First Report of "Candidatus Liberibacter psyllaurous" (synonym "Ca. L. solanacearum") Associated with 'Tomato Vein-Greening' and 'Tomato Psyllid Yellows' Diseases in Commercial Greenhouses in Arizona.

During the winter of 2006-2007, plants in commercial tomato greenhouses (GH-1 and GH-2; total 320 acres [129.5 ha]) in Arizona were infested with the potato psyllid Bactericera cockerelli (Sulc) and more than 60% and ~20% of the plants, respectively, exhibited leaf curling, chlorosis, and shortened internodes. In addition, some plants in GH-1 developed an unusual 'vein-greening' phenotype. Nucleic acids were isolated from 10 symptomatic and three asymptomatic plants from each greenhouse. PCR primers designed to amplify a phytoplasma-like 16S rDNA (850 bp) yielded the expected size product from GH-1 samples, whereas samples from GH-2 and the asymptomatic samples from both greenhouses did not. Several 16S rDNA PCR products (3 of 60) when cloned and sequenced, surprisingly shared 97% homology with 'Candidatus Liberibacter asiaticus' (GenBank No. GQ926917). PCR primers PSY680F 5'-GTTCGGAATAACTGGGCGTA-3' and PSY1R 5'-CCCATAAGGGCCATGAGGACT-3', based on the resultant 16S rDNA sequences, were used to amplify a 680-bp fragment from plant DNA extracts and psyllid lysates (1). A robust PCR product (~680 bp) was obtained from 10 of 10 GH-1 plant extracts (GQ926918) and from a GH-1-derived psyllid colony (28 of 35 adults) (GQ926919) and the tomato plants on which they were reared. In contrast, no 680-bp product was obtained from GH-1 asymptomatic plants (0 of 3), GH-2 plants (0 of 10 symptomatic; 0 of 3 asymptomatic), GH-2-derived psyllid colonies (0 of 35 adults), or psyllid colony tomato plants (data not shown). At least three 680-bp amplicons for each sample type were cloned and 8 to 10 inserts were sequenced for each. BLAST analysis revealed that all 680-bp sequences shared 99 to 100% nt identity with the analogous 16SrDNA from "Ca. Liberibacter psyllaurous" (2) and synonym "Ca. L. solanacearum" (3). A second molecular marker was obtained with the 1611F and 480R primers (2) to amplify the 16SrDNA-23S-ITS (980 bp) from >3 plant extracts and psyllid lysates that tested positive for liberibacter. Clustal W alignment of the 16S-23S-ITS sequences from GH-1 original tomato plants and psyllid colony plants (GQ926920) and psyllids (GQ926921) indicated they were 100% identical to each other and BLAST analysis indicated 99 to 100% shared identity with "Ca. L. psyllaurous" (EU812558) (synonym "Ca. L. solanacearum"). Transmission electron microscopy examination of GH-1 and GH-2 psyllids revealed rod and pleomorphic-shaped bacteria (0.5 to 2.0+ µm) at the brain-salivary gland interface in psyllids from the GH-1 liberibacter-positive colony. No such bacteria were observed in GH-2 liberibacter-negative psyllids. These results support an etiological role of a new liberibacter spp. in the development of the 'vein-greening' symptom phenotype. In contrast, the GH-2 'yellows' phenotype is reminiscent of 'psyllid toxicity' in tomato colonized by B. cockerelli (4). To our knowledge, this is the first report of distinct psyllid-associated diseases in greenhouse tomato in Arizona, one associated with a new 'Ca. Liberibacter' spp., manifest as 'vein-greening' disease, and the other associated with psyllid feeding, in which liberibacter is undetectable in plants and psyllids, and is manifest as the 'tomato psyllid yellows' disease. References: (1) D. R. Frohlich et al. Mol. Ecol. 8:1683, 1999. (2) A. K. Hansen et al. Appl. Environ. Microbiol. 74:5862, 2008. (3) L. W. Liefting et al. Plant Dis. 93:208, 2009. (4) H. J. Pack. Utah Agric. Exp. Stn. Bull. 209, 1929.

Efficacy of dose regimen and observation of herd immunity from a vaccine against Escherichia coli O157:H7 for feedlot cattle.

A clinical trial was conducted to test the effect of a vaccine product containing type III secreted proteins of Escherichia coli O157:H7 on the probability that feedlot steers shed E. coli O157:H7 in feces. Six hundred eight same-source steers were utilized. Of these, 480 steers were assigned randomly to 60 pens (eight head per pen) and to one of four vaccination treatments (120 cattle per treatment, two head per treatment per pen). The four treatments were (i) no vaccination; (ii) one dose, vaccinated once at reimplant (day 42); (iii) two doses, vaccinated on arrival (day 0) and again at reimplant (day 42); and (iv) three doses, vaccinated on arrival (day 0), on day 21, and again at reimplant (day 42). The remaining 128 steers were assigned randomly to 12 pens within the same feedlot to serve as unvaccinated external controls. The probability of detecting E. coli O157:H7 among cattle receiving different doses of vaccine was compared with that of unvaccinated external control cattle, accounting for clustering by repeated measures, block, and pen and fixed effects of vaccine, corn product, and test period. Vaccine efficacy of receiving one, two, and three doses of vaccine was 68, 66, and 73%, respectively, compared with cattle in pens not receiving vaccine. Cattle receiving three doses of vaccine were significantly less likely to shed E. coli O157:H7 than unvaccinated cattle within the same pen. Unvaccinated cattle housed with vaccinated cattle were 59% less likely to shed E. coli O157:H7 than cattle in pens not receiving vaccine, likely because they benefited from herd immunity. This study supports the hypothesis that vaccination with this vaccine product effectively reduces the probability for cattle to shed E. coli O157:H7. There was no indication that the vaccine affected performance or carcass quality. In addition, we found that vaccinating a majority of cattle within a pen offered a significant protective effect (herd immunity) to unvaccinated cattle within the same pen.

Effect of a vaccine product containing type III secreted proteins on the probability of Escherichia coli O157:H7 fecal shedding and mucosal colonization in feedlot cattle.

Preharvest intervention strategies to reduce Escherichia coli O157:H7 in cattle have been sought as a means to reduce human foodborne illness. A blinded clinical trial was conducted to test the effect of a vaccine product on the probability that feedlot steers, under conditions of natural exposure, shed E. coli O157:H7 in feces, are colonized by this organism in the terminal rectum, or develop a humoral response to the respective antigens. Steers (n = 288) were assigned randomly to 36 pens (eight head per pen), and pens were randomized to vaccination treatment in a balanced fashion within six dietary treatments of an unrelated nutrition study. Treatments included vaccination or placebo (three doses at 3-week intervals). Fecal samples for culture (n = 1,410) were collected from the rectum of each steer on pretreatment day 0 and posttreatment days 14, 28, 42, and 56. Terminal rectum mucosal (TRM) cells were aseptically collected for culture at harvest (day 57 posttreatment) by scraping the mucosa 3.0 to 5.5 cm proximal to the rectoanal junction. E. coli O157:H7 was isolated and identified with selective enrichment, immunomagnetic separation, and PCR confirmation. Vaccinated cattle were 98.3% less likely to be colonized by E. coli O157:H7 in TRM cells (odds ratio = 0.014, P < 0.0001). Diet was also associated with the probability of cattle being colonized (P = 0.04). Vaccinated cattle demonstrated significant humoral responses to Tir and O157 lipopolysaccharide. These results provide evidence that this vaccine product reduces E. coli O157:H7 colonization of the terminal rectum of feedlot beef cattle under conditions of natural exposure, a first step in its evaluation as an effective intervention for food and environmental safety.

Novel vaccines from biotechnology.

Vaccination continues to be the main approach to protecting animals from infectious diseases. Until recently, all licensed vaccines were developed using conventional technologies. However, the introduction of modern molecular biological tools and genomics, combined with a better understanding of not only which antigens are critical in inducing protection, but an appreciation of host defences that must be stimulated, has opened a new opportunity to develop safer and more effective vaccines. The authors describe the current and future trends in vaccine development and stress that in addition to identifying and producing the protective antigens, it is critical to formulate and deliver these vaccines appropriately to maximise the potential of modern advances in pathogenesis and vaccinology.

A distinct Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodidae) genotype cluster is associated with the epidemic of severe cassava mosaic virus disease in Uganda.

During the 1990s, an epidemic of cassava mosaic virus disease caused major losses to cassava production in Uganda. Two factors associated with the epidemic were the occurrence of a novel recombinant begomovirus, EACMV-Ug, and unusually high populations of the whitefly vector, Bemisia tabaci. Here we present molecular evidence for the occurrence of two cassava-colonizing B. tabaci genotype clusters, Ug1 and Ug2, one of which, Ug2, can be consistently associated with the CMD epidemic in Uganda at the time of collection in 1997. By contrast, a second genotype cluster, Ug1, only occurred 'at' or 'ahead of' the epidemic 'front', sometimes in mixtures with Ug2. Comparison of mitochondrial cytochrome oxidase I gene sequences for Ug1 and Ug2 and well-studied B. tabaci reference populations indicated that the two Ugandan populations exhibited approximately 8% divergence, suggesting they represent distinct sub-Saharan African lineages. Neither Ugandan genotype cluster was identified as the widely distributed, polyphagous, and highly fecund B biotype of Old World origin, with which they both diverged by approximately 8%. Within genotype cluster divergence of Ug1 at 0.61 +/- 0.1% was twice that of Ug2 at 0.35 +/- 0.1%. Mismatch analysis suggested that Ug2 has undergone a recent population expansion and may be of nonUgandan origin, whereas Ug1 has diverged more slowly, and is likely to be an indigenous genotype cluster.

Molecular Characterization of Rhynchosia mosaic virus-Puerto Rico Associated with Symptomatic Rhynchosia minima and Cajanus cajan in Puerto Rico.

A begomovirus (family Geminiviridae) has long been suspected to be associated with Rhynchosia mosaic (RhM) disease of Rhynchosia minima (L.) DC., a weed that is widespread in Puerto Rico (PR). The suspect virus has been transmitted by the Sida biotype of Bemisia tabaci (Genn.) and has been designated RhM virus-PR (RhMV-PR) (1) (synonym, Rhynchosia mosaic virus [RMV]). RhM symptoms in R. minima included yellow foliar mosaic and stunting. The virus has a broad experimental host range and infects species in the Fabaceae, including R. minima, pigeon pea (Cajanus cajan (L.) Millsp.), and Clitoria falcata L. (1). However, until now RhMV has not been identified from naturally infected pigeon pea or Clitoria falcata. R. minima and C. cajan plants exhibiting yellow foliar mosaic and stunting symptoms were collected in Puerto Rico. Using the B biotype of B. tabaci as the vector, their whitefly transmissibility from the respective source plant to R. minima and C. cajan test plants was confirmed, and symptoms in inoculated host were indistinguishable for both isolates. Using polymerase chain reaction (PCR) and primers (2), three amplicons were obtained and cloned for each isolate. PCR products (1.1 and 2.1 kbp) were assembled (~200 nucleotide [nt] overlap) to yield an apparent full-length DNA A component (~2.6 kbp) containing the diagnostically informative viral coat protein gene (CP) and common region (CR-A). PCR primers were used to amplify the DNA B component segment (0.7 kbp) containing the CR-B (2). The DNA sequence for the core CP (533 nt) and full CP (750 nt) were compared with analogous sequences for well-studied begomoviruses, and CR-A and CR-B (153 nt) were compared for RhMV isolates. All isolates noted were obtained from GenBank. The core CP for isolates from R. minima (AF442117) and C. cajan (AY062025) shared 97.9% nucleotide identity (100% AA similarity) and the CR-A (AF442118) and CR-B (AF442119) sequences for R. minima and C. cajan isolates were ~96% identical, indicating the A and B components are of the same begomovirus. Comparison of the core CP sequence for an independent isolate from C. cajan from PR (AY028308) (4) with those for R. minima and C. cajan isolates indicated 95.5% (99.4% AA) and 96.2% (99.4% AA) nucleotide identity, respectively, indicating association of RhMV with both C. cajan samples. The recently archived core CP (533 nt) (AY028308) is actually of RhMV-PR, rather than a distinct begomovirus species, as indicated (4). Interestingly, the core CP of R. minima (AF442117) and C. cajan (AY062025) isolates were 91.7% (98.9% AA) and 92.3% (98.9% AA) identical, respectively, with a PR isolate from Clitoria falcata (AF070924), also confirming that RhMV-PR naturally infects Clitoria falcata. Analysis of the full CP for the R. minima and C. cajan isolates revealed that their closest relatives were Macroptilium mosaic virus (MaMV-PR) (AF176092) and Bean golden mosaic virus (BGMV-PR) (M10070) at 89 and 84% nucleotide identity, respectively. Applying the 90% CP rule (3) to RhMV CP sequences, RhMV is a distinct begomovirus species. At least three begomoviruses, BGMV-PR, MaMV-PR, and RhMV-PR, naturally infect leguminous species in Puerto Rico. References: (1) J. Bird. Phytopathology 52:286, 1962. (2) A. M. Idris and J. K. Brown. Phytopathology 88:648, 1998. (3) M. A. Mayo and C. R. Pringle. J. Gen. Virol. 79:649, 1998. (4) R. L. Rodriguez et al. Plant Dis. 85:1119, 2001.

Melon chlorotic leaf curl virus, a New Begomovirus Associated with Bemisia tabaci Infestations in Guatemala.

In 2000, geminivirus-like symptoms were widespread in muskmelon (Cucumis melo L.) fields (70 to 80% incidence) in Zacapa Valley, Guatemala. Muskmelon fields were infested with the whitefly Bemisia tabaci (Genn.), and plants exhibited patchy foliar chlorosis, leaf curling, and reduced fruit set, which is reminiscent of symptoms caused by certain whitefly-transmitted geminiviruses. Quarantine restrictions prevented experimental transmission experiments from being carried out with the whitefly vector or biolistic inoculation. Leaves collected from six symptomatic plants were assessed for the presence of begomovirus DNA by polymerase chain reaction (PCR) with the use of degenerate primers that amplify the core region of the coat protein (CP) gene of most begomoviruses (1). PCR products of the expected size (approximately 576 bp) were obtained from all three melon samples. The core CP amplicons were cloned, and their nucleotide sequences were compared. Nucleotide sequences of core CP fragments shared 99.7% identity, suggesting the presence of a single begomovirus in all assayed symptomatic melon plants. Two additional pairs of degenerate primers were used to obtain contiguous viral fragments containing the CP gene, the common region of the A component (CR-A; approximately 2,100 bp), and a fragment containing the CR of the B component (CR-B; approximately 1,100 bp), respectively (2). At least three amplicons obtained with each primer pair were cloned and their nucleotide sequence was determined. Virus-specific PCR primers were then designed within the CP open reading frame and used to obtain fragments that overlapped with the 2,100-bp fragment to yield an apparent full-length A component of 2,662 nucleotides (accession no. AF325497). CR-A and CR-B (accession no. AF325498) sequences (161 nucleotides) shared 98.1% identity and contained an identical directly repeated, replication-associated protein (REP) binding site: GGTGT CCT GGTGT. Nucleotide sequence alignment, with CLUSTAL W, of the melon virus A-component with that of other well-studied begomoviruses revealed that its closest relatives were members of the Squash leaf curl virus (SLCV) group. The melon virus from Guatemala shared its greatest sequence identity, 83.1%, with SLCV extended (SLCV-E) (accession no. M38183), indicating that it is a new, previously unidentified begomovirus species, herein referred to as Melon chlorotic leaf curl virus (MCLCV). The next closest relatives of MCLCV were SLCV restricted (SLCV-R; 78.6%) (S. G. Lazarowitz, unpublished) Cucurbit leaf curl virus-Arizona (CuLCV-AZ; accession no. AF256199; 74.1%) (3), Cabbage leaf curl virus (CaLCV; 72.0%), Bean calico mosaic virus (BCMoV; 71.7%), and Texas pepper virus-Tamaulipas (71.4%). Additionally, the theoretical REP binding element, GGTGT, is 100% identical among MCLCV and BCMoV, CaLCV, CuLCV-AZ, SLCV-E, and SLCV-R. On the basis of shared nucleotide sequence identities with other begomoviruses described to date and the presence of B. tabaci in melon fields, it is likely that MCLCV also is whitefly-transmitted. Collectively, CP and CR sequences suggest that MCLCV is a new species of the SLCV lineage that contains other bipartite begomoviruses indigenous to Central America, Mexico, and the U.S. Sunbelt states. References: (1) S. D. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996. (2) A. M. Idris and J. K Brown. Phytopathology 88:648, 1998. (3) J. K. Brown et al. Plant Dis. 84:809, 2000.

Introduction of the Exotic Tomato yellow leaf curl virus-Israel in Tomato to Puerto Rico.

Thirty-five-day-old tomato plants (cultivar Florasette) exhibited yellow leaf curling, stunting, and extremely reduced fruit set in spring 2001, in Guanica, Puerto Rico (PR). Twenty percent disease incidence was observed in this field and, 8 weeks later, 75% of the plants showed symptoms. These symptoms were distinct from those caused by other tomato-infecting begomoviruses reported previously from PR, namely Merremia mosaic virus, Tomato mottle virus (ToMoV), and Potato yellow mosaic virus (1). A colony of the B biotype of Bemisia tabaci (Genn.) was used to transmit the suspect virus from symptomatic plants collected in the field and established in the greenhouse in Rio Piedras, PR. The suspect virus was transmitted readily to tomato cultivar Roma (10 of 10 plants), and symptoms were like those observed in the field. Symptoms also were reminiscent of those described for several Old World begomoviruses, referred to as Tomato yellow leaf curl virus (TYLCV). Total nucleic acids were isolated from three symptomatic field samples and three greenhouse-inoculated tomato plants showing typical disease symptoms. Extracts were analyzed by polymerase chain reaction (PCR) with primers AV2466 and AC1145 to amplify a begomoviral fragment (approximately 1.1 bp) that contains a portion of the intergenic region and the viral coat protein gene (CP) (2). Amplicons were cloned, and their nucleotide sequences were determined. A comparison of CP with other well-studied begomoviral nucleotide sequences revealed that the CP sequences for field isolates 1 to 6 shared 99.7 to 100% identity with each other and 99.9 to 100% identity with TYLCV from Israel (TYLCV-IL; accession no. X76319) as well as TYLCV-IL isolates discovered in the Dominican Republic (DO; accession no. AF024715) and, subsequently, in Florida. TYLCV-specific PCR primers (forward) 5'-GAATTCCGCCTTTAA-TTTG-3' and (reverse) 5'-GAATTCCCACTATCTTTCTC-3' were used to amplify the complete viral genome form a PR field isolate. An expected-sized amplicon of approximately 2.8 kb was obtained, and the nucleotide sequence of two cloned amplicons was determined. Genome organization revealed a predicted precoat open reading frame of 351 bp, which is characteristic of other Old World begomoviruses, including TYLCV-IL. Nucleotide comparisons indicated that the PR isolate shared 99% nucleotide sequence identity with TYLCV-IL (first reported from Israel) and introduced TYLCV-IL isolates in DO and Florida, thereby confirming the introduction of TYLCV-IL into PR. TYLCV-IL was first identified several years ago in the Western Hemisphere, and the virus has been reported in five offshore locations and three continental U.S. states since its initial introduction into the DO in the early 1990s. Considering the extreme virulence of TYLCV-IL compared with most New World tomato-infecting begomoviruses, this introduction, which likely occurred from a nearby Caribbean country or Florida, has the potential to destroy the fresh-market tomato industry in PR, which supplies tomatoes to the continental United States during the winter months. There is compelling evidence for the routine movement of tomato seedlings from the continental United States to this location in PR throughout the last 10 years, including the previous introduction of ToMoV (1). These incidences and others indicate the need for those in infected areas to take precautions to avoid further spread of this highly damaging virus in and adjacent to the Caribbean region. References: (1) A. M. Idris et al. Phytopathology 88:S42, 1998. (2) A. M. Idris and J. K. Brown, Phytopathology 88:648, 1998.

Current knowledge on the structural proteins of porcine reproductive and respiratory syndrome (PRRS) virus: comparison of the North American and European isolates.

Porcine reproductive and respiratory syndrome virus (PRRSV) belongs to the recently recognized Arteriviridae family within the genus Arterivirus, order Nidovirales, which also includes equine arteritis virus (EAV), lactate dehydrogenase-elevating virus (LDV), and simian hemorrhagic fever virus (SHFV). Mature viral particles are composed of an envelope 50-72 nm in diameter, with an isometric core about 20-30 nm enclosing a linear positive-stranded RNA genome of approximately 15 kb. The virions are assembled by the budding of preformed nucleocapsids into the lumen of the smooth endoplasmic reticulum and/or Golgi apparatus. The mature virions are then released by exocytosis. The viral genome contains eight open reading frames (ORFs) which are transcribed in cells as a nested set of subgenomic mRNAs. The ORF1a and ORF1b situated at the 5'end of the genome represent nearly 75% of the viral genome and code for proteins with apparent replicase and polymerase activities. The major structural proteins consist of a 25 kDa envelope glycoprotein (GP5), an 18-19 kDa unglycosylated membrane protein (M), and a 15 kDa nucleocapsid (N) protein, encoded by ORFs 5, 6 and 7, respectively. The N protein is the more abundant protein of the virion and is highly antigenic, which therefore makes it a suitable candidate for the detection of virus-specific antibodies and diagnosis of the disease. Four to five domains of antigenic importance have been identified for the N protein, a common conformational antigenic site for European and North American strains being localized in the central region of the protein. In cells and virions, both M and GP5 occur in heterodimeric complexes linked by disulfide bonds. The expression products of ORFs 2 and 4 are also incorporated into virus particles as additional minor membrane-associated glycoproteins designated as GP2 and GP4, with M(r) of 29 and 31 kDa, respectively. The structural nature of the ORF3 product, a highly glycosylated protein with an apparent M(r) of 42 kDa, is still being debated, in view of the apparently conflicting data on its presence in virus particles. Nonetheless, the GP3 of North American and European strains has been shown to be antigenic, providing protection for piglets against PRRSV infection in the absence of a noticeable neutralizing humoral response. Pigs exposed to the native form of GP5 by means of DNA immunization develop specific neutralizing and protecting antibodies. The GP5 is involved in antigenic variability, apoptosis, and possibly antibody-dependent enhancement phenomena. The GP4 also possesses antigenic determinants that trigger the immune system to produce neutralizing antibodies. Each of the PRRSV structural proteins carries common and type-specific antigenic determinants that permit the ability to differentiate between European and North American strains. The potential use of the PRRSV structural proteins in subunit recombinant-type vaccines is also discussed.

Full-length sequence of a Canadian porcine reproductive and respiratory syndrome virus (PRRSV) isolate.

Presently, one of the most economically important pathogens affecting swine is the porcine reproductive and respiratory syndrome virus (PRRSV). This virus is prevalent in herds throughout the world and continues to pose a significant threat as newer and more virulent disease phenotypes emerge. In this report we describe the full-length nucleotide sequence of a Canadian PRRSV isolate, designated PA8. A consecutive sequence of 15,411 nucleotides was obtained from a set of overlapping cDNA clones. In order to determine the extent of genetic variation among isolates recovered from swine in Canada and the US, as well as to understand the molecular mechanisms governing the evolution of PRRSV, the full-length sequence of PA8 was compared with that of two US isolates, VR2332 and 16244B. The genomic sequence of PA8 shared 98.2% and 99.2% identity with 16244B and VR2332, respectively. The untranslated regions (UTR) at the 5' and 3' ends of the genome were very well conserved. Notable exceptions include an eight nucleotide difference at the 5' end of the 5' UTR of VR2332 relative to PA8 and 16244B and a two nucleotide difference in the 3' UTR of PA8 relative to VR2332 and 16244B. In contrast to PA8 and VR2332, 16244B possessed two nucleotide differences within the RNA pseudoknot structure of the ribosomal frameshift region between open reading frame (ORF)1a and ORF1b. Amino acid differences were distributed throughout the genome, however they appeared to be most extensive in Nsp1beta and ORF5 of the nonstructural and structural coding regions, respectively, suggesting that the evolutionary pressure to conserve these viral genes is somewhat lower.

Intergenic transcription occurs throughout the human IL-4/IL-13 gene cluster.

Recent experiments have shown that the previously identified elements in the proximal promoter of IL-4 are not sufficient to fully explain the regulation of its transcription. Consequently we examined another aspect of transcriptional regulation, intergenic transcription, which has been observed throughout the prototypic gene cluster of human beta-globin. These intergenic transcripts are nuclear and it is possible that they play an important functional role in the beta-globin locus. Here we show that intergenic transcription also occurs in the IL-4/IL-13 gene cluster. Intergenic transcription occurs when the surrounding genes are not transcriptionally active; it also occurs in the promoters of these genes; the transcripts are polyadenylated and they remain in the nucleus. We also show that, in HeLa cells which do not express IL-4 or IL-13, intergenic transcription is absent from the region immediately surrounding the genes. This suggests a role for intergenic transcription in the regulation of the IL-4/IL-13 gene cluster.

Employee injuries and convenience store robberies in selected metropolitan areas.

The number of robberies and robbery-related injuries to employees in convenience stores (C-stores) during 1992 or 1993 were estimated for selected metropolitan areas around Miami and Tampa, Florida; Atlanta, Georgia; Chicago, Illinois; Baltimore, Maryland; Boston, Massachusetts; Detroit, Michigan; Pittsburgh and Philadelphia, Pennsylvania; Charleston, Columbia, Greenville, and Spartanburg, South Carolina; and Arlington, Chesterfield, and Henrico counties, Virginia. Of the 1835 C-store robberies that occurred during 1992 or 1993 in all selected areas (excluding Atlanta and Chicago), there were 12 homicides of C-store employees; 219 nonfatal injuries of C-store employees; 1071 robberies in which there were no injuries but a weapon was used, displayed, or implied toward a C-store employee; and 132 robberies in which there was no injury and no weapon used, but an employee was struck, pushed, or shoved. Corresponding figures for the 238 robberies that occurred in Chicago during January to June 1993, and for which victim employment status was unknown (customer or employee) were three homicides, 53 nonfatal injuries, 120 attacks in which a weapon was used but there was no injury, and 57 attacks in which a person was struck, pushed, or shoved but there was no injury. The proportion of robberies that resulted in a homicide or injury to an employee varied among selected areas from .03 to .25. The proportion of homicides and injuries to an employee was. 14 or higher for target areas in Baltimore (.24), Detroit (.25), and Virginia (.14); the proportion to an employee or customer was .24 in Chicago. The conclusions from these data are that the risk of employee injury in C-store robberies was high in selected metropolitan areas. This underscores the need for effective robbery prevention programs to reduce injury. In addition, further research is needed to determine the effectiveness of prevention programs in the C-store industry and the application of these programs to other retail industries.