Stochastic reaction-diffusion system modeling predator-prey interactions with prey-taxis and noises.

In this paper, we are concerned with a new stochastic system of nonlinear partial differential equations modeling the Lotka-Volterra interactions of predators and preys in the presence of prey-taxis, spatial diffusion, and noises. The spatial and temporal variations of the predator's velocity are determined by the prey gradient. In the first part, we derive a macroscopic model from stochastic kinetic equations by using the micro-macro decomposition method. In the second part, we sketch the proof of the existence of weak martingale solutions by using a Faedo-Galerkin method. In the last part, we develop a one- and two-dimensional finite volume approximation for the stochastic kinetic and macroscopic models, respectively. Our one-dimensional space numerical scheme is uniformly stable along the transition from kinetic to macroscopic regimes. We close with various numerical tests illustrating the convergence of our numerical method and some features of our stochastic macro-scale system.

HPV test by Hybrid Capture II for the diagnosis of HR-HPV persistent infection.

INTRODUCTION: Persistent high-risk HPV (HR-HPV) infection is associated with a greater risk of cervical cancer. PATIENTS AND METHODS: Statistical data on the prevalence of HR-HPV infections in the Algerian population is lacking. We conducted a prospective study of 300 women aged between 25 and 50 years, screened for cervical cancer from 2012 to 2015 in Sidi Bel Abbès, a western region of Algeria. We aimed to assess the reliability of the repeated use of the HC II test (three longitudinal HPV tests 9 months apart from each other) in diagnosing the persistence of HR-HPV infection. RESULTS: The prevalence of HR-HPV infection was 7.33% and infected women were aged 37.9±3years. For 90.9% of HR-HPV-positive patients, the infection persisted for a mean of 18.5months [95% CI: 16.9-22.1months]. Among these patients, 55.55% developed CIN1 and 11.11% developed CIN2. The sensitivity of the HC II test was 81.74% [95% CI: 71.3-89.6] and its positive predictive value associated with abnormal cervical biopsy was 27.49% [95% CI: 16.0-33.33]. CONCLUSION: Repeating the HC II test is a good predictor for identifying women at high risk of cervical cancer.

Display of epitopes on the surface of tobacco mosaic virus: impact of charge and isoelectric point of the epitope on virus-host interactions.

The biophysical properties of the tobacco mosaic tobamovirus (TMV) coat protein (CP) make it possible to display foreign peptides on the surface of TMV. The immunogenic epitopes G5-24 from the rabies virus (RV) glycoprotein, and 5B19 from murine hepatitis virus (MHV) S-glycoprotein were successfully displayed on the surface of TMV, and viruses accumulated to high levels in infected leaves of Nicotiana tabacum Xanthi-nn. The peptide RB19, which contains an arginine residue plus the 5B19 epitope fused to the CP (TMV-RB19), resulted in the induction of necrotic local lesions on inoculated leaves of N. tabacum Xanthi-nn and cell death of infected BY2 protoplasts. RNA dot blot assays confirmed that expression of the acidic and basic pathogenesis-related PR2 genes were induced in infected Xanthi-nn leaf tissue. TMV that carried epitope 31D from the RV nucleoprotein did not accumulate in inoculated tobacco leaves. Analysis of hybrid CPs predicted that the isoelectric points (pI):charge value was 5.31:-2 for wild-type CP, 5.64:-1 for CP-RB19, and 9.14:+2 for CP-31D. When acidic amino acids were inserted in CP-RB19 and CP-31D to bring their pI:charge to near that of wild-type CP, the resulting viruses TMV-RB19E and TMV-4D:31D infected N. tabacum Xanthi-nn plants and BY2 protoplasts without causing cell death. These data show the importance of the pI of the epitope and its effects on the hybrid CP pI:charge value for successful epitope display as well as the lack of tolerance to positively charged epitopes on the surface of TMV.

Enzyme histochemical characteristics of osteoblasts and mononucleated osteoclasts in a teleost fish with acellular bone (Oreochromis niloticus, Cichlidae).

Bone resorption by mononucleated cells was studied in the acellular bone of a teleost fish (Oreochromis niloticus) by histological and enzyme histochemical observations and by transmission electron microscopy. Bone resorbing cells (osteoclasts) were identified by their location at the sites of bone resorption, their frequent association with a band of concentrated activity of tartrate-resistant acid phosphatase at the bone surface and by the presence or lack of certain enzymes. Tartrate-resistant acid phosphatase was used as a marker for osteoclasts, and alkaline phosphatase as a marker for osteoblasts. Osteoclasts in O. niloticus are not multinucleated; however, during intense bone resorption, they form cell aggregations that resemble multinucleated giant cells in mammals. Conversely, during less intense bone degradation, osteoclasts are flat, have long narrow cytoplasmic processes and resemble the bone-lining cells of mammals. All bone-resorbing cells in O. niloticus are mononucleated and lack a ruffled border. Similarities to and differences from bone resorption by mononucleated cells in mammals are discussed.

The in vitro effect of some nitroimidazoles on microtubule formation.

The in vitro effects of some nitroimidazoles (metronidazole, ornidazole) and their metabolites on microtubule formation have been tested. Cyclic metabolites are without effect. Metabolites proceeding from cleavage of the imidazole ring inhibit microtubule formation and reduce the polymerization rate of tubulin. This inhibitory effect might be correlated to some of the side-effects of these drugs. Isaxonine phosphate corrects this effect.

Chimeric animal and plant viruses expressing epitopes of outer membrane protein F as a combined vaccine against Pseudomonas aeruginosa lung infection.

Outer membrane protein F of Pseudomonas aeruginosa has vaccine efficacy against infection by P. aeruginosa as demonstrated in a variety of animal models. Through the use of synthetic peptides, three surface-exposed epitopes have been identified. These are called peptides 9 (aa 261-274 in the mature F protein, TDAYNQKLSERRAN), 10 (aa 305-318, NATAEGRAINRRVE), and 18 (aa 282-295, NEYGVEGGRVNAVG). Both the peptide 9 and 10 epitopes are protective when administered as a vaccine. In order to develop a vaccine that is suitable for use in humans, including infants with cystic fibrosis, the use of viral vector systems to present the protective epitopes has been investigated. An 11-amino acid portion of epitope 10 (AEGRAINRRVE) was successfully inserted into the antigenic B site of the hemagglutinin on the surface of influenza virus. This chimeric influenza virus protects against challenge with P. aeruginosa in the mouse model of chronic pulmonary infection. Attempts to derive a chimeric influenza virus carrying epitope 9 have been unsuccessful. A chimeric plant virus, cowpea mosaic virus (CPMV), with epitopes 18 and 10 expressed in tandem on the large coat protein subunit (CPMV-PAE5) was found to elicit antibodies that reacted exclusively with the 10 epitope and not with epitope 18. Use of this chimeric virus as a vaccine afforded protection against challenge with P. aeruginosa in the mouse model of chronic pulmonary infection. Chimeric CPMVs with a single peptide containing epitopes 9 and 18 expressed on either of the coat proteins are in the process of being evaluated. Epitope 9 was successfully expressed on the coat protein of tobacco mosaic virus (TMV), and this chimeric virus is protective when used as a vaccine in the mouse model of chronic pulmonary infection. However, initial attempts to express epitope 10 on the coat protein of TMV have been unsuccessful. Efforts are continuing to construct chimeric viruses that express both the 9 and 10 epitopes in the same virus vector system. Ideally, the use of a vaccine containing two epitopes of protein F is desirable in order to greatly reduce the likelihood of selecting a variant of P. aeruginosa that escapes protective antibodies in immunized humans via a mutation in a single epitope within protein F. When the chimeric influenza virus containing epitope 10 and the chimeric TMV containing epitope 9 were given together as a combined vaccine, the immunized mice produced antibodies directed toward both epitopes 9 and 10. The combined vaccine afforded protection against challenge with P. aeruginosa in the chronic pulmonary infection model at approximately the same level of efficacy as provided by the individual chimeric virus vaccines. These results prove in principle that a combined chimeric viral vaccine presenting both epitopes 9 and 10 of protein F has vaccine potential warranting continued development into a vaccine for use in humans.

Significance of egg's zona pellucida glycoproteins in sperm-egg interaction and fertilization.

Mammalian fertilization is a highly programmed process by which sperm and egg unite to form a zygote, a cell with somatic chromosome numbers. To fertilize an egg, the capacitated (acrosome-intact) spermatozoa recognize and bind to the egg's extracellular glycocalyx coat, the zona pellucida (ZP). The tight and irreversible binding of the opposite gametes in the mouse and many other species studied, including man, results in the opening of Ca2+ channels on sperm plasma membrane (PM) and influx of Ca2+. The transient rise in Ca2+ and other second messengers, such as cAMP and IP3, initiates a cascade of signaling events that elevate sperm pH and triggers the fusion of the sperm PM and underlying outer acrosomal membrane at multiple sites (induction of the acrosomal reaction). The fusion of the two membranes results in the exocytosis of acrosomal contents at the site of sperm-egg adhesion. The hydrolytic action of the acrosomal enzymes (glycohydrolases, proteinases, esterases, sulfatases etc), released at the site of sperm-egg adhesion, along with the enhanced thrust generated by the hyperactivated spermatozoon, are important factors that regulate the penetration of the ZP and the fusion of the acrosome-reacted spermatozoon with the egg. Evidence accumulated over the past two decades strongly suggests that glycan units of the ZP have a significant role in the recognition and adhesion of the opposite gametes and induction of the AR. In this review article, we intend to highlight well programmed molecular events that results in the sperm-egg adhesion and fertilization. Our intention is also to discuss the increasing controversy on the role of ZP glycan chains in sperm-egg interactions.

Aggregation of TMV CP plays a role in CP functions and in coat-protein-mediated resistance.

Tobacco mosaic virus (TMV) coat protein (CP) in absence of RNA self-assembles into several different structures depending on pH and ionic strength. Transgenic plants that produce self-assembling CP are resistant to TMV infection, a phenomenon referred to as coat-protein-mediated resistance (CP-MR). The mutant CP Thr42Trp (CP(T42W)) produces enhanced CP-MR compared to wild-type CP. To establish the relationship between the formation of 20S CP aggregates and CP-MR, virus-like particles (VLPs) produced by TMV variants that yield high levels of CP-MR were characterized. We demonstrate that non-helical structures are found in VLPs formed in vivo by CP(T42W) but not by wild-type CP and suggest that the mutation shifts the intracellular equilibrium of aggregates from low to higher proportions of non-helical 20S aggregates. A similar shift in equilibrium of aggregates was observed with CP(D77R), another mutant that confers high level of CP-MR. The mutant CP(D50R) confers a level of CP-MR similar to wild-type CP and aggregates in a manner similar to wild-type CP. We conclude that increased CP-MR is correlated with a shift in intracellular equilibrium of CP aggregates, including aggregates that interfere with virus replication.

Engineering resistance against tomato yellow leaf curl virus (TYLCV) using antisense RNA.

One of the most severe diseases of cultivated tomato worldwide is caused by tomato yellow leaf curl virus (TYLCV), a geminivirus transmitted by the whitefly Bemisia tabaci. Here we describe the application of antisense RNAs to interfere with the disease caused by TYLCV. The target of the antisense RNA is the rare messenger RNA of the Rep protein, encoded by the C1 gene. Transgenic Nicotiana benthamiana plants expressing C1 antisense RNA were obtained and shown to resist infection by TYLCV. Some of the resistant lines are symptomless, and the replication of challenge TYLCV almost completely suppressed. The transgenes mediating resistance were shown to be effective through at least two generations of progeny.

Characterization of glycoconjugates in the epididymal epithelium and luminal fluid during postnatal development of the mouse.

The qualitative nature and distribution of glycoproteins in the mouse epididymis during postnatal development was examined by using lectin cytochemical procedures on paraffin sections and lectin blots on electrophoretically separated luminal fluid polypeptides transferred onto nitrocellulose. Histochemical results revealed the presence of glycoproteins with terminal alpha-D-mannose, N-acetyl-D-glucosamine and neuraminic acid in the principal cells along the epididymis during early stages of development (1st week), and glycoproteins containing terminal alpha-L-fucose, N-acetyl-D-galactosamine and alpha-D-galactose in specific regions of the duct during the differentiation state (2nd-3rd week). Lectin staining localized in the Golgi region and at the apical surface increased during development. Specific changes occurred with age and between cell types. Examination of the epididymal luminal fluid glycopeptides by lectin blot analysis revealed the presence of a large number of glycoproteins with various saccharide moieties at 7 days of age. Epididymal differentiation was accompanied either by the disappearance of some glycoproteins (apparent molecular mass: 16, 17.5, 22, 28, 30 and 74 kDa) or the appearance of new glycoproteins in the proximal (23, 13 kDa) and distal regions (29, 20.5, 19 and 14.4 kDa), or along the entire epididymal duct (26 kDa). The main changes occurred in the epididymis of 21-day-old mice and were completed before spermatozoa reached the epididymal lumen.

Synthesis, characterization and hormonal regulation of epididymal proteins during postnatal development of the mouse.

Maturation of mammalian spermatozoa depends on their interactions with epididymal proteins. The incorporation of 35S-methionine into these proteins was investigated by in vitro incubation of tissue minces from the mouse epididymis at different ages of postnatal development. The greatest amount of incorporation per wet weight of tissue was seen in 7 to 21-day-old mice. It decreased progressively during development while the rate of proteins released into the medium remained almost constant until the adult state. Separation of labeled proteins on sodium dodecyl sulphate polyacrylamide gels followed by fluorography showed that the great majority of secretory proteins synthesized in adult mouse epididymis could be recovered already from 7-day-old animals. Regional differences appeared at 21 days of age. These were marked by the secretion of proteins characteristic of the proximal (26, 25, 20, 19 kDa) and distal (44, 29 kDa) epididymis. Analysis of cytosol and luminal fluid proteins from prepubertal and adult epididymis revealed a number of proteins of the same mobility as those synthesized and secreted in vitro. Among the luminal proteins which showed variations during development and regional differences, four (29, 26, 20, 19 kDa) were characteristics of the epididymis and three (88, 34, 13 kDa) comigrated with testicular components. Castration or estrogen treatment of prepubertal mice for 4, 3 and 2 weeks inhibited or reduced the synthesis of the luminal proteins which appeared during postnatal development and/or presented regional differences. Testosterone replacement of castrated mice reversed this effect and induced the secretion of new proteins (37, 24 kDa).(ABSTRACT TRUNCATED AT 250 WORDS)

Calmodulin signals capacitation and triggers the agonist-induced acrosome reaction in mouse spermatozoa.

Capacitated acrosome-intact spermatozoa interact with specific sugar residues on neoglycoproteins (ngps) or solubilized zona pellucida (ZP), the egg's extracellular glycocalyx, prior to the initiation of a signal transduction cascade that results in the fenestration and fusion of the sperm plasma membrane and the outer acrosomal membrane at multiple sites and exocytosis of acrosomal contents (i.e., induction of the acrosome reaction (AR)). The AR releases acrosomal contents at the site of sperm-zona binding and is thought to be a prerequisite event that allows spermatozoa to penetrate the ZP and fertilize the egg. Since Ca(2+)/calmodulin (CaM) plays a significant role in several cell signaling pathways and membrane fusion events, we have used a pharmacological approach to examine the role of CaM, a calcium-binding protein, in sperm capacitation and agonist-induced AR. Inclusion of CaM antagonists (calmodulin binding domain, calmidazolium, compound 48/80, ophiobolin A, W5, W7, and W13), either in in vitro capacitation medium or after sperm capacitation blocked the npg-/ZP-induced AR. Purified CaM largely reversed the AR blocking effects of antagonists during capacitation. Our results demonstrate that CaM plays an important role in priming (i.e., capacitation) of mouse spermatozoa as well as in the agonist-induced AR. These data allow us to propose that CaM regulates these events by modulating sperm membrane component(s).

Immunization with a chimeric tobacco mosaic virus containing an epitope of outer membrane protein F of Pseudomonas aeruginosa provides protection against challenge with P. aeruginosa.

A chimeric tobacco mosaic virus (TMV) was constructed by inserting sequences representing peptide 9-14mer (TDAYNQKLSERRAN) of outer membrane (OM) protein F of Pseudomonas aeruginosa between amino acids Ser154 and Gly155 of the TMV coat protein (CP). This is the first example of TMV being used to construct a chimera containing a bacterial epitope. Mice immunized with TMV-9-14 produced anti-peptide-9-14mer-specific antibodies that reacted in whole-cell ELISA with all seven Fisher-Devlin (FD) immunotype strains of P. aeruginosa, reacted specifically by Western blotting with OM protein F extracted from all seven FD immunotypes, and were opsonic in opsonophagocytic assays. The chimeric TMV-9-14 vaccine afforded immunoprotection against challenge with wild-type P. aeruginosa in a mouse model of chronic pulmonary infection. TMV-9-14 is an excellent candidate for further development as a vaccine for possible use in humans to protect against P. aeruginosa infections.

Identification of viral mutants by mass spectrometry.

A method to identify mutations of virus proteins by using protein mass mapping is described. Comparative mass mapping was applied to a structural protein of the human rhinovirus Cys1199 --> Tyr mutant and to genetically engineered mutants of tobacco mosaic virus. The information generated from this approach can rapidly identify the peptide or protein containing the mutation and, in cases when nucleic acid sequencing is required, significantly narrows the region of the genome that must be sequenced. High-resolution matrix-assisted laser desorption/ionization (MALDI) mass spectrometry and tandem mass spectrometry were used to identify amino acid substitutions. This method provides valuable information for those analyzing viral variants and, in some cases, offers a rapid and accurate alternative to nucleotide sequencing.

Tomato yellow leaf curl virus from Sardinia is a whitefly-transmitted monopartite geminivirus.

The genome of an isolate of tomato yellow leaf curl virus from Sardinia, Italy (TYLCV-S), a geminivirus transmitted by the whitefly Bemisia tabaci, has been cloned and sequenced. The single circular DNA molecule comprises 2770 nucleotides. Genome organisation closely resembles that of the DNA A component of the whitefly-transmitted geminiviruses with a bipartite genome. A 1.8 mer of the TYLCV-S genome in a binary vector of Agrobacterium tumefaciens is infectious upon agroinoculation of tomato plants. Typical tomato yellow leaf curl disease symptoms developed about three weeks after inoculation. The disease was transmitted by the natural vector B.tabaci from agroinfected plants to test plants, reproducing in this way the full biological cycle and proving that the genome of TYLCV-S consists of only one circular single-stranded DNA molecule. Contrary to the other whitefly-transmitted geminiviruses described so far, there is no evidence for the existence nor the necessity of a second component (B DNA) in the TYLCV-S genome.

Studies of coat protein-mediated resistance to tobacco mosaic tobamovirus: correlation between assembly of mutant coat proteins and resistance.

Coat protein-mediated resistance (CP-MR) has been widely used to protect transgenic plants against virus diseases. To characterize the mechanisms of CP-MR to tobacco mosaic tobamovirus (TMV) we developed mutants of the coat protein that affected subunit-subunit interactions. Mutant CPs were expressed during TMV replication as well as in transgenic Nicotiana tabacum plants. The mutation T42-->W increased protein aggregation and T28-->W abolished aggregation and assembly, while the mutations T28-->W plus T42-->W and T89-->W altered normal CP subunit-subunit interactions. The mutant T28W was unable to assemble virus-like particles (VLPs) during infection and in transgenic plants failed to aggregate; this protein conferred no protection against challenge of transgenic plants by TMV. The mutant T42W had strong CP subunit-subunit interactions and formed VLPs but not infectious virions. Transgenic lines with this protein exhibited stronger protection against TMV infection than transgenic plants that contained the wild-type (wt) CP. It is proposed that increased resistance conferred by the T42W mutant results from strong interaction between transgenic CP subunits and challenge virus CP subunits. CP carrying the mutation T89-->W formed flexuous and unstable VLPs whereas the double mutant T28W:T42W formed open helical structures that accumulated as paracrystalline arrays. In transgenic plants, T89W and the double mutant CPs showed reduced ability to aggregate and provided lower protection against TMV infection than wt CP. A strong correlation between normal CP subunit-subunit interactions and CP-MR is observed, and a model for CP-MR involving interactions between the transgenic CP and the CP of the challenge virus as well as interference with virus movement is discussed.

Protective immunity against murine hepatitis virus (MHV) induced by intranasal or subcutaneous administration of hybrids of tobacco mosaic virus that carries an MHV epitope.

Hybrids of tobacco mosaic virus (TMV) were constructed with the use of fusion to the coat protein peptides of 10 or 15 amino acids, containing the 5B19 epitope from the spike protein of murine hepatitis virus (MHV) and giving rise to TMV-5B19 and TMV-5B19L, respectively. The TMV hybrids were propagated in tobacco plants, and the virus particles were purified. Immunogold labeling, with the use of the monoclonal MAb5B19 antibody, showed specific decoration of hybrid TMV particles, confirming the expression and display of the MHV epitope on the surface of the TMV. Mice were immunized with purified hybrid viruses after several regimens of immunization. Mice that received TMV-5B19L intranasally developed serum IgG and IgA specific for the 5B19 epitope and for the TMV coat protein. Hybrid TMV-5B19, administered by subcutaneous injections, elicited high titers of serum IgG that was specific for the 5B19 epitope and for coat protein, but IgA that was specific against 5B19 was not observed. Mice that were immunized with hybrid virus by subcutaneous or intranasal routes of administration survived challenge with a lethal dose (10 x LD50) of MHV strain JHM, whereas mice administered wild-type TMV died 10 d post challenge. Furthermore, there was a positive correlation between the dose of administered immunogen and protection against MHV infection. These studies show that TMV can be an effective vaccine delivery vehicle for parenteral and mucosal immunization and for protection from challenge with viral infection.