High Diversity of Rabies Viruses Associated with Insectivorous Bats in Argentina: Presence of Several Independent Enzootics

<div><h3>Background</h3><p>Rabies is a fatal infection of the central nervous system primarily transmitted by rabid animal bites. Rabies virus (RABV) circulates through two different epidemiological cycles: terrestrial and aerial, where dogs, foxes or skunks and bats, respectively, act as the most relevant reservoirs and/or vectors. It is widely accepted that insectivorous bats are not important vectors of RABV in Argentina despite the great diversity of bat species and the extensive Argentinean territory.</p> <h3>Methods</h3><p>We studied the positivity rate of RABV detection in different areas of the country, and the antigenic and genetic diversity of 99 rabies virus (RABV) strains obtained from 14 species of insectivorous bats collected in Argentina between 1991 and 2008.</p> <h3>Results</h3><p>Based on the analysis of bats received for RABV analysis by the National Rabies system of surveillance, the positivity rate of RABV in insectivorous bats ranged from 3.1 to 5.4%, depending on the geographic location. The findings were distributed among an extensive area of the Argentinean territory. The 99 strains of insectivorous bat-related sequences were divided into six distinct lineages associated with <em>Tadarida brasiliensis</em>, <em>Myotis spp</em>, <em>Eptesicus spp</em>, <em>Histiotus montanus</em>, <em>Lasiurus blosseviilli</em> and <em>Lasiurus cinereus</em>. Comparison with RABV sequences obtained from insectivorous bats of the Americas revealed co-circulation of similar genetic variants in several countries. Finally, inter-species transmission, mostly related with <em>Lasiurus</em> species, was demonstrated in 11.8% of the samples.</p> <h3>Conclusions</h3><p>This study demonstrates the presence of several independent enzootics of rabies in insectivorous bats of Argentina. This information is relevant to identify potential areas at risk for human and animal infection.</p> </div

Consensus amino acid sequences of bat rabies viruses from Argentina.

<p>The last 88 amino acids encoded by the rabies virus nucleoprotein gene at the carboxy terminus are shown.</p

Geographic distribution of RABV sublineages associated with insectivorous bats from Argentina.

<p>Geographic distribution of RABV sublineages associated with insectivorous bats from Argentina.</p

Phylogenetic tree of insectivorous bats rabies from Americas.

<p>Tree was generated of N-J method (Kimura two-parameter model) of a portion of the N gene coding sequence (264 nt). Bold font indicates RABV samples from Argentinean bats analyzed in this study. The geographical origins of comparator group sequences are included in the name of each sample. Sample numbers appeared as GenBank database.</p

Phylogenetic relationships among Argentinean isolates.

<p>Analysis was based on 264 nt of the nucleoprotein gene. A tree was constructed based on Kimura and neighbor joining parameters. TB, <i>Tadarida brasiliensis</i>; DR, <i>Desmodus rotundus</i>; MY, <i>Myotis spp.</i>; HM, <i>Histiotus montanus</i>; EP, <i>Eptesicus spp</i>; LB, <i>Lasiurus blosseviilli</i>; LA, <i>Lasiurus cinereus</i>; TR, Terrestrial.</p

Antigenic patterns of bat rabies viruses from Argentina.

a<p>LB, <i>Lasiurus blosseviilli</i> reactivity pattern found for sample Lb658-BA03; MY1–5, <i>Myotis</i> spp. reactivity pattern found for samples Epf457-SF04 and My594-CHA05 (MY1), Bamsbt121 (MY2), Myl15M-CBA03 (MY3), Sfemnbt116 (MY4) and Myn140-SF97 (MY5); HM1–2, <i>Histiotus montanus</i> reactivity pattern found for samples Stchmbt80 (HM1) and Hm620-CHU07 and Hm580CHU07 (HM2); EP1–3, <i>Eptesicus</i> spp reactivity pattern found for samples Epf1288-SF08 and Epf787-SF07 (EP1), Epf1202-SF06 and Epb497-SF05 (EP2) and Epf062-BA03 and Epb458-SF05 (EP3).</p>b<p>ARP, atypical reaction pattern.</p

Regional distribution of rabies in Argentina, 2008–2009.

<p>Argentina is divided into five epidemiological regions. Cuyo region has not reported cases of rabies in the period of this study.</p