Phylogenetic analysis of near full-length sequences of the Desmodus rotundus genetic lineage of rabies virus.

The World Health Organization (WHO), reports that rabies causes tens of thousands of deaths every year killing humans, non-human primates and other animals. Rabies continues to be a public health issue, despite the existence of effective vaccines. The dogs remain the primary reservoir and transmitter of rabies to humans globally. In the Americas, bats are regarded as the second most common source of rabies virus to humans. The vampire bat Desmodus rotundus has been identified as a natural reservoir of rabies virus (RABV) in this region. The complete genome of the RABV variant maintained by populations of vampire bats D. rotundus has rarely been reported. In this study, we sequenced and analyzed the genome of a RABV variant detected in D. rotundus. The sample, collected from an endemic area in São Paulo State, was phylogenetically compared with the genome of the standard sample for species Rabies virus as well as other samples belonging to terrestrial and bat-associated cycles of rabies transmission, available in GenBank. Distinct patterns linked to the genetic lineage were identified. These data can aid in the understanding of the molecular epidemiology of this virus and the epidemiological importance of this species in the transmission of the RABV.

Experimental infection of the bat tick Carios fonsecai (Acari: Ixodidae) with the rabies virus.

INTRODUCTION: This study assessed the viability of the rabies virus in the argasid tick Carios fonsecai following experimental infection. METHODS: The mouse inoculation test (MIT), fluorescent antibody test (FAT) and polymerase chain reaction (PCR) were used. The rabies virus was administered to ticks via the intra-coelomic route, and the ticks were sacrificed at different time points. RESULTS: The inoculated ticks were negative for rabies according to the MIT. Ticks macerated with rabies virus were positive according to the MIT and FAT. All of the tick lots tested by PCR were positive. CONCLUSIONS The rabies virus became unviable shortly after its inoculation into tick bodies. Ticks are not likely to play an important role in the epidemiology of rabies.

One-step protocol for amplification of near full-length cDNA of the rabies virus genome.

Full-length genome sequencing of the rabies virus is not a routine laboratory procedure. To understand fully the epidemiology, genetic variation and evolution of the rabies virus, full-length viral genomes need to be obtained. For rabies virus studies, cDNA synthesis is usually performed using nonspecific oligonucleotides followed by cloning. When specific primers are used, the cDNA obtained is only partial and is limited to the coding regions. Therefore, the development of methods for synthesizing long cDNA using rabies virus-specific primers is of fundamental importance. A new protocol for the synthesis of long cDNA and the development of 19 new primers are described in this study. This procedure allowed the efficient amplification of the full-length genome of the rabies virus variant maintained by hematophagous bat (Desmodus rotundus) populations following the synthesis of a complete long cDNA. Partial sequencing of the rabies virus genome was performed to confirm rabies-specific PCR amplification. Because degenerate primers were employed, this technique can be adapted easily to other variants. Importantly, this new method is faster and less expensive than cloning methods.