"People are now working together for a common good": The effect on social capital of participatory design for community-level sanitation infrastructure in urban informal settlements

Communities with higher levels of social capital perform better than communities with lower social capital in community-level water and sanitation interventions and have better health outcomes. Although research recommends bolstering social capital to improve intervention outcomes, few studies provide empirical evidence on the effect of intervention activities on social capital. This study aimed to evaluate the effect of participatory design and community engagement activities on social capital among urban informal settlements in Suva, Fiji and Makassar, Indonesia enrolled in the Revitalizing Informal Settlements and their Environments trial using the Short Adapted Social Capital Assessment Tool. We performed confirmatory factor analyses (CFA) to test tool performance and built structural equation models to assess intervention effect on CFA-informed, sub-scale scores for cognitive and structural social capital. Qualitative in-depth interviews in Fiji and Indonesia and focus group discussions in Fiji provided nuanced understanding of intervention effects on social capital from residents' perspectives. Results confirmed the hypothesized two-factor solution but revealed differences by country and by gender in Indonesia. The intervention appeared positively related to cognitive social capital among men and women in Indonesia and negatively related to cognitive and structural social capital among men and women in Fiji. While effect sizes were small and cluster-adjustment for a small number of settlements yielded non-significant effects, trends were consistent across models and bivariate analyses and were corroborated by qualitative findings. Several contextual factors may explain these results, including timing and duration of intervention activities and influence of COVID-19. Qualitative data suggested that the relationship between participatory design and social capital may be bidirectional, helping to explain why certain settlements appeared to be better equipped to benefit from intervention activities. Practitioners and program designers should carefully consider the social pre-conditions of communities in which they intend to work to optimize program outcomes and avoid unintended consequences.

Joint Food and Water Insecurity Had a Multiplicative Effect on Women's Depression in Urban Informal Settlements in Makassar, Indonesia during the COVID-19 Pandemic

BACKGROUND

Women living in urban informal settlements may be particularly vulnerable to the detrimental effects of the COVID-19 pandemic because of increased economic and psychosocial stressors in resource-limited environments.

OBJECTIVES

The objective of this study was to assess the associations between food and water insecurity during the pandemic and depression among women living in the urban informal settlements in Makassar, Indonesia.

METHODS

We implemented surveys at 3 time points among women enrolled in the Revitalizing Informal Settlements and their Environments trial. Depression was measured using the Center for Epidemiologic Studies Depression Scale-10 (CESD-10) between November and December 2019 and again between February and March 2021. Food insecurity was measured using questions from the Innovation for Poverty Action's Research for Effective COVID-19 Reponses survey and water insecurity was measured using the Household Water Insecurity Experiences Short Form. Both were measured between August and September 2020. We built 3 multivariate quantile linear regression models to assess the effects of water insecurity, food insecurity, and joint food and water insecurity during the COVID-19 pandemic on CESD-10 score.

RESULTS

In models with the full sample (n = 323), food insecurity (β: 1.48; 95% CI: 0.79, 2.17), water insecurity (β: 0.13; 95% CI: -0.01, 0.26), and joint food and water insecurity (β: 2.40; 95% CI: 1.43, 3.38) were positively associated with CESD-10 score. In subgroup analyses of respondents for whom we had prepandemic CESD-10 scores (n = 221), joint food and water insecurity (β: 1.96; 95% CI: 0.78, 3.15) maintained the strongest relationship with CESD-10 score. A limitation of this study is that inconsistency in respondents from households across the survey waves reduced the sample size used for this study.

CONCLUSIONS

Our results find a larger association between depression and joint resource insecurity than with water or food insecurity alone, underlining the importance of addressing food and water insecurity together, particularly as they relate to women's mental health and well-being.

Pattern of expression of CDX2 in colorectal cancer and its role in prognosis

Background

CDX2, a nuclear protein, is essential for the proliferation and development of intestinal epithelial cells and is frequently down-regulated during tumorigenesis. We have evaluated the pattern of CDX2 expression in all stages of colorectal cancer (CRC) and its association with prognosis.

Methods

We performed CDX2 staining by immunohistochemistry (IHC) on the available biopsy blocks of patients of CRC registered in our institute from January 2014 to January 2018. CDX2 scoring was done using the semi-quantitative method.

Results

A total of 286 patients were registered during the study period, of which only 110 biopsy blocks were available for staining. Of 110 patients, 77 (70%) had colon cancer and 33 (30%) had rectal cancer. The median age was 54.2 years, with 62 (56.4%) being male and 48 (43.6%) female with a male to female ratio of 1.3:1. In the study cohort, 33 (30%) patients had stage II disease, 30 (27.3%) had stage III, and 47 (42.7%) had stage IV. Seventy-three (66.4%) were positive for CDX2 and 37 (33.4%) were negative. Loss of CDX2 expression was significantly associated with advanced stage, rectal site, poor grade of differentiation, and presence of lymphovascular invasion. With a median follow-up of 16 months, progression-free survival (PFS) at 2 years was 30% for CDX2-negative patients compared to 67% for CDX2-positive patients (P = 0.009), whereas the overall survival (OS) at 2 years was 46% for CDX2-negative versus 77% for CDX2-positive patients (P = 0.01).

Conclusion

Loss of CDX2 expression is associated with advanced stage, higher tumor grade, presence of LVSI, worse PFS, and OS and thereby functions as a poor prognostic factor in CRC.

Pattern of Expression of CDX2 in Colorectal Cancer and its Role in Prognosis: An Ambispective Observational Study

Introduction Caudal-type homeobox 2 (CDX2), a nuclear protein, is essential for the proliferation and development of intestinal epithelial cells and is frequently downregulated during tumorigenesis. CDX2 inhibits cell growth as well as stimulates differentiation by activating intestinal specific genes, thus lack of CDX2 favors tumor growth and aggressiveness.

Objectives We aimed to evaluate the pattern of CDX2 expression in all stages of colorectal cancer (CRC) and study its association with baseline characteristics and prognosis.

Materials and Methods Study was conducted as an ambispective observational study, enrolling cases of CRC retrospectively from January 2014 to July 2016 (30 months), and prospectively during next 18-month period till January 2018. We performed CDX2 staining by immunohistochemistry on the available biopsy blocks of CRC patients during the study period. Total 286 patients were registered during the study period, of which only 110 biopsy blocks were available for staining. CDX2 scoring was done by a semiquantitative method on whole tissue section for the intensity and percentage of the cells showing positivity. Correlation of CDX2 expression was done with baseline clinical and histopathologic characteristics, and survival.

Results Of 110 patients, 77 (70%) constituted colon cancer and 33 (30%) were rectal cancer. The median age was 54.2 years, 62 (56.4%) being male and 48 (43.6%) female with male-to-female ratio 1.3:1. In the study cohort, 33 (30%) patients had stage II disease, 30 (27.3%) stage III, and 47 (42.7%) were stage IV. Seventy-three (66.4%) were positive for CDX2 and 37 (33.4%) were negative. Loss of CDX2 expression was significantly associated with advanced stage, rectal site, poor grade of differentiation, and presence of lymphovascular invasion (LVSI). With median follow-up of 16 months, progression-free survival (PFS) at 2 years was 30% for CDX2 negative patients compared with 67% for CDX2 positive (p = 0.009), while overall survival (OS) at 2 years was 46% for CDX2 negative versus 77% for positive patients (p = 0.01).

Conclusion Loss of CDX2 expression is associated with advanced stage, higher tumor grade, presence of LVSI, and worse PFS and OS and thereby functions as a poor prognostic factor in CRC.

Crystal structure of the dimer of two essential Salmonella typhimurium proteins, YgjD & YeaZ and calorimetric evidence for the formation of a ternary YgjD-YeaZ-YjeE complex

YgjD from COG0533 is amongst a small group of highly conserved proteins present in all three domains of life. Various roles and biochemical functions (including sialoprotease and endonuclease activities) have been ascribed to YgjD and orthologs, the most recent, however, is involvement in the post transcriptional modification of certain tRNAs by formation of N6-threonyl-adenosine (t⁶A) at position 37. In bacteria, YgjD is essential and along with YeaZ, YjeE, and YrdC has been shown to be 'necessary and sufficient' for the tRNA modification. To further define interactions and possible roles for some of this set of proteins we have undertaken structural and biochemical studies. We show that formation of the previously reported heterodimer of YgjD-YeaZ involves ordering of the C-terminal region of YeaZ which extends along the surface of YgjD in the crystal structure. ATPγS or AMP is observed in YgjD while no nucleotide is bound on YeaZ. ITC experiments reveal previously unreported binary and ternary complexes which can be nucleotide dependent. The stoichiometry of the YeaZ-YgjD complex is 1:1 with a K(D) of 0.3 µM. YgjD and YjeE interact only in the presence of ATP, while YjeE binds to YgjD-YeaZ in the presence of ATP or ADP with a K(D) of 6 µM. YgjD doesn't bind the precursors of t⁶A, threonine, and bicarbonate. These results show a more complex set of interactions than previously thought, which may have a regulatory role. The understanding gained should help in deriving inhibitors of these essential proteins that might have potential as antibacterial drugs.

Efficient stabilization of phosphodiester (PO), phosphorothioate (PS), and 2'-O-methoxy (2'-OMe) DNA·RNA hybrid duplexes by amino sugars

Antisense strategies that target DNA·RNA hybrid structures offer potential for the development of new therapeutic drugs. The α-sarcin loop region of the 23S [corrected] rRNA domain has been shown to be a high value target for such strategies. Herein, aminoglycoside interaction with three RNA·DNA α-sarcin targeted duplexes (rR·dY, rR·S-dY, and rR·2'OMe-rY) have been investigated to determine the overall effect of aminoglycoside interaction on the stability, affinity, and conformation of these hybrid duplexes. To this end, UV thermal denaturation, circular dichroism spectroscopy, fluorescence intercalator displacement, and ITC as well as DSC calorimetry experiments were carried out. The results suggest the following. (1) Of all the aminoglycosides studied, neomycin confers the highest thermal stability on all three hybrid duplexes studied. (2) There is no appreciable difference in aminoglycoside-induced thermal stability between the unmodified rR·dY and phophorothioate modified rR·S-dY duplexes. (3) The rR·2'OMe-rY duplexes thermal stability is slightly less than the other two hybrids. (4) In all three duplexes, aminoglycoside-induced thermal stability decreased as the number of amino groups decreased. (5) CD scans revealed similar spectra for the rR·dY and rR·S-dY duplexes as well as a more pronounced A-form signal for the rR·2'OMe-rY duplex. (6) FID assays paralleled the CD results, yielding similar affinity values between the rR·dY and rR·S-dY duplexes and higher affinities with the rR·2'OMe-rY duplex. (7) The overall affinity trend between aminoglycosides and the three duplexes was determined to be neomycin > paromomycin > neamine > ribostamycin. (8) ITC K(a) values revealed similar binding constants for the rR·dY and rR·S-dY duplexes with rR·dY having a K(1) of (1.03 ± 0.58) × 10(7) M(-1) and K(2) of (1.13 ± 0.07) × 10(5) M(-1) while rR·S-dY produced a K(1) of (1.17 ± 0.54) × 10(7) M(-1) and K(2) of (1.27 ± 0.69) × 10(5) M(-1). (8) The rR·2'OMe-rY produced a slightly higher binding constant values with a K(1) of (1.25 ± 0.24) × 10(7) M(-1) and K(2) of (3.62 ± 0.18) × 10(5) M(-1). (9) The ΔT(m)-derived K(Tm) of 3.81 × 10(7) M(-1) for rR·S-dY was in relative agreement with the corresponding K(1) of 1.17 × 10(7) M(-1) derived constant from the fitted ITC. These results illustrate that the increased DNA·RNA hybrid duplex stability in the presence of aminoglycosides can help extend the roles of aminoglycosides in designing modified ODNs for targeting RNA.

Applications of the Charged Aerosol Detector in Compound Management

Recent literature has described the exciting development of a new universal detection technology for high-performance liquid chromatography (HPLC), as well as some exploratory work on its application to quantitative measurement of solutes at millimolar concentrations. The new methodology, known as charged aerosol detection (CAD), has been recognized as a viable alternative to evaporative light-scattering detection and refractive index detection that, like CAD, respond to molecular structures independently of their absorbance, or lack thereof, in the ultraviolet region of the electromagnetic spectrum. In this article, the authors exemplify their use of CAD in-line with HPLC and mass spectrometry (MS) to provide both stand-alone and complementary information that aids decision making for sample storage and processing practices in the compound management setting. Illustrations include monitoring contaminants leached from different plate materials into the solvent dimethyl sulphoxide (DMSO) and profiling the concentrations of solutions destined for liquid storage and dispensing to assays, with the aim of improving processes.

Comparison of ligand-induced conformational changes and domain closure mechanisms, between prokaryotic and eukaryotic dehydroquinate synthases

Dehydroquinate synthase (DHQS) is a potential target for the development of novel broad-spectrum antimicrobial drugs, active against both prokaryotes and lower eukaryotes. Structures have been reported for Aspergillus nidulans DHQS (AnDHQS) in complexes with a range of ligands. Analysis of these AnDHQS structures showed that a large-scale domain movement occurs during the normal catalytic cycle, with a complex series of structural elements propagating substrate binding-induced conformational changes away from the active site to distal locations. Compared to corresponding fungal enzymes, DHQS from bacterial species are both mono-functional and significantly smaller. We have therefore determined the structure of Staphylococcus aureus DHQS (SaDHQS) in five liganded states, allowing comparison of ligand-induced conformational changes and mechanisms of domain closure between fungal and bacterial enzymes. This comparative analysis shows that substrate binding initiates a large-scale domain closure in both species' DHQS and that the active site stereochemistry, of the catalytically competent closed-form enzyme thus produced, is also highly conserved. However, comparison of AnDHQS and SaDHQS open-form structures, and analysis of the putative dynamic processes by which the transition to the closed-form states are made, shows a far lower degree of similarity, indicating a significant structural divergence. As a result, both the nature of the propagation of conformational change and the mechanical systems involved in this propagation are quite different between the DHQSs from the two species.

Neomycin binding to Watson-Hoogsteen (W-H) DNA triplex groove: a model

Neomycin is the most effective aminoglycoside (groove binder) in stabilizing a DNA triple helix. It stabilizes TAT, as well as mixed base DNA triplexes, better than known DNA minor groove binders (which usually destabilize the triplex) and polyamines. Neomycin selectively stabilizes the triplex (in the presence of salt), without any effect on the DNA duplex. (1) Triplex stabilization by neomycin is salt dependent (increased KCl and MgCl(2) concentrations decrease neomycin's effectiveness, at a fixed drug concentration). (2) Triplex stabilization by neomycin is pH dependent (increased pH decreases neomycin's effectiveness, at a fixed drug concentration). (3) CD binding studies indicate approximately 5-7 base triplets/drug apparent binding site, depending upon the structure/sequence of the triplex. (4) Neomycin shows nonintercalative groove binding to the DNA triplex, as evident from viscometric studies. (5) Neomycin shows a preference for stabilization of TAT triplets but can also accommodate CGC(+) triplets. (6) Isothermal titration calorimetry (ITC) studies reveal an association constant of approximately 2 x 10(5) M(-)(1) between neomycin and an intramolecular triplex and a higher K(a) for polydA.2polydT. (7) Binding/modeling studies show a marked preference for neomycin binding to the larger W-H groove. Ring I/II amino groups and ring IV amines are proposed to be involved in the recognition process. (8) The novel selectivity of neomycin is suggested to be a function of its charge and shape complementarity to the triplex W-H groove, making neomycin the first molecule that selectively recognizes a triplex groove over a duplex groove.

Synthesis of aminoglycoside-DNA conjugates

Development of aminoglycoside-nucleic acid conjugates is presented. Synthesis of a DNA dimer covalently linked to kanamycin and neomycin isothiocyanates has been carried out. The development of such conjugates will help couple the sequence specificity of nucleic acids to the electrostatic/shape complementarity of aminoglycoside antibiotics in binding nucleic acid targets.

Pyrene-neomycin conjugate: dual recognition of a DNA triple helix

We report the synthesis of pyrene-neomycin conjugate and its ability to stabilize DNA/RNA triple helices.

Tissue distribution of the human soluble guanylate cyclases

Soluble guanylate cyclase (sGC) is an important component of the NO signaling pathway. Human sGC isoforms alpha(1), alpha(2), and beta(1) show differential mRNA tissue distributions. alpha(1) and beta(1) are expressed in most tissues; however, the alpha(2) isoform shows a more restricted expression pattern with high levels in brain, placenta, spleen, and uterus only. Both alpha subunits exist as multiple transcripts whereas beta(1) exists as a single message. This study reports for the first time the tissue distribution of human sGC message and demonstrates that sGC isoforms are nonuniformly expressed which may be useful if the enzyme is to be exploited as a therapeutic target.

Nitric oxide synthase is expressed in human macrophages during foreign body inflammation

Although nitric oxide (NO) is a well documented effector molecule in rodent macrophages, its significance in human mononuclear phagocytic cells has been controversial. The foreign body inflammatory reaction around loosened joint replacement implants leads to formation of an osteolytic granulomatous pseudo-synovial membrane rich in activated macrophages. We studied 13 specimens of interface membrane tissue collected from revision surgery of aseptically loosened hip and knee prostheses for the presence of inducible NO synthase (iNOS). The presence of iNOS was demonstrated immunohistochemically in 10 of these specimens. Within the tissue this enzyme was confined to macrophages and vascular endothelial cells. iNOS activity was demonstrated biochemically by measuring the calcium-independent generation of citrulline from L-arginine, and the presence of iNOS mRNA was demonstrated using reverse transcriptase polymerase chain reaction. NO synthesis in the interface tissue may be an important factor in the maintenance of the inflammatory and osteolytic processes.

Role of the Bordetella pertussis P.69/pertactin protein and the P.69/pertactin RGD motif in the adherence to and invasion of mammalian cells

The role of the Bordetella pertussis P.69/pertactin protein in mammalian cell adhesion and invasion was investigated. Salmonella strains expressing surface-associated P.69/pertactin from a chromosomally located prn gene were significantly more invasive than isogenic parental strains. This effect was most pronounced in the poorly invasive, semi-rough S. typhimurium strain LB5010. Escherichia coli K-12 strain HB101 harbouring the plasmid p41869D, which encodes the full-length prn gene under the control of the tac promoter on the broad-host-range plasmid pMMB66EH, was significantly more adhesive to HEp-2 and Chinese Hamster Ovary (CHO) cells growing in culture than E. coli HB101(pMMB66EH). However, the ability of E. coli to invade mammalian cells was not affected by P.69/pertactin expression. P.69/pertactin-mediated adhesiveness of HB101 to HEp-2 and CHO cells was not influenced by the viability of the bacterial cells. However, adherence was markedly reduced when assays were performed for less than 3 h, at 4 degrees C or in the presence of cycloheximide, suggesting the active participation of the eukaryotic cell in bacterial adhesion. Site-directed mutagenesis was used to mutate Asp to Glu in an Arg-Gly-Asp (RGD-->RGE) sequence present in mature P.69/pertactin and the mutated gene was cloned in the same broad-host-range vector (plasmid p41869E). This mutation had no detectable influence on the ability of P.69/pertactin to mediate adhesion of HB101 to HEp-2 or CHO cells. Plasmids p41869D and p41869E were introduced into the bvg-negative B. pertussis strain BP347. Expression of P.69RGD or P.69RGE did not enhance the adhesiveness of BP347 for epithelial (HEp-2 and CHO) cells.

Identification of the domains of neuronal nitric oxide synthase by limited proteolysis

Nitric oxide synthase (EC 1.14.13.39) binds arginine and NADPH as substrates, and FAD, FMN, tetrahydrobiopterin, haem and calmodulin as cofactors. The protein consists of a central calmodulin-binding sequence flanked on the N-terminal side by a haem-binding region, analogous to cytochrome P-450, and on the C-terminal side by a region homologous with NADPH:cytochrome P-450 reductase. The structure of recombinant rat brain nitric oxide synthase was analysed by limited proteolyis. The products were identified by using antibodies to defined sequences, and by N-terminal sequencing. Low concentrations of trypsin produced three fragments, similar to those in a previous report [Sheta, McMillan and Masters (1994) J. Biol. Chem. 269, 15147-15153]: that of Mr approx. 135000 (N-terminus Gly-221) resulted from loss of the N-terminal extension (residues 1-220) unique to neuronal nitric oxide synthase. The fragments of Mr 90000 (haem region) and 80000 (reductase region, N-terminus Ala-728) were produced by cleavage within the calmodulin-binding region. With more extensive trypsin treatment, these species were shown to be transient, and three smaller, highly stable fragments of Mr 14000 (N-terminus Leu-744 within the calmodulin region), 60000 (N-terminus Gly-221) and 63000 (N-terminus Lys-856 within the FMN domain) were formed. The species of Mr approx. 60000 represents a domain retaining haem and nitroarginine binding. The two species of Mr 63000 and 14000 remain associated as a complex. This complex retains cytochrome c reductase activity, and thus is the complete reductase region, yet cleaved at Lys-856. This cleavage occurs within a sequence insertion relative to the FMN domain present in inducible nitric oxide synthase. Prolonged proteolysis treatment led to the production of a protein of Mr approx. 53000 (N-terminus Ala-953), corresponding to a cleavage between the FMN and FAD domains. The major products after chymotryptic digestion were similar to those with trypsin, although the pathway of intermediates differed. The haem domain was smaller, starting at residue 275, yet still retained the arginine binding site. These data have allowed us to identify stable domains representing both the arginine/haem-binding and the reductase regions.

Purification to homogeneity and characterisation of rat brain recombinant nitric oxide synthase

We have previously demonstrated high expression of rat neuronal nitric oxide synthase (NO synthase) in a baculovirus system [Charles, I. G., Chubb, A., Gill, R., Clare, J., Lowe, P. N., Holmes, L. S., Page, M., Keeling, J. G., Moncada, S. & Riveros-Moreno, V. (1993) Biochem. Biophys. Res. Commun. 196, 1481-1489], where a small proportion of the expressed enzyme was soluble and active, but the majority was insoluble (approximately 15% of the total insoluble proteins). NO synthase is a complex enzyme, requiring several cofactors for full activity. These include tightly bound FAD, FMN, heme and tetrahydrobiopterin, in addition to calmodulin and NADPH. Here, we report that a substantial proportion of the total NO synthase produced becomes soluble following addition of hemin (2.5 micrograms/ml) to the culture medium. However, the enzyme purified under these conditions had very low specific activity, 50 nmol.min-1.mg-1, after ADP-Sepharose affinity purification. Full activity (approximately 800 nmol.min-1.mg-1) could, however, be obtained by including precursors for the cofactors, nicotinic acid, riboflavin, and sepiapterin in the culture medium. We demonstrate that the enzyme activity is exclusively associated with the dimeric form of the enzyme, which had the following molar ratios for the cofactors: heme, 0.92; FAD, 0.57; FMN, 0.34; H4biopterin, 0.32, with a specific activity of 1500 nmol.min-1.mg-1. The provision of substantial quantities of good quality enzyme, as described here, will facilitate the studies on the relationship between enzyme structure and its mechanism of catalysis.

Expression of the Bordetella pertussis P.69 pertactin adhesin in Escherichia coli: fate of the carboxy-terminal domain

The mature pertactin protein (P.69) of Bordetella pertussis can be isolated from the bacterial cell surface as a polypeptide with an apparent molecular mass of 69,000 Da as determined by sodium dodecyl sulphate gel electrophoresis. However the open reading frame of prn, the pertactin gene, encodes a polypeptide with a predicted molecular mass of 93,478 Da, referred to as P.93. Expression of the prn gene in Escherichia coli leads to the synthesis of the full-length P.93 polypeptide, which is rapidly processed to the mature P.69 protein located at the cell surface. The P.93 precursor polypeptide is processed at both termini. A 34 amino acid long signal sequence is removed from the amino-terminus and a polypeptide sequence of about 30,000 Da (P.30) is cleaved from the carboxy-terminus. Deletion of the 3' region of prn, encoding P.30, results in the expression of an intracellular form of P.69. Antiserum which recognizes P.30 was raised using synthetic peptides based on the primary amino acid sequence of the region. This anti-P.30 serum was used in a Western blot analysis of fractionated cells of B. pertussis and E. coli harbouring the intact prn gene. The P.30 polypeptide was readily detected in outer membrane fractions prepared from both of these bacterial species, although it could not be shown to be exposed at the cell surface.

The inducible form of nitric oxide synthase (NOS2) isolated from murine macrophages maps near the nude mutation on mouse chromosome 11

Nitric oxide synthase has been shown to mediate streptozocin-induced diabetes and to act as an antimicrobial agent in murine macrophages. Using a cDNA probe for the inducible form of nitric oxide synthase (Nos2) isolated from murine macrophages we have determined that the gene maps within 1 cM of the nude mutation on mouse Chromosome 11. The position of Nos2 was also mapped relative to the markers 115, Evi2, Cchlbl (previously unmapped), and Gfap. This map location is discussed relative to map locations for disease susceptibility loci involved in mediating cutaneous leishmaniasis (ScII) and autoimmune type-I diabetes (Idd4).

Expression of P.69/pertactin from Bordetella pertussis in a baculovirus/insect cell expression system: protective properties of the recombinant protein

The surface antigen P.69/pertactin of Bordetella pertussis has been expressed using the polyhedron promoter of baculovirus in cultured insect cells. Either full-length or truncated prn DNA was used to express P.69 pertactin. The full-length gene gave rise to low levels of P.93 precursor protein, some of which was processed to P.69. The shortened prn expressed P.69 pertactin directly at levels up to 3.5 mg per litre. P.69 vaccinated animals were protected against aerosol challenge with virulent B. pertussis bacteria.

Repeated induction of nitric oxide synthase and leishmanicidal activity in murine macrophages

Murine macrophages express high levels of nitric oxide (NO) synthase and produce large amounts of NO when stimulated with interferon-gamma plus lipopolysaccharide in vitro. The expression of NO synthase peaks at 12 h after stimulation and declines rapidly to the background level by 72 h. These macrophages can be repeatedly reactivated to express similar levels of NO synthase. The reactivation is not due to newly divided cells since peritoneal macrophages which do not divide in vitro and J774 cells cultured in the presence of colchicine can also be restimulated to express NO synthase. The reactivation is accompanied by re-expression of NO synthase mRNA, as assessed by polymerase chain reaction analysis. Furthermore, the reactivated macrophages are fully capable of killing the intracellular protozoan parasite Leishmania major.

Characterization of a Salmonella typhimurium aro vaccine strain expressing the P.69 antigen of Bordetella pertussis

The P.69 Bordetella pertussis protective antigen was expressed by use of the trc promoter from the chromosome of a Salmonella typhimurium aro vaccine strain, BRD509, by integrating the prn gene, encoding the 93-kDa precursor of this protein, into the aroC locus. P.69 was detected on the cell surface of the S. typhimurium strain (BRD640) by agglutination and immunoelectron microscopy. BALB/c mice immunized orally or intravenously with BRD640 showed a significant level of protection against an aerosol challenge with virulent B. pertussis, compared with control animals. No anti-P.69 antibodies in the serum or anti-P.69 antibody-secreting cells in the lungs were detected in BRD640-vaccinated animals, although cells isolated from spleens showed a P.69-dependent cell proliferative response. In contrast, low levels of anti-P.69 antibodies in the serum and anti-P.69 antibody-secreting cells in the lungs were detected in immunized mice following a B. pertussis challenge.

Construction of a genetically defined Salmonella typhi Ty2 aroA, aroC mutant for the engineering of a candidate oral typhoid-tetanus vaccine

The construction of a Salmonella typhi Ty2 strain harbouring defined deletions in both the aroA and aroC genes is described. These deletions have been fully defined at the molecular level by DNA sequencing and have been introduced in such a way that no foreign DNA remains in the S. typhi genome. This strain is attenuated in mice when given by the intraperitoneal route suspended in hog gastric mucin and is attenuated to a similar level to strains harbouring deletions in aroA or aroC alone indicating that both lesions are capable of attenuating independently. We have used this defined S. typhi aroA aroC strain to express stably a non-toxic 50 kDa fragment of tetanus toxin (fragment C) from a gene incorporated into the chromosome. This strain has the advantage of harbouring no antibiotic-resistance markers and we consider it to be a candidate bivalent oral typhoid-tetanus vaccine.

The Mycobacterium tuberculosis shikimate pathway genes: evolutionary relationship between biosynthetic and catabolic 3-dehydroquinases

The Mycobacterium tuberculosis shikimate pathway genes designated aroB and aroQ encoding 3-dehydroquinate synthase and 3-dehydroquinase, respectively were isolated by molecular cloning and their nucleotide sequences determined. The deduced dehydroquinate synthase amino acid sequence from M. tuberculosis showed high similarity to those of equivalent enzymes from prokaryotes and filamentous fungi. Surprisingly, the deduced M. tuberculosis 3-dehydroquinase amino acid sequence showed no similarity to other characterised prokaryotic biosynthetic 3-dehydroquinases (bDHQases). A high degree of similarity was observed, however, to the fungal catabolic 3-dehydroquinases (cDHQases) which are active in the quinic acid utilisation pathway and are isozymes of the fungal bDHQases. This finding indicates a common ancestral origin for genes encoding the catabolic dehydroquinases of fungi and the biosynthetic dehydroquinases present in some prokaryotes. Deletion of genes encoding shikimate pathway enzymes represents a possible approach to generation of rationally attenuated strains of M. tuberculosis for use as live vaccines.

Insertional inactivation of the Staphylococcus aureus beta-toxin by bacteriophage phi 13 occurs by site- and orientation-specific integration of the phi 13 genome

Lysogenization of Staphylococcus aureus by the serotype F converting bacteriophage phi 13 results in loss of beta-toxin expression. Sequence analysis of the S. aureus beta-toxin gene (hlb), the attachment site (attP)-containing region of phi 13 DNA and the chromosome/bacteriophage DNA junctions of a phi 13 lysogen, revealed that the molecular mechanism of loss of beta-toxin expression was due to insertion of the phi 13 genome into the 5' end of hlb. The insertion site (attB) within hlb contained a 14 base pair core sequence in common with attP and both ends of the integrated linear prophage genome of a phi 13 lysogen. These findings indicate that integration of the phi 13 genome into hlb is site- and orientation-specific.

The role of a stress-response protein in Salmonella typhimurium virulence

We recently described the use of selective transposon mutagenesis to generate a series of avirulent mutants of a pathogenic strain of Salmonella typhimurium. Cloning and sequencing of the insertion sites from two of these mutants reveals that both have identical locations within an open reading frame that is highly homologous to a gene, htrA, encoding a heat-shock protein in Escherichia coli. DNA sequence analysis of S. typhimurium htrA reveals the presence of a gene capable of encoding a protein with a calculated Mr of 49316 that has 88.7% protein:protein homology with its E. coli counterpart. In E. coli, lesions in this gene, also known as degP, reduce proteolytic degradation of aberrant periplasmic proteins. Characteristics of the S. typhimurium htrA mutants, 046 and 014, in vivo and in vitro suggested that they are avirulent because of impaired ability to survive and/or replicate in host tissues. In vitro, the S. typhimurium htrA mutants 046 and 014 are not temperature-sensitive but were found to be more susceptible to oxidative stress than the parent, suggesting that they may be less able to withstand oxidative killing within macrophages.

Molecular cloning and characterization of the aroD gene encoding 3-dehydroquinase from Salmonella typhi

The aroD gene from Salmonella typhi, encoding 5-dehydroquinate hydrolyase (3-dehydroquinase), has been cloned into Escherichia coli and the DNA sequence determined. The aroD gene was isolated from a cosmid gene bank by complementation of an S. typhimurium aroD mutant. Analysis of the DNA sequence revealed the presence of an open reading frame capable of encoding a protein of 252 amino acids with a calculated Mr of 27706. Comparison of the deduced S. typhi 3-dehydroquinase protein sequence with that elucidated for E. coli revealed 69% homology. Alignment of the S. typhi sequence and equivalent Aspergillus nidulans and Saccharomyces cerevisiae sequences showed that homology was lower, at 24%, but still significant. Use of a minicell expression system demonstrated that a polyclonal antibody raised against E. coli 3-dehydroquinase cross-related with its S. typhi counterpart.

Cloning and characterization of the aroA gene from Mycobacterium tuberculosis

The aroA gene from Mycobacterium tuberculosis has been cloned by complementation of an aroA mutant of Escherichia coli after lysogenization with a recombinant DNA library in the lambda gt11 vector. Detailed characterization of the M. tuberculosis aroA gene by nucleotide sequencing and by immunochemical analysis of the expressed product indicates that it encodes a 5-enolpyruvylshikimate-3-phosphate synthase that is structurally related to analogous enzymes from other bacterial, fungal, and plant sources. The potential use of the cloned gene in construction of genetically defined mutant strains of M. tuberculosis by gene replacement is proposed as a novel approach to the rational attenuation of mycobacterial pathogens and the possible development of new antimycobacterial vaccines.

Gene expression and the development of live enteric vaccines

Rationally attenuated live Salmonella vaccines provide good protection against homologous challenge and can act as carriers of heterologous antigens. However, the optimum expression system for each heterologous antigen will need to be established individually. This will ensure that the antigen in question is produced at appropriate levels, in the correctly folded conformation, within or at the surface of the carrier cell, and can therefore elicit the optimal immune response.