Azacitidine-venetoclax versus azacitidine salvage treatment for primary induction failure or first relapsed acute myeloid leukaemia patients

OBJECTIVES

To compare the efficacy of venetoclax-azacitidine (VEN-AZA) with AZA in the real-life for patients with first relapsed or refractory acute myeloid leukaemia (R/R AML).

METHODS

We retrospectively analysed R/R AML patients treated with VEN-AZA at the Institut Paoli Calmettes between September 2020 and February 2022. We compared them to a historical cohort of patients treated with AZA between 2010 and 2021.

RESULTS

Thirty-five patients treated with VEN-AZA were compared with 140 patients treated with AZA. There were more favourable cytogenetics (25.7% vs. 8.6%; p = 0.01) and less FLT3-ITD mutated AML (8.8% vs. 25.5%; p = .049) in the VEN-AZA group. The overall 30-day mortality rate was 7.4% and the overall 90-day mortality was 20%, with no difference between the groups. The complete remission rate was 48.6% in the VEN-AZA group versus 15% (p < .0001). The composite complete response rate was 65.7% in the VEN-AZA group versus 23.6% (p < .0001). OS was 12.8 months in the VEN-AZA group versus 7.3 months (p = 0.059). Patients with primary refractory AML, poor-risk cytogenetics, prior hematopoietic stem-cell transplantation (HSCT) and FLT3-ITD mutated AML had lower response and survival rates.

CONCLUSION

VEN-AZA was associated with a better response rate and a longer survival than AZA monotherapy in AML patients who relapsed after or were refractory to intensive chemotherapy.

Bone involvement in primary cutaneous diffuse large B-cell lymphoma, leg-type

Primary cutaneous diffuse large B-cell lymphoma, leg-type (PCDLBCL-LT) is an aggressive cutaneous lymphoma. Bone involvement is rare and poorly described. We present five cases of PCDLBCL-LT with bone localization. In four cases, the bone involvement was diagnosed during the initial staging with positron emission tomography (PET) or computed tomography (CT) scan, and in the fifth case after tibial fracture during treatment with rituximab (RTX) and polychemotherapy (PCT). PCDLBCL-LT can be asymptomatic and involve bone sites distant from cutaneous lesions. None had other extracutaneous involvement. In our series, all patients received RTX-PCT as first-line chemotherapy and all had early relapses or progression. Second-line treatments had poor efficacy. Our series shows that bone involvement seems to be associated with poor prognosis in PCDLBCL-LT. Bone localization is not diagnosed with initial thoracic-abdominal-pelvic CT when asymptomatic and affecting the limbs only. If there is a suspicion of PCDLBCL-LT, patients should undergo systematic investigation with alternative imaging techniques, including PET, both at baseline and if there is any concern during follow-up.

Telangiectasias of the breasts showing diffuse dermal angiomatosis in a patient with diffuse livedo reticularis

The breasts are a common location for diffuse dermal angiomatosis (DDA) in a context of obesity and macromastia. The typical clinical presentation includes erythematous or purplish plaques, reticulated telangiectasias, and sometimes livedo reticularis, often complicated by painful ulcerations of the breasts. Biopsy usually confirms a dermal proliferation of endothelial cells staining positively for CD31, CD34 and SMAa and negatively for HHV8. We report herein a woman with DDA of the breasts presenting as diffuse livedo reticularis and acrocyanosis, both long-standing and considered idiopathic following extensive investigations. Since a biopsy of the livedo did not document DDA features in our case, we suggest that our patient's livedo reticularis and telangiectasias could constitute a vascular predisposition for DDA, as its pathogenesis frequently involves an underlying disease involving ischemia, hypoxia, or hypercoagulability.

[Facial ulcerated nodules revealing primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma]

BACKGROUND

Primary cutaneous CD8+ aggressive, epidermotropic, cytotoxic T-cell lymphoma is a rare disease with a poor prognosis. Herein we report a new case, with facial lesions, which was difficult to diagnose.

PATIENTS AND METHODS

A 39-year-old woman was hospitalized for ulcerated nodules on the face that had been developing rapidly for 8 weeks. She had visited Djerba, Tunisia, 3 months earlier. No abnormalities were found on previous routine blood tests. Histopathological analysis of a skin biopsy had revealed non-specific lymphocytic infiltrate. Various therapies, including amoxicillin/clavulanic acid, valaciclovir, corticosteroids, colchicine and doxycycline, proved ineffective. Screening of the cutaneous sample for leishmaniasis proved positive using PCR but negative by direct examination and culture. Treatment was initiated with meglumine antimoniate. A further cutaneous biopsy revealed diffuse lymphocytic proliferation and led to a diagnosis of cutaneous CD8+ aggressive, epidermotropic, cytotoxic T-cell lymphoma. A PET scan showed multiple sites of hypermetabolism affecting the face and lymph nodes. Meglumine antimoniate was stopped and the patient experienced complete remission after chemotherapy.

CONCLUSION

Ulcerated nodules with acute progression on acral sites are characteristic of cutaneous CD8+ aggressive, epidermotropic, cytotoxic T-cell lymphoma. In our case, the positive result of PCR screening for Leishmania that was ultimately considered a false positive was a confounding factor in the diagnostic process. Regarding therapy, aggressive treatment strategies such as multiagent chemotherapy and hematopoietic stem-cell transplantation are needed due to the rapid progression of the lymphoma.

A chemogenomic approach to identify personalized therapy for patients with relapse or refractory acute myeloid leukemia: results of a prospective feasibility study

Targeted next-generation sequencing (tNGS) and ex vivo drug sensitivity/resistance profiling (DSRP) have laid foundations defining the functional genomic landscape of acute myeloid leukemia (AML) and premises of personalized medicine to guide treatment options for patients with aggressive and/or chemorefractory hematological malignancies. Here, we have assessed the feasibility of a tailored treatment strategy (TTS) guided by systematic parallel ex vivo DSRP and tNGS for patients with relapsed/refractory AML (number NCT02619071). A TTS issued by an institutional personalized committee could be achieved for 47/55 included patients (85%), 5 based on tNGS only, 6 on DSRP only, while 36 could be proposed on the basis of both, yielding more options and a better rationale. The TSS was available in <21 days for 28 patients (58.3%). On average, 3 to 4 potentially active drugs were selected per patient with only five patient samples being resistant to the entire drug panel. Seventeen patients received a TTS-guided treatment, resulting in four complete remissions, one partial remission, and five decreased peripheral blast counts. Our results show that chemogenomic combining tNGS with DSRP to determine a TTS is a promising approach to propose patient-specific treatment options within 21 days.

Early prognostic factors in septic shock cancer patients: a prospective study with a proteomic approach

BACKGROUND

Organ failures are the main prognostic factors in septic shock. The aim was to assess classical clinico-biological parameters evaluating organ dysfunctions at intensive care unit admission, combined with proteomics, on day-30 mortality in critically ill onco-hematology patients admitted to the intensive care unit for septic shock.

METHODS

This was a prospective monocenter cohort study. Clinico-biological parameters were collected at admission. Plasma proteomics analyses were performed, including protein profiling using isobaric Tag for Relative and Absolute Quantification (iTRAQ) and subsequent validation by ELISA.

RESULTS

Sixty consecutive patients were included. Day-30 mortality was 47%. All required vasopressors, 32% mechanical ventilation, 33% non-invasive ventilation and 13% renal-replacement therapy. iTRAQ-based proteomics identified von Willebrand factor as a protein of interest. Multivariate analysis identified four factors independently associated with day-30 mortality: positive fluid balance in the first 24 h (odds ratio = 1.06, 95% CI = 1.01-1.12, P = 0.02), severe acute respiratory failure (odds ratio = 6.14_, 95% CI = 1.04-36.15, P = 0.04), von Willebrand factor plasma level > 439 ng/ml (odds ratio = 9.7, 95% CI = 1.52-61.98, P = 0.02), and bacteremia (odds ratio = 6.98, 95% CI = 1.17-41.6, P = 0.03).

CONCLUSION

Endothelial dysfunction, revealed by proteomics, appears as an independent prognostic factor on day-30 mortality, as well as hydric balance, acute respiratory failure and bacteremia, in critically ill cancer patients admitted to the intensive care unit. Endothelial failure is underestimated in clinical practice and represents an innovative therapeutic target.

[Shifting cellulitis in a patient with X-linked hypogammaglobulinemia]

BACKGROUND

In cases of immunodeficiency, a systemic infection may be revealed by atypical symptoms, particularly those involving the skin.

PATIENTS AND METHODS

The present case describes a 19-year-old male with X-linked hypogammaglobulinemia, or Bruton agammaglobulinemia, treated with intravenous immunoglobulin G antibodies. Over a 6-week period, the patient developed recurrent plaques in both legs, first on one and then on the other, without fever. Blood cultures were repeated and the fifth pair proved positive for Campylobacter jejuni. An abdominal scan showed appendicitis without intestinal signs. The patient was treated with azithromycin for 2 weeks, which resulted in full recovery from the skin lesions.

DISCUSSION

Campylobacter bacteremia infections are severe and carry a 15% mortality rate at 30 days. The majority of affected patients present humoral immunodeficiency. The literature contains reports of 10 patients with C. jejuni-associated cellulitis, of whom 6 presented hypogammaglobulinemia. We postulate that the cutaneous manifestations were caused by septic metastases. The immunoglobulin replacement therapy mainly comprised IgG antibodies; IgA and IgM antibodies appear to play a key role in the response to C. jejuni infection, which could explain the susceptibility observed. The American guidelines recommend blood and skin cultures in patients with cellular immune defects. We suggest that this recommendation be extended to patients with humoral immunodeficiency.

Mechanical ventilation in cancer patients

Acute respiratory failure (ARF) in cancer patients remains a frequent and severe complication, despite the general improved outcome over the last decade. The survival of cancer patients requiring ventilatory support in Intensive Care Unit (ICU) has dramatically improved over the last years. The diagnostic approach, including an invasive strategy using fiber optic bronchoscopy or a non-invasive strategy, must be effective to identify a diagnostic, as it is a crucial prognostic factor. The use of non-invasive ventilation (NIV) instead of invasive mechanical ventilation (IMV), has contributed to decrease mortality, but NIV has to be used in appropriate situations. Indeed, NIV failure (i.e., need for IMV) is deleterious. Classical prognostic factors are not relevant anymore. The number of organ failure at admission and over the first 7 ICU days governs outcomes. Ventilatory support can thus be included in different management contexts: full code management with unlimited use of life sustaining therapies, full code management for a limited period, no-intubation decision, or the use of palliative NIV. The objectives of this review article are to summarize the modified ARF diagnostic and therapeutic management, induced by improvements in both intensive care and onco-hematologic management and recent literature data.

A phytoplasma closely related to the pigeon pea witches'-broom phytoplasma (16Sr IX) is associated with citrus huanglongbing symptoms in the state of São Paulo, Brazil

In February 2007, sweet orange trees with characteristic symptoms of huanglongbing (HLB) were encountered in a region of São Paulo state (SPs) hitherto free of HLB. These trees tested negative for the three liberibacter species associated with HLB. A polymerase chain reaction (PCR) product from symptomatic fruit columella DNA amplifications with universal primers fD1/rP1 was cloned and sequenced. The corresponding agent was found to have highest 16S rDNA sequence identity (99%) with the pigeon pea witches'-broom phytoplasma of group 16Sr IX. Sequences of PCR products obtained with phytoplasma 16S rDNA primer pairs fU5/rU3, fU5/P7 confirm these results. With two primers D7f2/D7r2 designed based on the 16S rDNA sequence of the cloned DNA fragment, positive amplifications were obtained from more than one hundred samples including symptomatic fruits and blotchy mottle leaves. Samples positive for phytoplasmas were negative for liberibacters, except for four samples, which were positive for both the phytoplasma and 'Candidatus Liberibacter asiaticus'. The phytoplasma was detected by electron microscopy in the sieve tubes of midribs from symptomatic leaves. These results show that a phytoplasma of group IX is associated with citrus HLB symptoms in northern, central, and southern SPs. This phytoplasma has very probably been transmitted to citrus from an external source of inoculum, but the putative insect vector is not yet known.

First Report of a Huanglongbing-Like Disease of Citrus in Sao Paulo State, Brazil and Association of a New Liberibacter Species, "Candidatus Liberibacter americanus", with the Disease

Huanglongbing (HLB) (ex-greening) is one of the most serious diseases of citrus. The causal agent is a noncultured, sieve tube-restricted α-proteobacterium, "Candidatus Liberibacter africanus" in Africa and "Candidatus Liberibacter asiaticus" in Asia (2). The disease has never been reported from the American continent. However, Diaphorina citri, the Asian psyllid vector of HLB, is found in South, Central, and North America (Florida and Texas). Early in 2004, leaf and fruit symptoms resembling those of HLB were observed in several sweet orange orchards near the city of Araraquara, Sao Paulo State. Leaf mottling on small and large leaves was the major symptom. Shoots with affected leaves were yellowish. Fruits were small and lopsided, contained many aborted seeds, and appeared more severely affected than were plants infected with classic HLB. Forty-three symptomatic samples and twenty-five samples of symptomless sweet orange leaves from five farms were analyzed for the presence of the HLB-liberibacters using polymerase chain reaction (PCR) with two sets of HLB-specific primers for amplification of 16S rDNA (2,3) and ribosomal protein genes (1). None of the 43 symptomatic leaf samples gave a positive PCR amplification, while HLB-affected leaves from the Bordeaux HLB collection produced the characteristic amplicons with both sets of primers. The 43 symptomatic and the 25 symptomless leaf samples were then analyzed using PCR with universal primers for amplification of bacterial 16S rDNA (4). All symptomatic leaf samples, but none of the symptomless leaf samples, yielded the same 16S rDNA amplification product, indicating the presence of a bacterium in the symptomatic leaves. This was confirmed using the observation of a sieve tube restricted bacterium by electron microscopy. The 16S rDNA product was cloned, sequenced, and compared with those of "Ca. L. africanus" and "Ca. L. asiaticus". While the 16S rDNAs of these two liberibacter species have 97.5% sequence identity, the 16S rDNA sequence of the new bacterium shared only 93.7% identity with that of "Ca. L. asiaticus" and 93.9% with that of "Ca. L. africanus". The 16S rDNA sequence of the new bacterium had a secondary loop structure characteristic of the α subdivision of the proteobacteria and possessed all the oligonucleotide signatures characteristic of the liberibacters. For these reasons, the new bacterium is a liberibacter and is sufficiently different phylogenetically from known liberibacters to warrant a new species, "Candidatus Liberibacter americanus". Specific PCR primers for amplification of the 16S rDNA of the new species have been developed. They were able to detect "Ca. L. americanus" in 214 symptomatic leaf samples from 47 citrus farms in 35 municipalities, while the "old" species, "Ca. L. asiaticus", has been found only four times within the 47 farms. References: (1) A. Hocquellet et al. Mol. Cell. Probes, 13:373, 1999. (2) S. Jagoueix et al. Int. J. Syst. Bacteriol. 44:379, 1994. (3) S. Jagoueix et al. Mol. Cell. Probes 10:43, 1996. (4) W. G. Weisburg et al. J. Bacteriol. 173:697, 1991.

Disruption of a gene predicted to encode a solute binding protein of an ABC transporter reduces transmission of Spiroplasma citri by the leafhopper Circulifer haematoceps

Spiroplasma citri is transmitted from plant to plant by phloem-feeding leafhoppers. In an attempt to identify mechanisms involved in transmission, mutants of S. citri affected in their transmission must be available. For this purpose, transposon (Tn4001) mutagenesis was used to produce mutants which have been screened for their ability to be transmitted by the leafhopper vector Circulifer haematoceps to periwinkle plants. With one mutant (G76) which multiplied in leafhoppers as efficiently as S. citri wild-type (wt) strain GII-3, the plants showed symptoms 4 to 5 weeks later than those infected with wt GII-3. Thirty to fifty percent of plants exposed to leafhoppers injected with G76 remained symptomless, whereas for wt GII-3, all plants exposed to the transmission showed severe symptoms. This suggests that the mutant G76 was injected into plants by the leafhoppers less efficiently than wt GII-3. To check this possibility, the number of spiroplasma cells injected by a leafhopper through a Parafilm membrane into SP4 medium was determined. Thirty times less mutant G76 than wt GII-3 was transmitted through the membrane. These results suggest that mutant G76 was affected either in its capacity to penetrate the salivary glands and/or to multiply within them. In mutant G76, transposon Tn4001 was shown to be inserted into a gene encoding a putative lipoprotein (Sc76) In the ABCdb database Sc76 protein was noted as a solute binding protein of an ABC transporter of the family S1_b. Functional complementation of the G76 mutant with the Sc76 gene restored the wild phenotype, showing that Sc76 protein is involved in S. citri transmission by the leafhopper vector C. haematoceps.

[Perceived health survey of 3,800 French adolescents: methodological aspects]

An epidemiological survey was carried out by a local association network and was developed in partnership with regional and national institutions. The survey on well-being and health was conducted over an 18-month period in the French department of Charente. The purpose of the research was to test the hypothesis that "the change in context that is experienced by adolescents at the end of junior high school and at the beginning of high school leads to an increase in risky behaviours". To this end, the survey questioned 3,800 young people on a random basis, mixing those from different grades, those participating in vocational training and apprenticeships, and those from public and private schools. The accomplishment of this survey was made possible thanks to the motivation of a pre-existing strong local network organised and linked to education professionals, the technical contribution of the region's health observatory who conducted the statistical analysis of the data, and the assistance of Unit 472 of the French Institute of Health and Medical Research who provided scientific supervision and advice. The high participation rate and quality of the data (comparable with and even better than some existing studies) demonstrate that it is possible for local associations to carry out effective epidemiological surveys based on the needs keenly felt by the workers themselves, within the scope of a reasonable budget and in a short time span without sacrificing the precision demanded by the scientific method.

Mycoplasmas, plants, insect vectors: a matrimonial triangle

Plant pathogenic mycoplasmas were discovered by electron microscopy, in 1967, long after the discovery and culture in 1898 of the first pathogenic mycoplasma of animal origin, Mycoplasma mycoides. Mycoplasmas are Eubacteria of the class Mollicutes, a group of organisms phylogenetically related to Gram-positive bacteria. Their more characteristic features reside in the small size of their genomes, the low guanine (G) plus cytosine (C) content of their genomic DNA and the lack of a cell wall. Plant pathogenic mycoplasmas are responsible for several hundred diseases and belong to two groups: the phytoplasmas and the spiroplasmas. The phytoplasmas (previously called MLOs, for mycoplasma like organisms) were discovered first; they are pleiomorphic, and have so far resisted in vitro cultivation. Phytoplasmas represent the largest group of plant pathogenic Mollicutes. Only three plant pathogenic spiroplasmas are known today. Spiroplasma citri, the agent of citrus stubborn was discovered and cultured in 1970 and shown to be helical and motile. S. kunkelii is the causal agent of corn stunt. S. phoeniceum, responsible for periwinkle yellows, was discovered in Syria. There are many other spiroplasmas associated with insects and ticks. Plant pathogenic mycoplasmas are restricted to the phloem sieve tubes in which circulates the photosynthetically-enriched sap, the food for many phloem-feeding insects (aphids, leafhoppers, psyllids, etc.). Interestingly, phytopathogenic mycoplasmas are very specifically transmitted by leafhoppers or psyllid species. In this paper, the most recent knowledge on phytopathogenic mycoplasmas in relation with their insect and plant habitats is presented as well as the experiments carried out to control plant mycoplasma diseases, by expression of mycoplasma-directed-antibodies in plants (plantibodies).

Use of an internal control in a nested-PCR assay for Mycoplasma hyopneumoniae detection and quantification in tracheobronchiolar washings from pigs

We have previously reported a nested PCR assay for the detection of Mycoplasma hyopneumoniae directly in tracheobronchiolar washings from living pigs in field conditions. Here, we describe the construction and use of an internal control to monitor the presence of PCR inhibitors. A PCR modified target DNA was constructed by insertion of a small DNA fragment into the M. hyopneumoniae specific DNA target. We have demonstrated that the internal control failed to be amplified in only three tracheobronchiolar washings samples out of the 362 tested. This control molecule was inserted in a Spiroplasma citri derived plasmid vector and introduced into S. citri cells by electroporation. After a few passages we ensured that the recombinant plasmid became inserted into the genome of S. citri. PCR amplification of the DNA of this transformed S. citri strain using nested PCR primers led to amplification of a 900-bp fragment which can be discriminated from the M. hyopneumoniae PCR product 700 bp. The S. citri transformants with the integrated internal control were added to the tracheobronchiolar washings prior to PCR and used as an internal control to check the efficiency of sample processing, and to demonstrate the presence of inhibitors. Furthermore, we have been able to estimate the number of mycoplasma cells in the tracheobronchiolar washings. Quantitation was performed by comparing the PCR signal intensity of the specific M. hyopneumoniae template with known concentrations of the S. citri competitor. The titer in tracheobronchiolar washings ranged approximatively from 10(4)to 10(8)M. hyopneumoniae cells per ml of clinical specimen. Quantitative PCR can be a useful tool for monitoring the progression of M. hyopneumoniae in the disease process.

A nested PCR assay for the detection of Mycoplasma hyopneumoniae in tracheobronchiolar washings from pigs

A nested polymerase chain reaction (PCR) was developed for the detection of Mycoplasma hyopneumoniae, the etiological agent of enzootic pneumonia, in tracheobronchiolar washings from live pigs. Two nested pairs of oligonucleotide primers were designed from the sequence of a specific DNA probe (I 141; accession number U02537). The primer combination was Hp1/Hp3 for the first step PCR while the nested primers (Hp4/Hp6) allowed amplification of a 706 bp fragment. All strains of M. hyopneumoniae tested in this study could be detected by the nested PCR. DNA from other bacterial species isolated from the respiratory tract of pigs or from other mycoplasmal species were not amplified. The detection limit was estimated to be 1 fg, corresponding approximately to one organism, while in the one step PCR previously described 4 x 10(2) organisms were required. The nested PCR was evaluated on 362 tracheobronchiolar lavages collected from pigs at 2, 4 and 6 months of age in eight herds chronically infected with M. hyopneumoniae. The nested PCR was compared to a blocking ELISA performed with sera collected from the same pigs at the same ages, and to an immunofluorescence test at slaughter on 65 lungs from 6-month old pigs. The comparison indicated that the nested PCR was significantly (p<0.05) more sensitive (157 positive results of 362 samples) than ELISA (118 positive results of 362 samples) for detection of M. hyopneumoniae infection. Nested PCR was also significantly more sensitive (54 positive results of 65 samples) than immunofluorescence (29 positive results of 65 samples) for detection of M. hyopneumoniae in pig lungs at slaughter. Moreover, the nested PCR was used to confirm the absence of the mollicute in a pig herd without any history of M. hyopneumoniae infection. Thus, nested PCR appears to be a useful test to assess M. hyopneumoniae infection on pig farms.

PCR-RFLP and sequence analysis of a non-ribosomal fragment for genetic characterization of European stone fruit yellows phytoplasmas infecting various Prunus species

A 927 bp non-ribosomal fragment was used to assess the genetic variability of the European stone fruit yellows (ESFY) phytoplasma infecting 14 different Prunus species. For this, 175 isolates originating from four different Mediterranean countries were tested by PCR-RFLP analysis with seven restriction enzymes. No polymorphism among the ESFY phytoplasma could be observed but 12 out of 18 restriction sites differed between the homologous fragments of ESFY and apple proliferation (AP) phytoplasmas. An 846 bp fragment of a French ESFY isolate was sequenced, it included the 3'-end of a putative nitroreductase gene, an intergenic region and a truncated open reading frame. This ESFY phytoplasma sequence showed 89.7% identity with the equivalent AP phytoplasma nucleotide sequence (83. 9% identity at the amino acid level). The G+C content of the entire sequence was extremely low (15.4%) and A+T-rich codons were highly preferred in codon usage. In this paper, we report the presence of the ESFY phytoplasma for the first time in Turkey and in five Prunus hosts never reported previously. Our results also indicate that the ESFY phytoplasma isolates affecting various Prunus species are genetically homogenous but can be distinguished from the AP phytoplasma. Therefore, they are likely to represent different taxons.

Genetic variability of apple proliferation phytoplasmas as determined by PCR-RFLP and sequencing of a non-ribosomal fragment

Apple proliferation phytoplasmas are considered as quarantine organisms in Europe and north America, but reliable polymerase chain reaction (PCR) primers for their identification in routine diagnosis were missing, because they show genetic variability. Therefore, 100 apple proliferation phytoplasma isolates, derived from most of the European countries where apple proliferation disease has been detected, were analysed for their genetic variability. A detailed restriction fragment length polymorphism (RFLP) analysis of a 1.5 kbp chromosomal DNA fragment amplified by PCR (PCR-RFLP) from various isolates of apple proliferation phytoplasma revealed three different subtypes named AP, AT-1 and AT-2. Sequence analysis of a 846 bp fragment of each subtype showed that the sequences differed only in the restriction sites responsible for the observed polymorphism. Thus, the apple proliferation phytoplasma subtypes are very closely related. The observed point mutations were responsible for specific amino acid changes in the putative protein PR3. No geographic prevalence of a given subtype could be observed. In a 5-year study a given subtype could be repeatedly amplified from the same tree indicating a stable maintenance of the subtype. The AP-specific primers used in this study enabled a one-step identification of all isolates suitable for routine diagnosis

Gene organization and transcriptional analysis of the Spiroplasma citri rpsB/tsf/x operon

The nucleotide sequence of a 6863-bp Spiroplasma citri DNA fragment comprising the spiralin gene was determined. Sequence analysis revealed eight putative ORFs that encode ribosomal protein S2, elongation factor Ts, spiralin, 6-phosphofructokinase, pyruvate kinase, and three unidentified proteins (A, B, and X). The gene organization reported here is different from that previously published. Northern blot analysis of rpsB, tsf, and x transcripts indicates that these genes are organized into a single transcriptional unit (operon). However, the detection of an additional transcript corresponding to the rpsB gene alone suggests that a transcriptional mechanism should occur in the 3' region of the rpsB gene, allowing a conditional transcription termination.

Purification, cloning, and preliminary characterization of a Spiroplasma citri ribosomal protein with DNA binding capacity

The rpsB-tsf-x operon of Spiroplasma citri encodes ribosomal protein S2 and elongation factor Ts, two components of the translational apparatus, and an unidentified X protein. A potential DNA-binding site (a 20-base pair (bp) inverted repeat sequence) is located at the 3' end of rpsB. Southwestern analysis of S. citri proteins, with a 30-bp double-stranded oligonucleotide probe (IRS), containing the 20-bp inverted repeat sequence and the genomic flanking sequences, detected an IRS-binding protein of 46 kDa (P46). P46 protein, which displays preferential affinity for the IRS, was purified from S. citri by a combination of affinity and gel filtration chromatographies. The native form of P46 seems to be homomultimeric as estimated by SDS-polyacrylamide gel electrophoresis analysis and gel filtration. A 3.5-kilobase pair S. citri DNA fragment comprising the P46 gene and flanking sequences was cloned and sequenced. Sequence analysis of this DNA fragment indicated that the P46 gene is located within the S10-spc operon of S. citri at the position of the gene coding for ribosomal protein L29 in the known S10-spc operons. The similarity between the N-terminal domain of P46 and the L29 ribosomal protein family and the presence of a 46-kDa IRS-binding protein in S. citri ribosomes indicated that P46 is the L29 ribosomal protein of S. citri. We suggest that P46 is a bifunctional protein with an L29 N-terminal domain and a C-terminal domain involved in IRS binding.

Sequence analysis of Spiroplasma phoeniceum and Spiroplasma kunkelii spiralin genes and comparison with other spiralin genes

The spiralin genes from two phytopathogenic spiroplasmas, Spiroplasma phoeniceum and Spiroplasma kunkelii, were amplified by PCR, cloned, and sequenced. Comparison of the amino acid sequences of the five spiralins analyzed to date confirm that the spiralins have a general amphiphilic character and possess a conserved lipoprotein signal peptide. It also shows that a conserved central region and an amino acid repetition, including a VTKXE consensus sequence, are present in all spiralins analyzed.

Random insertion of transposon Tn4001 in the genome of Spiroplasma citri strain GII3

Electroporation of Spiroplasma citri strain GII3 with plasmid pMUT containing the Staphylococcus aureus transposon Tn4001 resulted in random insertion of Tn4001 into the spiroplasmal genome. Transformation frequencies reached 10(-8) per colony-forming unit (CFU) when 100 microg of plasmid DNA and 3 x 10(9) S. citri CFU were used. Three other strains of S. citri failed to be transformed under the same conditions. In most cases Tn4001 was randomly inserted in the genome of S. citri strain GII3, without insertion of the carrier plasmid. For most transformed spiroplasmas, Tn4001 was stably maintained in the absence of antibiotic selection for at least 80 bacterial generations, making Tn4001 a potential tool for S. citri mutagenesis.

Analysis of putative ABC transporter genes in Mycoplasma hyopneumoniae

A previously described DNA probe specific for Mycoplasma hyopneumoniae (I-141) was fully sequenced and found to consist of 1618 bp and to contain two tandemly repeated ORFs. The deduced amino acid sequence of the two ORFs showed significant homologies with ATP-binding cassette (ABC) transporter proteins, particularly those of the eukaryotic multidrug resistance (MDR) protein family (up to 21% identity and 47% similarity). A somewhat lower homology was evident with the secretion protein HlyB of the RTX-haemolysin from Escherichia coli. The location of the two ORFs on the M. hyopneumoniae chromosome was downstream of the rrl gene encoding the 23S rRNA, but transcribed in the opposite direction. PCR amplification and subsequent chromosomal analysis by Southern blot hybridization of several M. hyopneumoniae strains showed that all field strains contained the two putative ABC transporter genes. However, some culture collection strains derived from strain J had lost these genes as the result of a 2221 bp deletion.

Spiralin polymorphism in strains of Spiroplasma citri is not due to differences in posttranslational palmitoylation

Spiralin is defined as the major membrane protein of the helical mollicute Spiroplasma citri. According to the S. citri strain used, spiralin shows polymorphism in its electrophoretic mobility. The spiralin gene sequences of eight S. citri strains were determined by direct sequencing of the PCR-amplified genes. All spiralins were found to be 241 amino acids long, except for the spiralin of strain Palmyre, which is 242 amino acids long. The molecular masses calculated from these sequences did not explain the differences observed in the electrophoretic mobilities. In all of the spiralins examined, the first 24 N-terminal amino acids were conserved, including a cysteine at position 24, and had the features of typical signal peptides of procaryotic lipoproteins. When S. citri strains were grown in the presence of [3H]palmitic acid, at least 10 proteins, including spiralin, became labeled. In the presence of globomycin, a lipoprotein signal peptidase inhibitor in eubacteria, apparently unprocessed spiralin could be detected. Formic acid hydrolysis of the [3H]palmitic acid-labeled spiralins of four representative S. citri strains yielded two peptide fragments for each spiralin, as expected from the gene sequence. On fragment was [3H]palmitic acid labeled, and it had almost the same electrophoretic mobility irrespective of the spiralins used. Samples of the unlabeled peptide fragments from the four representative strains had slightly different electrophoretic mobilities (delta Da approximately equal to 800 Da); however, these were much smaller than those of the whole spiralins before formic acid hydrolysis (delta Da approximately equal to 8,000 Da). These results suggest that spiralin polymorphism in S. citri is not due to differences in posttranslational modification by palmitic acid and is certainly a structural property of the whole protein or could result from an unidentified posttranslational modification of spiralin.

Polymerase chain reaction for Mycoplasma hyopneumoniae detection in tracheobronchiolar washings from pigs

We have used the polymerase chain reaction (PCR) to detect Mycoplasma hyopneumoniae in tracheobronchiolar washings collected from experimentally infected piglets. On the basis of the published nucleotide sequence of M. hyopneumoniae I141 probe (accession number U02537), primers were chosen to produce an amplified fragment of 1561 bp. All the M. hyopneumoniae strains tested could be detected by the PCR test. DNA from other mycoplasmal and bacterial species currently isolated from respiratory tract of piglets gave negative result. The detection limit was estimated to be 500 fg of purified DNA corresponding to 4.10(2) organisms. The sensitivity of PCR reaction was also evaluated on microorganisms in culture, the limit sensitivity was 2.5 10(3) organisms. In the present study, a total of 143 tracheobronchiolar washings collected from experimentally infected piglets were submitted to PCR. For each tracheobronchiolar washing, PCR was performed on crude extracts treated with lysis buffer and on extracted DNA. The PCR results obtained with the two kinds of samples were compared to the immunofluorescence (IF) results. This comparison indicates a good correlation between PCR and IF test in 121/143 cases. The presence of M. hyopneumoniae is revealed in 19/143 of the washing samples only by PCR. In our hand, PCR appears to be the more sensitive test to detect M. hyopneumoniae in experimentally infected piglets.

Serological and molecular characterization of Mesoplasma seiffertii strains isolated from hematophagous dipterans in France

Three strains of nonhelical mollicutes previously isolated in France from two different mosquitoes and one tabanid fly were designated strains Ar 2328 (isolated from Aedes detritus), Ar 2392 (isolated from Aedes caspius), and CP 13 (isolated from Chrysops pictus). All of these strains exhibited properties of the genus Mesoplasma, a recently described genus of non-sterol-requiring mollicutes isolated from plants and insects. The results of metabolism inhibition and growth inhibition tests revealed that these strains and Mesoplasma entomophilum TAC or Mesoplasma florum L1 were not serologically related, but all three dipteran strains reacted strongly with Mesoplasma seiffertii F7T (T = type strain) antibodies. Using metabolism inhibition and growth inhibition tests, we found that the dipteran strains were related to each other and to strain F7T but were not identical. We also found that they were able to multiply and persist in the central nervous systems of suckling mice inoculated intracerebrally, a property that makes their use as biological control agents for pest dipterans inadvisable. Scanning electron microscopy revealed marked differences in the morphologies of the colonies of the different strains on SP4 solid medium. The levels of DNA-DNA homology for strains Ar 2328, Ar 2392, CP 13, and F7T were more than 70%, indicating that these strains are closely related members of the same species, M. seiffertii. In addition, one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that each strain produced about 40 protein bands. This technique also revealed differences between strains. Using the coefficient of Smeath-Jacquart, we constructed a dendrogram that allowed us to estimate of the levels of relatedness of these four strains. The results which we obtained were confirmed by two-dimensional protein electrophoresis results.

Differentiation of mycoplasmalike organisms (MLOs) in European fruit trees by PCR using specific primers derived from the sequence of a chromosomal fragment of the apple proliferation MLO

A 1.8-kb chromosomal DNA fragment of the mycoplasmalike organism (MLO) associated with apple proliferation was sequenced. Three putative open reading frames were observed on this fragment. The protein encoded by open reading frame 2 shows significant homologies with bacterial nitroreductases. From the nucleotide sequence four primer pairs for PCR were chosen to specifically amplify DNA from MLOs associated with European diseases of fruit trees. Primer pairs specific for (i) Malus-affecting MLOs, (ii) Malus- and Prunus-affecting MLOs, and (iii) Malus-, Prunus-, and Pyrus-affecting MLOs were obtained. Restriction enzyme analysis of the amplification products revealed restriction fragment length polymorphisms between Malus-, Prunus, and Pyrus-affecting MLOs as well as between different isolates of the apple proliferation MLO. No amplification with either primer pair could be obtained with DNA from 12 different MLOs experimentally maintained in periwinkle.

DNA relatedness between field isolates of Mycoplasma F38 group, the agent of contagious caprine pleuropneumonia, and strains of Mycoplasma capricolum

DNA-DNA hybridization experiments were carried out in order to clarify the taxonomic relationships between the F38 group of caprine mycoplasmas, the established etiologic agents of classical contagious caprine pleuropneumonia, and Mycoplasma capricolum, an organism associated with septicemia, arthritis, and mastitis in goats and sheep. The taxonomic status of the F38 group has been uncertain, principally because of the serological, genomic, and other properties which it shares with M. capricolum. Tritium-labeled DNAs from the M. capricolum type strain (California kid) and from prototype strain F38 were hybridized with unlabeled DNAs from these two strains and from four other isolates belonging to each group. The results showed consistent DNA relatedness values of about 70% between the F38 and M. capricolum groups, compared with levels of relatedness of about 90 and 85%, respectively, for the strains within each group. In addition, the results of comparisons of these 10 strains in which growth inhibition and immunofluorescence tests were used confirmed the previously reported serological relationships between the two groups and reinforced other observations concerning their shared genomic and cell membrane characteristics, indicating that there is a close taxonomic relationship. However, as the 70% DNA relatedness values between the M. capricolum and F38 groups also indicate a degree of genomic difference inconsistent with a relationship at the species level, we conclude that our findings support previous proposals for classification of the F38 group as a subspecies of M. capricolum.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of mollicute contamination in cell cultures by 16S rDNA amplification

A polymerase chain reaction (PCR) system was developed for the detection of mollicutes as contaminants of cell cultures. By using three oligonucleotides chosen in the 16S rDNA sequences, two sets of primers able to promote amplification of all Mycoplasma and Ureaplasma (molli1-molli2a) or all Acholeplasma (molli1-molli2b) species examined were determined. This PCR system, first applied to experimentally infected Vero cell lines, was then evaluated for the detection of mollicutes in 86 cell culture samples, comparatively to DNA staining, culture and ELISA. The results obtained by the four techniques were in agreement in 82 cases (36 positive, 46 negative). PCR allowed detection of contamination in one and two cases negative by ELISA and culture, respectively, and confirmed questionable results obtained by DNA staining. As described, PCR seems to be a very convenient tool for routine detection of cell culture contaminants.

Spiroplasma citri UGG and UGA tryptophan codons: sequence of the two tryptophanyl-tRNAs and organization of the corresponding genes

From the total tRNAs of Spiroplasma citri, we isolated and purified two tRNA(Trp) species by using chromatography on an RPC-5 column followed by denaturing polyacrylamide gel electrophoresis. The sequence of the two tRNAs, as well as the sequences of the corresponding genes, were determined. One of the two tRNA(Trp) species has a CCA anticodon and is able to pair with the universal UGG tryptophan codon, while the second has a U*CA (U* is a modified uridine) anticodon and is able to pair with UGA but also with UGG in accordance with the "U:N wobble" rule. Thus, in S. citri, UGA is not a stop codon but codes for tryptophan. The two tRNA(Trp) genes, together with a third tRNA gene, tRNA(Ser) (CGA), belong to a single transcription unit. The nucleotide sequences of the two tRNA(Trp) species show 82.9% similarity. The two spiroplasmal tRNA(Trp) species can be aminoacylated by using an aminoacyl-tRNA synthetase fraction from S. citri. In contrast, the enzyme fraction from Escherichia coli aminoacylates tRNA(Trp) (CCA) but not tRNA(Trp) (U*CA).

A specific DNA probe for detecting Mycoplasma hyopneumoniae in experimentally infected piglets

Mycoplasma hyopneumoniae is the primary agent of swine enzootic pneumonia. Because of fastidious growth requirements and its serological cross-reactions with other porcine mycoplasmas, we developed a specific DNA probe for its detection. A partial genomic library of M. hyopneumoniae was constructed in plasmid pBR 322 using Hind III chromosomal fragments. The recombinant plasmids were screened by differential hybridization with M. flocculare and M. hyorhinis genomic DNA probes. One non-hybridizing recombinant plasmid was selected and its 1.65 kbp insert (designated I141) tested for specificity against genomic DNA from numerous mycoplasmas, other bacteria species and DNA from lung tissue of specific pathogen free (SPF) piglets. The 32P labelled I141 could detect specifically down to 400 pg of M. hyopneumoniae genomic DNA. To test the suitability of the I141 probe for the laboratory diagnosis of M. hyopneumoniae infections, we used clinical tracheobronchial specimens from piglets which were experimentally infected with M. hyopneumoniae. The results with hybridization on each specimen were compared to findings with an immunofluorescence test. Of the clinical specimen tested, there was agreement in the two tests of 63%.

Spiralins of Spiroplasma citri and Spiroplasma melliferum: amino acid sequences and putative organization in the cell membrane

Spiralin is the major membrane protein of the helical mollicute Spiroplasma citri. A similar protein occurs in the membrane of Spiroplasma melliferum, an organism related to S. citri. The gene encoding spiralin has been sequenced. A restriction fragment of the spiralin gene has been used as a probe to detect the gene encoding S. melliferum spiralin. A 4.6-kilobase-pair ClaI DNA fragment from S. melliferum strongly hybridized with the probe. This fragment was inserted in pBR322 and cloned in Escherichia coli. It was further subcloned in the replicative forms of M13mp18 and M13mp19, and its nucleotide sequence was determined (GenBank accession number M33991). An open reading frame showing 88.6% base sequence homology with the S. citri spiralin gene could be identified and was assumed to be the gene encoding S. melliferum spiralin. The deduced amino acid sequence of the protein had 75% homology with the spiralin sequence. In particular, the two proteins possess a stretch of 20 amino acids which can form an alpha-helix, in which all polar amino acids occupy approximately one-third of the axial projection down the helix. On the basis of these data and published data, we propose a topological model for the structural organization of the spiralin in the cell membrane of spiroplasmas.

Genetic and serologic relatedness between Mycoplasma fermentans strains and a mycoplasma recently identified in tissues of AIDS and non-AIDS patients

A mycoplasma previously identified in the tissues of both AIDS and non-AIDS patients dying of an acute fatal disease was earlier shown to share some biologic and genetic properties with a strain of Mycoplasma fermentans, an organism occurring infrequently in the human lower urogenital tract. More extensive genetic and serologic comparisons using DNA/DNA hybridization, DNA base composition (guanine + cytosine), restriction endonuclease DNA analysis, cellular protein patterns and metabolism inhibition serologic procedures confirm that the organism previously designated as "Mycoplasma incognitus" (Mi) is indeed very closely related to strains of M. fermentans. While the genetic and serologic features observed among the newly isolated mycoplasma and two M. fermentans strains suggest a species relationship, it now seems useful to re-examine the biological activities of other freshly isolated M. fermentans strains from man.

Organization and nucleotide sequences of the Spiroplasma citri genes for ribosomal protein S2, elongation factor Ts, spiralin, phosphofructokinase, pyruvate kinase, and an unidentified protein

The gene for spiralin, the major membrane protein of the helical mollicute Spiroplasma citri, was cloned in Escherichia coli as a 5-kilobase-pair (kbp) DNA fragment. The complete nucleotide sequence of the 5.0-kbp spiroplasmal DNA fragment was determined (GenBank accession no. M31161). The spiralin gene was identified by the size and amino acid composition of its translational product. Besides the spiralin gene, the spiroplasmal DNA fragment was found to contain five additional open reading frames (ORFs). The translational products of four of these ORFs were identified by their amino acid sequence homologies with known proteins: ribosomal protein S2, elongation factor Ts, phosphofructokinase, and pyruvate kinase, respectively encoded by the genes rpsB, tsf, pfk, and pyk. The product of the fifth ORF remains to be identified and was named protein X (X gene). The order of the above genes was tsf--X--spiralin gene--pfk--pyk. These genes were transcribed in one direction, while the gene for ribosomal protein S2 (rpsB) was transcribed in the opposite direction.

Spiroplasma citri detection by enzyme-linked immunosorbent assay (ELISA), culture and dot hybridization

We have used ELISA and culture of spiroplasmas in SP4 or M1A medium to detect Spiroplasma citri in citrus trees, periwinkles (Catharantus roseus) and leafhoppers in Iraq and Syria. On the basis of hundreds of analyses, we have found that the sensitivity of ELISA and culture are of the same order of magnitude. With citrus, both tests are able to detect S. citri in 95% of symptomatic nursery or field trees. The tests are not sensitive enough to reliably detect S. citri in symptomless trees. Therefore, a DNA hybridization technique was developed. The radioactive DNA probe was prepared either with total S. citri DNA or with the cloned DNA fragment carrying the spiralin gene of S. citri. Used in dot hybridization, the probe was able to detect concentrations of S. citri one 100th the size of those revealed by ELISA.