Phylodynamics of vampire bat-transmitted rabies in Argentina

Abstract

Common vampire bat populations distributed from Mexico to Argentina are important rabies reservoir hosts in Latin America. The aim of this work was to analyse the population structure of the rabies virus (RABV) variants associated with vampire bats in the Americas and to study their phylodynamic pattern within Argentina. The phylogenetic analysis based on all available vampire bat-related N gene sequences showed both a geographical and a temporal structure. The two largest groups of RABV variants from Argentina were isolated from northwestern Argentina and from the central western zone of northeastern Argentina, corresponding to livestock areas with different climatic, topographic and biogeographical conditions, which determined their dissemination and evolutionary patterns. In addition, multiple introductions of the infection into Argentina, possibly from Brazil, were detected. The phylodynamic analysis suggests that RABV transmission dynamics is characterized by initial epizootic waves followed by local enzootic cycles with variable persistence. Anthropogenic interventions in the ecosystem should be assessed taking into account not only the environmental impact but also the potential risk of disease spreading through dissemination of current RABV lineages or the emergence of novel ones associated with vampire bats.

Keywords: Argentina; phylodynamics; phylogeography; rabies virus; vampire bats.

Fig. 1

Maximum-likelihood (ML) phylogenetic tree of complete N sequences of rabies virus related to vampire bats. Bootstrap values higher than 50% are shown at nodes for relevant groups. Individual sequences or groups of sequences containing isolates introduced in this work are shown in bold. Groups containing isolates from Argentina are indicated with coloured triangles and shown in Figs S1, S2 and S3, Supporting information (dotted lines). State or province, country (abbreviated in uppercase) and year of isolation are indicated when available. ARG: Argentina, BRA: Brazil, COL: Colombia, ECU; Ecuador, ESa: El Salvador, GUY: French Guyana, MEX: Mexico, PER: Peru, URU: Uruguay.

Fig. 2

Sampling sites coloured according to the phylogenetic analysis.

Fig. 3

Maximum clade credibility tree and phylodynamic reconstruction for the NWA group. The pink-red colour gradient and the thin-thick branches represent the relative dispersal rates (slower-faster). The dated tree is in the same temporal scale as the phylodynamic reconstruction. Posterior values for relevant groups are shown at nodes. Department, province (abbreviated in uppercase) and year of isolation are indicated after the name of the isolate. CAT: Catamarca, CHA: Chaco, FOR: Formosa, SAL: Salta, TUC: Tucumán. Note that samples from the same department may be originated in different cities (information available in Table S1, Supporting information). For the phylodynamic reconstruction, the RABV dispersal rate (median and HPD80%) was superimposed on the viral demography (median and HPD95%).

Fig. 4

Maximum clade credibility tree and phylodynamic reconstruction for the NEA group. The light blue-blue colour gradient and the thin-thick branches represent the relative dispersal rates (slower-faster). The dated tree is in the same temporal scale as the phylodynamic reconstruction. Posterior values for relevant groups are shown at nodes. Grey squares show the two major currently transmitted lineages in this region. Department, province (abbreviated in uppercase) and year of isolation are indicated after the name of the isolate. CHA: Chaco, CORR: Corrientes, FOR: Formosa, MIS: Misiones, SAL: Salta, STA FE: Santa Fe. Note that samples from the same department may be originated in different cities (information available in Table S1, Supporting information). For the phylodynamic reconstruction, the RABV dispersal rate (mean and HPD80%) was superimposed on the viral demography (median and HPD95%).

Fig. 5

Spatio-temporal diffusion processes for the RABV in the NWA and NEA regions. Lines represent the maximum clade credibility tree for each region projected on the surface. The uncertainty on the location is represented by polygons (HPD80%). The colour gradient represents the relative age of the dispersal pattern (older-recent), red-pink for NWA, blue-light blue for NEA, white-orange for polygons.