This study aimed to identify and characterize emerging ARV variants that originated from field outbreaks in commercial broiler flocks between 2021 and 2022 in El-Beheira and Qena governorates, Egypt. In addition, studying whether selenium nanoparticles (Se-NPs) treatment influenced the growth rate after the variant ARV challenge in broilers. First, for virus isolation, the collected samples were propagated into embryonated chicken eggs via the yolk sac route. ARV presence was verified by reverse transcriptase PCR (RT-PCR) and characterized by sequencing of seven representative samples targeting the sigma C gene (σC). Based on the amino acid sequences of the σC-encoding gene phylogenetic analysis revealed that the obtained seven variants of ARV isolates were grouped in the genetic cluster (GC) 4 and genetically distant from the available commercial vaccines and vaccine-related field strains. Depending on the σC gene's 256 amino acid sequence identity, the emerging ARV variants in this study shared only 39.5%-45.7% with available commercial vaccine strains, including S1133, 1733, and 2408. Second, Se-NPs were studied for their impact on the growth rate, gross, and microscopic lesions. The results revealed that the birds who received Se-NPs without ARV challenge had a mild, non-significant improvement in mean body weights when compared to the control. (P> 0.05) while the bird groups challenged with ARV either treated/ not treated with Se-NPs and Se revealed a significant difference (P < 0.05) in the mean body weights among each other and with the control group. The challenged birds showed mild and moderate gross and microscopic lesions in groups treated with Se-NPs and Se, respectively. In addition to stimulating the activity of innate immune system specially macrophages in group challenged with ARV and treated with Se-NPs. So, thorough genetic characterization of presently circulating ARV variants is critical for disease prevention and control planning and the usage of Se-NPs has an effective protection of poultry against ARV and any other pathogen.