Optimized protocol for DNA/RNA co-extraction from adults of Dirofilaria immitis

Dirofilaria immitis, the etiologic agent of canine heartworm disease, like several other filarial nematodes, harbors the bacterial endosymbiont Wolbachia. To investigate metabolic and functional pathways of D. immitis and Wolbachia individually, along with their interactions, the use of both transcriptomic and genome analysis has becoming increasingly popular. Although several commercial kits are available for the single extraction of either DNA or RNA, no specific protocol has been described for simultaneous extraction of DNA and RNA from such a large organism like an adult D. immitis, where female worms generally reach ∼25 cm in length. More importantly, adult worms of D. immitis can only be obtained either through necropsy of experimentally infected dogs or by minimally-invasive surgical heartworm removal of naturally infected dogs. This makes each individual worm sample extremely important. Thus, in the context of a project aimed at the evaluation of both gene expression analysis and Wolbachia population assessment following different treatments, an optimized protocol for co-extraction of DNA and RNA from a single sample of adult D. immitis has been developed.

•

An optimized method for DNA/RNA co-extraction from large size nematodes using TRIzol® reagent.

•

Allows maximum exploitation of unique samples as adults of D. immitis.

Novel Activity of a Synthetic Decapeptide Against Toxoplasma gondii Tachyzoites

The killer peptide KP is a synthetic decapeptide derived from the sequence of the variable region of a recombinant yeast killer toxin-like microbicidal single-chain antibody. KP proved to exert significant activities against diverse microbial and viral pathogens through different mechanisms of action, but little is known of its effect on apicomplexan protozoa. The aim of the present study was to evaluate the in vitro activity of KP against Toxoplasma gondii, a globally widespread protozoan parasite of great medical interest. The effect of KP treatment and its potential mechanism of action on T. gondii were evaluated by various methods, including light microscopy, quantitative PCR, flow cytometry, confocal microscopy, and transmission electron microscopy. In the presence of KP, the number of T. gondii tachyzoites able to invade Vero cells and the parasite intracellular proliferation were significantly reduced. Morphological observation and analysis of apoptotic markers suggested that KP is able to trigger an apoptosis-like cell death in T. gondii. Overall, our results indicate that KP could be a promising candidate for the development of new anti-Toxoplasma drugs with a novel mechanism of action.

Clinical assessment of post-adulticide complications in Dirofilaria immitis-naturally infected dogs treated with doxycycline and ivermectin

This study shows that a combination of doxycycline (10mg/kg/sid for 30 days) and ivermectin (6 μg/kg/every 15 days for 6 months) is well tolerated for the treatment of canine heartworm disease (HWD). Monthly echocardiography showed that 84% of treated dogs either progressively improved parameters indicative of pulmonary hypertension or, following slight worsening, resolved all signs. Thoracic radiography showed the persistence of interstitial inflammation, even though also in this case, approximately 70% of the dogs steadily improved or worsened but then improved by the end of the study.

Anti-Wolbachia Surface Protein antibodies are present in the urine of dogs naturally infected with Dirofilaria immitis with circulating microfilariae but not in dogs with occult infections

Heartworm infection (Dirofilaria immitis) can cause kidney damage due to the presence of circulating microfilariae (mf) that contribute to the production and deposit of immune complexes. It has been shown that mf are a major source of Wolbachia antigen during active infection. Here the authors compared urine samples from 19 naturally infected dogs with (mf+) and 12 without (mf-) microfilariae for the presence of proteinuria and anti-Wolbachia Surface Protein (-WSP) IgG in ELISA. Kidneys from 6 mf+ and 3 mf- dogs were also examined by anti-WSP immuno-histochemistry. All infected dogs showed proteinuria, but mf+ dogs had significantly higher values compared to mf-dogs. Mf+ dogs had optical density values for anti-WSP IgG consistently higher than established cut-off values and were significantly higher than values for mf- dogs. Kidneys from mf+ dogs showed Wolbachia+ mf in glomerular capillaries. Results strongly suggest that Wolbachia associated with circulating mf may contribute to immune-mediated kidney disease in dogs with heartworm infection.

Disseminated histoplasmosis in a cat in Europe

A cat was presented with a history of vomiting, decreased appetite and weight loss. Abnormal findings were poor body condition, pale mucous membranes, dehydration and a palpable abdominal mass. Abdominal ultrasound showed lymph node enlargement, a mass of uncertain origin, thickening of the muscularis layer of the small bowel, focal thickening of the ileum with loss of layering and free peritoneal fluid. Cytology revealed a piogranulomatous infiltrate and numerous macrophages containing oval or round yeast‐like cells 2 to 5 µm diameter with a central, spherical, lightly basophilic body surrounded by a clear halo, compatible with Histoplasma capsulatum, within the cytoplasm. Post‐mortem examination revealed cavity effusions, granulomatous nodules in lungs, intestine and omentum, thickened intestinal walls and intestinal perforation. Staining with Grocott and immunohistochemistry (IHC) revealed numerous organisms within the granulomatous reaction. H. capsulatum has a worldwide distribution in temperate and subtropical climates. To the author’s knowledge, this is the first report of feline histoplasmosis in Europe.

Expression and localization of stanniocalcin 1 in swine ovary

Stanniocalcin 1 (STC 1) is a glycoprotein involved in mineral homeostasis and was first identified in fish. Its mammalian homologue has been implicated in the regulation of various biological processes, including angiogenesis and steroidogenesis both of which are fundamental events in ovarian function. Interestingly, the highest level of STC 1 expression in mammals occurs in ovarian tissue but no information is available on swine species. Therefore, the present study was undertaken to investigate the expression and the immunolocalization of STC 1 in swine ovary. In addition, we evaluated whether swine granulosa cells synthesize STC 1 and its possible modulation by hypoxia, a physiological condition in ovarian follicle growth. Our data show STC 1 for the first time in swine ovary; moreover, we demonstrate STC 1 production by granulosa cells, both in basal condition and in response to oxygen deprivation. The latter is suggestive of a potential modulatory role for STC 1 in hypoxia-driven angiogenesis.

Measurement of the differential cross section for the reaction gamman-->pi- p from deuterium

We report a measurement of the differential cross section for the gamman-->pi- p process from the CLAS detector at Jefferson Laboratory in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles (thetac.m.) between 50 degrees and 115 degrees. We confirm a previous indication of a broad enhancement around a c.m. energy ([sqrt]s) of 2.1 GeV at thetac.m.=90 degrees in the scaled differential cross section s7dsigma/dt and a rapid falloff in a center-of-mass energy region of about 400 MeV following the enhancement. Our data show an angular dependence of this enhancement as the suggested scaling region is approached for thetac.m. from 70 degrees to 105 degrees.

Precise measurement of the neutron magnetic form factor G(M)n in the few-GeV2 region

The neutron elastic magnetic form factor was extracted from quasielastic electron scattering on deuterium over the range Q;{2}=1.0-4.8 GeV2 with the CLAS detector at Jefferson Lab. High precision was achieved with a ratio technique and a simultaneous in situ calibration of the neutron detection efficiency. Neutrons were detected with electromagnetic calorimeters and time-of-flight scintillators at two beam energies. The dipole parametrization gives a good description of the data.

Search for the photoexcitation of exotic mesons in the pi+pi+pi- system

A search for exotic mesons in the pi;{+}pi;{+}pi;{-} system photoproduced by the charge exchange reaction gammap-->pi;{+}pi;{+}pi;{-}(n) was carried out by the CLAS Collaboration at Jefferson Lab. A tagged-photon beam with energies in the 4.8 to 5.4 GeV range, produced through bremsstrahlung from a 5.744 GeV electron beam, was incident on a liquid-hydrogen target. A partial wave analysis was performed on a sample of 83 000 events, the highest such statistics to date in this reaction at these energies. The main objective of this study was to look for the photoproduction of an exotic J;{PC}=1;{-+} resonant state in the 1 to 2 GeV mass range. Our partial wave analysis shows production of the a_{2}(1320) and the pi_{2}(1670) mesons, but no evidence for the a_{1}(1260), nor the pi_{1}(1600) exotic state at the expected levels. An upper limit of 13.5 nb is determined for the exotic pi_{1}(1600) cross section, less than 2% of the a_{2}(1320) production.

Measurement of direct f0(980) photoproduction on the proton

We report on the results of the first measurement of exclusive f_{0}(980) meson photoproduction on protons for E_{gamma}=3.0-3.8 GeV and -t=0.4-1.0 GeV2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the pi;{+}pi;{-} channel by performing a partial wave analysis of the reaction gammap-->ppi;{+}pi;{-}. Clear evidence of the f_{0}(980) meson was found in the interference between P and S waves at M_{pi;{+}pi;{-}} approximately 1 GeV. The S-wave differential cross section integrated in the mass range of the f_{0}(980) was found to be a factor of about 50 smaller than the cross section for the rho meson. This is the first time the f_{0}(980) meson has been measured in a photoproduction experiment.

Measurement of deeply virtual compton scattering beam-spin asymmetries

The beam-spin asymmetries in the hard exclusive electroproduction of photons on the proton (e p-->epgamma) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x(B) from 0.11 to 0.58, Q2 from 1 to 4.8 GeV2, -t from 0.09 to 1.8 GeV2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A approximately a sinphi/(1+c cosphi). This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector.

Bayesian analysis of pentaquark signals from CLAS data

We examine the results of two measurements by the CLAS collaboration, one of which claimed evidence for a Theta(+) pentaquark, while the other found no such evidence. The unique feature of these two experiments was that they were performed with the same experimental setup. Using a Bayesian analysis, we find that the results of the two experiments are in fact compatible with each other, but that the first measurement did not contain sufficient information to determine unambiguously the existence of a Theta(+). Further, we suggest a means by which the existence of a new candidate particle can be tested in a rigorous manner.

Search for medium modifications of the rho meson

The photoproduction of vector mesons on various nuclei has been studied using the CLAS detector at Jefferson Laboratory. The vector mesons, rho, omega, and varphi, are observed via their decay to e;{+}e;{-}, in order to reduce the effects of final-state interactions in the nucleus. Of particular interest are possible in-medium effects on the properties of the rho meson. The rho mass spectrum is extracted from the data on various nuclei, 2H, C, Fe, and Ti. We observe no significant mass shift and some broadening consistent with expected collisional broadening for the rho meson.

Experimental study of exclusive 2H(e,e'p)n reaction mechanisms at high Q2

The reaction 2H(e,e'p)n has been studied with full kinematic coverage for photon virtuality 1.75<Q2<5.5 GeV2. Comparisons of experimental data with theory indicate that for very low values of neutron recoil momentum (p(n)<100 MeV/c) the neutron is primarily a spectator and the reaction can be described by the plane-wave impulse approximation. For 100<p(n)<750 MeV/c, proton-neutron rescattering dominates the cross section, while Delta production followed by the NDelta-->NN transition is the primary contribution at higher momenta.

Human subcutaneous dirofilariasis, Russia

We report 14 cases of human subcutaneous dirofilariasis caused by Dirofilaria repens, diagnosed from February 2003 through July 2004, in patients from Rostovon-Don, Russia. Serologic analysis showed evidence of high risk of exposure to D. repens. Surveillance studies on prevalence and prevention effectiveness of canine infection are needed to control this emerging zoonosis.

iNOs expression is stimulated by the major surface protein (rWSP) from Wolbachia bacterial endosymbiont of Dirofilaria immitis following subcutaneous injection in mice

The bacterial endosymbiont Wolbachia of several species of filarial nematodes plays an important role in the inflammatory pathology of filariasis. Nitric oxide (NO) production has also been implicated in the immune response during filarial infections. Here we present data indicating that a recombinant Wolbachia surface protein (rWSP) induces iNOs mRNA expression and NO production, as well as IFN-gamma and a Th1-type antibody response, in inoculated BALB/c mice. This effect is not observed when mice are inoculated with a recombinant heat shock protein from Wolbachia (GroEL).

Immunopathology of Dirofilaria immitis infection

Heartworm disease caused by Dirofilaria immitis affects canine and feline hosts, with infections occasionally being reported in humans. Studies have shown that both dirofilarial antigens and those derived from its bacterial endosymbiont Wolbachia, interact with the host organism during canine, feline and human infections and participate in the development of the pathology and in the regulation of the host's immune response. Both innate and acquired immune responses are observed and the development of the acquired response may depend on the host and, or on its parasitological status. This review aims at illustrating current research on the role of both D. immitis and Wolbachia, in the immunology and immunopathology of dirofilariosis.

Measurement of the N-->Delta(+)(1232) transition at high-momentum transfer by pi(0) electroproduction

We report a new measurement of the exclusive electroproduction reaction gamma(*)p-->pi(0)p to explore the evolution from soft nonperturbative physics to hard processes via the Q(2) dependence of the magnetic (M(1+)), electric (E(1+)), and scalar (S(1+)) multipoles in the N-->Delta transition. 9000 differential cross section data points cover W from threshold to 1.4 GeV/c(2), 4pi center-of-mass solid angle, and Q(2) from 3 to 6 GeV(2)/c(2), the highest yet achieved. It is found that the magnetic form factor G(M)(*) decreases with Q(2) more steeply than the proton magnetic form factor, the ratio E(1+)/M(1+) is small and negative, indicating strong helicity nonconservation, and the ratio S(1+)/M(1+) is negative, while its magnitude increases with Q(2).

Search for Theta++ pentaquarks in the exclusive reaction gammap-->K+K-p

The reaction gammap --> pK+K- was studied at Jefferson Lab with photon energies from 1.8 to 3.8 GeV using a tagged photon beam. The goal was to search for a Theta++ pentaquark, a narrow, doubly charged baryon state having strangeness S=+1 and isospin I=1, in the pK+ invariant mass spectrum. No statistically significant evidence of a Theta++ was found. Upper limits on the total and differential cross section for the reaction gammap --> K-Theta++ were obtained in the mass range from 1.5 to 2.0 GeV/c2, with an upper limit for a narrow resonance with a mass M(Theta++) = 1.54 GeV/c2 of about 0.15 nb, 95% C.L.. This result places a stringent upper limit on the Theta++ width Gamma(Theta++) <0.1 MeV/c2.

Measurement of deeply virtual compton scattering with a polarized-proton target

The longitudinal target-spin asymmetry AUL for the exclusive electroproduction of high-energy photons was measured for the first time in ep-->e;'pgamma. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinvarphi moment is 0.252+/-0.042stat+/-0.020sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H.

Search for the Theta+ Pentaquark in the gammad--> DeltanK+ reaction measured with the CLAS spectrometer

For the first time, the reaction gammad-->DeltanK+ has been analyzed in order to search for the exotic pentaquark baryon Theta+(1540). The data were taken at Jefferson Laboratory, using the Hall-B tagged-photon beam of energy between 0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No statistically significant structures were observed in the nK+ invariant-mass distribution. The upper limit on the gammad-->DeltaTheta+ integrated cross section has been calculated and found to be between 5 and 25 nb, depending on the production model assumed. The upper limit on the differential cross section is also reported.

The Intradermal Leishmanin Reaction Induces Antigen-specific Maturation of Canine Dendritic Cells with Up-regulation of MHCII Synthesis and Expression

Dendritic cells (DCs) are professional antigen-presenting cells that reside in many tissues, including the skin. This study showed that intradermal injection of leishmanin in Leishmania infantum-infected dogs induced the "up-regulation" of surface MHCII expression, associated with progressive ultrastrucutural changes characteristic of DC maturation, including the formation of multilaminar MHC class II-containing compartments and arrays of tubulo-vesicular structures. These changes were not observed in control dogs from L. infantum non-endemic areas. The results indicated that canine DCs were effector cells in delayed-type hypersensitivity, that the leishmanin reaction was specific for a cell-mediated reaction to L. infantum in infected dogs, and that canine DCs possessed ultrastructural organelles reminiscent of those in activated human DCs.

Search for the Theta+ pentaquark in the reaction gammad --> pK-K+n

A search for the Theta+ in the reaction gammad --> pK-K+n was completed using the CLAS detector at Jefferson Lab. A study of the same reaction, published earlier, reported the observation of a narrow Theta+ resonance. The present experiment, with more than 30 times the integrated luminosity of our earlier measurement, does not show any evidence for a narrow pentaquark resonance. The angle-integrated upper limit on Theta+ production in the mass range of 1.52-1.56 GeV/c2 for the gammad --> pK-Theta+ reaction is 0.3 nb (95% C.L.). This upper limit depends on assumptions made for the mass and angular distribution of Theta+ production. Using Lambda(1520) production as an empirical measure of rescattering in the deuteron, the cross section upper limit for the elementary gamman --> K-Theta+ reaction is estimated to be a factor of 10 higher, i.e., approximately 3 nb (95% C.L.).

Measurement of two- and three-nucleon short-range correlation probabilities in nuclei

The ratios of inclusive electron scattering cross sections of 4He, 12C, and 56Fe to 3He have been measured at 1 < xB <. At Q2 > 1.4 GeV2, the ratios exhibit two separate plateaus, at 1.5 < xB < 2 and at xB > 2.25. This pattern is predicted by models that include 2- and 3-nucleon short-range correlations (SRC). Relative to A = 3, the per-nucleon probabilities of 3-nucleon SRC are 2.3, 3.1, and 4.4 times larger for A = 4, 12, and 56. This is the first measurement of 3-nucleon SRC probabilities in nuclei.

Eta' photoproduction on the proton for photon energies from 1.527 to 2.227 GeV

Differential cross sections for the reaction gamma p --> eta' p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the eta'N channel to both the S11(1535) and P11(1710) resonances, known to couple strongly to the etaN channel in photoproduction on the proton, and the importance of J = 3/2 resonances in the process.

Search for Theta+ (1540) Pentaquark in High-Statistics Measurement of gammap-->K0K+n at CLAS

The exclusive reaction gammap-->K0K+n was studied in the photon energy range between 1.6 and 3.8 GeV searching for evidence of the exotic baryon Theta+ (1540)-->nK+. The decay to nK+requires the assignment of strangeness S=+1 to any observed resonance. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility corresponding to an integrated luminosity of 70 pb-1. No evidence for the Theta+ pentaquark was found. Upper limits were set on the production cross section as function of center-of-mass angle and nK+ mass. The 95% C.L. upper limit on the total cross section for a narrow resonance at 1540 MeV was found to be 0.8 nb.

Beam-helicity asymmetries in double-charged-pion photoproduction on the proton

Beam-helicity asymmetries for the two-pion-photoproduction reaction gammap-->ppi(+)pi(-) have been studied for the first time in the resonance region for center-of-mass energies between 1.35 and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these models currently do not provide an adequate description for the behavior of this new observable.

Aelurostrongylus abstrusus (cat lungworm) infection in five cats from Italy

Infection by the cat lungworm Aelurostrongylus abstrusus is considered uncommon. Here, the authors report the clinical, diagnostic and therapeutic features of five infections recently observed in Italy. All cats were under 12 months of age. All except one cat had symptomatic infections, with cough, dyspnea, and weight loss with radiographic signs of broncopneumonia. All cats were eosinophilic. Larvae were present in fresh fecal smears and on flotation exam in all cats. Baermann larval recovery permitted definitive identification and, in one case, larvae per gram of feces (lpg) counts. One dose of ivermectin (400 microg/kg) was not effective in one cat, while one dose of selamectin (6 mg/kg) was effective in one of three cases and fenbendazole at 50 mg/kg given daily for 15 days was effective in four of four cases.

Immune response to and tissue localization of the Wolbachia surface protein (WSP) in dogs with natural heartworm (Dirofilaria immitis) infection

Human and animal parasitic filarial nematodes, including the agent of canine and feline heartworm disease Dirofilaria immitis, harbour intracellular bacteria of the genus Wolbachia (Rickettsiaies). It is thought that these bacteria play an important role in the pathogenesis and immune response to filarial infection. Immunoglobulin G (total IgG, IgG1, IgG2) production against and immunohistochemical staining of tissues for the Wolbachia surface protein (WSP) from dogs with natural heartworm infection were evaluated. All infected dogs had significant total anti-WSP IgG levels compared to healthy controls. Interestingly, WSP was recognized by the IgG2 subclass in both microfilariemic dogs and in dogs with no circulating microfilariae (occult infection). However, microfilariemic dogs also produced gG1 antibodies. Positive staining for WSP was observed in lungs, liver and kidneys, in particular in glomerular capillaries of naturally infected dogs who had died from heartworm disease. Our results show for the first time that Wolbachia is recognized specifically by D. immitis--infected dogs and that the bacteria is released into host tissue. Furthermore, microfilariemic status appears to effect immune responses to this endosymbiont.

Onset of asymptotic scaling in deuteron photodisintegration

We investigate the transition from the nucleon-meson to the quark-gluon description of the strong interaction using the photon energy dependence of the d(gamma,p)n differential cross section for photon energies above 0.5 GeV and center-of-mass proton angles between 30 degrees and 150 degrees. A possible signature for this transition is the onset of cross-section s(-11) scaling with the total energy squared, s, at some proton transverse momentum P(T). The results show that the scaling has been reached for proton transverse momentum above about 1.1 GeV/c. This may indicate that the quark-gluon regime is reached above this momentum.

Proton source size measurements in the eA-->e'ppX reaction

Two-proton correlations at small relative momentum q were studied in the eA(3He,4He,C,Fe)-->e(')ppX reaction at E(0)=4.46 GeV using the CLAS detector at Jefferson Lab. The enhancement of the correlation function at small q was found to be in accordance with theoretical expectations. Sizes of the emission region were extracted, and proved to be dependent on A and on the proton momentum. The size of the two-proton emission region for He was measured in eA reactions for the first time.

Measurement of the generalized polarizabilities of the proton in virtual Compton scattering at Q2=0.92 and 1.76 GeV2

We report a virtual Compton scattering study of the proton at low c.m. energies. We have determined the structure functions P(LL)-P(TT)/epsilon and P(LT), and the electric and magnetic generalized polarizabilities (GPs) alpha(E)(Q2) and beta(M)(Q2) at momentum transfer Q(2)=0.92 and 1.76 GeV2. The electric GP shows a strong falloff with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a falloff; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from piN intermediate states.

Sequencing of the complete gene coding for the GroEL of the Wolbachia of Dirofilaria immitis and expression and purification of the recombinant protein

Wolbachia are intracellular bacteria that infect arthropods and filarial nematodes. These bacteria play an important role in the immunology and pathogenesis of filarial diseases through their proteins and, possibly, other molecules. GroEL is a constitutively expressed bacterial protein; it is highly conserved among bacteria and is involved in the correct folding of newly synthesized proteins. Here we report the production of recombinant GroEL from the Wolbachia of Dirofilaria immitis. Our goal is to test the hypothesis that GroEL is involved in the immunopathology of filariases. The complete groel gene was PCR-amplified, sequenced and cloned into an expression vector. The recombinant GroEL was purified by affinity chromatography by using high-performance liquid chromatography (HPLC).

Two-nucleon momentum distributions measured in 3He(e,e'pp)n

We have measured the 3He(e,e'pp)n reaction at 2.2 GeV over a wide kinematic range. The kinetic energy distribution for "fast" nucleons (p>250 MeV/c) peaks where two nucleons each have 20% or less, and the third nucleon has most of the transferred energy. These fast pp and pn pairs are back to back with little momentum along the three-momentum transfer, indicating that they are spectators. Calculations by Sargsian and by Laget also indicate that we have measured distorted two-nucleon momentum distributions by striking one nucleon and detecting the spectator correlated pair.

Observation of an exotic baryon with S=+1 in photoproduction from the proton

The reaction gamma p-->pi(+)K(-)K(+)n was studied at Jefferson Laboratory using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state with strangeness S=+1 and mass M=1555+/-10 MeV/c(2) was observed in the nK(+) invariant mass spectrum. The peak's width is consistent with the CLAS resolution (FWHM=26 MeV/c(2)), and its statistical significance is (7.8+/-1.0)sigma. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by the chiral soliton model for the Theta(+) baryon. In addition, the pK(+) invariant mass distribution was analyzed in the reaction gamma p-->K(-)K(+)p with high statistics in search of doubly charged exotic baryon states. No resonance structures were found in this spectrum.

Observation of an exotic S = +1 baryon in exclusive photoproduction from the deuteron

In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to an exotic baryon with strangeness S=+1 is seen in the K(+)n invariant mass spectrum. The peak is at 1.542+/-0.005 GeV/c(2) with a measured width of 0.021 GeV/c(2) FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is (5.2+/-0.6)sigma. The mass and width of the observed peak are consistent with recent reports of a narrow S=+1 baryon by other experimental groups.

Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS

Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value.

Measurement of ep-->e' ppi+ pi- and baryon resonance analysis

The cross section for the reaction ep-->e(')ppi(+)pi(-) was measured in the resonance region for 1.4<W<2.1 GeV and 0.5<Q2<1.5 GeV(2)/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N(*) and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

First measurement of transferred polarization in the exclusive ep-->e'K+Lambda--> reaction

The first measurements of the transferred polarization for the exclusive e-->p-->e(')K+Lambda--> reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567 GeV beam was used to measure the hyperon polarization over Q2 from 0.3 to 1.5 (GeV/c)(2), W from 1.6 to 2.15 GeV, and over the full K+ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A nonrelativistic quark-model interpretation of our data suggests that the ssmacr; quark pair is produced with spins predominantly antialigned. Implications for the validity of the most widely used quark-pair creation operator are discussed.

Immunohistochemical/immunogold detection and distribution of the endosymbiont Wolbachia of Dirofilaria immitis and Brugia pahangi using a polyclonal antiserum raised against WSP (Wolbachia surface protein)

Intracellular bacteria in filarial nematodes were described as early as the 1970s, yet it was only with the work on Dirofilaria immitis, the agent of canine and feline heartworm disease, that these microorganisms were identified as belonging to Wolbachia, a genus known for encompassing bacteria infecting insects and other arthropods. The implications for the presence of intracellular bacteria in filarial nematodes is now the subject of intense research, particularly regarding their role in the immunology and pathogenesis of disease in infected humans and animals and as a possible target for therapy. Here, the authors report results on the immunohistochemical and immunogold staining of Wolbachia in D. immitis and Brugia pahangi using polyclonal antibodies raised against the recombinant Wolbachia surface protein (WSP). The bacteria were present in the lateral hypodermal chords of both male and female worms and in the reproductive tract of adult females (oocytes, morulae, microfilariae). In D. immitis and B. pahangi from animals treated with tetracycline, positive staining was observed in the lateral chords of adult males and females, but was absent from the oocytes and morulae. These results indicate that Wolbachia endosymbionts can be identified immunohistochemically with anti-WSP polyclonal antibodies, that their distribution matches that already described for Wolbachia of other filarial worms, and that antibiotic treatment may impede the vertical transmission of these bacteria. Unequivocal detection of Wolbachia is essential for the study of this symbiont, in particular to monitor the effects of antibiotic treatment on worms. The use of a specific marker for bacteria in their nematode hosts represents an extremely useful tool in evaluating the pathogenic role and the effect of antibiotic treatment on these potential targets in the control of filarial disease.

Th1 response in BALB/c mice immunized with Dirofilaria immitis soluble antigens: a possible role for Wolbachia?

The immune response to filarial infection has been shown to be of both the Th1 and Th2 types. Studies aimed at developing immunization strategies against Dirofilaria immitis infection in dogs have shown that protection against larval challenge is of the Th2 type and that several proteins are recognized by immunized or infected animals. The bacterial endosymbiont Wolbachia, harbored by many filarial species including D. immitis, has recently been shown to interact with the host immune system. Specific antibodies to the Wolbachia recombinant surface protein (WSPr) have been observed in cats infected with D. immitis. In this work the authors have determined cytokine production and antibody response in BALB/c mice inoculated with soluble antigens from third stage larvae or from adult worms of D. immitis. Inoculated mice first produced IFN-gamma followed by a peak in IL-4. Specific antibodies to the Wolbachia protein WSPr were exclusively IgG2a, while antibodies against peptides derived from antigens of D. immitis were in the IgG1 and IgE subclasses. The cytokine response is thus similar to that reported for other filarial infection, where Th1 response shifts towards Th2. Antibody response indicates that Wolbachia may induce preferentially a Th1 response during filarial infection, while nematode antigens may be involved in Th2 response. There is thus an overall agreement with current opinions on the role of bacterial versus nematode molecules in driving the response towards the different directions.

Photoproduction of the omega meson on the proton at large momentum transfer

The differential cross section, dsigma/dt, for omega meson exclusive photoproduction on the proton above the resonance region (2.6<W<2.9 GeV) was measured up to a momentum transfer -t=5 GeV2 using the CLAS detector at Jefferson Laboratory. The omega channel was identified by detecting a proton and pi(+) in the final state and using the missing mass technique. While the low momentum transfer region shows the typical diffractive pattern expected from Pomeron and Reggeon exchange, at large -t the differential cross section has a flat behavior. This feature can be explained by introducing quark interchange processes in addition to the QCD-inspired two-gluon exchange.

Full season efficacy of moxidectin microsphere sustained release formulation for the prevention of heartworm (Dirofilaria immitis) infection in dogs

The authors report the efficacy of an injectable, moxidectin sustained release (SR) formulation for the prevention of canine heartworm infection in endemic areas in northern and central Italy. Three field trials were carried out on a total of 324 dogs. Two hundred forty-three dogs were treated with moxidectin SR 6 months apart and 81 dogs (positive controls) with moxidectin tablets given monthly for 5 consecutive months during the risk season each year throughout the study. Results of testing for microfilariae and circulating adult female antigens were negative for all the experimentally treated dogs at the 6, 7, 11 and 19 months after the last injection. No adverse reactions to moxidectin SR were observed but a moderate pain at palpation and swelling (5-6 cm) at the injection site after the first treatment. In the study areas, prevalence of Dirofilaria immitis infection calculated by testing dogs which had no preventive treatment in the previous transmission season ranged from 33 to 63%. This study confirms the efficacy and safety of injectable, moxidectin SR formulation in the prevention of heartworm infection in dogs and demonstrates that the prophylactic efficacy lasts for the full season and strongly suggests that the product gives 1-year protection.

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

Tetracycline treatment and sex-ratio distortion: a role for Wolbachia in the moulting of filarial nematodes?

Filarial nematodes harbour intracellular bacteria of the genus Wolbachia. These bacteria are thought to be beneficial to the host nematode. Indeed, tetracycline treatments reduce the population of Wolbachia in filarial worms and have detrimental effects on the nematode. Even though various antibiotic-curing experiments have been performed on filariae, the actual role of Wolbachia in the biology of these nematodes is not yet clear. To address this issue, we designed a first experiment on a model filaria (Brugia pahangi), maintained in the gerbil (Meriones unguiculatus). In this experiment, timing of tetracycline treatment was set on the basis of the larval stage of the nematode. This first experiment showed that 2 weeks of treatment started after the L(4)-L(5) moult of males, but before the moult of females, led to significant sex-ratio distortion of the nematodes. We thus hypothesised that tetracycline interferes with the moult in B. pahangi. To test this hypothesis, we designed a second experiment in which antibiotic treatments were started (1). before the moult of both sexes, (2). after the moult of males but before the moult of females, or (3). after the moult of both sexes. Treatment 1 determined a reduction of worm recovery with no sex bias. Treatment 2 led to a male-biased sex-ratio. Treatment 3 had no effect on either worm recovery or sex-ratio. These results thus support the hypothesis that tetracycline treatment interferes with the L(4)-L(5) moult of B. pahangi. The nematodes recovered from the treated and control animals were examined for the presence of Wolbachia using both immunohistochemistry and real-time PCR. In general, nematodes from treated animals showed a dramatic reduction in Wolbachia content. In one group, Wolbachia depletion, as observed at the end of the treatment, was followed by a rebound to 'normal' values 160 days later. Prospects for antifilarial therapy using Wolbachia-targeted tetracycline treatments should thus take into account the possibility of Wolbachia rebound.