Willian de Oliveira Fahl

A coronavirus detected in the vampire bat Desmodus rotundus

This article reports on the identification of a group 2 coronavirus (BatCoV DR/2007) in a Desmodus rotundus vampire bat in Brazil. Phylogenetic analysis of ORF1b revealed that BatCoV DR/2007 originates from a unique lineage in the archetypical group 2 coronaviruses, as described for bat species elsewhere with putative importance in Public Health.

Short-interfering RNAs as antivirals against rabies

This study aimed to test in vitro a RNA-interference based antiviral approach for rabies with short-interfering RNAs (siRNAs) against rabies virus nucleoprotein mRNA. BHK-21 cells were infected with serial dilutions of PV rabies virus strain and transfected with a pool of three siRNAs. Direct immunofluorescence staining showed a 5-time decrease in virus titer when compared to a non-treated plate, showing a promising new approach to the development of antivirals for rabies treatment.

Human rabies transmitted by vampire bats: Antigenic and genetic characterization of rabies virus isolates from the Amazon region (Brazil and Ecuador)

Since 2004, the main transmitter of human rabies in Latin America has been the vampire bat (Desmodus rotundus). Based on the nucleoprotein of the rabies virus (RV), we analyzed antigenic and genetic profiles of isolates from 29 samples taken from humans living in different areas of the Amazon region. Two isolates were from Ecuador and 27 from the Northern and Northeastern regions of Brazil, which were obtained during outbreaks in various municipalities in the states of Pará and Maranhão in the years 2004 and 2005. The partial N gene (nt 104-1477) of the 29 isolates was sequenced, and the sequences were used to build a neighbor-joining tree with the Kimura-2 parameter model. All 29 human RV isolates were identified as belonging to antigenic variant 3 (AgV3) and were genetically grouped into the D. rotundus cluster, which was divided into two subclusters (A and B), subcluster A in turn being divided into four genetic groups (A1, A2, A3 and A4). Genetic and molecular markers characterizing these genetic lineages were also identified. The results of this study show that the isolates belong to the same rabies cycle as that of the vampire bat D. rotundus. However, the division of clusters within the lineage associated with D. rotundus shows that different genetic sublineages of the virus were circulating in the Amazon region during the study period. Our findings suggest that there are phylogeographic differences between isolates obtained over a short period.

Genetic characterization of Rabies virus isolated from cattle between 1997 and 2002 in an epizootic area in the state of São Paulo, Brazil.

The biogeographical history of rabies can be reconstructed using molecular data. This work describes the genetic characterization of the Rabies virus variant that circulates in the Desmodus rotundus (vampire bat) population in an epizootic area and is transmitted to herbivorous livestock. The N and G genes of this virus were sequenced, and the phylogenetic trees generated were topologically concordant. Three genetic clusters were identified in the epizootic area and were designated RD1, RD2 and RD3. The results show that the origins of the epizootics in areas RD1 and RD2 were different and that the epizootic in area RD3 was the result of expansion of that in area RD2. The two genes analyzed are conserved, and their identities, which are greater than 98%, were maintained over time and space. The genetic sequences in this study were compared with others retrieved from GenBank, and the high identity of the N and G genes was also shown to be maintained over time and space. The results suggest that the D. rotundus lineages of the Rabies virus from the Atlantic coast of South America are highly conserved.

Molecular characterization of Rabies Virus isolates from dogs and crab-eating foxes in Northeastern Brazil.

Thirty-eight samples of Rabies Virus isolated from dogs and crab-eating foxes (Cerdocyon thous) in Northeastern Brazil were characterized genetically by analyzing the G gene and the psi region. The results show that there are two groups of Rabies Virus lineages circulating among domestic and wild animals in the region. The topologies of the phylogenetic trees of the G gene and psi region are similar and reveal the existence of geographic groups. The genetic diversity of the lineages isolated from wild animals (wild group) was approximately twice that of the lineages isolated from domestic animals (domestic group), and the genetic distance between the two groups was 9.93%. Polymorphism analysis revealed specific intra- and inter-group molecular signatures for both the G gene and psi region. Together with the analysis of the N gene undertaken previously, the results of this study confirm the existence of a Rabies Virus phylogroup in Northeastern Brazil (NB) circulating in the C. thous population, making this species a rabies biotype in the region.

Genetic characterization of rabies virus isolated from bovines and equines between 2007 and 2008, in the States of São Paulo and Minas Gerais

INTRODUCTION Rabies is an acute disease of the central nervous system and is responsible for the deaths of thousands of humans, wild animals and livestock, particularly cattle, as well as causing major economic losses. This study describes the genetic characterization of rabies virus variants that circulate in Desmodus rotundus populations and are transmitted to herbivores. METHODS Fifty rabies virus isolates from bovines and equines in the States of São Paulo and Minas Gerais, Brazil, were genetically characterized and compared with sequences retrieved from GenBank. RESULTS Two clusters (I and II) with mean nucleotide identities of 99.1 and 97.6% were found. The first of these contained nearly all the samples analyzed. Lineages from other Brazilian states grouped in cluster II. CONCLUSIONS Analysis of the amino acid sequences of the N proteins revealed the existence of genetic markers that may indicate possible variations between geographic regions, although the biologically active regions are conserved within the species over space and time.

A Comparative Study of Rabies Virus Isolates from Hematophagous Bats in Brazil

The Brazilian chiropteran fauna consists of 167 species; of which, three are hematophagous: the common vampire bat (Desmodus rotundus), the white-winged vampire bat (Diaemus youngi), and the hairy-legged vampire bat (Diphylla ecaudata). The aim of this study was to describe the isolation of Rabies virus from common and hairy-legged vampire bats and to report the first comparative antigenic and genetic studies of isolates from these bats. Antigenic and genetic typing of both isolates identified them as antigenic variant 3 (AgV3), the variant frequently isolated from common vampire bats. Phylogenetic analysis showed 99.3% identity between the isolates. This is the first time since 1934 that Rabies virus has been isolated from hairy-legged vampire bats in Brazil. Our analysis provides evidence that the existence of rabies-positive isolates from hairy-legged vampire bats may be the result of an interspecific rabies transmission event from common vampire bats and suggests that roost cohabitation may occur.

Desmodus rotundus and Artibeus spp. bats might present distinct rabies virus lineages

In Brazil, bats have been assigned an increasing importance in public health as they are important rabies reservoirs. Phylogenetic studies have shown that rabies virus (RABV) strains from frugivorous bats Artibeus spp. are closely associated to those from the vampire bat Desmodus rotundus, but little is known about the molecular diversity of RABV in Artibeus spp. The N and G genes of RABV isolated from Artibeus spp. and cattle infected by D. rotundus were sequenced, and phylogenetic trees were constructed. The N gene nucleotides tree showed three clusters: one for D. rotundus and two for Artibeus spp. Regarding putative N amino acid-trees, two clusters were formed, one for D. rotundus and another for Artibeus spp. RABV G gene phylogeny supported the distinction between D. rotundus and Artibeus spp. strains. These results show the intricate host relationship of RABVs evolutionary history, and are invaluable for the determination of RABV infection sources.

Phylogenetic analysis of partial RNA-polymerase blocks II and III of Rabies virus isolated from the main rabies reservoirs in Brazil

This study describes the results of the sequencing and analysis of segments of Blocks II and III of the RNA polymerase L gene of Rabies virus isolates from different reservoir species of Brazil. The phylogenetic relations of the virus were determined and a variety of species-specific nucleotides were found in the analyzed areas, but the majority of these mutations were found to be synonymous. However, an analysis of the putative amino acid sequences were shown to have some characteristic mutations between some reservoir species of Brazil, indicating that there was positive selection in the RNA polymerase L gene of Rabies virus. On comparing the putative viral sequences obtained from the Brazilian isolates and other Lyssavirus, it was determined that amino acid mutations occurred in low-restriction areas. This study of the L gene of Rabies virus is the first to be conducted with samples of virus isolates from Brazil, and the results obtained will help in the determination of the phylogenetic relations of the virus.

Species determination of Brazilian mammals implicated in the epidemiology of rabies based on the control region of mitochondrial DNA

Identification of animals that are decomposing or have been run over or burnt and cannot be visually identified is a problem in the surveillance and control of infectious diseases. Many of these animals are wild and represent a valuable source of information for epidemiologic research as they may be carriers of an infectious agent. This article discusses the results obtained using a method for identifying mammals genetically by sequencing their mitochondrial DNA control region. Fourteen species were analyzed and identified. These included the main reservoirs and transmitters of rabies virus, namely, canids, chiroptera and primates. The results prove that this method of genetic identification is both efficient and simple and that it can be used in the surveillance of infectious diseases which includes mammals in their epidemiologic cycle, such as rabies.