Mealybug wilt disease

Mealybug wilt disease (MWD) is a serious field disease of pineapples worldwide that was first described in Hawaii in 1910. MWD is thought to be caused by a complex involving viruses, mealybugs and ants. The viruses are transmitted by mealybugs, which in turn are tended by ants. Although a number of distinct viruses have been associated with the disease, the identity of the causal agent(s) has not been determined unequivocally. This chapter describes the disease symptopms, aetiology and management of MWD. In the last 20 years, significant advances have been achieved in identifying the causal viral agents, and gaining a better understanding of MWD. However, the interactions between the viruses, mealybugs and environmental factors are complicated, and the conditions required for the expression of MWD have only been partially elucidated at this time. The possible role of gene silencing, the identity of the additional ampelovirus(es) and badnavirus(es) that have been detected but not characterized, and the interaction between these disease-inducing factors are fertile areas for future research.

Detection of viral diseases in shrimp Litopenaeus vannamei in Iran with emphasis on white spot disease prevention by using marine alga extract

Nowadays, following was expanded shrimp breeding and culture; viral diseases have been main problem which threatened shrimp industry in the country. Therefore, shrimp samples were obtained from different stages of Litopenaeus vannmei life cycle (larval, post larval, juveniles, adults and broodstocks) based on clinical signs in the breeding center and shrimp farming from Bushehr, Khozestan and Sistan and Baluchestan provinces. Viral diseases were detected by PCR (Polymerase Chain Reaction), histopathology and transmission electron microscopy (TEM) methods. Results of the PCR were indicated present white spot virus (WSV) in juveniles, sub adults and adults shrimp with medium intensity from three provinces, but it was not showed in larval and post larval stages. Histopathological sections were indicated hypertrophy and basophilic Cowdry type A formation in nucleus cells of gill, haematopoietic, lymphoid and epithelial's cuticles and intestinal tissues which was associated with small vacuoles increased in B cells of hepatopancreas tissue of infection shrimps. Transmission electronic microscopic studies were demonstrated that the length and diameter virus was detected, respectively, 300 ± 20 nm and 75 ± 5 nm. Considerable, results of the PCR were only displayed IHHNV in juvenile, adult and broodstock shrimps from breeding and farming center of Bushehr province. The main lesion pathology was formed eosinophilic Cowdry type A in nucleus cells of gill, haematopoietic, lymphoid and epithelial's cuticles and intestinal tissues. Whereas penaeid shrimps are lack specific immune system, hence, in the present study was used of marine alga (Lurensia snideria) collected from along costal Persian Gulf of Bushehr province for viral diseases were prevented. Powder alga extract were added with a ratio of 1 % to shrimp diet. Total haemocyte count (THC) and total protein plasma (TPP) were increased after 5 days of oral administration diets. When shrimps were infected by with spot virus experimentally, THC and TPP gradually were increased in both two groups (shrimps fed with diet containing alga extract and without alga extract) after 48h. Nevertheless; THC, TPP and survival of shrimp fed with diet containing alga extract were more than shrimp control in 15 days. So, oral administration Lurensia snideria extract was capable prevention infected L. vannamei via stimulant specific immune system.

Mosquito Vectors of Zika Virus and Their Control

This powerpoint presentation describes the way that Zika is spread by mosquitoes. It shows places that mosquitoes breed, ways to control their breeding, establishing a mosquito control program and shows various mosquito repellents.

Predictive Models for Tomato Spotted Wilt Virus Spread Dynamics, Considering Frankliniella occidentalis Specific Life Processes as Influenced by the Virus

Several models have been studied on predictive epidemics of arthropod vectored plant viruses in an attempt to bring understanding to the complex but specific relationship between the three cornered pathosystem (virus, vector and host plant), as well as their interactions with the environment. A large body of studies mainly focuses on weather based models as management tool for monitoring pests and diseases, with very few incorporating the contribution of vector's life processes in the disease dynamics, which is an essential aspect when mitigating virus incidences in a crop stand. In this study, we hypothesized that the multiplication and spread of tomato spotted wilt virus (TSWV) in a crop stand is strongly related to its influences on Frankliniella occidentalis preferential behavior and life expectancy. Model dynamics of important aspects in disease development within TSWV-F. occidentalis-host plant interactions were developed, focusing on F. occidentalis' life processes as influenced by TSWV. The results show that the influence of TSWV on F. occidentalis preferential behaviour leads to an estimated increase in relative acquisition rate of the virus, and up to 33% increase in transmission rate to healthy plants. Also, increased life expectancy; which relates to improved fitness, is dependent on the virus induced preferential behaviour, consequently promoting multiplication and spread of the virus in a crop stand. The development of vector-based models could further help in elucidating the role of tri-trophic interactions in agricultural disease systems. Use of the model to examine the components of the disease process could also boost our understanding on how specific epidemiological characteristics interact to cause diseases in crops. With this level of understanding we can efficiently develop more precise control strategies for the virus and the vector.

HERITABILITY FOR RESISTANCE TO ROSETTE DISEASE IN EXOTIC VALENCIA GROUNDNUTS

Groundnut rosette disease (GRD) is the most destructive virus disease of Valencia groundnuts ( Arachis hypogaea L.) in sub-Saharan Africa. Cultural, biological and chemical control measures have received limited success due to small scale farmers’ inability to use them. Use of host plant resistance provides the most effective and economically viable management option for the resource poor farmers. This study was conducted to determine heritability for resistance to GRD in Valencia groundnuts. Six crosses; Valencia C (P1) × ICGV-SM 90704 (P2), Valencia C (P1) × ICGV-SM 96801(P2), Valencia C (P1) × ICGV-SM 99566 (P2), NuMex-M3 (P1) × ICGV-SM 90704 (P2), NuMex-M3 × ICGV-SM 96801 (P2), and NuMex-M3 (P1) × ICGV-SM 99566 (P2), were made to generate F1, F2, BC1P1 and BC1P2 populations. Data on GRD severity were collected on a 1-9 score scale. Genetic Advance as a percentage of the mean (GAM) and heritability were estimated using variance components. Phenotypic Coefficient of Variation (PCV) and Genotypic Coefficient of Variation (GCV) estimates were high (20.04-70.1%) in the six crosses, except for Valencia C × ICGV-SM 96801(18.1%) and NuMex-M3 × ICGV-SM 96801(17.1%), which exhibited moderate GCV values. Broad and narrow sense heritability estimates for GRD disease score ranged from 64.1 to 73.7% and 31 to 41.9%, respectively, in all the crosses. GAM was high in all the crosses (21-50.7%), except for Valencia C x ICGV-SM 96801 (14.67), M3 x ICGV-SM 99566 (18%) and NuMex-M3 x ICGV-SM 96801 (13.5%) crosses that exhibited moderate GAM. The study revealed the presence of variability of GRD resistance, implying that genetic improvement of these exotic materials is possible.

Development and evaluation of the polymerase chain reaction (PCR) method for diagnosis of spring viremia of carp virus (SVCV)

Aquaculture has been expanded rapidly to become a major commercial and food-producing sector worldwide in recent decade. In parallel, viral diseases rapidly spread among farms causing enormous economic losses. The accurate detection of pathogens at early stages of infection is a key point for disease control in aquaculture. Spring Viraemia of Carp Virus (SVCV) is a very severe pathogen of carp fishes in different parts of the world and is categorized as a reportable listed disease in the annual published list of World Organization for animal Health (OIE). The objective of this study was to develop and evaluate RT- PCR test for detecting SVC virus and also the sensitivity and specificity of this test. A semi nested RT- PCR was designed using combination of three primers: two external (SVCF , SVCR) and one internal (SVCS) primers which based on conserved region of G gen. The specificity of designed primers (only external ones) by examination on Viral Hemorrhagic Septicemia Virus (VHSV) and Infectious Hematopoietic Necrosis Virus (IHNV) was confirmed. For optimizing of the PCR test, primer concentration, primer annealing temperature, cycle number and Mgcl2 concentration were surveyed. Also for validity test, prevention of false negative and Assurance of its accuracy, a competitive internal control (mimic) designed and its suitable concentration was defined. Evaluation of the sensitivity of designed test were conducted first by comparing the different commercially available RNA isolation guidelines, two guidelines: isotiocyanate phenol–chloroform based protocols (RNX–Plus Iran, Iq2000 kit Taiwan ) and two column based protocols (Cinna pure RNA Iran , high pure viral RNA kit, Roche Germany ). The results indicated that the column based protocols (Roche method and Cinna pure), yield 36.77 ng/μl and 16/47 ng/μl RNA concentration respectively, which were significantly higher than other protocols(P<0.05). Then for evaluation of extracted RNA sensitivity, Serial dilution of SVCV strain 56.70 grown in EPC (1.9×105 TCID50/ml) was examined To compare sensitivity. Extracted RNA from serial dilution with stone's primers and commercial IQ-2000 kit were examined simultaneously. The result indicated that designed semi- nested RT- PCR was able to recognize SVC virus to 10-4 dilution and stone's primer recognize to 10-3 dilution whereas Iq-2000 commercial kit did not recognized in any dilution. In high virus titer in designed test two DNA band (462 bp and 266 bp) produced, and by decreasing virus titer 462 bp was omitted. In low virus titer or lack of virus, just DNA band (mimic) 729 bp can propagate. After designing and optimizing PCR test, a total of 400 suspected cultured Cyprinus carpio with high mortality from 4 aquaculture zone of Khuzestan province were collected and tested for SVCV during 2012- 2013 using developed PCR method and IQ- 2000. The results indicated that SVC virus was not observed in samples using both methods.

Investigating novel approaches to the detection of virus neutralising antibodies to rabies and Rift Valley fever virus

Serosurveillance is a powerful tool fundamental to understanding infectious disease dynamics. The presence of virus neutralising antibody (VNAb) in sera is considered the best evidence of infection, or indeed vaccination, and the gold standard serological assay for their detection is the virus neutralisation test (VNT). However, VNTs are labour intensive, costly and time consuming. In addition, VNTs for the detection of antibodies to highly pathogenic viruses require the use of high containment facilities, restricting the application of these assays to the few laboratories with adequate facilities. As a result, robust serological data on such viruses are limited. In this thesis I develop novel VNTs for the detection of VNAb to two important, highly pathogenic, zoonotic viruses; rabies and Rift Valley fever virus (RVFV). The pseudotype-based neutralisation test developed in this study allows for the detection of rabies VNAb without the requirement for high containment facilities. This assay was utilised to investigate the presence of rabies VNAb in animals from a variety of ecological settings. In this thesis I present evidence of natural rabies infection in both domestic dogs and lions from rabies endemic settings. The assay was further used to investigate the kinetics of VNAb response to rabies vaccination in a cohort of free-roaming dogs. The RVFV neutralisation assay developed herein utilises a recombinant luciferase expressing RVFV, which allows for rapid, high-throughput serosurveillance of this important neglected pathogen. In this thesis I present evidence of RVFV infection in a variety of domestic and wildlife species from Northern Tanzania, in addition to the detection of low-level transmission of RVFV during interepidemic periods. Additionally, the investigation of a longitudinal cohort of domestic livestock also provided evidence of rapid waning of RVF VNAb following natural infection. Collectively, the serological data presented in this thesis are consistent with existing data in the literature generated using the gold standard VNTs. Increasing the availability of serological assays will allow the generation of robust serological data, which are imperative to enhancing our understanding of the complex, multi-host ecology of these two viruses.

Étude de la reconstitution de l’immunité spécifique au cytomégalovirus et au virus de la varicelle suite à la transplantation de sang de cordon ombilical

La transplantation de sang de cordon ombilical (TSCO) constitue un traitement de choix pour une multitude de pathologies hématologiques malignes et non malignes chez l’enfant et dans certains cas l’adulte. La TSCO est associée à certaines complications, dont une reconstitution immunitaire plus lente et une incidence élevée d’infections opportunistes, notamment celles reliées au cytomégalovirus (CMV) et au virus varicella-zoster (VZV). Dans le cadre de ce travail, nous nous sommes intéressés dans un premier temps à la caractérisation de la reconstitution immunitaire spécifique au CMV et au VZV. Nos résultats ont démontré que la reconstitution de l’immunité cellulaire ne requiert ni un statut séropositif pré-transplantation ni le développement de la maladie. De plus, des reconstitutions spontanées ont été détectées chez certains patients séronégatifs vis-à-vis du CMV ou du VZV. Outre le fait qu’elle se manifeste surtout à partir de 6 mois post-transplantation, ladite reconstitution mérite le qualificatif de « protectrice » en termes de réactivations virales et du développement de signes cliniques lorsqu’une fréquence de 150 cellules produisant l’IFN-γ/million est dépassée. Toutefois, moins de 5% des patients développent une réponse T anti-VZV et anti-CMV au cours 100 premiers jours suivant la TSCO. Il est donc possible que les lymphocytes CD8+ T provenant du SCO, comparativement à leurs homologues provenant de la moelle osseuse (MO), présentent un défaut de fonctionnalité, communément appelé « épuisement clonal ». La caractérisation du répertoire de récepteurs inhibiteurs exprimés par les cellules T CD8+ suivant la TSCO ou la transplantation de moelle osseuse (TMO) a révélé une augmentation significative de la fréquence des cellules exprimant PD-1 tôt suivant la transplantation. Cette population, caractérisée majoritairement par un phénotype effecteur-mémoire (EM), démontre une perte significative de la capacité proliférative et exprime moins d'IFN-γ, d'IL-2, de TNF-α et de CD107a. Une meilleure caractérisation de la reconstitution immunitaire après TSCO permettrait, d'une part de sélectionner des biomarqueurs en vue d’une meilleure gestion des patients à risques de développer des infections virales et/ou de rechuter, et d'autre part d'améliorer leur pronostic.

Co-administration of plasmid-encoded granulocyte-macrophage colony-stimulating factor increases human immunodeficiency virus-1 DNA vaccine-induced polyfunctional CD4+ T-cell responses

T-cell based vaccines against human immunodeficiency virus (HIV) generate specific responses that may limit both transmission and disease progression by controlling viral load. Broad, polyfunctional, and cytotoxic CD4+ T-cell responses have been associated with control of simian immunodeficiency virus/HIV-1 replication, supporting the inclusion of CD4+ T-cell epitopes in vaccine formulations. Plasmid-encoded granulocyte-macrophage colony-stimulating factor (pGM-CSF) co-administration has been shown to induce potent CD4+ T-cell responses and to promote accelerated priming and increased migration of antigen-specific CD4+ T-cells. However, no study has shown whether co-immunisation with pGM-CSF enhances the number of vaccine-induced polyfunctional CD4+ T-cells. Our group has previously developed a DNA vaccine encoding conserved, multiple human leukocyte antigen (HLA)-DR binding HIV-1 subtype B peptides, which elicited broad, polyfunctional and long-lived CD4+ T-cell responses. Here, we show that pGM-CSF co-immunisation improved both magnitude and quality of vaccine-induced T-cell responses, particularly by increasing proliferating CD4+ T-cells that produce simultaneously interferon-γ, tumour necrosis factor-α and interleukin-2. Thus, we believe that the use of pGM-CSF may be helpful for vaccine strategies focused on the activation of anti-HIV CD4+ T-cell immunity.

Primary dengue virus infections induce differential cytokine production in Mexican patients

Severe dengue pathogenesis is not fully understood, but high levels of proinflammatory cytokines have been associated with dengue disease severity. In this study, the cytokine levels in 171 sera from Mexican patients with primary dengue fever (DF) and dengue haemorrhagic fever (DHF) from dengue virus (DENV) 1 (n = 116) or 2 (n = 55) were compared. DF and DHF were defined according to the patient’s clinical condition, the primary infections as indicated by IgG enzymatic immunoassay negative results, and the infecting serotype as assessed by real-time reverse transcriptionpolymerase chain reaction. Samples were analysed for circulating levels of interleukin (IL)-12p70, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-6, and IL-8 using a commercial cytometric bead array. Significantly higher IFN-γ levels were found in patients with DHF than those with DF. However, significantly higher IL-12p70, TNF-α, and IL-6 levels were associated with DHF only in patients who were infected with DENV2 but not with DENV1. Moreover, patients with DF who were infected with DENV1 showed higher levels of IL-12p70, TNF-α, and IL-6 than patients with DHF early after-fever onset. The IL-8 levels were similar in all cases regardless of the clinical condition or infection serotype. These results suggest that the association between high proinflammatory cytokine levels and dengue disease severity does not always stand, and it once again highlights the complex nature of DHF pathogenesis.

Cynomolgus monkeys ( Macaca fascicularis ) experimentally infected with B19V and hepatitis A virus: no evidence of the co-infection as a cause of acute liver failure

This study was conducted to analyse the course and the outcome of the liver disease in the co-infected animals in order to evaluate a possible synergic effect of human parvovirus B19 (B19V) and hepatitis A virus (HAV) co-infection. Nine adult cynomolgus monkeys were inoculated with serum obtained from a fatal case of B19V infection and/or a faecal suspension of acute HAV. The presence of specific antibodies to HAV and B19V, liver enzyme levels, viraemia, haematological changes, and necroinflammatory liver lesions were used for monitoring the infections. Seroconversion was confirmed in all infected groups. A similar pattern of B19V infection to human disease was observed, which was characterised by high and persistent viraemia in association with reticulocytopenia and mild to moderate anaemia during the period of investigation (59 days). Additionally, the intranuclear inclusion bodies were observed in pro-erythroblast cell from an infected cynomolgus and B19V Ag in hepatocytes. The erythroid hypoplasia and decrease in lymphocyte counts were more evident in the co-infected group. The present results demonstrated, for the first time, the susceptibility of cynomolgus to B19V infection, but it did not show a worsening of liver histopathology in the co-infected group.

In vitro anti-canine distemper virus activity of fucoidan extracted from the brown alga Cladosiphon okamuranus

Canine distemper virus (CDV) is a morbillivirus related to measles virus that infects dogs and other carnivores. CDV has a significant global impact on animal health; however, there is no current antiviral treatment for CDV infection. In recent years, it has been demonstrated that sulfated polysaccharides exhibit antiviral properties both in vivo and in vitro, despite their low cytotoxicity to host cells. Fucoidan is a sulfated polysaccharide found in the cell wall matrix of brown algae. In this study, we evaluated in vitro anti-CDV activity of fucoidan, which was derived from Cladosiphon okamuranus. Fucoidan actively inhibited CDV replication in Vero cells at a 50% inhibitory concentration (IC50) of 0.1 lg/ml. The derived selectivity index (SI50) was[20,000. This polysaccharide likely inhibits viral infection by interference in the early steps and by inhibiting CDV-mediated cell fusion. Fucoidan may be useful in development of pharmacological strategies to treat and control CDV infection.

Sobre-expresión de la proteína p 16 en biopsias con diagnóstico de NIC I, positivas para Genoma de Papiloma Virus Humano. Instituto del Cáncer. SOLCA Cuenca-Ecuador. 2009-2010.

Numerosos estudios mencionan que la sobreexpresión de la proteína p16, un marcador biológico que permite identificar lesiones preneoplásicas del epitelio exocervical, tendría una alta asociación con el Papiloma Virus Humano (HPV) de alto riesgo oncogénico. Es un estudio descriptivo correlacional cuyo objetivo fue establecer asociación de las Neoplasias Intraepiteliales Cervicales grado I (NIC I), HPV positivos, con la expresión del p16. Materiales, métodos y resultados: Es un estudio correlacional que se realizó en el período de noviembre de 2009 a noviembre de 2010; se presentaron 256 casos de NIC I de los cuales, 72 fueron HPV positivos; se practicó técnica de p16. La edad promedio de las mujeres fue de 41 años. Se encontró positividad para el p16 en 40 casos (55.6%) y fueron negativos 32 (44.4%). De los casos positivos para p16, los tipos virales más frecuentes fueron los de alto riesgo: 33 (82.5%). El p16 fue valorado en cuantía, distribución e intensidad, estableciéndose relación entre la intensidad del p16 con los virus de alto riesgo (p=0.038). Cuando se analizó la edad y el tipo viral, pacientes entre 20 y 40 años (36 casos, 90%) presentaron genoma de HPV de alto riesgo. Conclusiones: Existió correlación entre la intensidad del p16 con la presencia de HPV de alto riesgo, ayudando a seleccionar grupos con tendencia a la progresión de la enfermedad.

Detection of Rupestris stem pitting associated virus in seedlings of virus - infected maternal grapevine plants.

Rupestris stem pitting associated virus (RSPaV) is a species in the genus Foveavirus (Martelli and Jelkman, 1998) and the family Flexiviridae. The virion has a positive sense, single stranded, polyadenylated RNA genome of 8.7kb in size and a coat protein of 28kD (Martelli and Jelkman, 1998). The virus has been reported to be present in pollen (Rowhani et aI., 2000) and seeds (Stewart and Nassuth, 2001), however, it has not been proved to be seed-transmitted. In our investigation reported here we have proven that RSPaV transmits by seed from RSPaV-infected mother plants to their siblings.