Infectious bronchitis virus (IBV) is a positive-sense, single-stranded, enveloped RNA virus responsible for substantial economic losses to the poultry industry worldwide by causing a highly contagious respiratory disease. The virus can spread quickly through contact, contaminated equipment, aerosols, and personal-to-person contact. We highlight the prevalence and geographic distribution of all nine genotypes, as well as the relevant symptoms and economic impact, by extensively analyzing the current literature. Moreover, phylogenetic analysis was performed using Molecular Evolutionary Genetics Analysis (MEGA-6), which provided insights into the global molecular diversity and evolution of IBV strains. This review highlights that IBV genotype I (GI) is prevalent worldwide because sporadic cases have been found on many continents. Conversely, GII was identified as a European strain that subsequently dispersed throughout Europe and South America. GIII and GV are predominant in Australia, with very few reports from Asia. GIV, GVIII, and GIX originate from North America. GIV was found to circulate in Asia, and GVII was identified in Europe and China. Geographically, the GVI-1 lineage is thought to be restricted to Asia. This review highlights that IBV still often arises in commercial chicken flocks despite immunization and biosecurity measures because of the ongoing introduction of novel IBV variants and inadequate cross-protection provided by the presently available vaccines. Consequently, IB consistently jeopardizes the ability of the poultry industry to grow and prosper. Identifying these domains will aid in discerning the pathogenicity and prevalence of IBV genotypes, potentially enhancing disease prevention and management tactics.

Avian orthoreviruses have become a global challenge to the poultry industry, causing significant economic impacts on commercial poultry. Avian reoviruses (ARVs) are resistant to heat, proteolytic enzymes, a wide range of pH values, and disinfectants, so keeping chicken farms free of ARV infections is difficult. This review focuses on the global prevalence of ARVs and associated clinical signs and symptoms. The most common signs and symptoms include tenosynovitis/arthritis, malabsorption syndrome, runting–stunting syndrome, and respiratory diseases. Moreover, this review also focused on the characterization of ARVs in genotypic clusters (I–VI) and their relation to tissue tropism or viral distribution. The prevailing strains of ARV in Africa belong to all genotypic clusters (GCs) except for GC VI, whereas all GCs are present in Asia and the Americas. In addition, all ARV strains are associated with or belong to GC I-VI in Europe. Moreover, in Oceania, only GC V and VI are prevalent. This review also showed that, regardless of the genotypic cluster, tenosynovitis/arthritis was the predominant clinical manifestation, indicating its universal occurrence across all clusters. Globally, most avian reovirus infections can be prevented by vaccination against four major strains: S1133, 1733, 2408, and 2177. Nevertheless, these vaccines may not a provide sufficient defense against field isolates. Due to the increase in the number of ARV variants, classical vaccine approaches are being developed depending on the degree of antigenic similarity between the vaccine and field strains, which determines how successful the vaccination will be. Moreover, there is a need to look more closely at the antigenic and pathogenic properties of reported ARV strains. The information acquired will aid in the selection of more effective vaccine strains in combination with biosecurity and farm management methods to prevent ARV infections.

Orthomyxoviruses are negative-sense, RNA viruses with segmented genomes that are highly unstable due to reassortment. The highly pathogenic avian influenza (HPAI) subtype H5N8 emerged in wild birds in China. Since its emergence, it has posed a significant threat to poultry and human health. Poultry meat is considered an inexpensive source of protein, but due to outbreaks of HPAI H5N8 from migratory birds in commercial flocks, the poultry meat industry has been facing severe financial crises. This review focuses on occasional epidemics that have damaged food security and poultry production across Europe, Eurasia, the Middle East, Africa, and America. HPAI H5N8 viral sequences have been retrieved from GISAID and analyzed. Virulent HPAI H5N8 belongs to clade 2.3.4.4b, Gs/GD lineage, and has been a threat to the poultry industry and the public in several countries since its first introduction. Continent-wide outbreaks have revealed that this virus is spreading globally. Thus, continuous sero- and viro-surveillance both in commercial and wild birds, and strict biosecurity reduces the risk of the HPAI virus appearing. Furthermore, homologous vaccination practices in commercial poultry need to be introduced to overcome the introduction of emergent strains. This review clearly indicates that HPAI H5N8 is a continuous threat to poultry and people and that further regional epidemiological studies are needed.

This study was designed to undertake molecular characterization of an Infectious bronchitis virus (IBV) recovered from a suspected case of avian infectious bronchitis from commercial poultry. Initially the isolated IB-virus was characterized by RFLP using enzymes Alu I, Hae III, BstYI and XcmI. On the basis of its distinct RFLP pattern from other known IBV vaccine strains, the isolate was named as KU145467_NARC/786_Pakistan_2013 (also named as Pak-786) was subjected to Spike gene sequencing covering the amino-terminus region of 01 to 974 base pairs. The S protein sequence was submitted to the GenBank with accession number KU145467. Phylogenetic grouping and maximum nucleotide sequence identity values were used to identify the isolate that looked to be derived from recombination. It showed maximum nucleotide homology 99.5% with ck/CH/LHB/121010 (KP036503), India/IBV572 (KF809797) and Japan/JP/Wakayama-2/2004 (AB363951.2) and 99.3% with 4/91 vaccine (KF377577), Iran/491/08 (HQ842715) and 99.1% with India/NMK/72/VRI/10 (HM748585) and was least related to rest of IBV lineages compared in this study. It is concluded that Pak-786 isolate belongs to GI-13 lineage that include both the vaccine and virulent field strains, previously assigned to the 793B like. The study supports the concept that due to mass usage of live IBV vaccinal strains of diverse origin, variety of variants originate through random spontaneous mutation and genetic recombination which could lead to genetic drift. The emergent strain of IBV in this study points out the need to include such variants in killed-vaccine form in the vaccination program of the affected region.