The best defense is a good offense: Anti-predator behavior of the common octopus (Octopus vulgaris) against conger eel attacks

We present the description of defensive behavior in wild Octopus vulgaris against conger eel (Conger conger) attacks based on three video sequences recorded by recreational SCUBA divers in the eastern Atlantic off the coast of Galicia (NW Spain) and in the Cantabrian Sea (NW Spain). These records document common traits in defensive behavior: (1) the octopuses enveloped the conger eel's head to obscure its view; (2) they covered the eel's gills in an attempt to suffocate it; (3) they released ink; (4) the octopuses lost some appendages because of the fight. In the third video, the octopus did not exhibit the defensive behavior described in the first two videos due to an inability to utilize its arms in defense, and the conger eel's success in capturing octopuses is discussed. Additionally, both the cost that the octopus could face by losing some arms during the fight and whether the experience it acquires can be an advantage for future encounters are analyzed. The defensive behavior exhibited by octopuses in this study highlights their ability to survive in a hostile environment and serves as an example of the extensive repertoire of anti-predator strategies employed by these cephalopods.

Experimental dataset of the impact assessment of vegetable intercropping on agroeconomic performances, pests and beneficials, and soil resources

The data presented in this article were collected in the field at an experimental station in southern France under a Mediterranean climate. Experiments were conducted under three plastic walk-in tunnels used as blocks with organic farming practices over two successive years in a completely randomized design. The aim was to compare the intercropping of sweet pepper with basil, onion, lettuce, parsley or French bean to a sole crop of sweet pepper used as a control. The dataset provides information on cultural practices with details on inputs and working times used to estimate economic costs. The data also describe the climatic conditions under tunnels as well as the dynamics of soil nitrate concentration and water tension over time through treatments. Yields, economic benefits and the rates of products with visual defects are presented. In addition, some variables applied exclusively to sweet pepper crops, namely nitrate concentration in petiole sap, growth parameters, abundance of aerial pests and beneficials, incidence of root necrosis, arbuscular mycorrhizal fungi colonization rates and diversity in roots. The field dataset is made publicly available to allow free and easy access for the scientific and professional community to enable analysis and reuse. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Abstract A36: Assessment of effectiveness and molecular markers of CDK4/6 inhibitor Palbociclib in Pancreatic Ductal Adenocarcinomas

Pancreatic Ductal Adenocarcinoma (PDAC) continues to be the deadliest human cancer with a 5-year survival rate of 7%. One of the current standards of care for advanced PDAC is gemcitabine plus nab-paclitaxel, a regimen our group helped develop. Finding new agents to combine with this regimen remains necessary, particularly using drug targeting strategies. At the molecular level, genetic and genomic profiling identified CDKN2A as a very frequently disrupted gene in PDAC (<90%). This gene encodes the tumor suppressor p16, a cyclin dependent kinase 4 and 6 (CDK4/6) inhibitor, that controls cell cycle progression. Recently, the selective CDK4/6 inhibitor palbociclib was approved by the FDA for certain types of breast cancer patients. Whether palbociclib can also benefit patients with PDAC is unknown.

In the current study, we aimed to evaluate the effectiveness of palbociclib monotherapy and in combination with nab-paclitaxel and gemcitabine/nab-paclitaxel in a cohort of PDACs patient derived xenograft (PDX) models.

PDX models obtained from late stage PDAC patients were treated with palbociclib alone and in combination with gemcitabine/nab-paclitaxel. The majority of models displayed >50% tumor growth inhibition (TGI) following treatment with single agent palbociclib. Treatment with palbociclib plus nab-paclitaxel or palbociclib plus gemcitabine/nab-paclitaxel increased TGI to a greater degree than the gemcitabine/nab-paclitaxel combination and also increased the duration of response as compared to the standard of care therapy.

Moving forward, the palbociclib/nab-paclitaxel combination will be evaluated in a clinical trial for PDAC patients. We are currently expanding our analyses to a larger cohort of PDX models and performing molecular characterization of these models in order to gain insights on biomarkers and mechanism of action of the drug combinations in PDAC.

Citation Format: Beatriz Salvador, Pedro P. López-Casas, Camino Menéndez, Natalia Baños, Francesca Sarno, Yin Min-Jean, Peter Olson, Todd VanArsdale, David J. Shields, Manuel Hidalgo. Assessment of effectiveness and molecular markers of CDK4/6 inhibitor Palbociclib in Pancreatic Ductal Adenocarcinomas. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr A36.

Abstract B44: When murine tumors are thought to be human: A drawback of patient derived xenografts

The use of preclinical models is essential in every aspect of translational cancer research, from the biologic understanding of the disease to the development of new treatments. Patient Derived Xenograft (PDX) models are increasingly used in translational cancer research due to their advantages over other preclinical models. However, although it has been widely demonstrate that these kind of models are predictive of clinical outcome, there are also some drawbacks when working with them.

Analyzing our PDX model collection, we have observed that there is a small percentage of cases in which a murine tumor is developed instead of the original human one by a process that has been called horizontal oncogenesis. This process was already observed and described in the early 80´s, however, it is still not well understood and the molecular mechanisms by which it happens remain unknown.

In order to determine the origin of the different murine tumors observed in our mice, we performed immunohistochemistry characterization of our altered models and found two different types of murine tumors: murine fibrosarcomas, which were observed in Colorectal and Pancreatic Ductal Adenocarcinoma PDX models; and murine lymphomas, that were observed mainly in Lung PDX models when they were implanted in Nod-scid mice. We also found a case in which a human lymphoproliferation grew in the animals instead of the sample from the small cell lung cancer obtained from the patient.

As these murine tumors grow in the same place where the human donor tumor was implanted, it is important to have a quick and effective method to identify them before performing any study with these altered models. In this regard, we have implemented a simple technique based on PCR analysis with primers that recognize K-Ras. We have designed an estrategy in which we can obtain amplicons of different sizes depending on their human or murine origin.

Although we still have to analize some of our PDX models, using this methodology we have confirmed that murine tumors appear in a very low percentage of cases (less than 5% to date). However, even with this low incidence we consider that is essential to identify those murine tumors as soon as possible in order to avoid wasting time, money and resources.

Citation Format: Camino Menéndez, Beatriz Salvador, Manuel Muñoz, Natalia Baños, Francesca Sarno, Pedro P López-Casas, Manuel Hidalgo. When murine tumors are thought to be human: A drawback of patient derived xenografts.. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr B44.

Modulation of endothelial function by Toll like receptors

Endothelial cells (EC) are able to actively control vascular permeability, coagulation, blood pressure and angiogenesis. Most recently, a role for endothelial cells in the immune response has been described. Therefore, the endothelium has a dual role controlling homeostasis but also being the first line for host defence and tissue damage repair thanks to its ability to mount an inflammatory response. Endothelial cells have been shown to express pattern-recognition receptors (PRR) including Toll-like receptors (TLR) that are activated in response to stimuli within the bloodstream including pathogens and damage signals. TLRs are strategic mediators of the immune response in endothelial cells but they also regulate the angiogenic process critical for tissue repair. Nevertheless, endothelial activation and angiogenesis can contribute to some pathologies. Thus, inappropriate endothelial activation, also known as endothelial dysfunction, through TLRs contributes to tissue damage during autoimmune and inflammatory diseases such as atherosclerosis, hypertension, ischemia and diabetes associated cardiovascular diseases. Also TLR induced angiogenesis is required for the growth of some tumors, atherosclerosis and rheumatoid arthritis, among others. In this review we discuss the importance of various TLRs in modulating the activation of endothelial cells and their importance in immunity to infection and vascular disease as well as their potential as therapeutic targets.

Antitumor effects of a monoclonal antibody to human CCR9 in leukemia cell xenografts

Tumor expression of certain chemokine receptors is associated with resistance to apoptosis, migration, invasiveness and metastasis. Because CCR9 chemokine receptor expression is very restricted in healthy tissue, whereas it is present in tumors of distinct origins including leukemias, melanomas, prostate and ovary carcinomas, it can be considered a suitable candidate for target-directed therapy. Here, we report the generation and characterization of 91R, a mouse anti-human CCR9 IgG2b monoclonal antibody that recognizes an epitope within the CCR9 N-terminal domain. This antibody inhibits the growth of subcutaneous xenografts from human acute T lymphoblastic leukemia MOLT-4 cells in immunodeficient Rag2^−/− mice. Tumor size in 91R-treated mice was reduced by 85% compared with isotype-matched antibody-treated controls. Tumor reduction in 91R-treated mice was concomitant with an increase in the apoptotic cell fraction and tumor necrotic areas, as well as a decrease in the fraction of proliferating cells and in tumor vascularization. In the presence of complement or murine natural killer cells, 91R promoted in vitro lysis of MOLT-4 leukemia cells, indicating that this antibody might eliminate tumor cells via complement- and cell-dependent cytotoxicity. The results show the potential of the 91R monoclonal antibody as a therapeutic agent for treatment of CCR9-expressing tumors.

Diverse amino acid changes at specific positions in the N-terminal region of the coat protein allow Plum pox virus to adapt to new hosts

Plum pox virus (PPV)-D and PPV-R are two isolates from strain D of PPV that differ in host specificity. Previous analyses of chimeras originating from PPV-R and PPV-D suggested that the N terminus of the coat protein (CP) includes host-specific pathogenicity determinants. Here, these determinants were mapped precisely by analyzing the infectivity in herbaceous and woody species of chimeras containing a fragment of the 3' region of PPV-D (including the region coding for the CP) in a PPV-R backbone. These chimeras were not infectious in Prunus persica, but systemically infected Nicotiana clevelandii and N. benthamiana when specific amino acids were modified or deleted in a short 30-amino-acid region of the N terminus of the CP. Most of these mutations did not reduce PPV fitness in Prunus spp. although others impaired systemic infection in this host. We propose a model in which the N terminus of the CP, highly relevant for virus systemic movement, is targeted by a host defense mechanism in Nicotiana spp. Mutations in this short region allow PPV to overcome the defense response in this host but can compromise the efficiency of PPV systemic movement in other hosts such as Prunus spp.

A neutralizing monoclonal antibody targeting the acid-sensitive region in chikungunya virus E2 protects from disease

The mosquito-borne alphavirus, chikungunya virus (CHIKV), has recently reemerged, producing the largest epidemic ever recorded for this virus, with up to 6.5 million cases of acute and chronic rheumatic disease. There are currently no licensed vaccines for CHIKV and current anti-inflammatory drug treatment is often inadequate. Here we describe the isolation and characterization of two human monoclonal antibodies, C9 and E8, from CHIKV infected and recovered individuals. C9 was determined to be a potent virus neutralizing antibody and a biosensor antibody binding study demonstrated it recognized residues on intact CHIKV VLPs. Shotgun mutagenesis alanine scanning of 98 percent of the residues in the E1 and E2 glycoproteins of CHIKV envelope showed that the epitope bound by C9 included amino-acid 162 in the acid-sensitive region (ASR) of the CHIKV E2 glycoprotein. The ASR is critical for the rearrangement of CHIKV E2 during fusion and viral entry into host cells, and we predict that C9 prevents these events from occurring. When used prophylactically in a CHIKV mouse model, C9 completely protected against CHIKV viremia and arthritis. We also observed that when administered therapeutically at 8 or 18 hours post-CHIKV challenge, C9 gave 100% protection in a pathogenic mouse model. Given that targeting this novel neutralizing epitope in E2 can potently protect both in vitro and in vivo, it is likely to be an important region both for future antibody and vaccine-based interventions against CHIKV.

CHIKV is characterized by acute and chronic polyarthritis/polyarthralgia that can be debilitating and protracted. Currently there are no FDA-approved vaccines or specific antiviral treatments for CHIKV. We thus identified and characterized human monoclonal antibodies directed against CHIKV that could be utilized in prophylactic and immediate post-exposure settings. Such patient derived monoclonal antibodies could also provide useful information on critical antigens and epitopes for development of future vaccines and other biologics. We describe here the identification of two monoclonal antibodies (C9 and E8) isolated from recovered patients. C9 potently inhibited CHIKV infection in cells and prevented viremia and arthritis in a mouse model of CHIKV disease. The epitope for this antibody includes an amino-acid residue in a key acid-sensitive region of the E2 glycoprotein of CHIKV. Rearrangement of this region following exposure to low pH is critical for uncovering portions of the companion E1 glycoprotein, required for successful entry of CHIKV into cells. We hypothesize that binding of antibodies to this region stabilizes the native complex and thus prevents such rearrangements.

Classification of samples into two or more ordered populations with application to a cancer trial

In many applications, especially in cancer treatment and diagnosis, investigators are interested in classifying patients into various diagnosis groups on the basis of molecular data such as gene expression or proteomic data. Often, some of the diagnosis groups are known to be related to higher or lower values of some of the predictors. The standard methods of classifying patients into various groups do not take into account the underlying order. This could potentially result in high misclassification rates, especially when the number of groups is larger than two. In this article, we develop classification procedures that exploit the underlying order among the mean values of the predictor variables and the diagnostic groups by using ideas from order-restricted inference. We generalize the existing methodology on discrimination under restrictions and provide empirical evidence to demonstrate that the proposed methodology improves over the existing unrestricted methodology. The proposed methodology is applied to a bladder cancer data set where the researchers are interested in classifying patients into various groups.

Virus variants with differences in the P1 protein coexist in a Plum pox virus population and display particular host-dependent pathogenicity features

Subisolates segregated from an M-type Plum pox virus (PPV) isolate, PPV-PS, differ widely in pathogenicity despite their high degree of sequence similarity. A single amino acid substitution, K109E, in the helper component proteinase (HCPro) protein of PPV caused a significant enhancement of symptom severity in herbaceous hosts, and notably modified virus infectivity in peach seedlings. The presence of this substitution in certain subisolates that induced mild symptoms in herbaceous hosts and did not infect peach seedlings suggested the existence of uncharacterized attenuating factors in these subisolates. In this study, we show that two amino acid changes in the P1 protein are specifically associated with the mild pathogenicity exhibited by some PS subisolates. Site-directed mutagenesis studies demonstrated that both substitutions, W29R and V139E, but especially W29R, resulted in lower levels of virus accumulation and symptom severity in a woody host, Prunus persica. Furthermore, when W29R and V139E mutations were expressed concomitantly, PPV infectivity was completely abolished in this host. In contrast, the V139E substitution, but not W29R, was found to be responsible for symptom attenuation in herbaceous hosts. Deep sequencing analysis demonstrated that the W29R and V139E heterogeneities already existed in the original PPV-PS isolate before its segregation in different subisolates by local lesion cloning. These results highlight the potential complexity of potyviral populations and the relevance of the P1 protein of potyviruses in pathogenesis and viral adaptation to the host.

The determinant of potyvirus ability to overcome the RTM resistance of Arabidopsis thaliana maps to the N-terminal region of the coat protein

In Arabidopsis thaliana Columbia (Col-0) plants, the restriction of Tobacco etch virus (TEV) long-distance movement involves at least three dominant RTM (restricted TEV movement) genes named RTM1, RTM2, and RTM3. Previous work has established that, while the RTM-mediated resistance is also effective against other potyviruses, such as Plum pox virus (PPV) and Lettuce mosaic virus (LMV), some isolates of these viruses are able to overcome the RTM mechanism. In order to identify the viral determinant of this RTM-resistance breaking, the biological properties of recombinants between PPV-R, which systemically infects Col-0, and PPV-PSes, restricted by the RTM resistance, were evaluated. Recombinants that contain the PPV-R coat protein (CP) sequence in an RTM-restricted background are able to systemically infect Col-0. The use of recombinants carrying chimeric CP genes indicated that one or more PPV resistance-breaking determinants map to the 5' half of the CP gene. In the case of LMV, sequencing of independent RTM-breaking variants recovered after serial passages of the LMV AF199 isolate on Col-0 plants revealed, in each case, amino acid changes in the CP N-terminal region, close to the DAG motif. Taken together, these findings demonstrate that the potyvirus CP N-terminal region determines the outcome of the interaction with the RTM-mediated resistance.

Characterization of Chikungunya pseudotyped viruses: Identification of refractory cell lines and demonstration of cellular tropism differences mediated by mutations in E1 glycoprotein

Chikungunya virus (CHIKV) is an alphavirus responsible for a number of large outbreaks. Here we describe the efficient incorporation of CHIKV envelope glycoproteins into lentiviral and rhabdoviral particles. Vectors pseudotyped with CHIKV envelope proteins efficiently transduced many cell types from different species. However, hematopoietic cell types were either partially or completely refractory. A mutation in E1 (A226V) has been linked with expansion of tropism for mosquito species, although differences in in vitro infection of mosquito cell lines have not been noted. However, pseudovirion infectivity assays detected subtle differences in infection of mosquito cells, suggesting an explanation for the changes in mosquito tropism. The presence of C-type lectins increased CHIKV pseudotyped vector infectivity, but not infection of refractory cells, suggesting that they act as attachment factors rather than primary receptors. CHIKV pseudotypes will serve as an important tool for the study of neutralizing antibodies and the analysis of envelope glycoprotein functions.

Host-specific effect of P1 exchange between two potyviruses

The potyviruses Plum pox virus (PPV) and Tobacco vein mottling virus (TVMV) have distinct host ranges and induce different symptoms in their common herbaceous hosts. To test the relevance of the P1 protein in host compatibility and pathogenicity, hybrid viruses were constructed in which the P1 coding sequence of PPV was completely or partially replaced by the corresponding sequences from TVMV. Infections induced by these chimeric viruses revealed that the TVMV P1 and a PPV/TVMV hybrid P1 proteins are functionally equivalent in herbaceous plants to the P1 protein of a PPV isolate adapted to these hosts, in spite of having high sequence divergence. Moreover, the presence of TVMV P1 sequences enhanced the competence of a low-infectivity PPV-D-derived chimera in Nicotiana clevelandii. Conversely, all PPV/TVMV hybrids were unable to infect Prunus persicae, a specific host for PPV, suggesting that TVMV P1 is not functionally competent in this plant. Together, these data highlight the importance of the P1 protein in defining the virus host range.

Identification of Plum pox virus pathogenicity determinants in herbaceous and woody hosts

Plum pox virus (PPV) is a member of the genus Potyvirus that is able to infect a large variety of plant species, including trees of the genus Prunus, its natural host. When some PPV isolates are propagated for an extended time in herbaceous plants, their ability to infect trees is reduced. The molecular basis of this change in host infectivity is poorly understood. We report the construction of hybrid viruses from cDNA clones of two D-strain isolates of PPV, PPV-D and PPV-R, which differ in their host range. PPV-D can infect GF305 peach seedlings efficiently, however, it is unable to infect Nicotiana clevelandii plants. Conversely, PPV-R infects N. clevelandii, but not GF305 peach seedlings. The analyses of the hybrid viruses showed that, although determinants of PPV pathogenicity are extensively spread throughout the PPV genome, the 3' terminal region of the PPV-R genome, including the 3' noncoding region and the coding regions for the coat protein (CP), NIb, and part of NIa protein, is sufficient to confer infectivity of N. clevelandii in a PPV-D background. Our data demonstrate a high concentration of amino acid substitutions in the CP and a host-specific effect of a deletion at the N terminus of this protein in PPV pathogenicity in peach and N. clevelandii infectivity experiments. These results suggest that relevant host specificity determinants are located in the N-terminal region of the CP. The analyses of the PPV-R and PPV-D chimeras also showed that key host-specific pathogenicity determinants lie in the 5' terminal third of the PPV genome, a region that spans proteins P1, HCPro, and P3. The selection of mutations in only a few specific residues in proteins P1, P3, and 6K1 after partial adaptation of a chimeric virus (BD-GFP) to N. clevelandii further suggests a relevant role for these proteins in host adaptation.

PPV long-distance movement is occasionally permitted in resistant apricot hosts

The interactions between Plum pox virus (PPV), a member of the Potyvirus genus, and Prunus host plants are, up to now, poorly understood. In the current paper, fluorescence stereomicroscopy, in situ hybridisation and immunogold detection were performed in order to evaluate the virus transport and cellular distribution. The behavior of PPV in several susceptible (cv. "Moniqui" and "Screara") and resistant apricot genotypes (cv. "Harlayne", "Henderson", "Harcot", "Goldrich", "Stella" and "Stark Early Orange") were compared. Viral RNA was detected by in situ hybridisation in stem tissues close to the inoculation point, irrespective of the resistance status of the variety. Systemic infection was evidenced by virus immunodetection and by fluorescence detection of a GFP-tagged PPV in distant leaf sections. The signal obtained by in situ hybridisation colocalised with the fluorescence produced by GFP-tagged PPV in the same plant material but did not colocalise with the signal obtained by immunostaining. Intensity of the PPV infection in susceptible apricot cultivars varied depending on genotypes. The behavior of PPV in systemic leaves was clearly distinct between susceptible and resistant cultivars. While PPV was spreading widely around the major and minor veins in susceptible leaves, in the resistant apricot genotypes it was restricted to isolated spots consisting of few cells embedded in the mesophyll tissue. In summary, differences in the ability of PPV to systemically infect susceptible and resistant apricot cultivars were evident but nevertheless, long-distance transport of PPV occured in resistant apricot scions.

Application of GFP-tagged Plum pox virus to study Prunus-PPV interactions at the whole plant and cellular levels

The Sharka disease caused by the potyvirus Plum pox virus (PPV) is one of the most serious viral diseases affecting stone fruit trees. The study of PPV/Prunus interaction under greenhouse controlled conditions is space, time, labor consuming. While the PPV/Prunus interactions are now quite well known at the whole plant level, few data however are available on the interactions between the virus and the Prunus host plants at the cellular level. Using a green fluorescent protein (GFP)-tagged M type PPV strain, combined to an in vitro inoculation procedure, we developed a novel tool to track PPV invasion in Prunus persica (peach) cv. GF305 and Prunus armeniaca (apricot) cv. Screara susceptible hosts. Different graft combinations were performed using in vitro-maintained healthy or GFP-tagged PPV infected 'GF305' and 'Screara'. Contact for 30 days in grafts between the inoculum and the genotype to be tested were found sufficient to allow the systemic spread of the recombinant virus: fluorescence from GFP-tagged PPV could easily be detected in the entire plant under a binocular microscope allowing quick and reliable sorting of infected plants. Using a fluorescence stereomicroscopy or confocal microscopy, GFP could also be observed in stem cross-sections especially in epidermis and pith cells. In vitro grafting inoculation with GFP-tagged PPV provides a new and powerful tool to facilitate mid-term virus maintenance. Moreover, this tool will be of special importance in the study of PPV infection dynamics in Prunus, allowing as well precise observations of cellular events related to PPV/Prunus interactions.

Human influenza virus NS1 protein enhances viral pathogenicity and acts as an RNA silencing suppressor in plants

RNA silencing has a well-established function as an antiviral defence mechanism in plants and insects. Using an Agrobacterium-mediated transient assay, we report here that NS1 protein from human influenza A virus suppresses RNA silencing in plants in a manner similar to P1/HC-Pro protein of Tobacco etch potyvirus, a well-characterized plant virus silencing suppressor. Moreover, we have shown that NS1 protein expression strongly enhances the symptoms of Potato virus X in three different plant hosts, suggesting that NS1 protein could be inhibiting defence mechanisms activated in the plant on infection. These data provide further evidence that an RNA silencing pathway could also be activated as a defence response in mammals.

Host-specific involvement of the HC protein in the long-distance movement of potyviruses

Plum pox virus (PPV) is a member of the Potyvirus genus that, in nature, infects trees of the Prunus genus. Although PPV infects systemically several species of the Nicotiana genus, such as N. clevelandii and N. benthamiana, and replicates in the inoculated leaves of N. tabacum, it is unable to infect systemically the last host. The long-distance movement defect of PPV was corrected in transgenic tobacco plants expressing the 5"-terminal region of the genome of tobacco etch virus (TEV), a potyvirus that infects systemically tobacco. The fact that PPV was unable to move to upper noninoculated leaves in tobacco plants transformed with the same TEV transgene, but with a mutation in the HC protein (HC-Pro)-coding sequences, identifies the multifunctional HC-Pro as the complementing factor, and strongly suggests that a defect in an HC-Pro activity is responsible for the long-distance movement defect of PPV in tobacco. Whereas PPV HC-Pro strongly intensifies the symptoms caused by potato virus X (PVX) in the PPV systemic hosts N. clevelandii and N. benthamiana, it has no apparent effect on PVX pathogenicity in tobacco, supporting the hypothesis that long-distance movement and pathogenicity enhancement are related activities of the potyviral HC proteins. The movement defect of PPV in tobacco could also be complemented by cucumber mosaic virus in a mixed infection, demonstrating that at least some components of the long-distance machinery of the potyviruses are not strictly virus specific. A general conclusion of this work is that the HC-Pro might be a relevant factor for controlling the host range of the potyviruses.

Empiric treatment based on Helicobacter pylori serology cannot substitute for early endoscopy in the management of dyspeptic rural black Africans

BACKGROUND

Evidence that chronic gastric Helicobacter pylori (HP) infection is an aetiological factor in dyspepsia, peptic ulcer disease, gastric carcinoma and lymphoma has led to the suggestion that all serologically positive dyspeptic patients should be treated empirically with antibiotics to eradicate the infection, without endoscopic diagnosis. The following study was performed to determine whether such a policy would prove to be of benefit in rural Africa, where endoscopic facilities are lacking and infection rates high.

METHODS

Four district clinics were visited and 97 consecutive patients with persistent upper gastro-intestinal symptoms studied. After history-taking and physical examination, a blood sample was taken for HP serology (IgG anti-HP EIA) and endoscopy was performed.

RESULTS

In comparison with similar studies in westernised countries HP was considerably more common (80%), and similar to that reported for the background population (83-86%), but peptic ulceration (17%) and gastric cancer (1%) were not. HP status and antibody levels failed to predict the presence of serious disease; patients with 'alarm' signs (78%), cancer (78%) and peptic ulcers (81%) had similar seropositivity rates to patients with non-ulcer dyspepsia (81%). Interestingly, many patients with distal oesophagitis were seronegative (40%). Haemoglobin concentrations and nutritional status were similar in HP-positive and negative patients. On the basis of published decision analysis strategies, empiric treatment of HP-positive patients with uncomplicated dyspepsia could be expected to produce symptomatic relief in 50% of cases, but would have delayed the diagnosis of 3 cases of cancer if patients over the age of 45 were included.

CONCLUSION

The lack of association between HP serology and upper gastro-intestinal disease indicates that serological investigation cannot substitute for endoscopy in the management of black Africans with dyspepsia, and that empiric anti-HP therapy cannot be justified.