Maria Fátima da Silva Teixeira

Lentivírus de pequenos ruminantes (CAEV e Maedi-Visna): revisão e perspectivas

Small ruminant lentiviruses (SRLV), whose prototypes are Caprine Arthritis-Encephalitis virus (CAEV) and Maedi-Visna virus, are the causative agents of slow progressive degenerative diseases of goats and sheep (infected animals), responsible for significant economic losses. These viruses cause persistent infections with long periods of incubation and induce inflammatory and degenerative lesions. The lesions are induced in target organs of the host such as joints, CNS, lungs and mammary glands due to viral replication in cells of the monocyte/macrophage lineage which is the main target cell. Infections occur particularly in the young and are acquired through ingestion of virus in milk or colostrum from infected does or ewes. The induction of immune response is variable and does not protect against the infection. Diagnosis is primarily based on the presence of SRLV antibodies usually detected by agar gel immunodiffusion (AGID) or enzyme linked immunosorbent assays (ELISA). As no vaccine is available, most often employed schemes to prevent spread of SRLV are based on segregation or/and culling of positive animals associated with management practices, especially the offspring. The strategies of SRLV for dealing with the immune system make difficult to accomplish diagnosis of infection, control or prevention of the viral spread. This review shows aspects of SRLV based on their phylogenetic studies of fields isolates, clinical, and immuno-pathological features.

Risco de transmissão do vírus da raiva oriundo de sagui (Callithrix jacchus), domiciliado e semidomiciliado, para o homem na região metropolitana de Fortaleza, estado do Ceará

INTRODUCTION In the State of Ceará, a new variant of the rabies virus was identified associated with cases of human rabies transmitted by common marmosets (Callithrix jacchus), which are frequently kept as pets. This new variant does not present antigenic proximity or genetic relationship to variants of the virus isolated from bats and terrestrial mammals from the American continent. The present study aimed to evaluate the risk factors of rabies virus transmission from common marmosets (C. jacchus) maintained as pets in the metropolitan region of Fortaleza, State of Ceará, Brazil, to human beings. METHODS A questionnaire focusing on animal management and interaction between humans and primates was applied to individuals who had marmosets in the municipalities of Aquiraz and Maranguape. In order to evaluate the presence of rabies antigens by direct immunofluorescence test (DIF), samples of saliva were collected from domiciliary captive marmosets. Based on the detection of rabies antigens, biopsy samples of central nervous system (CNS) were analyzed. RESULTS Analysis of questionnaire data verified that a close relation exists between humans and their pet marmosets, especially during management practices. Additionally, these people showed minimal knowledge regarding rabies, which represents a greater risk of infection. Of the 29 saliva samples evaluated, one (3.4%) was positive for DIF reaction and of the 11 CNS samples, three (27.3%) were positive. CONCLUSIONS Laboratory data are in agreement with the questionnaire findings, which confirm an increased risk of rabies virus transmission due to the close relation between humans and marmosets.

Medium-term cryopreservation of rabies virus samples

INTRODUCTION The cryopreservation of rabies virus has been described in detail in the literature. To date, little information is available on the use of cryoprotective agents for cold preservation of this virus, and the available data focus only on short-term virus preservation. In this study, we investigated the medium-term cryopreservation of samples of rabies virus using different cryopreservation protocols. METHODS The cryopreservation protocols for the rabies virus samples were performed at -20°C and were divided according to the variables of time and cryoprotectant type used. The laboratory tests (intracerebral inoculation of mice, viral titration and direct immunofluorescence) were performed at regular intervals (360 and 720 days) to assess the viability of the viral samples according to the different preservation techniques used. RESULTS After 1 year of cryopreservation, the fluorescence intensity of intracellular corpuscles of the rabies virus and the median survival time of the mice differed between the positive controls and the treatments with the cryoprotectants. After 2 years, most of the samples subjected to the cryopreservation protocols (including the controls) did not produce fluorescence. However, the virus samples exposed to the cryoprotectant sucrose (68% solution) responded positively in the direct immunofluorescence assay and in the intracerebral inoculation of the mice. CONCLUSIONS Medium-term cryopreservation of the rabies virus inactivates the viral sample. However, the cryoprotectant agent sucrose (68%) produces a preservative effect in cryopreserved rabies virus samples.

Vírus do mosaico severo do caupi-CPSMV como molécula carreadora para a p28 do vírus da artrite-encefalite caprina-CAEV

Caprine arthritis-encephalitis virus (CAEV) belongs to Retroviridae family, Lentivirus genus. This virus infects caprine all over the world causing arthritis, encephalitis, mammitis and progressive emaciating. This research showed chimeras building made by mixing up CAEV p28, with glutaraldehyde, and CPSMV, purified through the chromotography in biogel and sephadex (G-150). After that, some measures in a spectrophometric were developed to absorbance at 280nm. Peaks, which contained chimera, were collected and submitted to SDS-PAGE, evidencing the band relative to itself. Groups of swiss mice were immunized with chimeric virus, purified CPSMV and with p28 protein using incomplete Freund Adjuvant. CPSMV and p28 specific antibodies recognized chimeric protein in Western Blotting and ELISA showing the efficacy of the method. The results showed the covalent coupling between CPSMV and CAEV p28 was successfully archieved, originating a stable molecule, which no disestablished the capside from CPSMV. Besides, it showed that chimeric virus presents more immunogenicity than protein p28 isolated. Its suggesting CPSMV can be used as a carrier molecule in the production of vaccines to the virus, which infect animals.