Detection by Rt-Pcr and Molecular Characterization of Tremovirus A Obtained from Clinical Cases of Avian Encephalomyelitis (AE) Outbreaks in Brazil

D De La Torre,Ajp Ferreira,Shs Parra,Cs Astolfi-Ferreira,Lf Nuñez

doi:10.1590/1806-9061-2018-0744

Abstract

This study determined the presence of Tremovirus A as the possible agent related to Avian Encephalomyelitis in broiler chicks from the states of São Paulo (SP) Paraná (PR), Goiás (GO), Santa Catarina (SC) and Rio Grande do Sul (RS), between the years 2006 and 2015. Samples of the nervous, digestive, respiratory, immune, and renal systems, plus muscular organs from broiler chicks with neurological problems such as ataxia and muscle tremors, and four (4) commercial vaccines as positive control, were tested by reverse-transcriptase (RT-PCR) amplification and DNA sequencing. A highly conserved region (P1) of the viral genome, was used to amplify a segment which encodes a structural protein VP4. Out of 112 samples, 46 were positive (42%) for Tremovirus A, that was identified in the nervous, digestive, respiratory, renal and immune systems. The phylogenetic analysis clustered together the nucleotide sequences of the 46 samples, the four commercial vaccine strains and the reference sequence of Calnek strain obtained from the GenBank. According to these results, we conclude that the presence of Tremovirus A in these Brazilian chicken flocks distributed in all states was due to flaws in the biosecurity measurements.

Highlights

Tremovirus A, known as Avian Encephalomyelitis Virus (AEV) until 2014 (Knowles et al, 2012), was described for the first time in the United Stated in 1932 (Jones, 1932) and it has been associated to the Avian Encephalomyelitis (AE) disease (Tannock & Shafren, 1994)
During the period of 2006 to 2015, the Laboratory of Avian Diseases – School of Veterinary Medicine of the University of São Paulo, received 112 samples comprised of different organs such as nervous, digestive, respiratory, renal and immune systems of broilers from 21 poultry farms distributed in five Brazilian states, with history of neurological problems and suspected of Avian Encephalomyelitis, which are in the states of SP (n=14), PR (23), Rio Grande do Sul (RS) (n=45), GO (n=11), Santa Catarina (SC)
From 112 samples tested with Reverse Transcriptase (RT)-PCR, the 619 bp specific segment was amplified in 46 samples (42%) (Table 1)

Summary

Introduction

Tremovirus A, known as Avian Encephalomyelitis Virus (AEV) until 2014 (Knowles et al, 2012), was described for the first time in the United Stated in 1932 (Jones, 1932) and it has been associated to the Avian Encephalomyelitis (AE) disease (Tannock & Shafren, 1994). This disease mainly affects young birds like broilers, turkeys, pheasants and quails between 1 or 2 weeks of age (Suarez, 2013).

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