# First Molecular Evidence of the Presence of Avian Astroviruses in Turkey Flocks of Ecuador Through the Standardization of RT-qPCR Assays Based on SYBR Green

## TL;DR

This study is the first to detect and characterize avian astroviruses in Ecuadorian turkey flocks using a highly sensitive RT-qPCR method.

## Contribution

The study introduces standardized RT-qPCR assays for detecting turkey astroviruses and avian nephritis virus in Ecuador.

## Key findings

- TAstV was detected in 93% of turkey samples with gastroenteritis.
- ANV was the most prevalent virus, followed by TAstV-2 and TAstV-1.
- Phylogenetic analysis showed genetic links between Ecuadorian and international strains.

## Abstract

Enteric diseases are a significant challenge for the poultry industry, causing substantial economic losses and affecting productivity. Turkey astrovirus (TAstV) types 1 and 2 and avian nephritis virus (ANV) are recognized as viral pathogens contributing with enteric diseases in turkeys, particularly in young poults. These viruses, part of the Astroviridae family, are small, round, non-enveloped, positive-sense RNA viruses with high prevalence in turkey flocks. Despite their importance, they had not been identified in Ecuador until now. This study presents the first detection and molecular characterization of TAstV-1, TAstV-2, and ANV in Ecuadorian turkeys using RT-qPCR assays based on SYBR Green, developed and optimized for high sensitivity and specificity. Two hundred intestinal samples were collected from turkeys with enteric disorders, along with fifty cloacal swabs from apparently healthy turkeys in Pichincha Province. The RT-qPCR assays developed demonstrated a limit of detection of one copy of viral genetic material and high repeatability, with inter and intra-assay coefficients of variation below 1%. Based on these tests, TAstV was detected in 93% of turkey samples with gastroenteritis, and none of the samples of the healthy group tested positive, with ANV being the most prevalent, followed by TAstV-2 and TAstV-1. Phylogenetic analysis of the partial ORF1b gene confirmed the genetic relationships between Ecuadorian strains and those from other countries, highlighting possible routes of introduction and evolution of the virus. Co-infections with TAstV-2 and ANV were common, while single infections were predominantly caused by ANV. These findings underscore the critical need for surveillance and biosecurity measures to control the spread of these viruses within Ecuador’s poultry industry. This study provides valuable insights on astrovirus presence in Ecuadorian turkey flocks and establishes robust diagnostic tools for monitoring and managing turkey astrovirus infections.