Evaluation of short-interfering RNAs treatment in experimental rabies due to wild-type virus

ABSTRACTWe have evaluated the efficacy of short-interfering RNAs targeting the nucleoprotein gene and also the brain immune response in treated and non-treated infected mice. Mice were inoculated with wild-type virus, classified as dog (hv2) or vampire bat (hv3) variants and both groups were treated or leaved as controls. No difference was observed in the lethality rate between treated and non-treated groups, although clinical evaluation of hv2 infected mice showed differences in the severity of clinical disease (p = 0.0006). Evaluation of brain immune response 5 days post-inoculation in treated hv2 group showed no difference among the analyzed genes, whereas after 10 days post-inoculation there was increased expression of 2',5'-oligoadenylate synthetase 1, tumor necrosis factor alpha, interleukin 12, interferon gamma, and C-X-C motif chemokine 10 associated with higher expression of Ngene in the same period (p < 0.0001). In hv2 non-treated group only higher interferon beta expression was found at day 5. The observed differences in results of the immune response genes between treated and non-treated groups is not promising as they had neither impact on mortality nor even a reduction in the expression of N gene in siRNA treated animals. This finding suggests that the use of pre-designed siRNA alone may not be useful in rabies treatment.

Fluorescent antibody test, quantitative polymerase chain reaction pattern and clinical aspects of rabies virus strains isolated from main reservoirs in Brazil

ABSTRACTRabies virus (RABV) isolated from different mammals seems to have unique characteristics that influence the outcome of infection. RABV circulates in nature and is maintained by reservoirs that are responsible for the persistence of the disease for almost 4000 years. Considering the different pattern of pathogenicity of RABV strains in naturally and experimentally infected animals, the aim of this study was to analyze the characteristics of RABV variants isolated from the main Brazilian reservoirs, being related to a dog (variant 2),Desmodus rotundus (variant 3), crab eating fox, marmoset, and Myotis spp. Viral replication in brain tissue of experimentally infected mouse was evaluated by two laboratory techniques and the results were compared to clinical evolution from five RABV variants. The presence of the RABV was investigated in brain samples by fluorescent antibody test (FAT) and real time polymerase chain reaction (qRT-PCR) for quantification of rabies virus nucleoprotein gene (N gene). Virus replication is not correlated with clinical signs and evolution. The pattern of FAT is associated with RABV replication levels. Virus isolates from crab eating fox and marmoset had a longer evolution period and higher survival rate suggesting that the evolution period may contribute to the outcome. RABV virus variants had independent characteristics that determine the clinical evolution and survival of the infected mice.

Detecção de Brucella spp. em leite bovino não pasteurizado através da Reação de Cadeia pela Polimerase (PCR) / Detection of Brucella spp. in unpasteurized cow milk by polymerase chain reaction (PCR)

A brucelose é uma importante zoonose causada por bactérias do gênero Brucella. O homem é infectado pelo contato com as secreções reprodutivas como placenta, lóquios placentários, sêmen e secreções penianas de animais infectados ou pelo consumo de leite e derivados não pasteurizados. Com o objetivo de pesquisar a presença da bactéria no leite, foram avaliadas, através da técnica da reação em cadeia da polimerase (PCR), 30 amostras de leite cru comercializadas clandestinamente na região de Botucatu, São Paulo, bem como 50 amostras de leite entregues em laticínio, previamente à pasteurização. Das 80 amostras analisadas pela técnica de PCR, 10 (12,5%) foram positivas e 70 (87,5%) negativas. Dentre as amostras positivas, 5 amostras (16,6%) eram provenientes de comerciantes ilegais e outras 5 amostras (10%) foram obtidas no laticínio. A positividade para Brucella spp. demonstra que o patógeno se encontra presente de forma importante na região de Botucatu, São Paulo, e que o risco associado à saúde pública devido à comercialização de produtos clandestinos sem prévia pasteurização é real.(AU)

Brucellosis is a zoonosis caused by bacteria of the genus Brucella. Man infection occurs through contact with reproductive secretions as placenta and its lochia, semen and penile secretion of infected animals or by consuming unpasteurized milk and dairy products. With the objective of investigating the presence of bacteria in milk, 30 samples of raw milk sold illegally in the region of Botucatu, São Paulo, Brazil, as well as 50 samples of milk delivered to a dairy industry previously to its pasteurization were evaluated by the polymerase chain reaction (PCR) technique. Of the 80 samples analyzed, 10 samples (12.5%) were positive and 70 (87.5%) were negative. Among the positive samples, 5 (16.6%) were from illegal traders and other 5 (10%) were obtained from the dairy industry. Brucella spp. positivity shows that the pathogen is representatively present in Botucatu, São Paulo, Brazil, and the risk associated to public health due to the commercialization of illegal products without pasteurization is real.(AU)