Bats (Mammalia: Chiroptera) in urban-rural interfaces: community structure associated with pathogen screening in São Paulo-the largest metropolitan region in Brazil.

Little is known about the influence of the urban environments on bat species 'ecology. The urbanization process potentially lead to critical ecological changes in bat communities' intra and interspecific pathogenic transmissions dynamics. To date, the monitoring of pathogens in bats in Brazil has only been done with bats found dead or alive in households, from rabies surveillance systems. The present work aimed to investigate how urbanization influenced bat richness, relative abundance and pathogen occurrence. Most captured bats were Phyllostomidae, especially Sturnira lilium, Artibeus lituratus, A. fimbriatus, Glossophaga soricina, and Platyrrhinus lineatus, among others. From preserved-rural towards urban areas the lesser the bat richness, the higher the relative abundance of the captured bats. Noise level, luminosity and relative humidity correlated with bat abundance. The proportion of genders, sexually active bats and their size (weight, right forearm length, and body condition index) were stable throughout the investigation. Still, the proportion of pregnant females was higher in Spring and the number of juveniles in Summer, evidencing the seasonality of reproduction. Several Enterobacteria were isolated, evidencing a significant role of bats in the circulation of pathogens of medical and veterinary interest. These results are crucial in the pursuit of a harmonious coexistence between humans, bats and domestic animals in areas with different levels of anthropization.

Evolution of Rabies Virus Isolates: Virulence Signatures and Effects of Modulation by Neutralizing Antibodies.

Lyssavirus rabies (RABV) is an RNA virus and, therefore, is subject to mutations due to low RNA polymerase replication fidelity, forming a population structure known as a viral quasispecies, which is the core of RNA viruses' adaptive strategy. Under new microenvironmental conditions, the fittest populations are selected, and the study of this process on the molecular level can help determine molecular signatures related to virulence. Our aim was to survey gene signatures on nucleoprotein and glycoprotein genes that might be involved in virulence modulation during the in vitro evolution of RABV lineages after serial passages in a neuronal cell system with or without the presence of neutralizing antibodies based on replicative fitness, in vivo neurotropism and protein structure and dynamics. The experiments revealed that amino acids at positions 186 and 188 of the glycoprotein are virulence factors of Lyssavirus rabies, and site 186 specifically might allow the attachment to heparan as a secondary cell receptor, while polymorphism at position 333 might allow the selection of escape mutants under suboptimal neutralizing antibodies titers.

Experimental infection of horses with Rickettsia rickettsii.

BACKGROUND: Rickettsia rickettsii is vectored by ticks, and some vertebrate hosts can be sources of infection to ticks during bacteremic periods. In Brazil, the main vector for R. rickettsii is the tick Amblyomma sculptum, a member of the A. cajennense complex. Horses, in turn, are one of the major hosts for A. sculptum. In this study, horses experimentally infected with R. rickettsii were assessed for clinical changes and their capability to transmit the infection to A. sculptum ticks. METHODS: Four horses were infected with R. rickettsii through either intraperitoneal injection or infestation with R. rickettsii-infected A. sculptum ticks. Simultaneously, the animals were infested with non-infected A. sculptum ticks. The horses were monitored for 30 days by clinical examination, hematological and biochemical tests, real-time PCR of blood for the detection of Rickettsia, and inoculation of blood in guinea pigs. IgG antibody titers were followed until the horses have shown seronegativity or until the end of the experiment. Uninfected ticks that fed on horses were subjected to real-time PCR and/or were fed on susceptible rabbits. RESULTS: The horses showed no clinical, hematological or blood biochemical alterations, and bacteremia was not detected by real-time PCR or by inoculation of horse blood into guinea pigs. Anti-R. rickettsii antibodies were detected in horses from 10 days to 2 years after infection. Uninfected ticks, after feeding on infected horses, showed 2.1 % positivity in real-time PCR, but failed to transmit the infection to rabbits at a next feeding stage. CONCLUSIONS: Rickettsia rickettsii-infected horses did not manifest illness and are not competent amplifier hosts of R. rickettsii for A. sculptum ticks.