During active viscerocutaneous leishmaniasis the anti-P2 humoral response is specifically triggered by the parasite P proteins.

In this work we show that in the sera from dogs naturally infected with the protozoan parasite Leishmania infantum there are antibodies that react specifically against the parasite acidic ribosomal proteins LiP2a and LiP2b, and that each one of the Leishmania P proteins elicits a specific humoral immune response. Using synthetic peptides, the antigenic epitope of these proteins has been mapped in a single region located adjacent to the C-terminal domain highly conserved among the eukaryotic P proteins. The anti-P antibodies elicited during the Leishmania infection do not recognize the conserved C-terminal domain of the parasite P proteins, in contrast with the findings reported in Chagas' disease or systemic lupus erythematosus. The antigenic epitopes of the LiP2a and LiP2b are almost identical in amino acid sequence. No reactivity against Trypanosoma cruzi and human P proteins was found in sera from L. infantum-infected dogs.     

Effects of long-term lamivudine therapy in renal-transplant patients.

BACKGROUND: Following renal transplantation (RT), chronic immunosuppression is associated in hepatitis B virus (HBV) (+) patients with a flare-up of the disease, which might be harmful in the long term. OBJECTIVES: We report on the effect of long-term lamivudine therapy given at an initial daily dose of 100mg in 18 HBV (+) RT patients. RESULTS: When lamivudine therapy was commenced, 14 patients (77%) had an increase in their aspartate (AST) and alanine (ALT) aminotransferase levels. During a mean follow-up, under treatment, of 36.5 +/- 3.5 months (up to 66 months), 10 patients (55%) had a sustained partial (HBV DNA < 4 x 10(5)copies/ml) (n = 4) or complete (HBV DNA < 400 copies/ml) (n = 6) virological response. Overall, 12 virological breakthroughs were observed. Of those who were HBe Ag(+) prior to lamivudine therapy (n = 4), one seroconverted to HBe Ab during therapy. At the last follow-up, AST and ALT levels were normal in 13 patients. When liver biopsy was repeated during treatment (n = 15), the virological responders showed a significant decrease in total Knodell score from 10 +/- 0.6 to 7 +/- 1 (P = 0.04), but no significant change in the stage of fibrosis. Conversely, in those patients with high HBV DNA titers, there were no significant changes in the total Knodell score or in the grade of fibrosis. CONCLUSION: In conclusion, lamivudine therapy is safe in HBV(+)ve renal-transplant patients. However, even if the full and partial virological response rates are still high (55%) in the long term, relapse or primary non-responses occur. The implementation of alternative efficient strategies is warranted.     

Cytokine gene expression in human peripheral blood mononuclear cells stimulated by mannoprotein constituents from Candida albicans.

The expression of cytokine genes in cultures of human peripheral blood mononuclear cells (PBMC) stimulated with mannoprotein constituents (MP) of Candida albicans has been studied by means of S1 nuclease mapping analysis, polymerase chain reaction, and enzyme-linked immunosorbent assay. MP induced early, consistent, and long-lasting production of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha, and IL-6 mRNAs. Similar results were obtained when the same PBMC cultures were stimulated with the purified protein derivative (PPD) from Mycobacterium tuberculosis or with IL-2, although lower levels of IL-6 mRNA were detected in IL-2-stimulated cells than in MP- or PPD-stimulated cells. MP, PPD, and IL-2 induced appreciable levels of granulocyte-macrophage colony-stimulating factor and gamma interferon, but only MP and PPD were able to induce IL-2 mRNA. MP were unable to stimulate a consistent expression of the genes encoding for IL-4, IL-5, and IL-10, while low, sometimes barely detectable levels of these cytokine mRNAs were observed in PPD- or IL-2-stimulated PBMC cultures. When protein synthesis of MP-stimulated PBMC was inhibited by cycloheximide, a superinduction of mRNAs for IL-4 and IL-10 and, more markedly, gamma interferon was observed. Overall, these results highlight the powerful, selective induction of cytokine gene expression by MP constituents of C. albicans in human PBMC cultures, thus providing some functional clues to explain the efficient state of the anticandidal response in normal human subjects.     

Identification of secreted proteins of Mycobacterium tuberculosis by a bioinformatic approach

Proteins secreted by Mycobacterium tuberculosis are usually targets of immune responses in the infected host. Here we describe a search for secreted proteins that combined the use of bioinformatics and phoA' fusion technology. The 3,924 proteins deduced from the M. tuberculosis genome were analyzed with several computer programs. We identified 52 proteins carrying an NH(2)-terminal secretory signal peptide but lacking additional membrane-anchoring moieties. Of these 52 proteins-the TM1 subgroup-only 7 had been previously reported to be secreted proteins. Our predictions were confirmed in 9 of 10 TM1 genes that were fused to Escherichia coli phoA', a marker of subcellular localization. These findings demonstrate that the systematic computer search described in this work identified secreted proteins of M. tuberculosis with high efficiency and 90% accuracy.     

The GAA triplet-repeat sequence in Friedreich ataxia shows a high level of somatic instability in vivo,with a significant predilection for large contractions

Friedreich ataxia is commonly caused by large expansions of a GAA triplet-repeat (GAA-TR) sequence in the first intron of the FRDA gene. We used small-pool PCR to analyze somatic variability among 7190 individual FRDA molecules from peripheral blood DNA of subjects carrying 12 different expanded alleles, ranging in size from 241 to 1105 triplets. Expanded alleles showed a length-dependent increase in somatic variability, with mutation loads ranging from 47% to 78%. We noted a strong contraction bias among long alleles (>500 triplets), which showed a 4-fold higher frequency of large contractions versus expansions. Some contractions were very large; of all somatic mutations scored, approximately 5% involved contractions of >50% of the original allele length, and 0.29% involved complete reversion to the normal/premutation length (< or =60 triplets). These observations contrast sharply with the strong expansion bias seen in expanded CTG triplet repeats in myotonic dystrophy. No somatic variability was detected in >6000 individual FRDA molecules analyzed from 15 normal alleles (8-25 triplets). A premutation allele with 44 uninterrupted GAA repeats was found to be unstable, ranging in size from 6 to 113 triplets, thus establishing the threshold for somatic instability between 26 and 44 GAA triplets. Analysis of an additional 7850 FRDA molecules from serially passaged lymphoblastoid cell lines carrying nine expanded alleles (132-933 triplets) showed very low mutation loads, ranging from 0% to 6.2%. Our data indicate that expanded GAA-TR alleles in Friedreich ataxia are highly mutable and have a natural tendency to contract in vivo, and that these properties depend on multiple factors, including DNA sequence, triplet-repeat length and unknown cell-type-specific factors.     

Intestinal immune response of volunteers ingesting a strain of enteroadherent (HEp-2 cell-adherent) Escherichia coli.

Enteroadherent Escherichia coli (EAEC) strains identified by adherence to HEp-2 tissue culture cells have been incriminated epidemiologically as important etiologic agents of diarrheal disease in both adult travelers and children in developing countries. One strain, JM 221, with no recognized E. coli virulence characteristics other than adherence to HEp-2 cells, caused diarrhea in 5 of 16 volunteers ingesting it. We studied the secretory immunoglobulin A (sIgA) responses to EAEC JM 221 of five volunteers with diarrhea and five volunteers who remained healthy after challenge. sIgA was extracted from stools obtained prechallenge and 7 days postchallenge. Total sIgA was standardized for all specimens. Specific sIgA titers were determined by dot blotting with the following JM 221 antigens: water-extractable surface antigens, whole cells, lipopolysaccharides, and outer membrane proteins. All five subjects who became ill had fourfold or greater rises in titers against each of the four antigens. The five subjects who remained healthy following challenge did not exhibit significant rises in titers to any JM 221 antigens, but their mean titers were significantly higher than the mean prechallenge titers of the volunteers with diarrhea, suggesting that high intestinal sIgA titers may be protective. The significant increases in intestinal antibody against JM 221 in the subjects who became ill is further evidence of the enteropathogenicity of EAEC strains.     

Tuberous sclerosis complex: neonatal deaths in three of four children of consanguineous, non-expressing parents.

We describe here four sibs, born to consanguineous, healthy, asymptomatic parents. Three of these infants had a rapidly fatal course in the neonatal period; death was attributed to congestive heart failure with radiographic evidence of cardiomegaly in all of them. Necropsy was done in only one of them and showed the typical findings of tuberous sclerosis complex (TSC) in the central nervous system (CNS), kidneys, heart, and liver. The fourth sib, currently 2 years old, also has typical signs of TSC, namely hypomelanotic skin macules and calcified subependymal nodules. Both parents and a living maternal grandmother had appropriate examination, which included skin inspection under Wood's lamp, dental examination, fundoscopy, echocardiography, abdominal and renal ultrasound, and head CT and MRI scans, and no signs of TSC were found in either parent or in the only living grandmother. By history alone there is no other relative with signs or symptoms suggestive of TSC. Linkage analysis and loss of heterozygosity (LOH) investigations on a variety of lesions obtained from postmortem and tissue or blood specimens from all available family members studied failed to identify a microdeletion in the chromosomal regions where TSC genes are located. It is very unusual that in a single TSC family there were three consecutive neonatal deaths, and very likely that all had cardiac rhabdomyomas. Moreover, to the best of our knowledge, there are no previous reports of TSC families with more than one affected sib, unusually severe manifestations of the disease, and completely normal, consanguineous parents.