Avian respiratory viruses in backyard and captive bird samples

Abstract

Avian respiratory viruses are an important cause of economic losses to the poultry industry worldwide, from loss of production as well as from additional costs of diagnostics, vaccines, and antimicrobials to prevent and treat secondary infections. Three avian viruses (avian influenza virus-AIV, Newcastle disease virus -NDV-, and infectious laryngotracheitis virus- ILTV) are the most important avian viruses and they are endemic in commercial flocks in several countries and can eventually cause outbreaks in countries free of these diseases. Commercial Brazilian poultry flocks are free of AIV, NDV; however, ILTV is endemic in three areas and some reports suggest that this virus is spreading to other regions. The present study aims to increase epidemiological knowledge about avian respiratory viruses in captive and backyard poultry samples. For this purpose, paraffin-embedded tissue from birds with lesions suggestive of respiratory diseases will be obtained in collaboration with laboratories from different Brazilian states. In addition to these samples, tissues or swab samples (oropharyngeal and cloacal) will also be tested. Virus isolation will be performed in cell cultures using tissues or swab samples. The viral RNA or DNA will be purified and real-time RT-PCR and PCR reactions specific to the three viruses will be performed. After that, DNA libraries will be prepared from the reverse transcription of the RNAs or DNAs from positive samples. The samples will be sequenced using a third-generation sequencing and the sequences will be analyzed using bioinformatics tools. The genomes will be analyzed and compared with the sequences available in the public database. The epidemiological surveillance of these agents in captive and subsistence poultry samples will allow the identification of possible viral agents that can threaten the Brazilian poultry flocks. Finally, the results obtained will increase the knowledge about the circulation of these agents and allow the development of tools to prevent the entry of viruses into commercial poultry. (AU)