Liquid Chromatographic Method for the Determination of Nine Phenolic Antioxidants in Butter Oil: Collaborative Study

Ten laboratories collaboratively studied a liquid chromatographic (LC) method for the determination of propyl, octyl, and dodecyl gallate (PG, OG, and DG, respectively), 2,4,5-trihydroxybutyrophenone (THBP), ferf-butylhydroquinone (TBHQ), nordihydroguaiaretic acid (NDGA), 2- and 3-tert-butyl-4- hydroxyanisole (BHA), 2,6-di-ferf-butyl-4-hydroxymethylphenol (lonox-100), and 3,5-di-terf-butyl-4- hydroxytoluene (BHT) in butter oil. The 10 samples analyzed were spiked in matched pairs at about 100,50, and 10 μg/g. In the method studied, antioxidants are extracted as in AOAC LC method 983.15, but different LC eluants are used to separate the 9 antioxidants. Results from 1 laboratory were rejected as not valid and were not included in any calculations. For the remaining 9 laboratories, the overall mean recoveries for PG, THBP, TBHQ, NDGA, BHA, OG, lonox, BHT, and DG were 100.9, 97.8,103.4,95.4, 97.4,93.6,95.5,79.0, and 96.2%, respectively. The overall reproducibility relative standard deviations were 8.55,17.4,25.6,14.5,6.60, 9.64,10.8,11.4, and 7.35%, respectively. The method was adopted first action by AOAC International as a modification of AOAC method 983.15.

Dual inversion recovery ultrashort echo time (DIR-UTE) imaging and quantification of the zone of calcified cartilage (ZCC)

OBJECTIVE

To develop ultrashort echo time (UTE) magnetic resonance imaging (MRI) techniques to image the zone of calcified cartilage (ZCC), and quantify its T2*, T1 and T1ρ.

DESIGN

In this feasibility study a dual inversion recovery UTE (DIR-UTE) sequence was developed for high contrast imaging of the ZCC. T2* of the ZCC was measured with DIR-UTE acquisitions at progressively increasing TEs. T1 of the ZCC was measured with saturation recovery UTE acquisitions at progressively increasing saturation recovery times. T1ρ of the ZCC was measured with spin-locking prepared DIR-UTE acquisitions at progressively increasing spin-locking times.

RESULTS

The feasibility of the qualitative and quantitative DIR-UTE techniques was demonstrated on phantoms and in six cadaveric patellae using a clinical 3 T scanner. On average the ZCC has a short T2* ranging from 1.0 to 3.3 ms (mean ± standard deviation = 2.0 ± 1.2 ms), a short T1 ranging from 256 to 389 ms (mean ± standard deviation = 305 ± 45 ms), and a short T1ρ ranging from 2.2 to 4.6 ms (mean ± standard deviation = 3.6 ± 1.2 ms).

CONCLUSION

UTE MR based techniques have been developed for high resolution imaging of the ZCC and quantitative evaluation of its T2*, T1 and T1ρ relaxation times, providing non-invasive assessment of collagen orientation and proteoglycan content at the ZCC and the bone cartilage interface. These measurements may be useful for non-invasive assessment of the ZCC, including understanding the involvement of this tissue component in osteoarthritis.

S3 guidelines for intensive care in cardiac surgery patients: hemodynamic monitoring and cardiocirculary system

Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery (Deutsche Gesellschaft für Thorax-, Herz- und Gefässchirurgie, DGTHG) and the German Society for Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und lntensivmedizin, DGAI) made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess the available monitoring methods with regard to indication, procedures, predication, limits, contraindications and risks for use. The differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilatators, inodilatators and calcium sensitizers and the use of intra-aortic balloon pumps will also be addressed. The guideline has been developed following the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical Societies in Germany (AWMF).

[Amyloidosis in muscular dystrophy]

Mutations in the gene encoding dysferlin (DYSF) cause limb-girdle muscular dystrophy 2B (LGMD2B) and Miyoshi myopathy (MM). We were able to examine eight patients suspected of LGMD2B clinically, histochemically. The genotype was determined in every case. We found sarcolemmal and interstitial amyloid deposits in four muscle sections. All of the mutations associated with amyloid were located in the N-terminal region of dysferlin, and dysferlin clearly proved to be a component of the amyloid deposits. Dysferlin-deficient muscular dystrophy is the first muscular dystrophy in which amyloidosis is involved. This fact must be considered in the process of developing therapeutic strategies. The influence of the amyloid deposits on the pathogenesis of the disease and the possible involvement of other organs in the progressive course are as yet unclear.

[Guidelines for intensive care in cardiac surgery patients: haemodynamic monitoring and cardio-circulatory treatment guidelines of the German Society for Thoracic and Cardiovascular Surgery and the German Society of Anaesthesiology and Intensive Care Medicine]

Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors, are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery and the German Society for Anaesthesiology and Intensive Care Medicine made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess available monitoring methods and their risks as well as the differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilators, inodilators and calcium-sensitizers and the use of intra-aortic balloon pumps. The guideline has been developed according to the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical Societies in Germany (AWMF).

Current practice of hemodynamic monitoring and vasopressor and inotropic therapy in post-operative cardiac surgery patients in Germany: results from a postal survey

BACKGROUND

In Germany, more than 100,000 patients are monitored and treated in 80 intensive care units (ICUs) following cardiac surgery each year. The controversies concerning the different methods of hemodynamic monitoring and the appropriate agents for volume therapy and inotropic support are well known. However, little is known about how monitoring and treatment are currently performed.

METHODS

A questionnaire with 39 questions was sent to the leading physicians of 80 ICUs in Germany, treating patients after cardiac surgery. The questions to be answered covered the current practice of hemodynamic monitoring, volume replacement, inotropic/vasopressor support and transfusions in patients after cardiac surgery.

RESULTS

Sixty-nine per cent of the questionnaires were completed and returned. All ICUs used basic monitoring as recommended by the societies. The use of advanced hemodynamic monitoring included the pulmonary artery catheter (58.2%), transesophageal echocardiography (38.1%) and transpulmonary dilution techniques (13%). Crystalloids (21.2%) and colloids (73%) were used for volume replacement. Epinephrine (41.8%) and dobutamine (30.9%) were the first-choice inotropic drugs for the treatment of low cardiac output syndrome, followed by phosphodiesterase inhibitors (14.5%). Second-choice drugs for the treatment of low cardiac output syndrome were enoximone (29%), milrinone (25%) and dobutamine (25%). A written transfusion protocol and a transfusion threshold for red blood cells existed in 59% and 79% of ICUs, respectively.

CONCLUSION

Hemodynamic monitoring and the variability in clinical practice with regard to volume replacement, transfusion triggers and the use of vasopressors/inotropes in cardiac surgery patients tend to follow the results of traditional experience rather than current scientific knowledge. Guidelines are therefore necessary to help to improve the standards of intensive care after cardiac surgery and thus the outcome of patients.

Measurement of the electric form factor of the neutron at Q2=0.5 and 1.0 GeV2/c2

The electric form factor of the neutron was determined from measurements of the d-->(e-->,e'n)p reaction for quasielastic kinematics. Polarized electrons were scattered off a polarized deuterated ammonia (15ND3) target in which the deuteron polarization was perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle detector. We find G(n)(E)=0.0526+/-0.0033(stat)+/-0.0026(sys) and 0.0454+/-0.0054+/-0.0037 at Q(2)=0.5 and 1.0 (GeV/c)(2), respectively.

Medaka eyeless is the key factor linking retinal determination and eye growth

The complete absence of eyes in the medaka fish mutation eyeless is the result of defective optic vesicle evagination. We show that the eyeless mutation is caused by an intronic insertion in the Rx3 homeobox gene resulting in a transcriptional repression of the locus that is rescued by injection of plasmid DNA containing the wild-type locus. Functional analysis reveals that Six3- and Pax6- dependent retina determination does not require Rx3. However, gain- and loss-of-function phenotypes show that Rx3 is indispensable to initiate optic vesicle evagination and to control vesicle proliferation, by that regulating organ size. Thus, Rx3 acts at a key position coupling the determination with subsequent morphogenesis and differentiation of the developing eye.

A genetic screen for mutations affecting embryonic development in medaka fish (Oryzias latipes)

In a pilot screen, we assayed the efficiency of ethylnitrosourea (ENU) as a chemical mutagen to induce mutations that lead to early embryonic and larval lethal phenotypes in the Japanese medaka fish, Oryzias latipes. ENU acts as a very efficient mutagen inducing mutations at high rates in germ cells. Three repeated treatments of male fish in 3 mM ENU for 1 h results in locus specific mutation rates of 1.1-1.95 x10(-3). Mutagenized males were outcrossed to wild type females and the F1 offspring was used to establish F2 families. F2 siblings were intercrossed and the F3 progeny was scored 24, 48 and 72 h after fertilization for morphological alterations affecting eye development. The presented mutant phenotypes were identified using morphological criteria and occur during early developmental stages of medaka. They are stably inherited in a Mendelian fashion. The high efficiency of ENU to induce mutations in this pilot screen indicates that chemical mutagenesis and screening for morphologically visible phenotypes in medaka fish allows the genetic analysis of specific aspects of vertebrate development complementing the screens performed in other vertebrate model systems.

Graded interference with FGF signalling reveals its dorsoventral asymmetry at the mid-hindbrain boundary

Signalling by fibroblast growth factors (FGFs) at the mid-hindbrain boundary (MHB) is of central importance for anteroposterior neural patterning from the isthmic organiser. Graded suppression of FGF signalling by increasing amounts of a dominant negative FGF receptor provides evidence that in addition to anteroposterior patterning, FGF signalling is also involved in patterning along the dorsoventral axis at the MHB. FGF signalling at the MHB is required for the activation of the HH target gene spalt at the MHB. Our results indicate that FGF signalling mediates the competence of the MHB to activate spalt in response to SHH. This interdependence of the two signalling pathways is also found in the outbudding optic vesicle where HH requires functional FGF signalling to activate spalt in the proximal eye region.

The midbrain-hindbrain boundary genetic cascade is activated ectopically in the diencephalon in response to the widespread expression of one of its components, the medaka gene Ol-eng2

In vertebrates, the engrailed genes are expressed at early neurula stage in a narrow stripe encompassing the midbrain-hindbrain boundary (MHB), a region from which a peculiar structure, the isthmus, is formed. Knock-out experiments in mice demonstrated that these genes are essential for the development of this structure and of its derivatives. In contrast, little is known about the effect of an overexpression of engrailed genes in vertebrate development. Here we report the isolation of Ol-eng2, a medaka fish (Oryzias latipes) engrailed gene. We have monitored the effects of its widespread expression following mRNA injections in 1- and 2-cell medaka and Xenopus embryos. We found that the ectopic expression of Ol-eng2 predominantly results in an altered development of the anterior brain, including an inhibition of optic vesicle formation. No change in the patterns of mesencephalic and telencephalic markers were observed. In contrast, expressions of markers of the diencephalon were strongly repressed in injected embryos. Furthermore, the endogenous Ol-eng2, Pax2, Wnt1 and Fgf8, which are essential components of the MHB genetic cascade, were ectopically expressed in this region. Therefore, we propose that Ol-eng2 induces de novo formation of an isthmus-like structure, which correlates with the development of ectopic midbrain structures, including optic tectum. A competence of the diencephalon to change to a midbrain fate has been demonstrated in isthmic graft experiments. Our data demonstrate that this change can be mimicked by ectopic engrailed expression alone.

Identification of a novel mRNA-associated protein in oocytes of Pleurodeles waltl and Xenopus laevis

Amphibian oocytes accumulate a large pool of mRNA molecules for future embryonic development. Due to their association with specific proteins the stored maternal RNAs are translationally repressed. The identification of these RNA-binding proteins and the characterization of their functional domains may contribute to the understanding of the translational repression mechanisms and the subsequent activation processes during early embryogenesis. Here we present the complete Pleurodeles cDNA sequence of a cytoplasmic protein which is present in oocytes, eggs, and very early cleavage stage embryos but undetectable in postcleavage embryo and adult tissues. The predicted molecular mass of the protein is 55 kDa and the apparent molecular mass as determined by SDS-PAGE, 68 kDa. The deduced amino acid sequence reveals proline- and serine-rich domains in the aminoterminal part as well as two RGG boxes which represent characteristic motifs of several RNA-binding proteins. No distinct homologies to the consensus RNA recognition motif were found. The 55-kDa protein was recovered in cytoplasmic ribonucleoprotein (RNP) particles containing poly(A)+ RNA. It was therefore termed RAP55 for mRNA-associated protein of 55 kDa. However, a direct interaction of RAP55 with mRNA could not be demonstrated by UV-crosslinking experiments, indicating that it is bound to mRNP complexes via protein-protein interactions. RAP55 is evolutionarily conserved since antibodies raised against a recombinant Pleurodeles RAP55 fragment recognize the protein from Pleurodeles and Xenopus. The expression pattern and intracellular distribution of RAP55 suggest that it is part of those mRNP particles which are translationally repressed during oogenesis and become activated upon progesterone-induced oocyte maturation.

Six3, a medaka homologue of the Drosophila homeobox gene sine oculis is expressed in the anterior embryonic shield and the developing eye

The conserved transcription factor Pax6 is essential for eye development in Drosophila and mammals (Hill, R.E., Favor, J., Hogan, B.L.M., Ton, C.C.T., Saunders, G.F., Hanson, I.M., Prosser, J., Jordan, T., Hastie, N.D., van Heyningen, V., 1991. Mouse small eye results from mutations in a paired-like homeobox containing gene. Nature 354, 522-525; Ton, C., Hirvonen, H., Miwa, H., Weil, M., Monaghan, P., Jordan, T., van Heyningen, V., Hastie, N., Meijers-Heijboer, H., Drechsler, M., Royer-Pokora, B., Collins, F., Swaroop, A., Strong, L.C., Saunders, G.F., 1991. Positional cloning and characterization of a paired box- and homeobox-containing gene from the aniridia region. Cell 6, 1059-1074; Matsuo, T., Osumi-Yamashita, N., Noji, S., Ohuchi, H., Koyama, E., Myokai, F., Matsuo, N., Toniguchi, S., Dari, H., Jseki, S., Ninomiya, Y., Fujiwara, M., Watanabe, T., Eto, K., 1993. A mutation at the Pax-6 gene in rat small eye is associated with impaired migration of midbrain crest cells. Nature genet. 3, 299-304; Quiring, R., Walldorf, U., Kloter, U., Gehring, W.J., 1994. Homology of the eyeless gene of Drosophila to the small eye gene in mice and aniridia in humans. Science 265, 785-789). These findings led to the hypothesis that additional genes involved in invertebrate and vertebrate eye development are structurally and functionally conserved (Halder, G., Callaerts, P., Gehring, W.J., 1995. New perspectives on eye evolution. Curr. Opin. Gen. Dev. 5, 602-609; Quiring, R., Walldorf, U., Kloter, U., Gehring, W.J., 1994. Homology of the eyeless gene of Drosophila to the small eye gene in mice and aniridia in humans. Science 265, 785-789). Candidates for such conserved genes are the Drosophila homeobox gene sine oculis (Cheyette, B.N.R., Green, P.J., Martin, K., Garren, H., Hartenstein, V., Zipursky, S.L., 1994. The Drosophila sine oculis locus encodes a homeodomain-containing protein required for the development of the entire visual system. Neuron l2, 977-996) and its murine homologue Six3 (Oliver, G., Mailhos, A., Wehr, R., Copeland, N.G., Jenkins, N.A., Gruss, P., 1995. Six3, a murine homologue of the sine oculis gene, demarcates the most anterior border of the developing neural plate and is expressed during eye development. Development 121, 4045-4055). sine oculis (so) is essential for the development of the larval and adult visual system (Cheyette, B.N.R., Green, P.J., Martin, K., Garren, H., Hartenstein, V., Zipursky, S.L., 1994. The Drosophila sine oculis locus encodes a homeodomain-containing protein required for the development of the entire visual system. Neuron l2, 977-996). Six3 is expressed in the anterior neural plate and optic vesicles, lens, olfactory placodes and ventral forebrain (Oliver, G., Mailhos, A., Wehr, R., Copeland, N.G., Jenkins, N.A., Gruss, P., 1995. Six3, a murine homologue of the sine oculis gene, demarcates the most anterior border of the developing neural plate and is expressed during eye development. Development 121, 4045-4055). Overexpression of mouse Six3 gene in medaka fish embryos (Orvzias latipes) results in the formation of an ectopic lens, indicating that Six3 activity can trigger the genetic pathway leading to lens formation (Oliver, G., Loosli, F., Koster, R., Wittbrodt, J., Gruss, P., 1996. Ectopic lens induction in fish in response to the murine homeobox gene Six3. Mech. Dev. 60, 233-239). We isolated the medaka Six3 homologue and analyzed its expression pattern in the medaka embryo. It is expressed initially in the anterior embryonic shield and later in the developing eye and prosencephalon. The early localized expression of Six3 suggests a role in the regionalization of the rostral head.

[The difficulty of ultrasound diagnosis of lymph node metastases of malignant melanoma in protracted tumor growth]

Lymph node ultrasound examinations are performed during the follow-up of cutaneous melanoma in order to early recognise regional metastases. The excision of regional metastases is the only way to inhibit disseminated metastasis in a certain percentage of cases. Lymph node ultrasound has a sensitivity of 95% in the diagnosis of pathological lymph node changes. Sonographic findings normally show typical features of malignancy; only in some doubtful cases are further control examinations warranted over a period of 4-6 weeks. In violation of this rule, two cases are presented with a delayed onset of metastases causing difficulties in the diagnosis of malignant transformation. Four years after the excision of a nodular melanoma with 0.8 mm tumor thickness at the right lower leg, a suspicious lymph node change in the right groin was sonographically detected which did not fulfill all criteria of malignancy. Control examinations over a period of 1 year found only a further growth of 3 mm. Excision after 1 1/2 years showed a lymph node metastasis. The second case presented 9 years after the excision of a superficial spreading melanoma with 0.76 mm tumor thickness with a suspicious lymph node in the right axilla which similarly grew very slowly. The subsequent excision showed likewise a melanoma metastasis. A protracted growth may occur in thin malignant melanomas with late development of ultrasound features of malignancy. In doubtful cases an early biopsy is recommended.

Short-term IgM and IgG antibody responses to hepatitis E virus infection

53 adult patients with acute hepatitis caused by hepatitis E virus were identified by the presence of IgM antibody to hepatitis E virus, and followed for 12 months to evaluate the kinetics of anti-HEV antibodies. All but 1 female Kuwaiti patient were expatriate workers from the Indian subcontinent, temporarily working in Kuwait. Follow-up samples obtained at 1, 3, 6 and 12 months were evaluated for IgM and IgG antibodies to hepatitis E virus. IgM-class antibodies to hepatitis E virus were detectable in 12/27 (44%) patients at 1 months, in 0/26 at 3 months, in 0/8 at 6 months and 0/6 at 12 months. IgG antibodies to hepatitis E virus were detectable in 46/47 (98%) at onset, 26/27 (96%) at 1 month, in 26/29 (90%) at 3 months, 16/16 (100%) at 6 months and 8/8 (100%) at 12 months of follow-up. This study suggests that IgM antibodies to hepatitis E virus decline rapidly after an acute infection but IgG antibodies to hepatitis E virus persists for at least 1 year in many patients.

A monoclonal antibody against DNA topoisomerase II labels the axial granules of Pleurodeles lampbrush chromosomes

By immunizing Balb/c mice with oocyte nuclei of Pleurodeles waltl we obtained a monoclonal antibody, mAb 4A6, that labels distinct globular domains of the lampbrush chromosomal axes of Pleurodeles. These domains are found at corresponding sites of homologous chromosomes, often at telomeric and putative centromeric regions, and appear to be devoid of DNA. Because of these characteristic features it is most likely that the mAb 4A6-positive domains correspond to the central part of the "axial granules" of urodelan lampbrush chromosomes. In immunoblotting analyses mAb 4A6 reacts with a nuclear antigen of approximately Mr 180000 and a structurally nonrelated cytoplasmic protein of Mr 98000, which was not characterized any further. Comparative immunofluorescence and immunoblotting studies with mAb 4A6 and an antiserum against DNA topoisomerase II (topo II) as well as immunodepletion experiments demonstrated that the nuclear 4A6 antigen is topo II. Our results indicate that topo II is not a constituent of a continuous, loop-anchoring scaffold in lampbrush chromosomes of Pleurodeles but, rather, is restricted to the axial granules.

Positron emission tomography and ultrasonography. A comparative retrospective study assessing the diagnostic validity in lymph node metastases of malignant melanoma

BACKGROUND AND DESIGN

A retrospective study involving 20 patients with melanoma with clinically suspicious lymph nodes was conducted to compare the diagnostic validity of fludeoxyglucose F 18 positron emission tomography (PET) and real-time ultrasonography in lymph node metastases of malignant melanoma.

RESULTS

A total of 83 lymph nodes were assessed with ultrasonography and PET. Imaging results were confirmed by histologic studies or close follow-up ultrasonographic examinations. Positron emission tomography revealed a sensitivity of 74% and a specificity of 93%. Both investigative methods show comparative sensitivity and specificity.

CONCLUSIONS

Ultrasonography is much easier to perform, less time-consuming, and less expensive than PET and it is nonhazardous; therefore, it is ideal for follow-up procedures. Since in routine staging procedures, only sites of expected lymph node involvement are examined, there is a risk of metastases being missed in cases of atypical drainage patterns. Fludeoxyglucose F 18 PET can image proliferating tumors in multiple organ systems and lymph node sites in one session, making it suitable for screening in primary staging procedures and for monitoring response to therapy. Since it is based on metabolic changes, there is good differentiation between scar and tumor tissue. Major disadvantages are restricted access to investigation centers, high imaging costs, and limited anatomical location of metastatic lesions. We conclude that PET does not offer significant advantages in the diagnosis of lymph node metastases compared with ultrasonography.

Purification of a baculovirus-expressed hepatitis E virus structural protein and utility in an enzyme-linked immunosorbent assay

We report on the purification of the full-length structural protein encoded by open reading frame 2 (ORF-2) of hepatitis E virus. The ORF-2 protein, expressed in Sf9 cells by using a recombinant baculovirus vector system, was successfully purified to homogeneity. Gel electrophoresis of the purified ORF-2 protein showed a single polypeptide of 75 kDa by Coomassie blue staining and by Western blot (immunoblot) analysis. We demonstrated that the partially purified ORF-2 protein could be used successfully in a sensitive and specific enzyme-linked immunosorbent assay for the detection of antibodies to hepatitis E virus.

Prevalence of antibody to hepatitis E virus among healthy individuals in southern Taiwan

The seroprevalence of hepatitis E virus (HEV) among 997 healthy individuals aged 6 to 84 years, collected between July 1993 and June 1994 at Kaohsiung-Pingtung area in Southern Taiwan was studied. Of the study populations of vegetable farmers, elementary school children, volunteer blood donors and college students, the prevalence of IgG anti-HEV ranged from 6.4% to 8.8%. In suburban elemantary school children of Mang-Chou Village at Pingtung-Hsien, the seroprevalence rate (9.6%) was significantly higher than the positive rate (1.5%) found in rural aboriginal elementary school of San-Min Village at Kaohsiung-Hsien. IgG anti-HEV antibodies were widely distributed among all age groups, with a significantly higher percentage (13.1%) in the age group of 46-55 years old.

Inhibition of dengue virus by novel, modified antisense oligonucleotides

Five different target regions along the length of the dengue virus type 2 genome were compared for inhibition of the virus following intracellular injection of the cognate antisense oligonucleotides and their analogs. Unmodified phosphodiester oligonucleotides as well as the corresponding phosphorothioate oligonucleotides were ineffective in bringing about a significant inhibition of the virus. Novel modified phosphorothioate oligonucleotides in which the C-5 atoms of uridines and cytidines were replaced by propynyl groups caused a significant inhibition of the virus. Antisense oligonucleotide directed against the target region near the translation initiation site of dengue virus RNA was the most effective, followed by antisense oligonucleotide directed against a target in the 3' untranslated region of the virus RNA. It is suggested that the inhibitory effect of these novel modified oligonucleotides is due to their increased affinity for the target sequences and that they probably function via an RNase H cleavage of the oligonucleotide:RNA heteroduplex.

Identification of capsule-forming Bacillus anthracis spores with the PCR and a novel dual-probe hybridization format

Anthrax is a fatal infection of humans and livestock that is caused by the gram-positive bacterium Bacillus anthracis. The virulent strains of B. anthracis are encapsulated and toxigenic. In this paper we describe the development of a PCR technique for identifying spores of B. anthracis. Two 20-mer oligonucleotide primers specific for the capB region of 60-MDa plasmid pXO2 were used for amplification. The amplification products were detected by using biotin- and fluorescein-labeled probes in a novel dual-probe hybridization format. Using the combination of PCR amplification and dual-probe hybridization, we detected two copies of the bacterial genome. Because the PCR assay could detect a minimum of 100 unprocessed spores per PCR mixture, we attempted to facilitate the release of DNA by comparing the effect of limited spore germination with the effect of mechanical spore disruption prior to PCR amplification. The two methods were equally effective and allowed us to identify single spores of B. anthracis in PCR mixtures.

Acute sporadic hepatitis E in Kuwait

Fifty-seven adult patients with acute hepatitis and 34 comparison patients without liver disease were evaluated using a newly developed Western blot assay for IgM antibody to hepatitis E virus. The mean age of patients with hepatitis was 32 years (range, 18-55 years); 88% were male. Among patients with acute hepatitis, hepatitis A (anti-HAV IgM positive) was diagnosed in two (4%), hepatitis B (anti-HBc IgM positive) in three (5%), and hepatitis E (anti-HEV IgM positive) in 34 (60%). One hepatitis patient had CMV IgM, another had EBV IgM, and 16 others (28%) were negative for all serologic markers of acute viral hepatitis. No patient with acute hepatitis A or B and none of the comparison patients without acute hepatitis had anti-HEV IgM. All but one case of acute hepatitis E were found among expatriates of Asian origin, and acute hepatitis E was associated significantly with recent travel to the Indian subcontinent. These data suggest that acute hepatitis E is common among foreign workers in Kuwait but that little HEV transmission is occurring directly in Kuwait.

Expression of hepatitis E virus putative structural proteins in recombinant vaccinia viruses

Hepatitis E virus (HEV) is a polyadenylated, positive-stranded RNA virus which is a major cause of enterically transmitted non-A, non-B hepatitis in many developing countries. The viral genome contains three different open reading frames (ORFs): ORF1, which is believed to encode nonstructural proteins, and ORF2 and ORF3, which are believed to encode structural proteins. The full-length putative structural proteins encoded by ORF2 and ORF3 of HEV have been cloned and expressed in recombinant vaccinia virus. Proteins encoded by ORF2 and ORF3 when expressed in vaccinia virus are recognized by pooled sera obtained from individuals with acute hepatitis E. Vaccinia-expressed viral gene products of HEV will have utility in characterizing the cell-mediated immune response to HEV.

Activation and enhanced contact of human T-lymphocytes with autologous red blood cells are required for their stable adherence at 37 degrees

The adherence of human red blood cells (RBC) to autologous T-cells does not occur in the body, and in vitro is elicited at 4 degrees. Autologous E-rosetting at 37 degrees has not previously been described. In this work, lymphocyte-RBC adherence has been studied in mixed leukocyte-RBC cultures and in whole blood from healthy donors. Vital, cytochemical and electron microscopic studies have shown that T-cells may form stable E-rosettes with autologous RBC at 37 degrees. As in the previously reported cold-dependent reversible rosetting, stable rosetting is mediated by the erythrocyte LFA3 and lymphocyte CD2 molecules. Uniquely, this phenomenon requires both T-cell activation and an enhanced contact between the T-cell and RBC membranes. These requirements were met by exposure of cell cultures to: (1) PHAE, the erythroagglutinating component of PHAP, or (2) to either non-erythroagglutinating mitogens, PHAL, Con A, OKT3 or SEA, or to antigens of typhus group rickettsiae or salmonellae, provided that the RBC membrane was desialyted. Cultures derived from individuals seropositive to rickettsiae or vaccinated with salmonellae demonstrated the adherence phenomenon after antigen exposure when neuraminidase was present in the culture medium. The system 2 described here can be used as a diagnostic tool for defining activated T-cells and T-cell clones with the memory to antigens capable of inducing cell-mediated immunity.

Expression and diagnostic utility of hepatitis E virus putative structural proteins expressed in insect cells

The full-length putative structural proteins encoded by open reading frame 2 (ORF2) and ORF3 of hepatitis E virus have been cloned and expressed in recombinant baculovirus. Sera obtained from 28 Sudanese pediatric patients with acute hepatitis and 19 pediatric control patients were analyzed for reactivity to hepatitis E virus by using the baculovirus-expressed ORF2 and ORF3 proteins in a Western blot (immunoblot) format. Seventeen of the 18 patients classified as having non-A, non-B hepatitis, without acute antibody markers for hepatitis A, B, or C viruses, Epstein-Barr virus, or cytomegalovirus, were shown to have immunoglobulin M (IgM) antibodies to the recombinant ORF2 protein, as did two patients with chronic hepatitis B, three of seven patients with acute hepatitis A, and one patient with acute hepatitis B. None of the 19 control patients had IgM antibodies against the ORF2 or ORF3 proteins. The Western blot assay using the baculovirus-expressed ORF3 protein did not appear to be as sensitive as the assay based on the ORF2 protein. Only 10 of the patients classified as having non-A, non-B hepatitis had IgM antibodies to the baculovirus-expressed ORF3 protein. We conclude that a Western blot assay which uses a baculovirus-expressed ORF2 protein is both sensitive and specific for diagnosing acute hepatitis E.

Acute sporadic hepatitis E in children living in Cairo, Egypt

Seventy-three pediatric patients with acute hepatitis and 19 control patients without liver disease living in Cairo, Egypt, were evaluated with a newly developed Western blot assay for IgM antibody to hepatitis E virus (IgM anti-HEV). The mean age of acute hepatitis patients was 6.4 years (range, 1-13 years); 56% were male. Among the 73 acute cases, hepatitis A was diagnosed in 30 (41%), possible acute hepatitis B in three (4%), hepatitis E in nine (12%), and by exclusion, non-A, non-B hepatitis in 29 (40%). Two additional acute cases were positive for both IgM anti-HAV and IgM anti-HEV. None of the 19 control subjects had IgM anti-HEV. Parenteral risk factors were associated with cases of non-A, non-B hepatitis but were not associated with acute hepatitis E. Contact with a family member with jaundice was associated with acute hepatitis A. In contrast to prior epidemics of enterically-transmitted non-A, non-B hepatitis, HEV was found to be a common cause of acute hepatitis in a pediatric population. This study provides additional evidence that HEV may be a frequent cause of acute sporadic hepatitis among children living in some developing countries.

Detection of spores of Bacillus anthracis using the polymerase chain reaction

The polymerase chain reaction (PCR) was used to identify spores of Bacillus anthracis. By using an assay capable of amplifying a 1247-bp fragment from the gene that encodes the edema factor of B. anthracis, as few as 10(3) copies of a plasmid containing the edema factor gene and as few as 2 x 10(4) spores were detected. Subjecting the product of this PCR to a second PCR designed to amplify a 208-bp fragment nested within the 1247-bp product improved detection to a single plasmid copy per PCR and to two spores of B. anthracis per PCR.

Acute sporadic hepatitis E in Sudanese children: analysis based on a new western blot assay

A newly developed Western blot assay for antibody to hepatitis E virus (anti-HEV) was used to evaluate 39 cases of acute pediatric hepatitis and 39 control patients in Khartoum, Sudan. The mean age of cases was 6.5 years (range, 2-14); 64% were male. Acute hepatitis A (IgM anti-HAV-positive) was diagnosed in 13 cases, acute hepatitis B (IgM anti-HBc-positive) in 1, and acute hepatitis E (positive for IgM anti-HEV) in 23 (59%). None of the cases with IgM anti-HAV or IgM anti-HBc had IgM anti-HEV; 3 controls had IgM anti-HEV. Acute hepatitis E was associated with recent contact with a family member or acquaintance with jaundice and the presence of indoor plumbing. The newly developed hepatitis E assay appeared to be specific for the diagnosis of acute icteric non-A, non-B hepatitis. Hepatitis E was found to be the most common cause of acute sporadic hepatitis in children living in an urban area of Africa.

Interaction of immune sera with synthetic peptides corresponding to the structural protein region of hepatitis C virus

Comparison of the deduced amino acid sequence from the structural region of the Hutchinson strain of hepatitis C virus (HCV-H) with four other HCV isolates clearly divides the five isolates into two groups based on sequence homology. The first group includes HCV-H, HCV-1, and HC-J1, while the second includes HCV-J1 and HC-J4. Among the five isolates the first 190 residues (putative nucleocapsid) are highly conserved whereas residues 196-513 exhibit significant diversity and include a hypervariable region encompassing residues 386-404. A series of overlapping decapeptides were synthesized by solid-phase pin technology according to sequence from HCV-H (amino acids 1-513), HC-J4 (amino acids 181-513), and regions from the three other isolates which exhibited sequence variation. A modified ELISA was used to measure immunoreactivity of sera from clinical posttransfusion cases and experimentally infected chimpanzees. Comparison of pre- and postinfection samples revealed 16 clusters of immunoreactive peptides within the structural region, none of which was found in the hypervariable region. Only one cluster (amino acids 73-89) was recognized by all human and chimpanzee sera. Clear variation in the immune response was observed between individuals, although no obvious difference in reactivity between acute and chronic cases was observed. Within individual profiles, the reactivity to each peptide cluster and the total number of reactive clusters increased over time.

Human linear B-cell epitopes encoded by the hepatitis E virus include determinants in the RNA-dependent RNA polymerase

Hepatitis E virus is responsible for both sporadic and epidemic hepatitis in developing countries. The nonenveloped virus is 27-34 nm in diameter and has been shown to contain a single-strand, positive-sense, polyadenylylated RNA genome of approximately 7.5 kilobases. The nucleotide sequence of the Burma strain of hepatitis E virus has been reported and three open reading frames (ORFs) have been identified. The deduced amino acid sequence from each of these ORFs was used to synthesize overlapping peptides (decamers overlapping at every fourth amino acid) on a solid phase. These peptides were then tested in an ELISA with pooled acute-phase sera from known cases of enterically transmitted non-A, non-B hepatitis collected in the Sudan. Linear B-cell epitopes were identified in all three ORFs. Epitopes were identified throughout the polyprotein encoded by ORF1, but they appeared to be particularly concentrated in the region of the RNA-dependent RNA polymerase. Distinct epitopes were identified in the presumed structural protein encoded by ORF2, and one epitope was identified close to the carboxyl terminus of the protein encoded by ORF3. These data precisely pinpoint linear B-cell epitopes recognized by antibodies from patients with acute hepatitis E and identify an antibody response directed against the RNA-dependent RNA polymerase.

Association of mycoplasma and human immunodeficiency virus infection: detection of amplified Mycoplasma fermentans DNA in blood

A cross-sectional study was undertaken to determine the prevalence of Mycoplasma fermentans infection in patients with human immunodeficiency virus (HIV) infection using polymerase chain reaction methodology. Targeted M. fermentans DNA sequences could be amplified from the DNA extracted from the blood of 6 (11%) of 55 HIV-seropositive patients but from none of 26 HIV-seronegative subjects at low risk for HIV infection (P = .17). There was no correlation between M. fermentans infection and HIV clinical stage. There was a nonsignificant trend toward an association between M. fermentans infection and a history of syphilis. Infection with M. fermentans may occur more commonly in HIV-infected patients; however, a role as a copathogen or opportunistic infection was not established in this study.

Mapping of monoclonal antibody binding sites on CNBr fragments of the S-layer protein antigens of Rickettsia typhi and Rickettsia prowazekii

The 120 kDa surface protein antigens (SPAs) of typhus rickettsiae lie external to the outer membrane in regular arrays and chemically resemble the S-layer proteins of other bacteria. These proteins elicit protective immune responses against the rickettsiae. In order to study the immunochemistry of these proteins, purified SPAs from Rickettsia typhi and Rickettsia prowazekii were fragmented with CNBr. The fragments were separated by SDS-PAGE and were recovered on PVDF membrane following electroblotting. The origin of eight major fragments from R. prowazekii and seven major fragments from R. typhi was determined by automated N-terminal amino acid sequencing and by comparison with the DNA sequence encoding R. prowazekii SPA. The cleavage patterns and protein sequences of the two proteins differed significantly. CNBr fragments corresponding to the C-terminus (amino acid 1372-1612 of the deduced sequence from encoding gene spaP) were not present in both SPAs. This suggests that the corresponding C-terminal region was not synthesized or was removed during SPA translocation to the cell surface. Modified amino acids were detected in each protein. Eighteen monoclonal antibodies selected for varied reactivity with both native and denatured SPA proteins could be classified into eight different types based on western blot analysis of the CNBr fragments. Six of the monoclonal antibody types reacted predominantly with a single region of the SPAs. Two types of antibodies bound to several CNBr fragments which contained both limited sequence similarity and modified amino acids either of which might account for the multisite binding of these antibodies.

Genetic characterization and transovarial transmission of a typhus-like rickettsia found in cat fleas

The identification of apparently fastidious microorganisms is often problematic. DNA from a rickettsia-like agent (called the ELB agent) present in cat fleas could be amplified by PCR with conserved primers derived from rickettsial 17-kDa common protein antigen and citrate synthase genes but not spotted fever group 190-kDa antigen gene. Alu I sites in both the 17-kDa and citrate synthase PCR products obtained with the rickettsia-like agent and Rickettsia typhi were different even though both agents reacted with monoclonal antibodies previously thought specific for R. typhi. The DNA sequence of a portion of the 17-kDa PCR product of the rickettsia-like agent differed significantly from all known rickettsial sequences and resembled the 17-kDa sequences of typhus more than spotted fever group rickettsiae. The rare stable transovarial maintenance of this rickettsia in cat fleas has important implications for the disease potential of cat fleas.

Characterization of the gene encoding the protective paracrystalline-surface-layer protein of Rickettsia prowazekii: presence of a truncated identical homolog in Rickettsia typhi

The DNA sequence of the gene encoding the protective surface protein antigen (SPA) of Rickettsia prowazekii has been determined. The open reading frame of 4836 nucleotides with promoter and ribosome-binding site is present on a 10.1-kilobase EcoRI fragment. The encoded carboxyl terminus of the 169-kDa protein contains a potential transmembrane region and hydrophilic regions with many lysine and arginine residues potentially accessible to proteolytic cleavage. Because the rickettsia-derived SPA has an estimated molecular mass of only 120 kDa and does not contain several predicted large carboxyl-region CNBr fragments, the SPA product appears to be processed by the rickettsiae. Eight other CNBr fragments were identical in sequence to those predicted from the encoded gene. A complementary 8.7-kilobase EcoRI fragment of Rickettsia typhi DNA was cloned. This fragment lacked a 1433-base-pair region that included the promoter, ribosome-binding site, and the initial 1162 base pairs of the open reading frame encoding the R. prowazekii SPA but had a 3674-base-pair region identical with the remainder of the R. prowazekii SPA gene sequence.

Detection of Rickettsia tsutsugamushi by gene amplification using polymerase chain reaction techniques

Scrub typhus is commonly undiagnosed in endemic areas due, in part, to dependence on retrospective serodiagnosis. Since the etiologic agent, R. tsutsugamushi, will not grow in cell-free systems, a rapid direct-agent detection system such as provided by polymerase chain reaction (PCR) methodology is needed. Genes coding for the variable 56-kDa antigen of R. tsutsugamushi were amplified through 35 cycles using 20-mer oligonucleotide primers and Taq polymerase. Amplification of 1-ng samples of DNA extracted from purified prototype R. tsutsugamushi Karp, Gilliam, and Kato strains was detected by direct visual inspection of the electrophoresed, ethidium bromide-stained, specific bands. Specificity of the PCR was shown when PCR amplification of various non-scrub typhus rickettsial DNAs was unsuccessful. R. tsutsugamushi DNA extracted from the blood of infected mice could be PCR amplified and the 1477-base pair product detected by either direct visualization or by specific hybridization with amplified non-radioactive digoxigenin-11-dUTP-labeled Karp 56-kDa DNA probe.

Diagnosis of acute typhus infection using the polymerase chain reaction

We used the polymerase chain reaction (PCR) for the diagnosis of an acute rickettsial infection. A primer pair derived from the 17-kDa antigen sequence of Rickettsia rickettsii amplified specifically a 434-bp DNA fragment from the genome of Rocky Mountain spotted fever and endemic and epidemic typhus. The assay was able to detect as few as 30 rickettsiae. Detection of PCR-amplified DNA with a digoxigenin-labeled DNA probe confirmed an acute human infection with Rickettsia prowazekii.

Diagnosis of acute typhus infection using the polymerase chain reaction

The first use of the polymerase chain reaction (PCR) for the diagnosis of an acute rickettsial infection is described. A primer pair derived from the 17-kDa antigen sequence of Rickettsia rickettsii gave specific amplification of a 434-base pair DNA fragment from the genome of Rocky Mountain spotted fever and endemic and epidemic typhus. The assay could detect as few as 30 rickettsiae. Detection of PCR-amplified DNA with a nonradioactive DNA probe confirmed an acute infection with Rickettsia prowazekii.

Detection of murine typhus infection in fleas by using the polymerase chain reaction

Polymerase chain reaction (PCR) amplification of DNA was used to detect the etiologic agent of murine typhus, Rickettsia typhi, in experimentally infected adult fleas. A primer pair derived from the 17-kilodalton antigen sequence of typhus and spotted fever group rickettsiae was used to amplify a 434-base-pair (bp) fragment of the genome of the murine typhus rickettsiae. The amplified 17-kilodalton protein antigen-specific sequence was detected in ethidium bromide-stained agarose gels in individual fleas as early as 2 days after exposure to rickettsemic rats (two of six tested). The 434-bp sequence was not detected in uninfected control fleas. A dot hybridization assay used to detect the 434-bp fragment was also specific and about 100-fold more sensitive than the agarose gel PCR assay. Since the PCR assay employed a boiled extract of triturated fleas, both PCR and an antigen capture enzyme-linked immunosorbent assay (ELISA) could be performed on the same individual flea homogenate. The ELISA identified 12 infected fleas out of 29 randomly selected fleas, compared with 14 specimens which were positive by PCR. The PCR assay detected rickettsiae in samples in which no viable rickettsiae were detected by plaque assay. Like the ELISA, the PCR assay sensitivity was due in part to its suitability for detecting small numbers of both live and dead R. typhi in fleas.

The importance of the crystalline surface layer protein antigens of rickettsiae in T-cell immunity

Studies in animal models have demonstrated that solid immunity to typhus rickettsiae is dependent on immune T cells. In addition, the surface protein antigen (SPA) of typhus rickettsiae has been shown to be an effective immunogen, protecting vaccinated animals against subsequent challenge with virulent organisms. In the present studies we describe three classes of human lymphocytes which are capable of lysing cells infected with typhus rickettsiae. The first class is CD3,8-positive and is capable of specially lysing both HLA-matched and mismatched targets infected with typhus rickettsiae. Since this cytotoxic effector can be generated with IL-2 as well as with SPA it appears to be a lymphokine-activated killer (LAK). The second class of lymphocytes is CD3,4-positive and is capable of producing gamma interferon in response to the SPA of typhus rickettsiae. Gamma interferon in turn can cause the lysis of cells infected with typhus rickettsiae as well as inhibit intracellular rickettsial growth. A third cytotoxic effector which is CD3,4-positive and which is capable of lysing only HLA-matched targets infected with typhus rickettsiae was generated with a sonicated antigen, and its fine antigenic specificity is not known at present. We conclude that the SPA is an immunologically important protein for the human host and represents an outstanding candidate for a subunit vaccine against typhus.

Heterogeneity of CD4-positive human T-cell clones which recognize the surface protein antigen of Rickettsia typhi

Immunity to the typhus group of rickettsiae is largely dependent on the effector function of several classes of T lymphocytes, including those which produce gamma interferon. Since the surface protein antigen (SPA) derived from typhus group rickettsiae has been shown to be an effective immunogen in animal models, human T-cell clones specific for the SPA of Rickettsia typhi were isolated and tested for their antigenic specificity, as well as for their ability to produce gamma interferon. Eighteen CD4-positive clones specific for the SPA of R. typhi exhibited considerable diversity in their response to the SPAs derived from two strains of Rickettsia prowazekii and from Rickettsia canada. The vast majority of clones also recognized the SPAs from R. prowazekii but not from R. canada. Two heteroclitic clones demonstrated significantly higher proliferative responses to the SPAs derived from one or both of the R. prowazekii strains than to the SPA of R. typhi, and one clone demonstrated a significantly higher response to the SPA of R. typhi than to the other SPAs. All 18 clones produced gamma interferon in response to SPA stimulation. We conclude that the SPAs from typhus group rickettsiae can elicit both a diverse T-cell response in humans and the efficient stimulation of gamma interferon-mediated immunity.

Ultrastructural and functional effects of lipopolysaccharide and interleukin-2 on human NK cells

Bacterial endotoxin (lipopolysaccharide, LPS) and interleukin-2 (IL-2) are known to stimulate NK cell mediated cytotoxicity against tumor cells. In the present report we sought to correlate the stimulatory effect of LPS and IL-2 on NK cell activity with ultrastructural changes which occurred as a result of such stimulation. Peripheral blood mononuclear cells (PBMC) were purified from healthy donors by a Ficoll-Hypaque density gradient technique. Leu-11a+ NK cells were isolated by flow microfluorometry using a monoclonal FITC conjugated anti-Leu-11a antibody and a FACS II cell sorter. The PBMC were incubated, respectively, with E. coli LPS or recombinant IL-2 (IL-2) for various time periods. Sorted Leu-11a+ NK cells were incubated with LPS for 24 hours. The NK cytotoxicity in the PBMC and sorted Leu-11a+ cells was assessed by a 51Cr release technique using K562 tumor cells as targets. Leu-11a+ NK cells were identified by immunoelectron microscopy using anti-Leu-11a antibody and labeling with horseradish peroxidase or colloidal gold. Results showed that both LPS and IL-2 significantly enhanced the cytotoxic activity of PBMC. The cytotoxicity of sorted Leu-11a+ cells was augmented by LPS. Recombinant IL-2 induced a significant increase in the number of dense granules, hypertrophy of Golgi apparatus and rough endoplasmic reticulum, and mitosis of Leu-7+ cells and Leu-11a+ cells 4 or 7 days after stimulation. These data indicate that: (1) the effect of LPS on the enhancement of NK cytotoxicity in PBMC may be a direct and/or indirect process involving production of lymphokines; (2) LPS has a direct effect on sorted Leu-11a+ cells; (3) IL-2 stimulates mitosis of Leu-7+ cells and Leu-11a+ cells; and (4) the LPS or IL-2 induced ultrastructural changes in Leu-11a+ cells are consistent with the enhanced NK cytotoxicity.

Recognition of typhus group rickettsia-infected targets by human lymphokine-activated killer cells

Lymphokine-activated killer cells caused significant lysis of target cells infected with typhus group rickettsiae (TGR) but not cells infected with Rickettsia tsutsugamushi. Monoclonal and polyclonal antibodies against TGR or TGR-infected cells failed to bind specifically to infected targets, as determined by flow cytometry or by immunoprecipitation of radiolabeled cell surface proteins. Major unaltered antigenic determinants of TGR therefore cannot be detected on the surface of infected targets.