Serotype-converting bacteriophages and O-antigen modification in Shigella flexneri

O-antigen modification (serotype conversion) in Shigella flexneri, which is an important virulence determinant, is conferred by temperate bacteriophages. Several serotype-converting phages have been isolated and preliminary characterization has identified the genes involved in O-antigen modification, and has also provided insight into the molecular biology of these phages.

Hypogammaglobulinaemia after rituximab treatment-incidence and outcomes

BACKGROUND

Rituximab, a chimeric monoclonal antibody against CD20, is increasingly used in the treatment of B-cell lymphomas and autoimmune conditions. Transient peripheral B-cell depletion is expected following rituximab therapy. Although initial clinical trials did not show significant hypogammaglobulinaemia, reports of this are now appearing in the literature.

METHODS

We performed a retrospective review of patients previously treated with rituximab that were referred to Clinical Immunology with symptomatic or severe hypogammaglobulinaemia. Patient clinical histories, immunological markers, length of rituximab treatment and need for intravenous immunoglobulin replacement therapy (IVIG) were evaluated. An audit of patients receiving rituximab for any condition in a 12-month period and frequency of hypogammaglobulinaemia was also carried out.

RESULTS

We identified 19 post-rituximab patients with persistent, symptomatic panhypogammaglobulinaemia. Mean IgG level was 3.42 ± 0.4 g/l (normal range 5.8-16.3 g/l). All patients had reduced or absent B-cells. Haemophilus Influenzae B, tetanus and Pneumococcal serotype-specific antibody levels were all reduced and patients failed to mount an immune response post-vaccination. Nearly all of them ultimately required IVIG. The mean interval from the last rituximab dose and need for IVIG was 36 months (range 7 months-7 years). Of note, 23.7% of 114 patients included in the audit had hypogammaglobulinaemia.

CONCLUSION

With the increasing use of rituximab, it is important for clinicians treating these patients to be aware of hypogammaglobulinaemia and serious infections occurring even years after completion of treatment and should be actively looked for during follow-up. Referral to clinical immunology services and, if indicated, initiation of IVIG should be considered.

Immune deficiency and autoimmunity in patients with CTLA-4 (CD152) mutations

Immune deficiency disorders are a heterogeneous group of diseases of variable genetic aetiology. While the hallmark of immunodeficiency is susceptibility to infection, it is increasingly clear that autoimmunity is prevalent, suggestive of a more general immune dysregulation in some cases. With the increasing use of genetic technologies, the underlying causes of immune dysregulation are beginning to emerge. Here we provide a review of the heterozygous mutations found in the immune checkpoint protein CTLA-4, identified in cases of common variable immunodeficiency disorders (CVID) with accompanying autoimmunity. Study of these mutations provides insights into the biology of CTLA-4 as well as suggesting approaches for rational treatment of these patients.

Identification and sequence of rfbS and rfbE, which determine antigenic specificity of group A and group D salmonellae

Salmonella group A, group B, and group D strains have paratose, abequose, and tyvelose, respectively, as the immunodominant sugar in their O antigens, which are otherwise identical; only the final steps differ in the biosynthetic pathways of these sugars. The gene rfbJ from a group B strain, encoding abequose synthase, the final and only unique step in the biosynthesis of CDP-abequose, has been cloned and sequenced (P. Wyk and P. Reeves, J. Bacteriol. 171:5687-5693, 1989). In this study, we locate and sequence rfbS and rfbE from serovars typhi and paratyphi, representative of groups A and D. Gene rfbS is present in both groups and encodes paratose synthase, which carries out a step parallel to that of abequose synthase, but the product is CDP-paratose. The DNA and inferred amino acid sequences are compared with those of rfbJ. We conclude that the genes are homologous, but the divergence is extremely ancient. Gene rfbE encodes CDP-tyvelose epimerase, which converts CDP-paratose to CDP-tyvelose in group D strains; the gene is active in group D strains, and we find it to be present in a mutant form in group A strains. These two genes encode the steps unique to groups A and D and, like rfbJ of group B, are of low G+C content, suggesting transfer from outside of salmonellae. The evolutionary origin of these genes is discussed.

Molecular characterization of the O-acetyl transferase gene of converting bacteriophage SF6 that adds group antigen 6 to Shigella flexneri

Bacteriophage SF6 antigenically converts Shigella flexneri serotype Y strains (-;3,4) to type 3b carrying group antigen 6,3,4 by means of an O-acetylation of the O-antigenic polysaccharide chain. The gene for O-acetyl transferase of bacteriophage SF6 has been cloned, identified and sequenced. The predicted O-acetyl transferase protein encoded by this gene was found to consist of 333 amino acids, (37,185 daltons) and to have some similarity with the galactose-1-phosphate uridylyltransferase protein of Escherichia coli. The gene has been shown to function in a live vaccine strain of S. flexneri Y type (delta aroD), making it a 3b type. The converted type 3b strain, SFL1104, was found to elicit significant protection against challenge by both wild-type serotypes 3b and Y in a guinea-pig keratoconjunctivitis model.

Combination of PUVAsol and topical calcipotriol in vitiligo

BACKGROUND

A large variety of therapeutic agents are being tried for the treatment of vitiligo, but psoralens continue to be mainstay of treatment although they are not uniformly effective. Recent advances in pathophysiology have established a perturbed calcium homeostasis in affected skin, and melanocytes were shown to express vitamin D3 receptors.

OBJECTIVE

The purpose of present study was to determine the efficacy of the combination of PUVAsol with topical calcipotriol in the treatment of vitiligo.

METHODS

Nineteen patients with essentially bilateral symmetrical lesions were enrolled in a randomized, double-blind, right/left comparative study of 18 months duration. An oral dose of 0.6 mg/kg 8-methoxypsoralen was given 2 h before exposure to sunlight thrice weekly to all patients. The patients were advised to apply calcipotriol (50 microgram/g) on one side of the body and placebo ointment over the lesions on the other side twice daily.

RESULTS

At the end of 6 months, 12 patients (70%) showed marked to complete improvement on calcipotriol-treated sides as compared to 6 patients (35%) showing similar improvement on placebo-treated sides (p <0.05). At the end of treatment, 13 patients (76%) showed marked improvement in calcipotriol-treated lesions whereas 9 patients (53%) showed moderate to marked improvement in placebo-treated lesions. The repigmentation of hands and feet was much better with the combination of PUVAsol and calcipotriol.

CONCLUSION

The combination of PUVA and calcipotriol is highly effective and works faster and may be used for shortening the therapy with PUVA in the treatment of vitiligo.

Mechanical properties of a self-assembling oligopeptide matrix

We have begun studies of a novel type of biomaterial derived from a recently-discovered class of ionic self-complementary oligopeptides. These short peptides (typically 8, 16, 24, or 32 amino acid residues with internally-repeating sequences) self-assemble in aqueous salt solution into three-dimensional matrices capable of favorable interactions with cells, and offer promise for useful bioengineering design based on rational changes in sequence. In this paper we present preliminary results on mechanical properties, combining experimental and theoretical approaches, of one particular example of these peptide materials, EFK8. The static elastic modulus was measured using an apparatus designed to allow sample fabrication and mechanical testing in the same system with the sample in aqueous solution. The material microstructure was examined by SEM and the measurements interpreted with the aid of a model for cellular solids. Values for the elastic modulus increased from 1.59 +/- 0.06 to 14.7 +/- 1.0 kPa for peptide concentrations increasing from 2.7 to 10 mg ml-1. SEM photographs showed the microstructure to consist of a relatively homogeneous lattice with fiber thickness of 10-30 nm independent of peptide concentration, but with fiber density increasing with peptide concentration. This behavior is consistent with scaling predictions from the cellular solids model and yields an estimate for the individual fiber elastic modulus in the range of 1-20 MPa. We therefore have provided some initial physical principles for guiding improvement of the mechanical properties of these new materials.

Relationships among the rfb regions of Salmonella serovars A, B, and D

The O antigens of Salmonella serogroups A, B, and D differ structurally in their side chain sugar residues. The genes encoding O-antigen biosynthesis are clustered in the rfb operon. The gene rfbJ in strain LT2 (serovar typhimurium, group B) and the genes rfbS and rfbE in strain Ty2 (serovar typhi, group D) account for the known differences in the rfb gene clusters used for determination of group specificity. In this paper, we report the nucleotide sequence of 2.9 kb of DNA from the rfb gene cluster of strain Ty2 and the finding of two open reading frames which have limited similarity with the corresponding open reading frames of strain LT2. These two genes complete the sequence of the rfb region of group D strain Ty2 if we use strain LT2 sequence where restriction site data show it to be extremely similar to the strain Ty2 sequence. The restriction map of the rfb gene cluster in group A strain IMVS1316 (serovar paratyphi) is identical to that of the cluster in strain Ty2 except for a frameshift mutation in rfbE and a triplicated region. The rfb gene clusters of these three strains are compared, and the evolutionary origin of these genes is discussed.

Enzymatic synthesis and isolation of thymidine diphosphate-6-deoxy-D-xylo-4-hexulose and thymidine diphosphate-L-rhamnose. Production using cloned gene products and separation by HPLC

A two-step enzymatic synthesis of dTDP-L-rhamnose is developed using enzymes from sonicated extracts of cultures of Escherichia coli K12 strains harboring plasmids containing different parts of the rfb gene cluster of Salmonella enterica LT2. The intermediate dTDP-6-deoxy-D-xylo-4-hexulose was isolated after a 1-h reaction, using only dTDP-D-glucose and dTDP-D-glucose 4,6-dehydratase, followed by protein precipitation and desalting by gel chromatography (yield 89%). In a two-step reaction using dTDP-D-glucose and dTDP-D-glucose 4,6-dehydratase in the first step, and with NADPH, dTDP-6-deoxy-D-xylo-4-hexulose 3,5-epimerase and NADPH:dTDP-6-deoxy-L-lyxo-4-hexulose-4-reductase in the second hour of incubation, the dTDP-D-glucose was fully converted to dTDP-L-rhamnose. The hexoses of both products were identified by mass spectroscopy. The molar yield of dTDP-L-rhamnose, after protein precipitation, anion-exchange chromatography and desalting by gel chromatography, was 62%, corresponding to more than 150 mg, starting from 250 mg of dTDP-D-glucose. When stored lyophilysed under nitrogen, these products were found to be stable for several months. Both dTDP-6-deoxy-D-xylo-4-hexulose and dTDP-L-rhamnose have light absorption maxima at 267 nm, with molar absorption coefficients close to that of dTMP. However, the absorption coefficient of dTDP-6-deoxy-D-xylo-4-hexulose at the absorption maximum of 320 nm (specific for sugars containing keto groups) was found to be approximately 20% higher than values presented earlier. Furthermore, an HPLC technique is presented for determining the net activity of dTDP-6-deoxy-D-xylo-4-hexulose 3,5-epimerase and NADPH:dTDP-6-deoxy-L-lyxo-4-hexulose-4-reductase, based on separation of dTDP-6-deoxy-D-xylo-4-hexulose and dTDP-L-rhamnose. The HPLC technique is also suitable for determination of all the nucleotide components involved in the synthesis.

Molecular characterization of the genes involved in O-antigen modification, attachment, integration and excision in Shigella flexneri bacteriophage SfV

Bacteriophage SfV is a temperate phage of Shigella flexneri responsible for converting serotype Y (3,4) to serotype 5a (V; 3,4) through its glucosyl transferase gene. The glucosyl transferase (gtr) gene of SfV has been cloned and shown to partially convert S. flexneri serotype Y to serotype 5a. In this study, we found that the serotype-converting region of SfV was approximately 2.5 kb in length containing three continuous ORFs. The recombinant strain carrying the three complete ORFs expressed the type V and group antigen 3,4, both indistinguishable from that of S. flexneri 5a wild-type strain. The interruption of orf5 or orf6 gave partial conversion in the S. flexneri recombinant strain indicated by the incomplete replacement of group antigen 3,4. The region adjacent to the serotype-conversion genes was found to be identical to the attP-int-xis region of phage P22. Altogether, an approximately 2.2-kb sequence covering a portion of the serotype-conversion (approximately 500 nt)-attP-int-xis regions of SfV was remarkably similar to that of P22.

The major histocompatibility complex in bovines: a review

Productivity in dairy cattle and buffaloes depends on the genetic factors governing the production of milk and milk constituents as well as genetic factors controlling disease resistance or susceptibility. The immune system is the adaptive defense system that has evolved in vertebrates to protect them from invading pathogens and also carcinomas. It is remarkable in the sense that it is able to generate an enormous variety of cells and biomolecules which interact with each other in numerous ways to form a complex network that helps to recognize, counteract, and eliminate the apparently limitless number of foreign invading pathogens/molecules. The major histocompatibility complex which is found to occur in all mammalian species plays a central role in the development of the immune system. It is an important candidate gene involved in susceptibility/resistance to various diseases. It is associated with intercellular recognition and with self/nonself discrimination. It plays major role in determining whether transplanted tissue will be accepted as self or rejected as foreign.

Visual loss in immunocompetent patients with Cryptococcus neoformans var. gattii meningitis

In Papua New Guinea cryptococcal meningitis occurs predominantly in immunocompetent patients in whom Cryptococcus neoformans var, gattii is implicated in 95% of cases. Ocular complications are common. We have reviewed ophthalmic findings in 82 immunocompetent patients and have attempted to identify those features of the disease that predict an unfavourable visual outcome. Visual loss occurred in 52.6% of survivors and was associated with optic atrophy following optic disc swelling in 60.9%. Progression of disc swelling to optic atrophy was predicted by the presence of an abducens palsy (P = 0.049) and cerebrospinal fluid (CSF) cryptococcal antigen titres > 1:1024 (P = 0.036). Raised intracranial pressure (defined as opening CSF pressure > or = 300 mm on admission) was not associated with visual loss. Vision deteriorated in 17.3% of patients despite anticryptococcal therapy and in 3.7% it followed curative therapy. The high rate of visual loss in immunocompetent patients with C. neoformans var. gattii infection contrasts with others' experience of immunosuppressed patients with C. neoformans var. neoformans infection, in whom visual loss was rare. This difference may reflect immune mediated optic nerve dysfunction in C. neoformans var. gattii meningitis caused by either compression due to arachnoid adhesions or oedema and inflammatory cell-mediated damage.

Pharmacokinetics of valproic acid in young and elderly subjects

The disposition of valproic acid was studied following single dose intravenous administration in seven young male volunteers aged 20-35 years and six elderly male in-patients aged 75-87 years. Following administration of 400 mg sodium valproate, blood samples were collected for 48 h and valproic acid concentrations analysed by enzymatic immunoassay. The median elimination half-life was 7.2 h in the young subjects but 14.9 h in the elderly patients (P less than 0.01). However, clearance did not differ significantly between groups, the values for young and old being 0.69 and 0.58 1/h respectively. The prolonged half-life resulted from a greater volume of distribution in the elderly. The median values (1/kg) for young and old were 0.13 and 0.19 respectively (P less than 0.01). These pharmacokinetic changes are unlikely to be of clinical importance.

Treatment with interleukin-4 prolongs allogeneic neonatal heart graft survival by inducing T helper 2 responses

BACKGROUND

The T helper (Th) 2 cytokine interleukin (IL)-4 has been implicated as a major regulatory cytokine for the induction of transplant tolerance, but few studies have examined the capacity of IL-4 to induce tolerance. The effect of IL-4 therapy alone or with low doses of anti-CD4 monoclonal antibody (mAb) therapy on survival of fully allogeneic PVG neonatal heart graft in adult DA rats was examined.

METHODS

Rat recombinant (r) IL-4 was given at 30 microg (10(4) U)/kg daily intraperitoneally for 10 days and MRC OX35 (anti-CD4, nondepleting) or MRC OX81 (anti-IL-4) was given intraperitoneally on days 0, 3, 7, and 10. Semiquantitative reverse transcriptase-polymerase chain reaction was used to assay mRNA for cytokine in the graft, regional node and spleen and fluorescence-activated cell sorting was used to assay alloantibody Ig isotypes.

RESULTS

Grafts in rIL-4-treated rats survived a median period of 39 days (range, 28-52 days), significantly longer than in both untreated and nontransfected Chinese hamster ovary-K1 supernatant-treated controls (median, 14 days; range, 10-16 days, P=0.009). rIL-4 treatment with a suboptimal dose of anti-CD4 mAb prolonged median survival to 70 days (range, 63-80 days), which was longer than rIL-4 treatment alone or anti-CD4 mAb alone (median, 36 days; range, 30-55 days; P<0.0045). Combining MRC OX81 with MRC OX35 therapy led to earlier rejection at a median period of 26 days (range, 20-28 days); MRC OX81 alone had no effect on graft survival. Alloantibody titers, especially IgG1, were higher in rIL-4-treated animals and lower in anti-CD4 mAb-treated animals than in animals with normal rejection (P<0.05). IL-4 mRNA was increased in regional lymph nodes and spleen of the rIL-4-treated groups compared with all other groups, but there were no differences for IL-2, interferon-gamma, or IL-10.

CONCLUSIONS

rIL-4 therapy markedly prolonged neonatal cardiac allograft survival, and, with anti-CD4 therapy, it further prolonged survival. It induced IL-4 mRNA in lymphoid tissues and enhanced alloantibody production, especially IgG1, which demonstrated enhanced Th2 responses, but did not affect Th1 cytokines.

Bioactivities of the leaf essential oil of Curcuma longa (var. ch-66) on three species of stored-product beetles (Coleoptera)

Essential oil extracted from the leaves of turmeric, Curcuma longa L., was investigated for contact and fumigant toxicity and its effect on progeny production in three stored-product beetles, Rhyzopertha dominica F. (lesser grain borer), Sitophilus oryzae L. (rice weevil), and Tribolium castaneum Herbst (red flour beetle). Oviposition-deterrent and ovicidal actions of C. longa leaf oil were also evaluated against T. castaneum. The oil was insecticidal in both contact and fumigant toxicity assays. The adults of R. dominica were highly susceptible to contact action of C. longa leaf oil, with LD50 value of 36.71 microg/mg weight of insect, whereas in the fumigant assay, adults of S. oryzae were highly susceptible with LC50 value of 11.36 mg/liter air. Further, in T. castaneum, the C. longa oil reduced oviposition and egg hatching by 72 and 80%, respectively at the concentration of 5.2 mg/cm2. At the concentration of 40.5 mg/g food, the oil totally suppressed progeny production of all the three test insects. Nutritional indices indicate >81% antifeedant action of the oil against R. dominica, S. oryzae and T castaneum at the highest concentration tested.

O-antigen variation in Salmonella spp.: rfb gene clusters of three strains

The O antigens of Salmonella serogroups A, B, and D differ structurally in their side-chain sugar residue. These genes encoding O-antigen biosynthesis are clustered in the rfb operon. We report here the molecular cloning and analysis of the rfb operons of Salmonella paratyphi A (serogroup A) and S. typhi (serogroup D). The regions of DNA nonhomology between the rfb operons of these serogroup A, B, and D representatives are identified, and the evolutionary derivation of serogroup A from a serogroup D progenitor is discussed.

Antifungal anthraquinones from Saprosma fragrans

A new 3,4-dihydroxy-1-methoxy anthraquinone-2-corboxaldehyde (1) together with a known anthraquinone, damnacanthal (2), were isolated from the chloroform fraction of the aerial part (whole plant without root) of Saprosma fragrans. The isolated anthraquinones (1) and (2) were found to exhibit antifungal activity against Trichophyton mentagrophytes and Sporitrichum schenckii. Their structures were established by chemical and spectral analysis.

Experience with dose escalation using CHARTWEL (continuous hyperfractionated accelerated radiotherapy weekend less) in non-small-cell lung cancer

Results from the multicentre randomized trial of CHART (continuous, hyperfractionated, accelerated radiotherapy) in non-small-cell lung cancer (NSCLC) showed a significant increase in survival (P=0.004) compared with conventional radiotherapy and a therapeutic benefit relative to late radiation-induced morbidity. However, 60% of patients died because of failure to control locoregional disease. These findings have stimulated interest in assessing the feasibility of dose escalation using a modified CHART schedule. Acute and late morbidity with a CHARTWEL (CHART WeekEnd Less) schedule of 54 Gy in 16 days was compared with that observed with 60 Gy in 18 days in patients with locally advanced NSCLC. The incidence and severity of dysphagia and of analgesia were scored using a semiquantitative clinical scale. Late radiation-induced morbidity, namely pulmonary, spinal cord and oesophageal strictures, were monitored using clinical and/or radiological criteria. Acute dysphagia and the analgesia required to control the symptoms were more severe and lasted longer in patients treated with CHARTWEL 60 Gy (P< or = 0.02). However, at 12 weeks, oesophagitis was similar to that seen with 54 Gy and did not lead to consequential damage. Early radiation pneumonitis was not increased but, after 6 months, there was a higher incidence of mild pulmonary toxicity compared with CHARTWEL 54 Gy. No cases of radiation myelitis, oesophageal strictures or of grade 2 or 3 lung morbidity have been encountered. CHARTWEL 60 Gy resulted in an enhancement of oesophagitis and grade 1 lung toxicity compared with CHARTWEL 54 Gy. These were of no clinical significance, but may be important if CHARTWEL is used with concomitant chemotherapy. These results provide a basis for further dose escalation or the introduction of concurrent chemotherapy.

The effect of corticosteroids on visual loss in Cryptococcus neoformans var. gattii meningitis

In Papua New Guinea visual loss is a frequent sequal to Cryptococcus neoformans var. gattii meningitis in immunocompetent patients. We have previously postulated that visual loss may occur as a result of the immunological response to infection around the optic nerve. This retrospective study set out to explore the effect of corticosteroids on visual outcome. Sixteen patients received varying doses of corticosteroid (mainly 100-250 mg of hydrocortisone daily for the prevention of febrile reactions to amphotericin) and 10 received anticryptococcal therapy alone. Visual deterioration occurred less frequently in those treated with corticosteroids (2/16 [12.5%] vs. 7/10 [70%], P = 0.007), blindness was less frequent (1/16 [5.3%] vs. 5/10 [50%], P = 0.018), and in 3 patients vision improved. Corticosteroids may have a role in preventing or halting visual loss in C. neoformans var. gattii meningitis in immunocompetent patients.

Leishmania donovani in blood smears of asymptomatic persons

Leishmania amastigotes have been detected in the peripheral blood smears of Indian kala-azar patients mostly during night. It was, therefore, thought worthwhile to find out whether such amastigotes could be shown in healthy subjects who did not have any symptoms by history or signs on clinical examination. Leishmania-stained blood smears of 450 asymptomatic healthy individuals residing in an endemic village in Bihar (India) were examined by oil-immersion microscopy for the detection of amastigote, six people (1.3%) showed the presence of Leishmania amastigotes. Given the low sensitivity of a single smear examination it is likely that a much greater proportion of asymptomatic persons had parasitemia than the observed 1.3%. This finding is important from the point of view of transmission of disease, as also for modifying the current control measures.

Improving access to specialist care for remote Aboriginal communities: evaluation of a specialist outreach service

OBJECTIVE

To identify barriers faced by Aboriginal people from remote communities in the Northern Territory (NT) when accessing hospital-based specialist medical services, and to evaluate the impact of the Specialist Outreach Service (SOS) on these barriers.

DESIGN

Combined quantitative and qualitative study.

SETTING

Remote Aboriginal communities in the "Top End" of the NT, 1993-1999 (spanning the introduction of the SOS in 1997).

PARTICIPANTS

25 remote health practitioners, patients and SOS specialists.

MAIN OUTCOME MEASURES

Numbers of consultations with specialists; average cost per consultation; perceived barriers to accessing hospital-based outpatient care; and perceived impact of specialist outreach on these barriers.

RESULTS

Perceived barriers included geographic remoteness, poor doctor-patient communication, poverty, cultural differences, and the structure of the health service. Between 1993 and 1999, there were 5,184 SOS and non-SOS outreach consultations in surgical specialties. Intensive outreach practice (as in gynaecology and ophthalmology) increased total consultations by up to 441% and significantly reduced the number of transfers to hospital outpatient clinics (P< 0.001). Average cost per consultation was $277 for SOS consultations, compared with $450 at Royal Darwin Hospital and $357 at the closest regional hospital. Outreach has reduced barriers relating to distance, communication and cultural differences, and potentially bolsters existing primary healthcare services.

CONCLUSIONS

When compared with hospital-based outpatient services alone, outreach is a more accessible, appropriate and efficient method of providing specialist medical services to remote Aboriginal communities in the NT.

Oral miltefosine for Indian post-kala-azar dermal leishmaniasis: a randomised trial

OBJECTIVE

Standard treatment of Indian post-kala-azar dermal leishmaniasis (PKDL) is unsatisfactory because to achieve therapeutic effectiveness, heroic courses of parenteral and toxic agents have to be administered. Our objective was to evaluate oral miltefosine for its potential to provide effective as well as tolerable treatment for this disease.

METHOD

Open-label, randomised, parallel-group multicentric trial. Miltefosine, 100 mg/day to all but one patient, was administered for 12 weeks or 8 weeks, with a target of 18 patients in each treatment group. Key endpoints were tolerance during treatment and efficacy at 12 months of follow-up.

RESULTS

The ITT and per-protocol cure rates after 12 months of follow-up for patients receiving 12 weeks of therapy were 78% (14 of 18 patients: 95% CI = 61-88%) and 93% (14 of 15 patients: 95% CI = 71-95%), respectively, after 12 months of follow-up. The ITT and per-protocol cure rates for patients receiving 8 weeks of therapy were 76% (13 of 17 patients: 95% CI = 53-90%) and 81% (13 of 16 patients: 95% CI = 57-93%), respectively. Gastrointestinal and other adverse events were rare.

CONCLUSIONS

This study suggests that oral miltefosine for 2-3 months can be considered a treatment of choice for Indian PKDL.

Delivery of class I and class II MHC-restricted T-cell epitopes of listeriolysin of Listeria monocytogenes by attenuated Salmonella

Using a Salmonella vaccine-Listeria infection model of intracellular infection, we studied the capacity of an attenuated strain of Salmonella carrying T-cell epitopes of listeriolysin (LLO) of L. monocytogenes to elicit epitope-specific T-cell responses. Class II (LLO 215-226) or class I (LLO 91-99) MHC-restricted T-cell epitopes of LLO were inserted within a central, hypervariable domain of the flagellin protein of an attenuated delta aroA Salmonella dublin strain. T cells from Listeria-immunized mice were activated by lysates or heat-killed preparations of Salmonella construct expressing the LLO 215-226 epitope, indicating that LLO 215-226 is processed and presented to T cells when offered to antigen-presenting cells as part of a flagellin-epitope fusion protein. The chimeric flagellin genes were integrated into the chromosome of the flagellin-negative S. dublin strain to obtain stable expression of the epitopes. Immunization with the living, chromosomally integrated Salmonella construct carrying LLO 215-226 epitope as part of the flagellin protein generated T cells reactive with the corresponding LLO peptide, indicating that this chimera can stimulate a class-specific immune response in vitro. The effect of flanking residues on the processing and presentation of MHC class I LLO 91-99 epitope was studied using Salmonella vaccine strains that express chimeric flagellins containing one of three LLO 91-99 inserts: 91-99 (normal flagellin amino acids as flanking residues); KK91-99KK (Lys-Lys flanking residues); and AAA91-99AAA (Ala-Ala-Ala flanking residues).(ABSTRACT TRUNCATED AT 250 WORDS)

Serotype 1a O-antigen modification: molecular characterization of the genes involved and their novel organization in the Shigella flexneri chromosome

The factors responsible for serotype 1a O-antigen modification in Shigella flexneri were localized to a 5.8-kb chromosomal HindIII fragment of serotype 1a strain Y53. The entire 5.8-kb fragment and regions up- and downstream of it (10.6-kb total) were sequenced. A putative three-gene operon, which showed homology with other serotype conversion genes, was identified and shown to confer serotype 1a O-antigen modification. The serotype conversion genes were flanked on either side by phage DNA. Multiple insertion sequence (IS) elements were located within and upstream of the phage DNA in a composite transposon-like structure. Host DNA homologous to the dsdC and the thrW proA genes was located upstream of the IS elements and downstream of the phage DNA, respectively. The sequence analysis indicates that the organization of the 10.6-kb region of the Y53 chromosome is unique and suggests that the serotype conversion genes were originally brought into the host by a bacteriophage. Several features of this region are also characteristic of pathogenicity islands.

Shigella flexneri type-specific antigen V: cloning, sequencing and characterization of the glucosyl transferase gene of temperate bacteriophage SfV

With lysogeny by bacteriophage SfV, Shigella flexneri serotype Y is converted to serotype 5a. The glucosyl transferase gene (gtr) from bacteriophage SfV of S. flexneri, involved in serotype-specific conversion, was cloned and characterized. The DNA sequence of a 3.7 kb EcoRI-BamHI fragment of bacteriophage SfV which includes the gtr gene was determined. This gene, encoding a polypeptide of 417 aa with 47.67 kDa molecular mass, caused partial serotype conversion of S. flexneri from serotype Y to type V antigen as demonstrated by Western blotting and the sensitivity of the hybrid strain to phage Sf6. The deduced protein of the partially sequenced open reading frame upstream of the gtr showed similarity to various glycosyl transferases of other bacteria. Orf3, separated from the gtr by a non-coding region and transcribed convergently, codes for a 167 aa (18.8 kDa) protein found to have homology with tail fibre genes of phage lambda and P2.