Molecular detection of Leptospira spp. in small wild rodents from rural areas of São Paulo State, Brazil

ABSTRACT Background: Leptospirosis represents a One Health issue, affecting humans and animals. This study investigated pathogenic leptospires in small wild rodents in São Paulo, Brazil. Methods: Kidney samples from 164 rodents underwent qPCR testing, targeting pathogenic Leptospira spp. Results: Thirty-five animals (21.34%) tested positive, including five rodent species: Akodon montensis (2/21; 9.5%), Necromys lasiurus (1/4; 25%), Oligoryzomys nigripes (24/92; 26.1%), Oligoryzomys flavescens (5/26; 19.2%), and Sooretamys angouya (3/14; 21.4%). Botucatu municipality exhibited the highest prevalence, with 42.5% (20/47) of the animals testing positive. Conclusions: The presence of Leptospira spp. in wild rodents suggests they may be chronic carriers, contaminating the environment.

Ticks infesting wild small rodents in three areas of the state of São Paulo, Brazil / Carrapatos infestando pequenos roedores silvestres em três municípios do estado de São Paulo, Brasil

ABSTRACT: From May to September 2011, a total of 138 wild rodents of the Cricetidae family were collected in the cities of Anhembi, Bofete and Torre de Pedra, in São Paulo State. All animals were examined for the presence of ticks, which were collected and identified at species level in the laboratory by morphological examination (for adults, nymphs and larvae) and molecular biology, by sequencing of a fragment of the 16S mitochondrial rDNA (for larvae). A total of 47 ticks (21 larvae and 26 nymphs) were collected from rodents, identified as 21 larvae and 23 nymphs of Amblyomma ovale (collected on Oligoryzomys nigripes, Oligoryzomys flavescens, Sooretamys agouya and Nectomys squamipes), two nymphs of Ixodes schulzei (O. nigripes and O. flavescens) and an Amblyomma sculptum nymph in S. agouya. The overall prevalence of parasitism by A. ovale was 4.3% for larvae, and 10.1% for nymphs. The mean intensity of parasitism was 3.5 larvae/parasitized animal, and 1.6 nymphs/parasitized animal. One O. nigripes was found parasitized by both larva and nymph of A. ovale, and another O. nigripes was parasitized simultaneously by an I. schulzei nymph and five A. ovale nymphs. This research reports the following unpublished records: A. ovale on O. flavescens, O. nigripes and S. agouya; A. sculptum on S. agouya; and I. schulzei on O. flavescens and O. nigripes.

RESUMO: De maio a setembro de 2011, um total de 138 roedores silvestres da família Cricetidae foram coletados nos municípios de Anhembi, Bofete e Torre de Pedra, no estado de São Paulo. Todos os animais foram examinados quanto à presença de carrapatos, os quais foram coletados e identificados ao nível de espécie em laboratório, através de análises morfológicas (para adultos, ninfas e larvas) e por biologia molecular para confirmar estas análises, através do sequenciamento de um fragmento do gene 16S rDNA mitocondrial (para uma parte das larvas). Um total de 47 carrapatos (21 larvas e 26 ninfas) foi coletado dos roedores, sendo identificados como 21 larvas e 23 ninfas de Amblyomma ovale (coletados sobre Oligoryzomys nigripes, Oligoryzomys flavescens, Sooretamys agouya e Nectomys squamipes), duas ninfas de Ixodes schulzei (em O. nigripes e O. flavescens) e uma ninfa de Amblyomma sculptum em S. agouya. A prevalência geral de parasitismo por A. ovale foi de 4,3% e de 10,1% para larvas e ninfas, respectivamente. As intensidades médias de parasitismo foram de 3,5 larvas/animal parasitado e de 1,6 ninfas/animal parasitado. Um O. nigripes foi encontrado parasitado simultaneamente por larva e ninfa de A. ovale, e outro O. nigripes estava parasitado simultaneamente por uma ninfa de I. schulzei e cinco ninfas de A. ovale. O presente trabalho reporta os seguintes registros inéditos: A. ovale em O. flavescens, O. nigripes e S. agouya; A. sculptum em S. agouya; e I. schulzei em O. flavescens e O. nigripes.

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.