Caprine Arthirtis Encephalitis Virus (CAEV) and Visna Virus are two viruses of the lentivirus family. They encode three structural genes (gag, pol, and env) and two regulatory genes (rev and tat). The Rev protein regulates Gag, Pol and Env expression by transporting their mRNAs to the cytoplasm by binding to the RRE (Rev Response Element) found on their mRNAs. Previous studies have indicated that Rev may be toxic to transfected cells, overexpression of exogenous RREs or a better binding RRE can inhibit Rev activity and Rev-C (CAEV Rev) can trans-activate RRE-V (Visna Virus RRE). To test these possibilities FACS analysis, RNA binding assays, cotransfections, and SELEX were done. The results indicated that Rev is not acutely toxic to cells, inhibition of Rev activity could not be achieved by making a better binder or through expression of exogenous RREs, and Rev-C can trans-activate RRE-V implicating conservation of Rev/RRE interactions in lentiviruses.

Nous avons récemment développé un prototype lentivecteur ADN non intégratif vaccinal contre VIH-1/SIDA que nous avons testé chez des modèles animaux. L'immunisation avec une dose unique de ce vaccin (CAL-SHIV-IN-) a permis la mise en place rapide de réponses immunes spécifiques contre tous les antigènes exprimés par le vaccin chez tous les animaux vaccinés. Les analyses longitudinales ont démontré la mise en place de réponses cellulaires et humorales spécifiques et persistantes sur une durée de plus de 74 semaines en absence de réintroduction d'antigènes chez tous les macaques vaccinés. La caractérisation de ces réponses a révélé la présence de cellules T CD4+ et CD8+ polyfonctionnelles composées de fractions de cellules effectrices mémoires à fonction immédiate (EM), de cellules centrales mémoires (CM) et de cellules précurseurs mémoires ayant une haute capacité de prolifération (PHPC). Ces réponses corrèlent, chez tous les macaques vaccinés (6/6), avec un contrôle du virus d'épreuve hautement hétérologue et pathogénique (SIVmac251) inoculé à petites doses répétées par la voie mucosale rectale. Cette protection est maintenue durant toute la période d'un an de suivi après l'infection avec une différence statistiquement significative de la charge virale plasmatique des groupes contrôles et vaccinés au moins jusqu'à 18 semaines post-infection. Par ailleurs, le contrôle du virus d'épreuve est maintenu plus de 10 mois (correspondant au temps d'arrêt de l'étude) après l'infection. Parmi les corrélats immunologiques de protection nous avons identifié la présence de cellules de type PHPC spécifiques des antigènes du vaccin et qui sont dotées d'une capacité importante de prolifération ex vivo en présence des signaux antigéniques et homéostatiques. Nous avons démontré que ces PHPC contiennent une fraction de cellules T souches mémoires « TSCM » spécifiques du vaccin. Ces TSCM récemment identifiées constitueraient un atout majeur en faveur de notre vecteur et notre stratégie vaccinale du fait de leur haute capacité d'auto-régénération/maintien en absence d'antigène et leur capacité à se différencier en d'autres cellules mémoires TCM et TEM. / We recently developed an innovative prototype non-integrative lentivector DNA vaccine against HIV-1 /AIDS that we tested in pilot studies using animal models of HIV vaccine. We found that a single immunization with our prototype vaccine (CAL-SHIV-IN-) allowed the implementation of potent humoral and cellular responses in all immunized macaques. In addition, both types of responses persisted over a period of 74 weeks post-immunization in absence of antigenic boost. The characterization of the above revealed that vaccine specific T cell responses included polyfunctional CD4+ and CD8+ T cells against all antigens expressed by the vaccine. Detailed phenotypic and functional examinations of these cells showed that they were composed of effector (EM) and central memory (CM) T cells. More importantly they also contained a fraction of precursor memory T cells with high proliferative capacity (PHPC). Immune responses primed by our vaccine regiment correlated with protection in all vaccinated macaques (6/6). As expected our vaccine-induced immune responses did not prevent from infection acquisition but controlled the replication of the highly pathogenic and heterologous SIVmac251 challenge given as repeated low dose by the intrarectal mucosal route. All vaccinated animals (6/6) controlled their viremia to undetectable level using conventional PCR during at least 10 months post infection (end of the experiment). We further focused on PHPC responses associated with viral control and found that these cells vigorously proliferate upon ex vivo stimulation with specific antigens in presence of the homeostatic IL-7 and IL-15 cytokines. Proliferating antigen specific cells contained a type of stem cell-like memory T cells (TSCM). These latter (TSCM) might be a major asset in favor of our lentivector and vaccination strategy due to their high capacity for self-regeneration/maintenance in absence of antigen source.

Made available in DSpace on 2014-06-11T19:35:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2005Bitstream added on 2014-06-13T18:46:40Z : No. of bitstreams: 1 stachissini_avm_dr_botfmvz.pdf: 401033 bytes, checksum: 00097ff342cd7c1ca0227bf9fbcb1d11 (MD5) / Fundação para o Desenvolvimento da UNESP (FUNDUNESP) / With the aim of evaluating the seroepidemiological profiles of the toxoplasmosis and neosporosis in dairy goats from Sao Paulo state; possible risks of the toxoplasmosis for the public health and the associations of the diseases with the co-infection by the caprine arthritis-encephalitis virus (CAEV); and to stablish a quantitative indicator of the health (L°sanitary statusLl) of the farms, 923 caprine serum samples were obtained from 17 different properties. The animals were male and female , over three months old, subdivided in three age groups: < 1 year-old, between 1 and 4 years-old and > 4 years-old. For toxoplasmosis, neosporosis and caprine arthritis-encephalitis diagnosis, were used, respectively, indirect immunofluorescent antibody test (IFATLÃ16), Neospora agglutination test (NATLÃ25) and agar gel immunodiffusion (IDGA, positive or negative). A questionnaire containing reproductive and epidemiologic information was applied for all the farms. All the discussion were realized at 5% significance level. The positivity rates were 23.40 % for the toxoplasmosis and 19.77 % for the neosporosis. Two properties presented no positive result for T. gondii and in one there was no seropositive animal for N. caninum. There were no associations between the frequency of seropositivity and sex for both diseases. A more advanced age influenced positively in the occurrence of anti-T. gondii antibodies, but there no statistical difference for N. caninum. The presence of cats and dogs in farms was associated to the raise of positive rates for toxoplasmosis and neosporosis, respectively. The seropositivity for just one of the agents (T. gondii or N. caninum) did not influence the ocurrence of reproductive failures. There was no association between anti-CAEV antibodies and the presence of antibodies anti-T. gondii or anti-N. caninum... (Complete abstract, click electronic access below)