Each vector strain carried ten engineered mutations designed to optimize safety and immunogenicity. Two S. Typhi vector strains (χ9639 and χ9640) were derived from the rpoS mutant strain Ty2 and one (χ9633) from the RpoS+ strain ISP1820. In χ9640, the nonfunctional rpoS gene was replaced with the functional rpoS gene from ISP1820. Plasmid pYA4088, encoding a secreted form of PspA, was moved into the three vector strains. The resulting RASTyV strains were evaluated for safety in vitro and for immunogenicity in mice. All three RASTyV strains were similar to the live attenuated typhoid vaccine Ty21a in their ability to survive in human blood and human monocytes. They were more sensitive to complement and were less able to survive and persist in sewage and surface water than their wild-type counterparts. Adult mice intranasally immunized with any of the RASTyV strains developed immune responses against PspA and Salmonella antigens. The RpoS+ vaccines induced a balanced Th1/Th2 immune response while the RpoS− strain χ9639(pYA4088) induced a strong Th2 immune response. Immunization with any RASTyV provided protection against S. pneumoniae challenge; the RpoS+ strain χ9640(pYA4088) provided significantly greater protection than the ISP1820 derivative, χ9633(pYA4088). In the pre-clinical setting, these strains exhibited a desirable balance between safety and immunogenicity and are currently being evaluated in a Phase 1 clinical trial to determine which of the three RASTyVs has the optimal safety and immunogenicity profile in human hosts
A complex MLL rearrangement identified five years after initial MDS diagnosis results in out-of-frame fusions without progression to acute leukemia
Chromosomal rearrangements of the MLL gene are uncommon in myelodysplastic syndromes (MDSs), and few studies of their molecular structures and oncogenic mechanisms exist. Here, we present a case of de novo MDS with a normal karyotype at initial diagnosis and a mild clinical course. Five years after the initial diagnosis, investigators identified a complex rearrangement of the MLL gene without progression to acute leukemia. The 5' part of the MLL gene is fused out of frame with the LOC100131626 gene, and the 3' part of the MLL gene out of frame with the TCF12 gene. Rapid amplification of complementary DNA 3' ends yielded two main fusion transcripts, which is in concordance with the two described isoforms of the LOC100131626 gene. For both isoform-fusion transcripts, the open reading frame terminates shortly after the breakpoint that is predicted to form two de facto truncated MLL proteins and disrupts the open reading frame of the LOC100131626, TCF12, and UBE4A genes. Neither dimerization nor a transcriptional activation domain, each of which is causally linked to MLL protein-mediated transformation, is present. This and other unusual MLL rearrangements probably represent a subclass of MLL gene abnormalities that have intrinsically no ability or only a weak ability to transform hematopoeitic cells and are identified only in the context of other hematopoetic malignancies.link_to_subscribed_fulltex
Blood
MLL translocations in adult B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) are largely restricted to the immature CD10– immunophenotypes. MLL-AF4 is known to be the most frequent fusion transcript, but the exact frequencies of MLL aberrations in CD10– adult BCP-ALL are unknown. We present a genetic characterization of 184 BCR-ABL– CD10– adult ALL cases (156 cyIg–, 28 cyIg+) diagnosed between 2001 and 2007 at the central diagnostic laboratory of the GMALL study group. Patient samples were investigated by RT-PCR for MLL-AF4, MLL-ENL, and MLL-AF9 and by long-distance inverse polymerase chain reaction, thus also allowing the identification of unknown MLL fusion partners at the genomic level. MLL-AF4 was detected in 101 (54.9%) and MLL-ENL in 11 (6.0%) cases. In addition, rare MLL fusion genes were found: 2 MLL-TET1 cases, not previously reported in ALL, 1 MLL-AF9, 1 MLL-PTD, a novel MLL-ACTN4, and an MLL-11q23 fusion. Chromosomal breakpoints were determined in all 118 positive cases, revealing 2 major breakpoint cluster regions in the MLL gene. Characteristic features of MLL+ patients were significantly lower CD10 expression, expression of the NG2 antigen, a higher white blood count at diagnosis, and female sex. Proposals are made for diagnostic assessment. The clinical studies are registered at http://www.clinicaltrials.gov as NCT00199056 [ClinicalTrials.gov] and NCT00198991 [ClinicalTrials.gov]