International Society of Cardiovascular Infectious Diseases Guidelines for the Diagnosis, Treatment and Prevention of Disseminated Mycobacterium chimaera Infection Following Cardiac Surgery with Cardiopulmonary Bypass

Mycobacterial infection-related morbidity and mortality in patients following cardiopulmonary bypass surgery is high and there is a growing need for a consensus-based expert opinion to provide international guidance for diagnosing, preventing and treating in these patients. In this document the International Society for Cardiovascular Infectious Diseases (ISCVID) covers aspects of prevention (field of hospital epidemiology), clinical management (infectious disease specialists, cardiac surgeons, ophthalmologists, others), laboratory diagnostics (microbiologists, molecular diagnostics), device management (perfusionists, cardiac surgeons) and public health aspects.

Evaluation of Lightmix Mycoplasma macrolide assay for detection of macrolide-resistant Mycoplasma pneumoniae in pneumonia patients

OBJECTIVES

Rapid detection of macrolide resistance-associated mutations in Mycoplasma pneumoniae is crucial for effective antimicrobial treatment. We evaluated the Lightmix Mycoplasma macrolide assay for the detection of point mutations at nucleotide positions 2063 and 2064 in the 23S ribosomal RNA (rRNA) gene of M. pneumoniae that confer macrolide resistance.

METHODS

Samples from 3438 patients with a respiratory tract infection were analysed by M. pneumoniae real-time PCR, and 208 (6%) of them were tested positive. In this retrospective study, 163 M. pneumoniae real-time PCR-positive samples were analysed by the Lightmix assay, and results were compared to targeted 23S rRNA sequencing.

RESULTS

Macrolide-resistant M. pneumoniae were found in 15 (9%) of 163 retrospectively analysed samples. The Lightmix assay showed a sensitivity of 100% (95% confidence interval, 78.2-100) and a specificity of 100% (95% confidence interval, 97.5-100) as the detected M. pneumoniae genotype (148 wild type and 15 non-wild type) was confirmed by 23S rRNA sequencing in all samples.

CONCLUSIONS

The Lightmix assay is an easy-to-use and accurate molecular test that allows rapid determination of macrolide resistance in M. pneumoniae.

Comparison of Löwenstein-Jensen and BACTEC MGIT 960 culture for Mycobacterium tuberculosis in people living with HIV

OBJECTIVES

The aim of the study was to clarify how HIV infection affects tuberculosis liquid and solid culture results in a resource-limited setting.

METHODS

We used baseline data from the Study on Outcomes Related to Tuberculosis and HIV Drug Concentrations in Uganda (SOUTH), which included 268 HIV/tuberculosis (TB)-coinfected individuals. Culture results from Löwenstein-Jensen (LJ) solid culture and mycobacteria growth indicator tube (MGIT) liquid culture systems and culture-based correlates for bacillary density from the sputum of HIV/TB-coinfected individuals at baseline were analysed.

RESULTS

Of 268 participants, 243 had a CD4 cell count available and were included in this analysis; 72.2% of cultures showed growth on solid culture and 82.2% in liquid culture systems (P < 0.015). A higher CD4 cell count was predictive of LJ positivity [adjusted odds ratio (OR) 1.14; 95% confidence interval (CI) 1.03-1.25 per 50 cells/μL increase; P = 0.008]. The same, but insignificant trend was observed for MGIT positivity (adjusted OR 1.09; 95% CI 0.99-1.211 per 50 cells/μL increase; P = 0.094). A higher CD4 cell count was associated with a higher LJ colony-forming unit grade (adjusted OR 1.14; 95% CI 1.05-1.25 per 50 cells/μL increase; P = 0.011) and a shorter time to MGIT positivity [adjusted hazard ratio (HR) 1.08; 95% CI 1.04-1.12 per 50 cells/μL increase; P < 0.001].

CONCLUSIONS

In a resource-limited setting, the MGIT liquid culture system outperformed LJ solid culture in terms of culture yield and dependence on CD4 cell counts in HIV/TB-coinfected individuals. We therefore suggest considering an adaptation of diagnostic algorithms: when resources allow only one culture method to be performed, we recommend that MGIT liquid culture should be used exclusively in HIV-positive individuals as a first-line culture method, to reduce costs and make TB culture results accessible to more patients in resource-limited settings.

Molecular detection of fungal pathogens in clinical specimens by 18S rDNA high-throughput screening in comparison to ITS PCR and culture

The rising incidence of invasive fungal infections and the expanding spectrum of fungal pathogens makes early and accurate identification of the causative pathogen a daunting task. Diagnostics using molecular markers enable rapid identification of fungi, offer new insights into infectious disease dynamics, and open new possibilities for infectious disease control and prevention. We performed a retrospective study using clinical specimens (N = 233) from patients with suspected fungal infection previously subjected to culture and/or internal transcribed spacer (ITS) PCR. We used these specimens to evaluate a high-throughput screening method for fungal detection using automated DNA extraction (QIASymphony), fungal ribosomal small subunit (18S) rDNA RT-PCR and amplicon sequencing. Fungal sequences were compared with sequences from the curated, commercially available SmartGene IDNS database for pathogen identification. Concordance between 18S rDNA RT-PCR and culture results was 91%, and congruence between 18S rDNA RT-PCR and ITS PCR results was 94%. In addition, 18S rDNA RT-PCR and Sanger sequencing detected fungal pathogens in culture negative (N = 13) and ITS PCR negative specimens (N = 12) from patients with a clinically confirmed fungal infection. Our results support the use of the 18S rDNA RT-PCR diagnostic workflow for rapid and accurate identification of fungal pathogens in clinical specimens.

Detection limit of Mycobacterium chimaera in water samples for monitoring medical device safety: insights from a pilot experimental series

BACKGROUND

A growing number of Mycobacterium chimaera infections after cardiosurgery have been reported by several countries. These potentially fatal infections were traced back to contaminated heater-cooler devices (HCDs), which use water as a heat transfer medium. Aerosolization of water contaminated with M. chimaera from HCDs enables airborne transmission to patients undergoing open chest surgery. Infection control teams test HCD water samples for mycobacterial growth to guide preventive measures. The detection limit of M. chimaera in water samples, however, has not previously been investigated.

AIM

To determine the detection limit of M. chimaera in water samples using laboratory-based serial dilution tests.

METHODS

An M. chimaera strain representative of the international cardiosurgery-associated M. chimaera outbreak was used to generate a logarithmic dilution series. Two different water volumes, 50 and 1000mL, were inoculated, and, after identical processing (centrifugation, decantation, and decontamination), seeded on mycobacteria growth indicator tube (MGIT) and Middlebrook 7H11 solid media.

FINDINGS

MGIT consistently showed a lower detection limit than 7H11 solid media, corresponding to a detection limit of ≥1.44 × 10⁴cfu/mL for 50mL and ≥2.4cfu/mL for 1000mL water samples. Solid media failed to detect M. chimaera in 50mL water samples.

CONCLUSION

Depending on water volume and culture method, major differences exist in the detection limit of M. chimaera. In terms of sensitivity, 1000mL water samples in MGIT media performed best. Our results have important implications for infection prevention and control strategies in mitigation of the M. chimaera outbreak and healthcare water safety in general.

Persistence of the efficacy of zoster vaccine in the shingles prevention study and the short-term persistence substudy

BACKGROUND

The Shingles Prevention Study (SPS; Department of Veterans Affairs Cooperative Study 403) demonstrated that zoster vaccine was efficacious through 4 years after vaccination. The Short-Term Persistence Substudy (STPS) was initiated after the SPS to further assess the persistence of vaccine efficacy.

METHODS

The STPS re-enrolled 7320 vaccine and 6950 placebo recipients from the 38 546-subject SPS population. Methods of surveillance, case determination, and follow-up were analogous to those in the SPS. Vaccine efficacy for herpes zoster (HZ) burden of illness, incidence of postherpetic neuralgia (PHN), and incidence of HZ were assessed for the STPS population, for the combined SPS and STPS populations, and for each year through year 7 after vaccination.

RESULTS

In the STPS as compared to the SPS, vaccine efficacy for HZ burden of illness decreased from 61.1% to 50.1%, vaccine efficacy for the incidence of PHN decreased from 66.5% to 60.1%, and vaccine efficacy for the incidence of HZ decreased from 51.3% to 39.6%, although the differences were not statistically significant. Analysis of vaccine efficacy in each year after vaccination for all 3 outcomes showed a decrease in vaccine efficacy after year 1, with a further decline thereafter. Vaccine efficacy was statistically significant for the incidence of HZ and the HZ burden of illness through year 5.

CONCLUSIONS

Vaccine efficacy for each study outcome was lower in the STPS than in the SPS. There is evidence of the persistence of vaccine efficacy through year 5 after vaccination but, vaccine efficacy is uncertain beyond that point.

A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults

BACKGROUND

The incidence and severity of herpes zoster and postherpetic neuralgia increase with age in association with a progressive decline in cell-mediated immunity to varicella-zoster virus (VZV). We tested the hypothesis that vaccination against VZV would decrease the incidence, severity, or both of herpes zoster and postherpetic neuralgia among older adults.

METHODS

We enrolled 38,546 adults 60 years of age or older in a randomized, double-blind, placebo-controlled trial of an investigational live attenuated Oka/Merck VZV vaccine ("zoster vaccine"). Herpes zoster was diagnosed according to clinical and laboratory criteria. The pain and discomfort associated with herpes zoster were measured repeatedly for six months. The primary end point was the burden of illness due to herpes zoster, a measure affected by the incidence, severity, and duration of the associated pain and discomfort. The secondary end point was the incidence of postherpetic neuralgia.

RESULTS

More than 95 percent of the subjects continued in the study to its completion, with a median of 3.12 years of surveillance for herpes zoster. A total of 957 confirmed cases of herpes zoster (315 among vaccine recipients and 642 among placebo recipients) and 107 cases of postherpetic neuralgia (27 among vaccine recipients and 80 among placebo recipients) were included in the efficacy analysis. The use of the zoster vaccine reduced the burden of illness due to herpes zoster by 61.1 percent (P<0.001), reduced the incidence of postherpetic neuralgia by 66.5 percent (P<0.001), and reduced the incidence of herpes zoster by 51.3 percent (P<0.001). Reactions at the injection site were more frequent among vaccine recipients but were generally mild.

CONCLUSIONS

The zoster vaccine markedly reduced morbidity from herpes zoster and postherpetic neuralgia among older adults.

Role of caspases in human renal proximal tubular epithelial cell apoptosis

In the present study, we have used an in vitro model of apoptosis using primary human renal proximal tubular epithelial (RPTE) cells to investigate the mechanisms involved in renal cell apoptosis. Treatment of RPTE cells with okadaic acid for 24-48 h induced apoptosis in a concentration-dependent manner. Apoptosis was accompanied by the activation of the p38 mitogen-activated protein kinase (MAPK) pathway followed by the activation of caspase-9, -3, and -7. The induction of caspase activity correlated with the proteolytic cleavage of beta-catenin, suggesting that beta-catenin is a caspase substrate. The caspase inhibitor, Z-Val-Ala-Asp-fluoromethylketone (Z-VAD-fmk), resulted in a dose-dependent inhibition of apoptosis and beta-catenin cleavage. These data suggest that okadaic acid-induced apoptosis is p38 MAPK and caspase-dependent and that proteolytic cleavage of beta-catenin by caspases is likely to be a downstream molecular event associated with the morphological and cytoskeletal changes induced during apoptosis.

Structure-based combinatorial library design: discovery of non-peptidic inhibitors of caspases 3 and 8

Structure-based design of a combinatorial array was carried out in order to identify non-peptidic thiomethylketone inhibitors of caspases 3 and 8. Five compounds from the designed array were active against caspase 3, and two were active against caspase 8. A 2.5-A resolution co-crystal structure of caspase 3 and a thiomethylketone array member is reported. The structure-based design strategy has proved useful for identifying caspase inhibitors.

An enhanced and scalable process for the purification of SIV Gag-specific MHC tetramer

A recently developed method for the identification and quantitation of antigen-specific T lymphocytes involves the use of complexes of biotinylated major histocompatibility complex (MHC) and avidin conjugated to a fluorescent reporter group. This complex, dubbed the "tetramer," binds to antigen-specific T lymphocytes in vitro, which can then be sorted and counted by fluorescence-activated flow cytometry to measure immune response. Our research has focused on developing the purification process for preparing tetramer reagent. Our goal was to reengineer a published lab-scale purification process to reduce the number of processing steps and to make the process scalable. In our reengineered process, recombinant MHC alpha chain is isolated from Escherichia coli as inclusion bodies by tangential flow filtration. The purified MHC alpha chain is refolded with beta-2-microglobulin and the target peptide antigen to form the class I MHC. The resulting MHC is purified by hydrophobic interaction chromatography (HIC) and biotinylated enzymatically, and the biotinylated MHC is purified by a second HIC step. The tetramer is prepared by mixing biotinylated MHC with an avidin-fluorophore conjugate. The tetramer is further purified to remove any excess MHC or avidin components. Analysis by flow cytometry confirmed that the tetramers generated by this new process gave bright staining and specific binding to CD3+/CD8+ cells of vaccinated monkeys and led to results that were equivalent to those generated with tetramer produced by the original process.

Inhibitors of bacterial enoyl acyl carrier protein reductase (FabI): 2,9-disubstituted 1,2,3,4-tetrahydropyrido[3,4-b]indoles as potential antibacterial agents

An SAR study of a screening lead has led to the identification of 2,9-disubstituted 1,2,3,4-tetrahydropyrido[3,4-b]indoles as inhibitors of Staphylococcus aureus enoyl acyl carrier protein reductase (FabI).

Biochemical and genetic characterization of the action of triclosan on Staphylococcus aureus

Triclosan, a widely used antibacterial agent, possesses potent activity against Staphylococcus aureus. This study reports on an investigation of the antibacterial target of triclosan in this pathogen. A strain of S. aureus overexpressing the enoyl-[acyl-carrier-protein] reductase (FabI), demonstrated by Western immunoblotting, gave rise to an increase in the MIC of triclosan, while susceptibilities to a range of unrelated antibacterials were unaffected. There are approximately 12 000 molecules of FabI per cell in mid-log phase growth. This number increased by approximately three- to four-fold in the S. aureus FabI overexpressor. Triclosan selectively inhibited the incorporation of [(14)C]acetate into TCA-precipitable product, an indicator of fatty acid biosynthesis. Furthermore, it inhibited de novo fatty acid biosynthesis in this organism. In vitro, triclosan inhibited recombinant, purified S. aureus FabI with an IC(50) of approximately 1 microM. The combination of these biochemical and genetic data provide further evidence that the mode of action of triclosan in S. aureus is via inhibition of FabI.

Potent and selective nonpeptide inhibitors of caspases 3 and 7

5-Dialkylaminosulfonylisatins have been identified as potent, nonpeptide inhibitors of caspases 3 and 7. The most active compound within this series (34) inhibited caspases 3 and 7 in the 2-6 nM range and exhibited approximately 1000-fold selectivity for caspases 3 and 7 versus a panel of five other caspases (1, 2, 4, 6, and 8) and was at least 20-fold more selective versus caspase 9. Sequence alignments of the active site residues of the caspases strongly suggest that the basis of this selectivity is due to binding in the S2 subsite comprised of residues Tyr204, Trp206, and Phe256 which are unique to caspases 3 and 7. These compounds inhibit apoptosis in three cell-based models: human Jurkat T cells, human chondrocytes, and mouse bone marrow neutrophils.

Fast characterization of intact proteins using a high-throughput eight-channel parallel liquid chromatography/mass spectrometry system

The preparation of protein substrates requires that a large number of chromatographic fractions be analyzed for the presence of reactants, products and by-products. Analyses using linear matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) or single column liquid chromatography/mass spectrometry (LC/MS) have been inadequate because of mass resolution or throughput. Therefore, a high-throughput method employing an eight-channel parallel reverse-phase LC/MS system was developed. This system is capable of screening fractions from preparative ion-exchange chromatography with the required mass accuracy and throughput so that the protein purification process can be monitored in a relatively short period of time. As an example, the purification and analysis of an acylated protein with a molecular weight of 8.9 kDa is described and the detection of a contaminating by-product that differs in size by less than 20 Da is demonstrated. Using the current instrumentation and approach, it is practical to analyze 50 protein-containing fractions from column chromatography in less than 1 hour using parallel LC/MS.

Potent and selective nonpeptide inhibitors of caspases 3 and 7 inhibit apoptosis and maintain cell functionality

Caspases have been strongly implicated to play an essential role in apoptosis. A critical question regarding the role(s) of these proteases is whether selective inhibition of an effector caspase(s) will prevent cell death. We have identified potent and selective non-peptide inhibitors of the effector caspases 3 and 7. The inhibition of apoptosis and maintenance of cell functionality with a caspase 3/7-selective inhibitor is demonstrated for the first time, and suggests that targeting these two caspases alone is sufficient for blocking apoptosis. Furthermore, an x-ray co-crystal structure of the complex between recombinant human caspase 3 and an isatin sulfonamide inhibitor has been solved to 2.8-A resolution. In contrast to previously reported peptide-based caspase inhibitors, the isatin sulfonamides derive their selectivity for caspases 3 and 7 by interacting primarily with the S(2) subsite, and do not bind in the caspase primary aspartic acid binding pocket (S(1)). These inhibitors blocked apoptosis in murine bone marrow neutrophils and human chondrocytes. Furthermore, in camptothecin-induced chondrocyte apoptosis, cell functionality as measured by type II collagen promoter activity is maintained, an activity considered essential for cartilage homeostasis. These data suggest that inhibiting chondrocyte cell death with a caspase 3/7-selective inhibitor may provide a novel therapeutic approach for the prevention and treatment of osteoarthritis, or other disease states characterized by excessive apoptosis.

Inhibition of caspase-3-like activity prevents apoptosis while retaining functionality of human chondrocytes in vitro

Apoptosis was induced in a human chondrocyte cell line, T/C 28a4, by treatment with various stimuli, including camptothecin, tumor necrosis factor-alpha, staurosporine, okadaic acid, and reduced serum conditions. All stimuli induced a cytosolic DEVDase activity, coincident with apoptosis. Caspase activities in the lysates were characterized and quantitated with peptide cleavage profiles. To confirm that the results were not related to the immortalized nature of the cell line, primary human chondrocytes also were shown to undergo apoptosis under similar conditions, which resulted in increased cytosolic DEVDase activity. There was little or no caspase-1 (interleukin-1beta-converting enzyme) or caspase-8-like activity in the apoptotic cells. In all cases, the irreversible nonselective caspase inhibitor, Z-VAD-FMK, and the caspase-3-selective inhibitor, Ac-DMQD-CHO, inhibited DEVDase activity and apoptosis, whereas the caspase-1-selective inhibitor, Ac-YVAD-CHO, had no effect. Human chondrocytes were stably and transiently transfected with a type-II collagen gene (COL2A1) regulatory sequence driving a luciferase reporter as a specific marker of chondrocyte gene expression. Treatment of the cells with camptothecin or tumor necrosis factor-alpha plus cycloheximide significantly inhibited COL2A1 transcriptional activity. Significantly, cotreatment with Z-VAD-FMK or Ac-DMQD-CHO maintained COL2A1-reporter gene activity, indicating that the prevention of apoptosis by caspase-3 inhibition was sufficient to maintain cell functionality as assessed by the retention of type-II collagen promoter activity.

Apoptosis in polycystic kidney disease: involvement of caspases

Polycystic kidney disease (PKD) is characterized by the development of large renal cysts and progressive loss of renal function. Although the cause of the development of renal cysts is unknown, recent evidence suggests that excessive apoptosis occurs in PKD. With the use of terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, we have confirmed the presence of apoptotic bodies in cystic kidneys of congenital polycystic kidney (cpk) disease mice carrying a homozygous mutation at 3 wk of age. Apoptosis was localized primarily to the interstitium with little evidence of cell death in cyst epithelium or noncystic tubules. In addition, we observed that the expression of various caspases, bax and bcl-2, was upregulated in cystic kidneys. With the use of various substrates in enzyme activity assays, we have demonstrated a greater than sevenfold increase in caspase 4 activity and a sixfold increase in caspase 3 activity. These data suggest that there is a caspase-dependent apoptosis pathway associated with PKD and support the hypothesis that apoptotic cell death contributes to cyst formation in PKD.

Purification of virus-like particles of recombinant human papillomavirus type 11 major capsid protein L1 from Saccharomyces cerevisiae

Recombinant major capsid protein, L1 (M(r) = 55,000), of human papillomavirus type 11 was expressed intracellularly at high levels in a galactose-inducible Saccharomyces cerevisiae expression system by an HPV6/11 hybrid gene. The capsid protein self-assembled into virus-like particles (VLPs) and accounted for 15% of the total soluble protein. A purification process was developed that consisted of two main steps: microfiltration and cation-exchange chromatography. The purified VLPs were 98% homogeneous, and the overall purification yield was 10%. The final product was characterized by several analytical methods and was highly immunogenic in mice.

A substrate combinatorial array for caspases

An efficient strategy for the synthesis of a tetrapeptidyl substrate combinatorial array directed toward the caspases is described. Testing of this array with caspases 1 and 4 gave substrate hydrolytic profiles characteristic of each caspase, and permitted the identification of efficiently processed substrates. A comparison of this approach to that using a positional scanning library is presented.

The L1 major capsid protein of human papillomavirus type 11 recombinant virus-like particles interacts with heparin and cell-surface glycosaminoglycans on human keratinocytes

The L1 major capsid protein of human papillomavirus (HPV) type 11, a 55-kDa polypeptide, forms particulate structures resembling native virus with an average particle diameter of 50-60 nm when expressed in the yeast Saccharomyces cerevisiae. We show in this report that these virus-like particles (VLPs) interact with heparin and with cell-surface glycosaminoglycans (GAGs) resembling heparin on keratinocytes and Chinese hamster ovary cells. The binding of VLPs to heparin is shown to exhibit an affinity comparable to that of other identified heparin-binding proteins. Immobilized heparin chromatography and surface plasmon resonance were used to show that this interaction can be specifically inhibited by free heparin and dextran sulfate and that the effectiveness of the inhibitor is related to its molecular weight and charge density. Sequence comparison of nine human L1 types revealed a conserved region of the carboxyl terminus containing clustered basic amino acids that bear resemblance to proposed heparin-binding motifs in unrelated proteins. Specific enzymatic cleavage of this region eliminated binding to both immobilized heparin and human keratinocyte (HaCaT) cells. Removal of heparan sulfate GAGs on keratinocytes by treatment with heparinase or heparitinase resulted in an 80-90% reduction of VLP binding, whereas treatment of cells with laminin, a substrate for alpha6 integrin receptors, provided minimal inhibition. Cells treated with chlorate or substituted beta-D-xylosides, resulting in undersulfation or secretion of GAG chains, also showed a reduced affinity for VLPs. Similarly, binding of VLPs to a Chinese hamster ovary cell mutant deficient in GAG synthesis was shown to be only 10% that observed for wild type cells. This report establishes for the first time that the carboxyl-terminal portion of HPV L1 interacts with heparin, and that this region appears to be crucial for interaction with the cell surface.

One-step fluorescent probe product-enhanced reverse transcriptase assay

Recently developed PCR-based reverse transcriptase (RT) assays are useful in the detection of retroviruses since they are approximately a millionfold more sensitive than conventional RT assays. However, these assays are both labor- and time-intensive. The previously described product-enhanced reverse transcriptase (PERT) assay involves a two-step RT-PCR followed by detection and quantitation of PCR products by either Southern blot or enzyme-linked immunosorbent assay (ELISA). We have modified the PERT assay to be a one-step, fluorescent probe, PCR-based RT assay that can be completed from sample dilution to final quantitative assay results in approximately 5 h without loss of assay sensitivity or specificity. The assay has a dynamic range of 6 logs, and therefore, extensive sample dilution is not necessary for quantitation. This newly enhanced fluorescent PERT assay can play an important role in the high-throughput detection of retroviral infection and characterization of RT activity.

Anti-human immunodeficiency virus type 1 human monoclonal antibodies that bind discontinuous epitopes in the viral glycoproteins can identify mimotopes from recombinant phage peptide display libraries

A phage display library screening approach was used to identify peptide sequences that could bind to anti-HIV-1 MAbs whose binding specificities are complex. Most of the antibodies used recognize discontinuous epitopes in gp120 and one recognizes gp41. Both a 15-mer and a 21-mer display library (each with a complexity of greater than 60 x 10[6]) and two constrained, V3 region-biased libraries, all expressed as recombinant pIII protein of filamentous phage, were used. The unmapped anti-gp120 human MAb A32 recognized a set of related linear sequences and repeatedly identified a single phage sequence that could form a cyclic disulfide structure. Selection methods were also developed so that phage could be obtained by competition selection in the presence of antibody bound to native, monomeric gp120 antigen (used with MAb IgG1b12 and the anti-gp120 V3 region MAb 447-52D) or gp120 variable region 3 synthetic peptides (used with anti-gp120 V3 region MAb 19b). The potent, virus-neutralizing MAb IgG1b12 recognized numerous sequences and, when used in competition with gp120, recognized only one sequence. These studies extend the range of antibody determinant studies that can be performed with display phage libraries, demonstrate a workable experimental strategy for use of competition ligands to discriminate among phage mimotopes, and provide a large number of mimotopes that bind potent virus-neutralizing MAbs for HIV-1 vaccine studies.

Endothelin-converting enzyme: substrate specificity and inhibition by novel analogs of phosphoramidon

Endothelin converting enzyme was partially purified by detergent extraction and ion exchange chromatography from porcine aortic endothelial cells. This kinetically homogeneous preparation catalyzes the hydrolysis of porcine big endothelin-1 to endothelin-1 with a pH optimum of 7. Human big endothelins-1, -2, and -3 are also hydrolyzed, but at progressively lower rates. Fragments of big porcine endothelin-1 comprising residues 16-39 and 16-29 are good substrates, but additional C-terminal truncations are devoid of substrate activity. Endothelin converting enzyme is characteristically inhibited by phosphoramidon and other metalloproteinase inhibitors including EDTA, o-phenanthroline, and diethylpyrocarbonate, but not by inhibitors of other classes of proteases or thiorphan. The inhibition by phosphoramidon is competitive with big porcine endothelin-1 suggestive of a common binding site for substrate and inhibitor. A number of novel analogs of phosphoramidon were synthesized by modifying various regions of the molecule and tested for inhibitory activity. The most potent of these, a methylphosphonic acid, has an IC50 of 0.05 microM.

Progressive congenital scoliosis treatment using a transpedicular anterior and posterior convex hemiepiphysiodesis and hemiarthrodesis. A preliminary report

STUDY DESIGN

Patients treated with a transpedicular anterior and posterior convex hemiepiphysiodesis and hemiarthrodesis for progressive congenital scoliosis were followed to evaluate this treatment.

OBJECTIVE

To evaluate an alternative to a separate anterior approach for performing an anterior hemiepiphysiodesis for progressive congenital scoliosis.

SUMMARY OF BACKGROUND DATA

Previous investigators have reported a transpedicular anterior fusion combined with a bilateral posterior fusion. The authors are unaware of a previous report on a transpedicular anterior convex hemiepiphysiodesis and fusion combined with a unilateral convex posterior spinal fusion to treat progressive congenital scoliosis.

METHODS

Nineteen curves were fused in 16 patients who had a variety of congenital anomalies. The average age at surgery was 4.8 years (range, 11 months to 13 years) The average follow-up period was 4.8 years (range, 2 to 9.6 years).

RESULTS

The average preoperative and postoperative fused curves measured 36 degrees and 38 degrees, respectively. Of the 19 fused curves, seven curves (37%) improved, eight curves (42%) were unchanged or progressed less than 7 degrees, three curves (16%) progressed 10 degrees to 15 degrees, and one curve (5%) progressed more than 15 degrees.

CONCLUSIONS

This procedure appears to be most effective in arresting growth in the young patient who has an isolated hemivertebrae and no excessive kyphosis. The epiphysiodesis effect is less predictable.

Neutralization of divergent human immunodeficiency virus type 1 variants and primary isolates by IAM-41-2F5, an anti-gp41 human monoclonal antibody

The antiviral characteristics of monoclonal antibody IAM-41-2F5 (2F5) were determined in cell culture. The antibody had been previously shown to bind a specific sequence, ELDKWA, within the external domain of the gp41 envelope glycoprotein human immunodeficiency virus type 1 (HIV-1). Selection by 2F5 of recombinant phage from an epitope library confirmed the identification of the antibody's binding determinant. The antibody was found to be capable of neutralizing a broad range of lymphoid cell culture-adapted HIV-1 variants as well as HIV-1 primary isolates. Sequence analysis of the latter showed that neutralization was related to the presence of the antibody binding site. From kinetic measurements using an epitope-containing peptide or gp41, the half-time of dissociation for 2F5 was determined to be 122 min for the peptide and 156 min for gp41. The region of gp41 expressing this sequence exhibits greater conservation among HIV-1 isolates than do the variable domains of gp120.

Identification of HIV vaccine candidate peptides by screening random phage epitope libraries

Most synthetic HIV-1 gp120 V3 loop peptides that are used as immunogens in experimental HIV-1 vaccine studies are modeled from the naturally occurring viral gp120 V3 loops. In experimental animals these immunogens generally elicit type (or variant)-specific neutralizing antibodies that are not broadly reactive among HIV-1 variants. In an attempt to find a more general structure for the V3 loop, we have obtained candidates that mimic V3 loop sequences by screening random epitopes displayed in a fusion phage 15-residue epitope library. Human monoclonal antibody 447-52D, a highly potent and broadly reactive virus-neutralizing antibody that recognizes the conserved V3 loop tip motif GPXR, was the probe. By using a screening method that was designed specifically for this work, we identified hundreds of reactive phage clones, 70 of which were sequenced. Over 98% of the epitopes contain the motif GPXR, yet none of the 70 are an identical match to any V3 variant loop described to date. One of these sequences was synthesized as the beta-maleimidopropionyl 15-mer peptide, covalently conjugated to a carrier and used to immunize rabbits. High anti-peptide titers were obtained in all animals with three of four individual responses also binding to a peptide that is representative of the "North American consensus" V3 loop. The sera from these three positive rabbits neutralized HIV-1 variant SF-2 in vitro. In addition, one of them was capable of neutralizing variant AL-1. Both of these variants are considered to have V3 loops of the North American consensus type. Thus, neutralizing responses were obtained by use of an immunogen that was selected for its ability to bind a broadly reactive human monoclonal antibody rather than modeled from an HIV-1 gp120 V3 loop sequence.

Cloning of the cDNA and expression of moubatin, an inhibitor of platelet aggregation

Moubatin, a new type of specific inhibitor of collagen-induced platelet aggregation, has been isolated from the soft tick Ornithodoros moubata (Waxman, L., and Connolly, T. M. (1993) J. Biol. Chem. 268, 5445-5449). A polymerase chain reaction-generated hybridization probe, produced using primers based on moubatin protein sequence, identified phage containing the entire cDNA sequence of moubatin. Analysis of the predicted amino acid sequence yielded a mature protein of 156 amino acids with a putative prepeptide of 15 amino acids. Comparison of the sequence of moubatin to that of other proteins in the Swiss PROT data base revealed no significant homology. The cDNA sequence was cloned into the yeast expression vector pKH4 alpha 2, producing a biologically active protein which inhibited collagen-stimulated aggregation of washed human platelets with an IC50 of about 100 nM, which is similar to the potency of native tick moubatin. A concentration of recombinant moubatin that fully inhibited collagen-stimulated aggregation did not inhibit aggregation induced by a variety of other platelet agonists, again demonstrating comparable properties of the recombinant and native proteins. Moubatin did not inhibit platelet adhesion to collagen even at a concentration up to 16 times its IC50 for the inhibition of aggregation. This specificity for inhibiting collagen-stimulated aggregation and not adhesion to collagen indicates that moubatin is unique among the natural product inhibitors of collagen stimulation of platelets. Further examination of the mechanism of moubatin-mediated inhibition of collagen-stimulated aggregation revealed that 1-6 microM moubatin diminished the second phase of aggregation induced by ADP, inhibited aggregation in response to submaximal concentrations of the thromboxane A2 mimetic U46619, and competed for the binding of a thromboxane A2 receptor antagonist to platelet membranes. Therefore, at higher concentrations, moubatin may affect more than one aspect of platelet signal transduction including the thromboxane A2 receptor. The availability of recombinant moubatin will allow further investigation of its unique activities in vitro and in vivo.

Nonoperatively treated isolated posterior cruciate ligament injuries

To evaluate the theory that isolated posterior cruciate ligament injuries do well when treated nonoperatively, we reviewed 40 patients (mean age, 33 years at followup; average interval from injury, 6 years) who completed a modified Noyes knee questionnaire and were reevaluated by physical examination, radiographs, and isokinetic testing. Thirty of the injuries to the posterior cruciate ligament were sports-related. On the questionnaire, 65% of the patients revealed that their activity level after injury was limited and 49% stated that the involved knee had not recovered fully despite rehabilitation. Ninety percent complained of knee pain with activity and 43% complained of problems with walking. The longer the interval between injury and this followup, the lower the knee questionnaire score and the greater the radiographic degenerative changes. The patients as a group exhibited excellent muscular strength with a mean isokinetic score of 99% of the contralateral extremity. There was no correlation between isokinetic testing and knee questionnaire score. Patients with greater posterior laxity, as measured by the posterior drawer examination, appeared to have greater subjective complaints. Our study suggests that patients with isolated posterior cruciate ligament injuries treated nonoperatively may maintain excellent muscle strength, but significant symptoms and degenerative changes increase with increasing interval from injury.

Characterization of recombinant antistasin secreted by Saccharomyces cerevisiae

Secretion from recombinant yeast was used as a potential source of large quantities of the leech protein antistasin (ATS), a potent and highly specific inhibitor of the serine protease coagulation factor Xa. Mature recombinant ATS (r-ATS) is obtained after intracellular cleavage by the yscF protease of the mating factor alpha-1 pre-proleader from the fusion protein at the Lys-Arg sequence junction. Production levels are relatively low (ca. 1 mg/liter). Purification of the secreted product from a complex growth medium involved cell removal by microfiltration and diafiltration, cation-exchange capture and concentration on S-Sepharose Fast Flow, C-4 reverse-phase high-performance liquid chromatography (RP-HPLC), and HPLC cation-exchange chromatography step, and RP-HPLC concentration and desalting. The process was scaled up from the 16- to the 250-liter level with a corresponding increase in amount of r-ATS. From the 250-liter fermentation two major forms, r-ATS-I and r-ATS-II, distributed approximately 60:40, and a minor form, r-ATS-minor (ca. 1% of the purified r-ATS), were characterized. Limited N-terminal sequence analysis by Edman degradation indicated that r-ATS-I has the predicted mature N-terminus starting with Gln, that r-ATS-II is N-terminally blocked with pyroglutamate, and that r-ATS-minor is an incompletely processed form. RP-HPLC, hydrophilic-interaction HPLC, cation-exchange HPLC analysis, and electrophoresis results are consistent with the differences observed by sequencing. Preliminary in vitro characterization by intrinsic Ki determination for factor Xa inhibition indicated that the yeast r-ATS forms are indistinguishable from each other as well as from r-ATS expressed by the insect baculovirus host-vector system. Nevertheless, r-ATS-I and r-ATS-II appear less potent than insect-derived r-ATS in the activated partial thromboplastin time clotting assay. Further characterization indicated that C-terminal cleavage at Pro-116 had occurred in r-ATS-I and r-ATS-II as well as oxidation of methionine residues to methionine sulfoxide. The possible role of the C-terminus in inhibition of the prothrombinase complex is discussed.

An inhibitor of collagen-stimulated platelet activation from the salivary glands of the Haementeria officinalis leech. II. Cloning of the cDNA and expression

Salivary glands of the leech Haementeria officinalis contain a protein, leech antiplatelet protein (LAPP), that specifically blocks collagen-mediated platelet aggregation (Connolly, T. M., Jacobs, J. W., and Condra, C. (1992) J. Biol. Chem. 267, 6893-6898). Degenerate oligonucleotides whose sequences were derived from two short peptides from V8 digests of the native LAPP were used as primers to generate a polymerase chain reaction (PCR) product which contains the cDNA region coding for the sequence between these two peptides. Using this PCR product as a hybridization probe, phage containing cDNA clones were isolated containing the entire deduced amino acid sequence for LAPP. Computer analysis of the amino acid sequence predicts a peptidase cleavage site between a 21-residue pre-peptide and a mature protein of 126 amino acids. A DNA insert to express the predicted mature LAPP protein was generated by PCR amplification using phage-derived cDNA clones as a substrate. This insert encoded a fusion protein with the leader sequence of the yeast alpha mating factor and the mature LAPP cDNA. These PCR products were cloned into the yeast expression vector pKH4 alpha 2. A KEX 2 Lys-Arg endopeptidase cleavage site was placed NH2-terminal to the predicted mature protein. This vector transfected into the yeast Saccharomyces cerevisiae directs expression of a secreted mature protein at levels up to 200 mg of LAPP/liter of culture medium. The recombinant protein was comparable to native LAPP in its electrophoretic mobility, its reactivity with anti-LAPP antisera, and its biological activity including inhibition of collagen-stimulated platelet aggregation and the adhesion of platelets to collagen. Availability of significant quantities of recombinant LAPP opens the way to further biochemical structure/function studies and to studies on the effects of an inhibitor of collagen-stimulated platelet aggregation in vivo.

Cell-mediated immune responses after immunization of healthy seronegative children with varicella vaccine: kinetics and specificity

Humoral and cell-mediated immune responses were determined in seronegative children immunized with live attenuated Oka strain varicella vaccine. At 2 weeks after immunization, 80% of children had detectable lymphocyte proliferation to varicella-zoster virus (VZV) antigens, while only 40% had antibodies to VZV as detected by ELISA. By 6 weeks after immunization, 97% of children seroconverted, and 95% of these responded to VZV antigens in the proliferation assay. A high proportion of immunized children also responded in the proliferation assay to purified glycoproteins I, II, and III of VZV. These results indicate that most children develop a broad cell-mediated immune response to VZV antigens within weeks after immunization with varicella vaccine.

3-Deazaadenosine 5'-triphosphate: a novel metabolite of 3-deazaadenosine in mouse leukocytes

Evidence has been obtained for the metabolic formation of small amounts (1-2% of the ATP pool) of 3-deazaadenosine 5'-triphosphate (c3ATP) from 3-deazaadenosine (c3Ado) in mouse cytolytic lymphocytes and mouse resident peritoneal macrophages. With intact leukocytes, pharmacological evidence was obtained that adenosine kinase was not the enzyme chiefly responsible for the phosphorylation of c3Ado. Moreover, in the presence of MgCl2, NaCl and IMP, purified rat liver 5'-nucleotidase catalyzed the phosphorylation of c3Ado to 3-deazaadenosine 5'-monophosphate (c3AMP). Two lines of evidence suggest that the metabolic formation of c3ATP is not involved in the inhibition of leukocyte function caused by c3Ado. First, the inhibitory action of c3Ado on antibody-dependent phagocytosis and lymphocyte-mediated cytolysis was reversed markedly upon removal of the drug from the medium. However, the intracellular content of c3ATP remained constant in lymphocytes and macrophages after removal of c3Ado. Second, in macrophages and in lymphocytes, similar intracellular amounts of c3ATP were formed from both c3Ado and 3-deazaadenine under conditions in which the former was biologically active and the latter was essentially inactive. Thus, it appears unlikely that the novel c3ATP metabolite is of relevance for the mechanism of action of c3Ado in mouse leukocytes.

Cloning and expression of cDNA encoding antistasin, a leech-derived protein having anti-coagulant and anti-metastatic properties

As a factor Xa inhibitor, antistasin is a potent anti-coagulant and anti-metastatic agent that is found in the salivary gland of the Mexican leech Haementaria officinalis. cDNA clones that encode antistasin have been isolated. Subsequent sequence analysis and comparison with the amino acid sequence of the mature protein indicates that antistasin is produced as a pre-protein containing a 17-amino acid signal peptide. Antistasin exists as at least two variants. By sequence analysis of multiple cDNA clones, we found two additional sites for amino acid substitutions, confirming variants that differ from each other by amino acid changes at a minimum of four residues. These sequence variations appear to be the result of allelic variation rather than gene duplication as deduced from DNA blot analyses. Sequence data suggest that antistasin may have evolved from a smaller ancestral gene by a duplication event giving rise to a two-fold structural homology between the N- and C-terminal halves of the molecule. Insect cells transfected with a recombinant baculovirus expressed antistasin which was biologically active and had an electrophoretic mobility identical to that of the native molecule.

Successful infection of the common marmoset (Callithrix jacchus) with human varicella-zoster virus

The common marmoset, Callithrix jacchus, can be infected with human varicella-zoster virus (VZV), both wild-type strain KMcC and attenuated vaccine strain Oka/Merck. Infection was accomplished with either whole-cell-associated or cell extract VZV by combined oral-nasal-conjunctival application and was characterized by substantial and persistent anti-VZV antibody responses. The infectivity of VZV for marmosets was destroyed by treatment of inocula with heat or UV light. Diluted inocula with as few as 40 PFU/ml were infectious for marmosets. The lungs were demonstrated to be a major site of viral replication; both the presence of viral antigens and signs of pneumonia were demonstrated in lung tissues. Four serial passages of VZV KMcC were carried out in C. jacchus by a process of in vitro isolation and culturing of VZV from infected lung tissue and reapplication of the cultured isolates to fresh animals. The isolated viruses were identified as VZV both serologically and by restriction endonuclease analyses. The C. jacchus infectivity model should prove useful for determining the efficacy of subunit and live recombinant VZV vaccines as well as for the study of zoster.

Antibodies to the three major glycoproteins of varicella-zoster virus: search for the relevant host immune response

Clinical manifestations of chickenpox have occurred in individuals known to have seroconverted after vaccination against varicella. To determine whether these "breakthroughs" might be due to the absence of specific antibodies, we tested sera from vaccinees before or at the time of exposure to varicella for antibodies to the three major glycoproteins of varicella-zoster virus (VZV). Protection could not be correlated with the presence or level of any of these antibodies. Levels of antibodies to glycoproteins before onset of zoster were similar to those in sera of individuals who had had varicella previously and did not develop varicella after household exposure. Thus, protection against infections with VZV cannot be explained by the presence of specific antibodies to glycoproteins.

Immunization of monkeys with varicella-zoster virus glycoprotein antigens and their response to challenge with simian varicella virus

African green monkeys (Cercopithecus aethiops) were immunized with three intramuscular injections of gpI, gpII, or gpIII glycoprotein antigens of varicella-zoster virus (VZV). Antibody responses to VZV were determined by enzyme-linked immunosorbent assay (ELISA) and to simian varicella virus (SVV) by immunofluorescence and by serum neutralization assays. Two weeks following the third immunization with VZV glycoproteins, the monkeys were challenged by inoculation of SVV. Antibodies to gpII or gpIII partially prevented infection by SVV, while the presence of antibodies to gpI was ineffective in preventing disease induced by SVV challenge. Factors affecting the immunogenicity of these antigens in this model are discussed.

Clinical isolate of herpes simplex virus type 2 that induces a thymidine kinase with altered substrate specificity

In vitro and in vivo studies were done on a herpes simplex virus type 2 strain recovered from a patient on acyclovir (ACV) which was ACV resistant but expressed thymidine (dThd) kinase (EC 2.7.1.21) activity. Plaque-purified clones derived from the original clinical sample were heterogeneous with respect to plaque size and drug susceptibility. The heterogeneity of this viral mixture was also evident from varied 125I-labeled 5-iodo-2'-deoxycytidine autoradiographic patterns and from varied expression of dThd kinase-associated phosphorylating activities. Four clones from this mixture were 1-beta-D-arabinofuranosylthymine (ara-T) susceptible and ACV resistant. Extracts of cells infected with these clones catalyzed the phosphorylation of ara-T but little of ACV. The virus-coded dThd kinase was purified from one of these clones to determine whether its substrate specificity was altered. The amount of virus-coded dThd phosphorylating activity with the cell extracts was estimated to be sevenfold lower with the resistant clone than with the MS strain of herpes simplex virus type 2. The dThd kinase eluted from a dThd-agarose affinity column under the same conditions with extracts from both sources and substrate saturations of both enzymes by acyclic nucleoside analog phosphate acceptors were classical hyperbolic functions. However, there were significant differences in the kinetic parameters of substrates between the two enzymes. Apparent Km (Km') values for dThd, deoxycytidine, ara-T, ACV, and the acyclic guanosine analog 9-[[2-hydroxyl-1-(hydroxymethyl)ethoxy]methyl]guaine (BW B759U) were 2- to 60-fold higher with the variant enzyme than with the enzyme from laboratory strain MS. Comparing these two enzymes, relative maximal phosphorylation rates (Vm) were eightfold lower for ACV but unchanged for BW B759U. In contrast, the relative rates for deoxycytidine and ara-T were eight- and twofold higher, respectively. The surprisingly good substrate activity with BW B759U compared with that of ACV (Vm/Km' = 0.39 versus 0.01) coincided with susceptibility of the ACV-resistant virus to BW B759U. This clinical variant retained its pathogenicity for mice and was only moderately less neurovirulent than wild-type virus. Although such mutants have the potential to induce illness less responsive to therapy, the recurrence from which the isolate was obtained was typical for this patient in severity and duration. Since this episode, the patient has been treated successfully with ACV.

Varicella-zoster virus as a live vector for the expression of foreign genes

The previous demonstration of the efficacy and tolerability of the Oka strain of varicella-zoster virus (VZV) in clinical trials involving vaccination of both normal and immunocompromised individuals has laid the foundation for its use in preventing chickenpox. In this context, VZV could be useful as a vector for vaccinating against other infectious agents as well. As an initial application, a live recombinant VZV expressing Epstein-Barr virus (EBV) membrane glycoproteins (gp350/220) was generated by inserting a gene fusion of the VZV gpI promoter and hydrophobic leader-encoding sequence with the gp350/220 coding sequence into the thymidine kinase (TK) gene of VZV (Oka). Insertion of the foreign DNA into the thymidine kinase gene was demonstrated by Southern blot analysis and the ability of the recombinant virus to replicate in the presence of bromodeoxyuridine. RNA splicing, glycosylation, and plasma membrane presentation of gp350/220 in cells infected with the recombinant virus were similar to those seen in EBV-infected cells. In addition, the expression of VZV-specific glycoproteins was unaltered by the concomitant expression of this large foreign glycoprotein. Thus, VZV can be used as a live viral vector for active immunization against EBV and other pathogens.

Identification and sequence of the gene encoding gpIII, a major glycoprotein of varicella-zoster virus

The genome of varicella-zoster virus (VZV) encodes three major glycoproteins, two (gpI and gpII) having been mapped and sequenced, which carry epitopes capable of eliciting neutralizing antibodies. The product of the third major glycoprotein gene (gpIII) was purified, and seven consecutive amino acids at its N-terminus were identified. A degenerate pool of oligonucleotides based upon this sequence was used as a probe to localize the gpIII gene to the HindIII B fragment of the VZV genome. An analysis of the DNA sequence from this region revealed an open reading frame (ORF) encoding 841 amino acids. Rabbit antisera against three synthetic peptides derived from the putative gpIII gene recognized a protein which comigrated with gpIII in Western blots and immunoprecipitation analysis. Preclearing with a monoclonal antibody to gpIII specifically abolished immunoprecipitation of this protein. Also a polypeptide translated from mRNA selected by the putative gpIII gene could be immunoprecipitated by the anti-peptide sera. Therefore, we conclude that gpIII is encoded by the identified ORF in HindIII B. In addition, gpIII is implicated as essential for the cell-to-cell spread of VZV.

Identification of an Epstein-Barr virus glycoprotein which is antigenically homologous to the varicella-zoster virus glycoprotein II and the herpes simplex virus glycoprotein B

The Epstein-Barr virus (EBV) antigenic homologue of the varicella-zoster virus glycoprotein II and the herpes simplex virus (HSV) glycoprotein B (gB) was identified through cross-reactivity with anti-glycoprotein II and anti-glycoprotein B peptide sera. The homologue is the previously characterized EBV glycoprotein, with an apparent molecular weight of 125,000 Da, which is synthesized late during productive EBV infection and appears to be encoded by the BamHI A EBV fragment. This glycoprotein, but not other EBV proteins, reacted with the antisera in immunoprecipitation experiments and by ELISA. In addition, absorption of the sera with the purified EBV 125-kDa glycoprotein removed the cross-reacting antibody. Whether the EBV gB homologue has the same biological functions associated with HSV gB has yet to be determined.

Purification of individual varicella-zoster virus (VZV) glycoproteins gpI, gpII, and gpIII and their use in ELISA for detection of VZV glycoprotein-specific antibodies

We have utilized monoclonal antibodies in immune affinity chromatography to purify each of the 3 major glycoproteins of varicella-zoster virus (VZV), gpI, gpII, and gpIII, in immunologically active form. Upon injection into guinea pigs, each preparation elicited the production of specific antibodies capable of immunoprecipitating the homologous glycoprotein and of neutralizing VZV infectivity in vitro. Also, total glycoproteins from VZV-infected cells have been purified by lectin affinity chromatography. Each of the individual purified glycoproteins, as well as total VZV glycoproteins and appropriate uninfected cell protein controls, have been employed as solid-phase reagents in enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies directed against specific VZV glycoproteins. The specificity of the purified glycoproteins as ELISA reagents was verified by the ability of individual monoclonal antibodies to bind specifically to individual glycoprotein preparations. We have demonstrated the utility of the glycoprotein-specific ELISA by detecting antibodies in sera from post-zoster and post-varicella patients. The assay detects antibodies directed against each of the 3 major glycoproteins and is sensitive enough to detect antibodies in a 1:320 000 dilution of some sera. This assay, as well as the purified individual glycoproteins per se, should prove to be very useful reagents in understanding the role of each of gpI, gpII, and gpIII in immunity to VZV.

Identification and structure of the gene encoding gpII, a major glycoprotein of varicella-zoster virus

The genome of varicella-zoster virus (VZV) encodes three major families of glycoproteins (gpI, gpII, and gpIII). mRNA from VZV-infected cells was hybrid selected using a library of VZV recombinant plasmids and translated in vitro; polypeptide products were immunoprecipitated by polyclonal monospecific guinea pig antibodies to gpII. The mRNA encoding a 100-kD polypeptide precipitable by anti-gpII antibodies mapped to the HindIII D fragment near the center of the UL region. DNA sequence analysis of this region of the VZV genome revealed a 2.6-kbp open reading frame (ORF) potentially encoding a 98-kDa polypeptide possessing the characteristics of a glycoprotein. The 100-kDa polypeptide was specified by mRNA isolated by hybrid selection using a plasmid containing part of the 2.6-kbp ORF, and immunoprecipitation of this protein by anti-gpII antibodies and by convalescent zoster serum was blocked specifically by purified gpII. We conclude that the 2.6-kbp ORF encodes gpII. The imputed primary amino acid sequence of gpII shows a high degree of homology to that of herpes simplex virus type 1 (HSV-1) gB, a result consistent with the equivalent map locations of the respective genes in the HSV and VZV genomes and with the recently reported serological cross-reactivity of HSV-1 gB and VZV gpII. Unlike the mature gene products of gB, those of gpII have been described as a pair of glycoproteins with approximate molecular weights of 60 kDa in reducing gels, products of a single glycoprotein species with approximate mol mass of 125-140 kDa in nonreducing gels. Amino-terminal sequences of purified gpII were determined and compared to the imputed amino acid sequence. This comparison implies that the primary translational product is cleaved approximately into halves in vivo and suggests that mature gpII is a disulfide-linked heterodimer.

New common nomenclature for glycoprotein genes of varicella-zoster virus and their glycosylated products

The accumulation of recent data concerning the reactivity of monoclonal antibodies with particular varicella-zoster virus (VZV) glycoproteins and the mapping of several of their respective genes on the VZV genome has led to a unified nomenclature for the glycoprotein genes of VZV and their mature glycosylated products. Homologs to herpes simplex virus glycoprotein genes are noted.

Modifications on the heterocyclic base of acyclovir: syntheses and antiviral properties

A group of compounds was prepared in which variations of the ring portion of the acyclovir (ACV) structure were made. These modifications included monocyclic (isocytosine, triazole, imidazole), bicyclic (8-azapurine, pyrrolo[2,3-d]pyrimidine, pyrazolo[3,4-d]pyrimidine) and tricyclic (linear benzoguanine) congeners. The derivatives were evaluated against herpes simplex virus type 1 (HSV-1) by the plaque-inhibition and plaque-reduction methods with only the 8-azapurine analogue 28 showing some activity. In a test measuring the ability of these compounds to inhibit the HSV-1 thymidine kinase, 28 and the tricyclic derivative 38 exhibited competition with ACV for binding to the enzyme. The inability of the group to exert significant antiherpetic action is attributed to their lack of phosphorylation to the requisite triphosphate stage.