EVOLUTION ANALYSIS AND PHYLOGEOGRAPHIC RECONSTRUCTION OF FOOT-AND-MOUTH DISEASE IN MAR CHIQUITA ? ARGENTINA

LOZANO CALDERON LC; CABANNE GS; MARCOS A; TORRES C; PEREZ AM; KÖNIG GA

Congreso; VI Global Foot-and-Mouth Disease Research Alliance (GFRA) Scientific Meeting; 2021

Foot-and-mouth is a highly contagious disease produced by a picornavirus. At present, Argentina, like most South American countries, is considered free of the disease (applying vaccination or not). However, in 2001 the country was the focus of an important epidemic that left data and samples available for subsequent epidemiological analysis. The objective of this work is to analyze the viral evolution in an Argentinean district and propose possible transmission routes. Field samples with positive PCR diagnosis and serology, for strain A/Argentina/2001, were selected from 21 farms located in the Mar Chiquita district. In the NSB4OIE biosafety SENASA laboratory, the samples wereinactivated with Trizol®, and subsequently, RT-PCR with high fidelity enzymes was performed to amplify the whole virus genome in seven fragments. The amplicons were sequenced by the Sanger technique and later, different analyzes were carried out through phylogenetic trees (using MaximumLikelihood) and phylogeographic reconstruction (estimated through BEAST v.10.4 program with a Relaxed Random Walk continuous diffusion model). These analyses were run twice for 10 million generations providing dates and location of each sample. Finally, to visualize the inferred contagions we use the SPREAD program and later, Google Earth. Three local transmission clusters were observed in the Mar Chiquita district. It was also possible to identify relatively longgeographical links between pairs of very similar sequences. The viral evolutionary mean rate was 9.15x103 substitution/site/year (95% HPD 3.29x10-3- 1.48 × 10-2). All sampled sequences divergedfrom the most recent common ancestor approximately one month before the first event report. A low correlation between geographic and genetic distance suggesting different spread routes of transmission as non-replicating vectors (by machinery, water, and human transport) and closecontacts contagion (i.e., aerosols) among the studied herds.