Phylogenetic study of a Rabies terrestrial variant in South America

CARABALLO, D. A.; RUSSO, S.; NOVARO, L.; GURY DOHMEN, F. E.; BELTRÁN, F. J.; LEMA, C.; PALACIOS, G.; CISTERNA, D. M.

Montpelier

Congreso; EEID 2021 Conference - 18th Ecology and Evolution of Infectious Diseases meeting; 2021

Centre National de la Recherche Scientifique

One of the main outcomes of long-term dog-maintained rabies virus (RABV) enzootics has been the establishment of variants in a wide variety of mesocarnivores. In South America, there are two antigenic variants (AgV) circulating among terrestrial carnivores: AgV1 present in dogs and foxes and AgV2 circulating among dogs, foxes, and other mesocarnivores. This study aims to analyze the phylogenetic relationships of AgV2 lineages and their position in the terrestrial tree.Full nucleoprotein gene sequences were obtained from 38 AgV2 and 18 AgV1 samples from Argentina, Brazil, and Paraguay isolated between the years 1989-2017. A total of 116 Genbank dog-related RABV sequences were included. A Bayesian phylogenetic analysis was carried out with MrBayes for 2x.108 MCMC generations.All AgV2 and AgV1 variants from Argentina, Brazil, and Paraguay are reciprocally monophyletic, both included within the Cosmopolitan lineage. The AgV2 lineage splits into three main clades. The first clade (A) is composed of Brazilian dog isolates and splits into two groups (South East 1986-2001; North East 2002-2005); a distinct subclade is related to the SE lineage: Mato Grosso-Paraguay (1989-1991). The second clade (B) is composed of samples from the Brazilian northeastern region (2001-2005): a dog clade and a wild clade. The third clade (C) is composed of three lineages: Argentinean dog strains (1995-1996), Paraguayan dog strains (1991-1992), and a large group of intermingled dog and wild strains from Argentina.Different epidemiologic scenarios take place in the region where AgV2 circulates. In Brazil, domestic and wild cycles occur independently. In Argentina, higher contact levels between dogs and wild species, impede the fixation of host-specific variants. Paraguay would be an overlapping zone between Brazilian and Argentinian cycles. Taking the region as a whole, we conclude that there is an ongoing circulation of RABV which has shifted multiple times between domestic and wild carnivore hosts.