Three chromosomal forms of Anopheles gambiae s.s., designated as Bamako, Mopti and Savanna, were studied for diagnostic PCR assays based on the analysis of the X-linked ribosomal DNA (rDNA). The study was performed on a 1.3 kb fragment containing part of the 28S coding region and part of the intergenic spacer region. The amplified material was cut with fourteen restriction enzymes to detect Restriction Fragment Length Polymorphisms (RFLPs). The enzymes Tru9I and HhaI produced patterns of DNA bands which differentiated Mopti from Savanna and Bamako; moreover, a distinct 'hybrid' pattern was recognized in the F1 female progeny from the cross of Mopti with either one of the other two chromosomal forms. The diagnostic significance of the PCR-RFLP assay was verified on 203 karyotyped females from field samples collected in two villages in Mali and one village in Burkina Faso. Agreement was observed between the chromosomal and the molecular identifications. No 'hybrid' molecular patterns were detected even among carriers of rare heterokaryotypes hypothetically produced by crosses between Mopti and Savanna. The results confirm previous observations indicating barriers to gene flow within An. gambiae s.s. and supporting the specific status of the taxonomic units proposed on cytogenetic ground.

The sequence of a 2.3 kb long DNA segment derived from the 5'-most end of the ribosomal intergenic spacer was determined in three chromosomal forms of Anopheles gambiae s.s. The analysis revealed that the sequence of the Mopti form differed from that of the Bamako and Savanna forms by a total of ten nucleotide substitutions. Using these sequence variations we set up a diagnostic polymerase chain reaction (PCR) assay to distinguish mosquitoes belonging to the three chromosomal forms, facilitating studies on the distribution and the ecology of these incipient taxa. The assay also allows to distinguish whether a given specimen could represent a heterozygote between Mopti and Savanna or Bamako.

BackgroundIn order to improve malaria control, and under the aegis of WHO recommendations, many efforts are being devoted to developing new tools for identifying geographic areas with high risk of parasite transmission. Evaluation of the human antibody response to arthropod salivary proteins could be an epidemiological indicator of exposure to vector bites, and therefore to risk of pathogen transmission. In the case of malaria, which is transmitted only by anopheline mosquitoes, maximal specificity could be achieved through identification of immunogenic proteins specific to the Anopheles genus. The objective of the present study was to determine whether the IgG response to the Anopheles gambiae gSG6 protein, from its recombinant form to derived synthetic peptides, could be an immunological marker of exposure specific to Anopheles gambiae bites.Methodology/Principal FindingsSpecific IgG antibodies to recombinant gSG6 protein were observed in children living in a Senegalese area exposed to malaria. With the objective of optimizing Anopheles specificity and reproducibility, we designed five gSG6-based peptide sequences using a bioinformatic approach, taking into consideration i) their potential antigenic properties and ii) the absence of cross-reactivity with protein sequences of other arthropods/organisms. The specific anti-peptide IgG antibody response was evaluated in exposed children. The five gSG6 peptides showed differing antigenic properties, with gSG6-P1 and gSG6-P2 exhibiting the highest antigenicity. However, a significant increase in the specific IgG response during the rainy season and a positive association between the IgG level and the level of exposure to Anopheles gambiae bites was significant only for gSG6-P1.Conclusions/SignificanceThis step-by-step approach suggests that gSG6-P1 could be an optimal candidate marker for evaluating exposure to Anopheles gambiae bites. This marker could be employed as a geographic indicator, like remote sensing techniques, for mapping the risk of malaria. It could also represent a direct criterion of efficacy in evaluation of vector control strategies.

A genome-wide expression analysis was undertaken to identify novel genes specifically activated from early stages of gametocytogenesis in Plasmodium falciparum. A comparative analysis was conducted on sexually induced cultures of reference parasite clone 3D7 and its gametocyteless derivative clone F12. Competitive hybridisations on long-oligomer microarrays representing 4488 P. falciparum genes identified a remarkably small number of transcripts differentially produced in the two clones. Upregulation of the mRNAs for the early gametocyte markers Pfs16 and Pfg27 was however readily detected in 3D7, and such genes were used as reference transcripts in a comparative time course analysis of 3D7 and F12 parasites between 30 and 40 h post-invasion in cultures induced to enter gametocytogenesis. One hundred and seventeen genes had expression profiles which correlated to those of pfs16 and pfg27, and Northern blot analysis and published proteomic data identified those whose expression was gametocyte-specific. Immunofluorescence analysis with antibodies against two of these gene products identified two novel parasite membrane associated, sexual stage-specific proteins. One was produced from stage I gametocytes and the second showed peak production in stage II gametocytes. The two proteins were named Pfpeg-3 and Pfpeg-4, for P. falciparum proteins of early gametocytes.

Spatially and temporally controlled expression of inflammatory mediators is critical for an appropriate immune response. In this study, we define the role for interferon regulatory factor 5 (IRF5) in secretion of tumor necrosis factor (TNF) by human dendritic cells (DCs). We demonstrate that DCs but not macrophages have high levels of IRF5 protein, and that IRF5 is responsible for the late-phase expression of TNF, which is absent in macrophages. Sustained TNF secretion is essential for robust T IntroductionTumor necrosis factor (TNF) is one of the major cytokines responsible for effector immune functions. As well as playing a central role in host defense against infection, TNF is a major factor in the pathogenesis of chronic inflammatory disease such as rheumatoid arthritis (RA). Consequently, tightly controlled regulation of its expression is critical for an appropriate immune response. This occurs at the transcriptional and posttranscriptional levels, with transcriptional regulation showing specificity for both stimulus and cell type. 1 The NF-B family of transcription factors (TFs) plays a major role in transcriptional up-regulation of the TNF gene by lipopolysaccharide (LPS) in both mouse and human myeloid cells. [2][3][4][5] Regulation of transcription for many immune genes in response to Toll-like receptor (TLR) signaling involves a combination of NF-B and interferon regulatory factor (IRF) factors. 6 IRFs appear to provide a mechanism for conferring signal specificity to a variety of target gene subsets, with IRF3 being essential for type I interferon (IFN) response, 7 and IRF5 playing a key role in induction of proinflammatory cytokines, including TNF, Consequently, IRF5 Ϫ/Ϫ mice show resistance to lethal shock induced by CpG-B or LPS. 8 Unlike other IRF family members, IRF5 contains 2 nuclear localization signals (NLSs), 1 in the N-terminus and the other in the C-terminus of the protein. This results in low levels of nuclear translocation and therefore weak trans-activation activity of IRF5, even in unstimulated cells. 9 The molecular pathways leading to IRF5 activation are not well understood, but it was shown that TLR signaling induces the formation of MyD88-IRF5-TRAF6 complexes, 8 and is probably followed by phosphorylation of specific sites within the IRF5 C-terminal autoinhibitory domain. 10 Human IRF5 is expressed as multiple spliced variants with distinct cell type-specific expression, cellular localization, differential regulation, and dissimilar functions. 11 Moreover, genetic polymorphisms in the IRF5 gene leading to expression of several unique isoforms have been implicated in autoimmune diseases, including systemic lupus erythematosis (SLE), RA and Sjogren syndrome. 12-15 IRF5 mRNA expression has been detected in B cells, dendritic cells (DCs), monocytes, and natural killer (NK) cells but not in T cells, 11 yet little is known about the IRF5 protein expression in these cells.Here, we demonstrate that human monocytes acquire high levels of IRF5 protein during differentiation into monocyte-d...