Structure-activity relationships of actively FhuE transported rifabutin derivatives with potent activity against Acinetobacter baumannii

Hospital-acquired infections are on the rise and represent both, a clinical and financial burden. With resistance emerging and an ever-dwindling armamentarium at hand, infections caused by Acinetobacter baumannii are particularly problematic, since these bacteria have a high level of resistance and resilience to traditional and even last-resort antibiotics. The antibiotic rifabutin was recently found to show potent in vitro and in vivo activity against extensively drug resistant A. baumannii. Building on this discovery, we report on the synthesis and activity of rifabutin analogs, with a focus on N-functionalization of the piperidine ring. The antimicrobial testing uncovered structure activity relationships (SAR) for A. baumannii that were not reflected in Staphylococcus aureus. The cellular activity did not correlate with cell-free transcription inhibition, but with bacterial intracellular compound accumulation. Mass spectrometry-based accumulation studies confirmed the involvement of the siderophore receptor FhuE in active compound translocation at low concentrations, and they showed a strong impact of the culture medium on the accumulation of rifabutin. Overall, the study underlines the structural feature required for strong accumulation of rifabutin in A. baumannii and identifies analogs as or more potent than rifabutin against A. baumannii.

Roles of aconitase in growth, metabolism, and morphological differentiation of Streptomyces coelicolor

The studies of aconitase presented here, along with those of citrate synthase (P. H. Viollier, W. Minas, G. E. Dale, M. Folcher, and C. J. Thompson, J. Bacteriol. 183:3184-3192, 2001), were undertaken to investigate the role of the tricarboxylic acid (TCA) cycle in Streptomyces coelicolor development. A single aconitase activity (AcoA) was detected in protein extracts of cultures during column purification. The deduced amino acid sequence of the cloned acoA gene constituted the N-terminal sequence of semipurified AcoA and was homologous to bacterial A-type aconitases and bifunctional eukaryotic aconitases (iron regulatory proteins). The fact that an acoA disruption mutant (BZ4) did not grow on minimal glucose media in the absence of glutamate confirmed that this gene encoded the primary vegetative aconitase catalyzing flux through the TCA cycle. On glucose-based complete medium, BZ4 had defects in growth, antibiotic biosynthesis, and aerial hypha formation, partially due to medium acidification and accumulation of citrate. The inhibitory effects of acids and citrate on BZ4 were partly suppressed by buffer or by introducing a citrate synthase mutation. However, the fact that growth of an acoA citA mutant remained impaired, even on a nonacidogenic carbon source, suggested alternative functions of AcoA. Immunoblots revealed that AcoA was present primarily during substrate mycelial growth on solid medium. Transcription of acoA was limited to the early growth phase in liquid cultures from a start site mapped in vitro and in vivo.

A three-dimensional model of endothelin-converting enzyme (ECE) based on the X-ray structure of neutral endopeptidase 24.11 (NEP)

Endothelin-converting enzyme 1 (ECE-1, EC 3.4.24.71) is a zinc-dependent type II mammalian membrane protein comprising the active site in the ectodomain. It exists in multiple splice variants that all catalyze the last and rate-limiting step in the activation of preproendothelin to the highly potent vasoconstrictor endothelin. There is high interest in finding small and potent inhibitors for this enzyme that could be used in numerous indications, e.g. hypertension. Since there is no structural information available for this important enzyme, we built a model of the complete ectodomain using the recently solved structure of human NEP as template. The naturally derived metalloproteinase inhibitor phosphoramidon was docked in the active site of this model and comparisons with the respective NEP complex were made.

Role of acid metabolism in Streptomyces coelicolor morphological differentiation and antibiotic biosynthesis

Studies of citrate synthase (CitA) were carried out to investigate its role in morphological development and biosynthesis of antibiotics in Streptomyces coelicolor. Purification of CitA, the major vegetative enzyme activity, allowed characterization of its kinetic properties. The apparent K(m) values of CitA for acetyl coenzyme A (acetyl-CoA) (32 microM) and oxaloacetate (17 microM) were similar to those of citrate synthases from other gram-positive bacteria and eukaryotes. CitA was not strongly inhibited by various allosteric feedback inhibitors (NAD(+), NADH, ATP, ADP, isocitrate, or alpha-ketoglutarate). The corresponding gene (citA) was cloned and sequenced, allowing construction of a citA mutant (BZ2). BZ2 was a glutamate auxotroph, indicating that citA encoded the major citrate synthase allowing flow of acetyl-CoA into the tricarboxylic acid (TCA) cycle. Interruption of aerobic TCA cycle-based metabolism resulted in acidification of the medium and defects in morphological differentiation and antibiotic biosynthesis. These developmental defects of the citA mutant were in part due to a glucose-dependent medium acidification that was also exhibited by some other bald mutants. Unlike other acidogenic bald strains, citA and bldJ mutants were able to produce aerial mycelia and pigments when the medium was buffered sufficiently to maintain neutrality. Extracellular complementation studies suggested that citA defines a new stage of the Streptomyces developmental cascade.

A vibrational structure of 7,8-dihydrobiopterin bound to dihydroneopterin aldolase

Dihydroneopterin aldolase (DHNA) catalyzes the conversion of 7, 8-dihydroneopterin to 6-hydroxymethyl-7,8-dihydropterin and glycolaldehyde. An inhibitor of the enzyme, 7,8-dihydrobiopterin, free in solution and bound in its complex with the enzyme has been studied by Raman difference spectroscopy. By using isotopically labeled 7,8-dihydrobiopterin and normal mode analyses based on ab initio quantum mechanic methods, we have positively identified some of the Raman bands in the enzyme-bound inhibitor, particularly the important N5=C6 stretch mode. The spectrum of the enzyme-bound inhibitor shows that the pK(a) of N5 is not significantly increased in the complex. This result suggests that N5 of 7,8-dihydroneopterin is not protonated before the bond cleavage of 7,8-dihydroneopterin during the DHNA-catalyzed reaction as has been suggested. Our results also show that the N5=C6 stretch mode of 7, 8-dihydrobiopterin shifts 19 cm(-)(1) upon binding to DHNA. Various possibilities on how the enzyme can bring about such large frequency change of the N5=C6 stretch mode are discussed.

Purification and crystallization of the extracellular domain of human neutral endopeptidase (neprilysin) expressed in Pichia pastoris

Neutral endopeptidase (NEP) is a mammalian zinc metalloprotease involved in the inactivation of a wide variety of regulatory peptides such as enkephalins and atrial natiuretic factor. The soluble extracellular domain of NEP (sNEP) was expressed in the methylotrophic yeast Pichia pastoris. The protein was purified to homogeneity and single crystals have been obtained. Enzymatic deglycosylation of the enzyme was essential for the production of crystals suitable for X-ray analysis for both the NEP-phosphoramidon binary complex and the apo enzyme.

Structure of human neutral endopeptidase (Neprilysin) complexed with phosphoramidon

Neutral endopeptidase is a mammalian type II integral membrane zinc-containing endopeptidase, which degrades and inactivates a number of bioactive peptides. The range of substrates cleaved by neutral endopeptidase in vitro includes the enkephalins, substance P, endothelin, bradykinin and atrial natriuretic factor. Due to the physiological importance of neutral endopeptidase in the modulation of nociceptive and pressor responses there is considerable interest in inhibitors of this enzyme as novel analgesics and anti-hypertensive agents. Here we describe the crystal structure of the extracellular domain (residues 52-749) of human NEP complexed with the generic metalloproteinase inhibitor phosphoramidon at 2.1 A resolution. The structure reveals two multiply connected folding domains which embrace a large central cavity containing the active site. The inhibitor is bound to one side of this cavity and its binding mode provides a detailed understanding of the ligand-binding and specificity determinants.

Crystal engineering: deletion mutagenesis of the 24 kDa fragment of the DNA gyrase B subunit from Staphylococcus aureus

The 24 kDa fragment of DNA gyrase B from Staphylococcus aureus was expressed in Escherichia coli and purified for crystallization. Crystals of the wild-type protein grew in the presence of cyclothialidine but proved difficult to reproduce. In order to improve the crystallization, the flexible regions of the protein were deleted by mutagenesis. The mutant proteins were analyzed by differential scanning calorimetry and the most stable mutants produced crystals. It was possible to reproducibly grow single well defined crystals in the microbatch system which belonged to the space group C2 and diffracted isotropically to approximately 2 A resolution.

The structure and function of the 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase from Haemophilus influenzae

The gene encoding the 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase of Haemophilus influenzae has been cloned and expressed in Escherichia coli. A complex of the purified protein with a substrate analog has been crystallized and its structure solved by multiple anomalous dispersion using phase information obtained from a single crystal of selenomethione-labeled protein. The enzyme folds into a four-stranded antiparallel beta-sheet flanked on one side by two alpha-helices and on the other by three consecutive alpha-helices, giving a novel beta1alpha1beta2beta3alpha2beta4alpha3alpha4alpha5 polypeptide topology. The three-dimensional structure of a binary complex has been refined at 2.1 A resolution. The location of the substrate analog and a sulfate ion gives important insight into the molecular mechanism of the enzyme.

Crystal structure and reaction mechanism of 7,8-dihydroneopterin aldolase from Staphylococcus aureus

Dihydroneopterin aldolase catalyzes the conversion of 7,8-dihydroneopterin to 6-hydroxymethyl-7,8-dihydropterin during the de novo synthesis of folic acid from guanosine triphosphate. The gene encoding the dihydroneopterin aldolase from S. aureus has been cloned, sequenced and expressed in Escherichia coli. The protein has been purified for biochemical characterization and its X-ray structure determined at 1.65 A resolution. The protein forms an octamer of 110,000 Mr molecular weight. Four molecules assemble into a ring, and two rings come together to give a cylinder with a hole of at least 13 A diameter. The structure of the binary complex with the product 6-hydroxymethyl-7,8-dihydropterin has defined the location of the active site. The structural information and results of site directed mutagenesis allow an enzyme reaction mechanism to be proposed.

Structure and function of the dihydropteroate synthase from Staphylococcus aureus

The gene encoding the dihydropteroate synthase of staphylococcus aureus has been cloned, sequenced and expressed in Escherichia coli. The protein has been purified for biochemical characterization and X-ray crystallographic studies. The enzyme is a dimer in solution, has a steady state kinetic mechanism that suggests random binding of the two substrates and half-site reactivity. The crystal structure of apo-enzyme and a binary complex with the substrate analogue hydroxymethylpterin pyrophosphate were determined at 2.2 A and 2.4 A resolution, respectively. The enzyme belongs to the group of "TIM-barrel" proteins and crystallizes as a non-crystallographic dimer. Only one molecule of the substrate analogue bound per dimer in the crystal. Sequencing of nine sulfonamide-resistant clinical isolates has shown that as many as 14 residues could be involved in resistance development. The residues are distributed over the surface of the protein, which defies a simple interpretation of their roles in resistance. Nevertheless, the three-dimensional structure of the substrate analogue binary complex could give important insight into the molecular mechanism of this enzyme.

A single amino acid substitution in Staphylococcus aureus dihydrofolate reductase determines trimethoprim resistance

A single amino acid substitution, Phe98 to Tyr98, in dihydrofolate reductase (DHFR) is the molecular origin of trimethoprim (TMP) resistance in Staphylococcus aureus. This active site amino acid substitution was found in all S. aureus TMP-resistant clinical isolates tested. In order to explore the structural role of Tyr98 in TMP-resistance the ternary complexes of the chromosomal S. aureus DHFR (SaDHFR) with methotrexate (MTX) and TMP in the presence of nicotinamide adenine dinucleotide phosphate (NADPH) as well as that of mutant Phe98Tyr DHFR SaDHFR(F98Y) ternary folate-NADPH complex have been determined by X-ray crystallography. Critical evidence concerning the resistance mechanism has also been provided by NMR spectral analyses of 15N-labelled TMP in the ternary complexes of both wild-type and mutant enzyme. These studies show that the mutation results in loss of a hydrogen bond between the 4-amino group of TMP and the carbonyl oxygen of Leu5. This mechanism of resistance is predominant in both transferable plasmid-encoded and non-transferable chromosomally encoded resistance. Knowledge of the resistance mechanism at a molecular level could help in the design of antibacterials active against multi-resistant Staphylococcus aureus (MRSA), one of todays most serious problems in clinical infectology.

Cloning and characterization of a novel, plasmid-encoded trimethoprim-resistant dihydrofolate reductase from Staphylococcus haemolyticus MUR313

In recent years resistance to the antibacterial agent trimethoprim (Tmp) has become more widespread, and several trimethoprim-resistant (Tmpr) dihydrofolate reductases (DHFRs) have been described from gram-negative bacteria. In staphylococci, only one Tmpr DHFR has been described, the type S1 DHFR, which is encoded by the dfrA gene found on transposon Tn4003. In order to investigate the coincidence of high-level Tmp resistance and the presence of dfrA, we analyzed the DNAs from various Tmpr staphylococci for the presence of dfrA sequences by PCR with primers specific for the thyE-dfrA genes from Tn4003. We found that 30 or 33 isolates highly resistant to Tmp (MICs, > or = 512 micrograms/ml) contained dfrA sequences, whereas among the Tmpr (MICs, < or = 256 micrograms/ml) and Tmps isolates only the Staphylococcus epidermidis isolates (both Tmpr and Tmps) seemed to contain the dfrA gene. Furthermore, we have cloned and characterized a novel, plasmid-encoded Tmpr DHFR from Staphylococcus haemolyticus MUR313. The dfrD gene of plasmid pABU17 is preceded by two putative Shine-Dalgarno sequences potentially allowing for the start of translation at two triplets separated by nine nucleotides. The predicted protein of 166 amino acids, designated S2DHFR, encoded by the longer open reading frame was overproduced in Escherichia coli, purified, and characterized. The molecular size of the recombinant S2DHFR was determined by ion spray mass spectrometry to be 19,821.2 +/- 2 Da, which is in agreement with the theoretical value of 19,822 Da. In addition, the recombinant S2DHFR was shown to exhibit DHFR activity and to be highly resistant to Tmp.

Characterization of the gene for the chromosomal dihydrofolate reductase (DHFR) of Staphylococcus epidermidis ATCC 14990: the origin of the trimethoprim-resistant S1 DHFR from Staphylococcus aureus?

The gene for the chromosomally encoded dihydrofolate reductase (DHFR) of Staphylococcus epidermidis ATCC 14990 has been cloned and characterized. The structural gene encodes a polypeptide of 161 amino acid residues with a calculated molecular weight of 18,417. This trimethoprim-sensitive (Tmps) DHFR, SeDHFR, differs in only three amino acids (Val-31-->Ile, Gly-43-->Ala, and Phe-98-->Tyr) from the trimethoprim-resistant (Tmpr) S1 DHFR encoded by transposon Tn4003. Since in addition the S. epidermidis gene also forms part of an operon with thyE and open reading frame 140 as in Tn4003, the chromosomally located gene encoding the Tmps SeDHFR is likely to be the molecular origin of the plasmid-located gene encoding the Tmpr S1 DHFR. Site-directed mutagenesis and kinetic analysis of the purified enzymes suggest that a single Phe-->Tyr change at position 98 is the major determinant of trimethoprim resistance.

Increased solubility of trimethoprim-resistant type S1 DHFR from Staphylococcus aureus in Escherichia coli cells overproducing the chaperonins GroEL and GroES

The production of the trimethoprim-resistant type S1 dihydrofolate reductase (DHFR) from Staphylococcus aureus in Escherichia coli cells overproducing the chaperonins GroEL and GroES is described. The simultaneous overproduction of the chaperonins with DHFR results in an increased solubility of the enzyme. We compare the time course of production of active type S1 DHFR by measuring enzyme activity in cells overproducing or not overproducing the chaperonins. Although co-overproduction of the chaperonins reduces the total production level of type S1 DHFR, the amount of soluble and active DHFR is increased several-fold in comparison with cells producing only DHFR. Thus, the higher concentrations of GroES and GroEL in cells overproducing the chaperonins partially protect DHFR from aggregation, resulting in higher concentrations of soluble and active DHFR in the cell. Furthermore, we also demonstrate that the chaperonins can improve in vitro refolding yields of type S1 DHFR. These results suggest that it is possible to purify suitable amounts of trimethoprim-resistant type S1 DHFR for X-ray crystallographic studies.

Improving protein solubility through rationally designed amino acid replacements: solubilization of the trimethoprim-resistant type S1 dihydrofolate reductase

In recent years resistance to the antibacterial agent trimethoprim (Tmp) has become more widespread and several Tmp-resistant (Tmpr) dihydrofolate reductases (DHFRs) have been described from Gram-negative bacteria. In staphylococci, however, only one Tmpr DHFR (type S1 DHFR) has been found so far, and this is located on transposon Tn4003. To help understand the mechanism of resistance, we are interested in determining the 3-D structure of the recombinant enzyme produced in Escherichia coli. However, the production level of the type S1 DHFR was very low and > 95% of the total recombinant protein accumulated in inclusion bodies. Furthermore, as a result of an internal start of translation, a truncated derivative of the enzyme that copurified with the full-length enzyme was produced. We were able to increase the expression level 20-fold by changing 18 N-terminal codons and to eliminate the internal start of translation. In addition, through molecular modelling and subsequent site-directed mutagenesis to replace two amino acids, we constructed a biochemically similar but soluble derivative of the type S1 DHFR that, after production in E.coli, resulted in a 264-fold increase in DHFR activity. The highly overproduced enzyme was purified to homogeneity, characterized biochemically and crystallized.

Characterization of the gene for chromosomal trimethoprim-sensitive dihydrofolate reductase of Staphylococcus aureus ATCC 25923

The gene for the trimethoprim-sensitive (Tmps) chromosomal dihydrofolate reductase (DHFR) of Staphylococcus aureus ATCC 25923 was cloned and characterized. The structural gene encodes a polypeptide of 159 amino acid residues and has a calculated molecular weight of 18,251. The amino acid sequences of this Tmps DHFR and those of the trimethoprim-resistant type S1 DHFR encoded by transposon Tn4003 are 80% identical. In contrast to the trimethoprim-resistant enzyme, the Tmps DHFR can be highly overexpressed in Escherichia coli, with most of the recombinant protein occurring in a soluble and an active form.

Expression of the trimethoprim resistant dihydrofolate reductase encoded by transposon TN4003 in a soluble form and its subsequent purification to homogeneity

A high level expression in E. coli of the Tmpr type S1 DHFR was achieved by: (1) elimination of an internal start of translation within the RNA, and (2) optimization of gene expression by replacing nucleotides at the 5' end of the gene by nucleotides present in the highly expressible gene for SaDHFR. In addition, by replacing amino acids supposed to be on the surface of the protein, the mutein S1 DHFR[N48E,N130D] was constructed, which can be expressed in E. coli to high levels in a soluble and active form. The mutein S1 DHFR[N48E,N130D] was purified nearly to homogeneity. The enzyme is highly active and remains soluble even at a protein concentration of 10 mg/ml.

Relationships between Lewy bodies and pale bodies in Parkinson's disease

The prevalence of pale bodies and Lewy bodies was studied in the substantia nigra of 12 patients with typical Parkinson's disease (PD), in 5 patients with diffuse Lewy body disease (DLBD), and in a group of neurologically normal controls. Anti-ubiquitin antibodies labelled pale bodies and Lewy bodies in typical PD and DLBD, and there was a strong positive correlation between numbers of ubiquitin-immunoreactive pale bodies and Lewy bodies. BF10, a monoclonal antibody against a phosphate-dependent epitope of neurofilament 155-kDa polypeptide subunit, immunolabelled 57% of Lewy bodies and 15% of pale bodies in typical PD. Some pale bodies and Lewy bodies were seen in the substantia nigra of 2 of 5 neurologically normal, aged controls, probably representing "incidental PD". We conclude that there is a close relationship between pale bodies and typical Lewy bodies in the substantia nigra in clinical varieties of PD, and that these inclusions share antigenic determinants. If pale bodies and Lewy bodies reflect separate aspects of the cellular pathology in PD, their formation probably occurs in parallel. Alternatively, these observations may suggest that pale bodies represent a stage in the formation of Lewy bodies.

Stress protein inclusions in cerebral vessels in dialysis encephalopathy

Dialysis encephalopathy, a complication of long-term haemodialysis, is a syndrome characterized by progressive dementia, myoclonus, dysarthria and ataxia associated with high serum and brain levels of aluminium. Expression of heat-shock or stress proteins, including ubiquitin can be induced in cell culture experiments by aluminium. We report immunohistochemical studies of heat shock protein (HSP) expression in the frontal cortex of three patients with dialysis dementia. Immunolabelling with antibody to the 72 kD heat shock protein revealed punctate granules in most endothelial cells of cortical vessels in patients with dialysis encephalopathy. These granules, 1-5 microns in diameter, aggregated to form inclusions that resembled stress-granules, typically induced in plant or animal cell culture by repeated insult. These granules did not express epitopes of ubiquitin. They were rare in endothelial cells in the brains of subjects dying with other neurological disorders or of non-neurological causes. We suggest that these stress granules represent a toxic response of endothelial cells in the brain to aluminium.

Neurofibrillary tangles in dementia pugilistica are ubiquitinated

Ubiquitin, a protein thought to be involved in the ATP-dependent non-lysosomal degradation of abnormal proteins, has already been identified as a component of neurofibrillary tangles in Alzheimer's disease. We have examined ubiquitin immunoreactivity in a unique collection of brains from 16 ex-boxers including 11 with dementia pugilistica. Neurofibrillary tangles of dementia pugilistica were labelled with an affinity purified antiserum to ubiquitin, and BF10, a monoclonal antibody to a neurofilament epitope.

Spinal cord trauma in man: studies of phosphorylated neurofilament and ubiquitin expression

Changes in neuronal proteins are a major feature of the neurodegenerative disorders, but the biological significance of these changes is not understood. We describe alterations in neuronal proteins as a result of surgical tractotomy on the human spinal cord at 3, 5, 7, 14 and 72 days after operation. Antibodies to phosphorylated neurofilaments labelled neuronal cell bodies in the nucleus dorsalis and anterior horns. Axonal swellings showed positive staining for ubiquitin, but ubiquitinated neuronal inclusions were not evident. The presence of phosphorylated neurofilaments in the neuronal cell bodies and of ubiquitination of axonal swellings may be indicators of interrupted axonal transport. The changes found in intracellular proteins in neurons after trauma do not resemble those found in motor neuron disease, suggesting that the intraneuronal ubiquitinated inclusions may have a unique significance in the cytopathology of that disorder.

Microdissection: a novel method for the study of intracellular inclusion bodies

The purification of many intracellular and extracellular inclusions is often difficult to achieve due to the low concentration of the abnormalities in the tissue under study, or due to the degradation of components during extraction. We describe the use of microdissection for the isolation of neurons and intraneuronal inclusion bodies. The resulting suspension may be used for biochemical, immunological or ultrastructural studies. The technique is applicable to the study of a wide range of cellular abnormalities.

New aspects of the pathology of neurodegenerative disorders as revealed by ubiquitin antibodies

Ubiquitin has previously been identified as a component of neuronal inclusions in neurodegenerative disorders. In this investigation, we examined tissue from cases of Alzheimer's disease (AD), Pick's disease, Parkinson's disease (PD), and progressive supranuclear palsy (PSP) to identify previously unrecognized ubiquitinated structures and to assess the evolution of neuronal inclusions. In AD, approximately 60% of neurofibrillary tangles (NFTs) that were stained with an anti-paired helical filaments (PHF) serum were identified by the ubiquitin antibodies. Extracellular NFTs were not labelled with anti-PHF but were unlabelled or weakly labelled with anti-ubiquitin antibodies. In Pick's disease, most Pick bodies were strongly labelled by the ubiquitin antibodies, and in addition some hippocampal CA1 neurones contained granular or strand-like ubiquitin-immunoreactive (IR) inclusions associated with more typical Pick bodies. Typical Lewy bodies in PD cases showed an unlabelled central core with an outer ring intensely labelled by ubiquitin antibodies. Pale bodies in pigmented substantia nigra neurones appeared as large well-defined, rounded structures without an identifiable core or peripheral zone. Some pale bodies were unlabelled by ubiquitin antibodies, but others showed labelling of variable intensity. Pale bodies which were labelled by ubiquitin antibodies tended also to be labelled by BF10, a monoclonal antibody against phosphorylated neurofilaments. We suggest that pale bodies in PD may represent stages in the formation of Lewy bodies. In addition, we observed numerous spindle-shaped ubiquitin-IR swellings of dendrites of pigmented substantia nigra neurones. In contrast to inclusions of AD and Pick's disease, the PHF-positive fibrillary neuronal inclusions of PSP were either unlabelled or only weakly labelled by ubiquitin antibodies. No ubiquitinated structures were seen in neurones from corresponding areas in aged controls. Identification of ubiquitinated proteins in neurodegenerative disorders may provide insights into molecular events associated with cell death.

Prevalence of antibodies to herpes simplex virus types 1 and 2 in pregnant women, and estimated rates of infection

There has been a recent increase in notifications of genital herpes but it is not known whether this has been reflected in the pregnant population. We have therefore carried out a study to determine the prevalence of herpes simplex antibodies in pregnant women and to estimate the incidence of primary infection. Sera were collected from 3533 women at antenatal clinics and tested for total antibodies to herpes simples virus (HSV), and if positive, for specific antibodies to HSV-2. Estimates of HSV-1 seroprevalence were derived from the HSV-2 seronegative population. HSV-1 seroprevalence was nearly 100% in black women born in Africa or the Caribbean and 60-80% in white, Asian and UK born black women. It was lower in women in non-manual employment. HSV-2 seroprevalence was related to age, rising from 0 at age 16 to 40% at age 35 in black women, and to about 10% in Asian and white women. The estimated incidence of primary HSV-2 infection during pregnancy, per 1000 pregnancies, was about 2.4 in Asian women, 5 in white women, and 20 in black women. Estimates of the incidence of neonatal infection were derived from these figures and compared to the nationally reported rates.

Class-specific herpes simplex virus antibodies in sera and cervical secretions from patients with cervical neoplasia: a multi-group comparison

Serum and cervical secretions were collected from patients with cervical dysplasia, carcinoma-in-situ (CIS), squamous cell carcinoma (cervical SCC), and controls with normal cervices, attending clinics within the West Lambeth Health District, London. Enzyme-linked immunosorbent assays were used to examine cervical secretory IgA (sIgA) and serum IgG and IgA antibodies to herpes simplex virus (HSV). Sexual and demographic factors were considered during data analysis, which involved fitting multiple linear or multiple logistic regressions to HSV antibody levels. Prevalence of sIgA-HSV and levels of serum antibodies to HSV in all groups were compared with those of gynaecology controls. Caucasian women with mild dysplasia had a significantly higher prevalence of sIgA-HSV. Serum IgG levels to HSV (IgG-HSV) were significantly elevated in women with mild dysplasia and severe dysplasia/CIS. Serum IgA levels to HSV1 (IgG-HSV1) were significantly higher in women with cervical SCC (after adjusting for smoking habits) and other genital tumours. Significantly higher levels of serum IgA to HSV2 (IgA-HSV2) were also found among Caucasian women with cervical SCC. The possible role of HSV as a co-factor in cervical carcinogenesis is discussed.