Rabies virus diversification in aerial and terrestrial mammals.

Rabies is a fatal zoonotic infection of the central nervous system of mammals and has been known to humans for millennia. The etiological agent, is a neurotropic RNA virus in the order Mononegavirales, family Rhabdoviridae, genus Lyssavirus. There are currently accepted to be two cycles for rabies transmission: the urban cycle and the sylvatic cycle. The fact that both cycles originated from a common RABV or lyssavirus ancestor and the adaptive divergence that occurred since then as this ancestor virus adapted to a wide range of fitness landscapes represented by reservoir species in the orders Carnivora and Chiroptera led to the emergence of the diverse RABV lineages currently found in the sylvatic and urban cycles. Here we study full genome phylogenies and the time to the most recent common ancestor (TMRCA) of the RABVs in the sylvatic and urban cycles. Results show that there were differences between the nucleotide substitution rates per site per year for the same RABV genes maintained independently in the urban and sylvatic cycles. The results identify the most suitable gene for phylogenetic analysis, heterotachy among RABV genes and the TMRCA for the two cycles.

Phylogenetic analysis of rabies viruses isolated from cattle in southern Brazil.

Bats and dogs are the main reservoirs of rabies virus (RABV) in Latin America and are responsible for the maintenance of different cycles of infection. In the two neighbour and most southern Brazilian states of Rio Grande do Sul (RS) and Santa Catarina (SC), rabies in dogs has been successfully controlled for more than 30 years. However, rabies associated to the rural cycle remains endemic, with a significant, though oscillating-annual incidence of rabies in cattle. Despite the plethora of studies on genetic analyses of Brazilian RABV, isolates from southern Brazil have only scarcely been investigated. This work was performed to identify the genetic lineages of RABVs circulating in states of RS and SC. Fifty-nine RABV cattle isolates from RS and SC were selected and submitted to reverse transcription/polymerase chain reaction (RT-PCR) followed by sequencing of the nucleoprotein gene. In RS, the circulation of two sublineages (1A and 1B) of RABV was detected, both with characteristics of lineages usually detected in vampire bats (Desmodus rotundus). In SC, only one sublineage of RABV (1B) was detected. Nevertheless, the findings reported here are expected to contribute to the understanding of the biology of the virus in the region and its interactions with the natural host D. rotundus.

Detecção de núcleoproteína-RNA do vírus rábico em diversos órgãos fora do sistema nervoso central de morcegos hematófagos infectados naturalmente / Detection of rabies virus nucleoprotein-RNA in several organs outside the Central Nervous System in naturally-infected vampire bats

Rabies is a neurological disease, but the rabies virus spread to several organs outside the central nervous system (CNS). The rabies virus antigen or RNA has been identified from the salivary glands, the lungs, the kidneys, the heart and the liver. This work aimed to identify the presence of the rabies virus in non-neuronal organs from naturally-infected vampire bats and to study the rabies virus in the salivary glands of healthy vampire bats. Out of the five bats that were positive for rabies in the CNS, by fluorescent antibody test (FAT), viral isolation in N2A cells and reverse transcription - polymerase chain reaction (RT-PCR), 100 percent (5/5) were positive for rabies in samples of the tongue and the heart, 80 percent (4/5) in the kidneys, 40 percent (2/5) in samples of the salivary glands and the lungs, and 20 percent (1/5) in the liver by RT-PCR test. All the nine bats that were negative for rabies in the CNS, by FAT, viral isolation and RT-PCR were negative for rabies in the salivary glands by RT-PCR test. Possible consequences for rabies epidemiology and pathogenesis are discussed in this work.

A raiva é uma doença neurológica, mas o vírus da raiva se dispersa para diversos órgãos fora do sistema nervoso central (SNC). Antígeno ou RNA do vírus da raiva já foram detectados em vários órgãos, tais como glândula salivar, pulmão, rim, coração e fígado. O presente trabalho teve como objetivo identificar a presença do vírus da raiva em órgãos não neuronais de morcegos hematófagos infectados naturalmente, e pesquisar a presença do vírus na glândula salivar de morcegos hematófagos sadios. Dos cinco morcegos positivos para a raiva no SNC pelas técnicas de imunofluorescência direta e isolamento viral em células N2A, 100 por cento (5/5) foram positivos para a raiva nas amostras de língua e coração, 80 por cento (4/5) no rim, 40 por cento (2/5) nas amostras de glândula salivar e pulmão, e 20 por cento (4/5) no fígado pe la técnica de RT-PCR. Todos os nove morcegos negativos no SNC, pela imunofluorescência e isolamento viral, foram negativos na glândula salivar pela RT-PCR. Possíveis consequências para a epidemiologia e patogênese da raiva são discutidas.

Outbreaks of Eastern equine encephalitis in northeastern Brazil.

Outbreaks of eastern equine encephalitis observed from May 2008 to August 2009 in the Brazilian states of Pernambuco, Ceará, and Paraíba are reported. The disease occurred in 93 farms affecting 229 equids with a case fatality rate of 72.92%. Main clinical signs were circling, depression or hyperexcitability, ataxia, and progressive paralysis with a clinical manifestation period of 3-15 days. Main histologic lesions were a diffuse lymphocytic encephalomyelitis with neuronal death, satellitosis, neuronophagia, and hemorrhages being more severe in the cerebral gray matter of the telencephalon, diencephalon, and mesencephalon. Some animals also had areas of malacia in the telencephalon, thalamus, and basal nuclei. From 1 case, the virus was isolated by mice inoculation, and in other 13 cases was identified as Eastern equine encephalitis virus by semi-nested reverse transcription polymerase chain reaction. After DNA sequencing, all samples were identified as eastern equine encephalitis through the BLASTn analysis, but samples from the Ceará and Paraíba states corresponded to the same cluster, while the sample from the state of Pernambuco corresponded to a different cluster.

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.