# Pathological and phylogenetic characteristics of fowl AOAV-1 and H5 isolated from naturally infected Meleagris Gallopavo

## TL;DR

This study reports the first isolation of AOAV-1 and H5Nx viruses in Hybrid Converter Turkeys in Egypt, highlighting the need for disease monitoring and vaccination.

## Contribution

First report of AOAV-1 and H5Nx viruses in Hybrid Converter Turkeys in Egypt.

## Key findings

- AOAV-1 and H5 AIV were detected in turkey samples, but not H9 or TRT.
- Phylogenetic analysis showed H5 belonged to the 2.3.4.4b sublineage and AOAV-1 to genotype VII 1.1.
- Histopathology and IHC confirmed viral antigens in multiple organs with severe lesions.

## Abstract

In this study, we investigated the prevalence of respiratory viruses in four Hybrid Converter Turkey (Meleagris gallopavo) farms in Egypt. The infected birds displayed severe respiratory signs, accompanied by high mortality rates, suggesting viral infections. Five representative samples from each farm were pooled and tested for H5 & H9 subtypes of avian influenza viruses (AIVs), Avian Orthoavulavirus-1 (AOAV-1), and turkey rhinotracheitis (TRT) using real-time RT-PCR and conventional RT-PCR. Representative tissue samples from positive cases were subjected to histopathology and immunohistochemistry (IHC).

The PCR techniques confirmed the presence of AOAV-1 and H5 AIV genes, while none of the tested samples were positive for H9 or TRT. Microscopic examination of tissue samples revealed congestion and hemorrhage in the lungs, liver, and intestines with leukocytic infiltration. IHC revealed viral antigens in the lungs, liver, and intestines. Phylogenetic analysis revealed that H5 HA belonged to 2.3.4.4b H5 sublineage and AOAV-1 belonged to VII 1.1 genotype.

The study highlights the need for proper monitoring of hybrid converter breeds for viral diseases, and the importance of vaccination programs to prevent unnecessary losses. To our knowledge, this is the first study that reports the isolation of AOAV-1 and H5Nx viruses from Hybrid Converter Turkeys in Egypt.