Infectious Bronchitis Virus in Egypt: Genetic Diversity and Vaccination Strategies

Abstract

Infectious bronchitis virus (IBV) is a highly evolving avian pathogen that has increasingly imposed a negative impact on poultry industry worldwide. In the last 20 years, IBV has been continuously circulating among chicken flocks in Egypt causing huge economic losses to poultry production. Multiple IBV genotypes, namely, GI-1, GI-13, GI-16, and GI-23 have been reported in Egypt possessing different genetic and pathogenic features. Different vaccine programs are being used to control the spread of the disease in Egypt. However, the virus continues to spread and evolve where multiple IBV variants and several recombination evidence have been described. In this review, we highlight the current knowledge concerning IBV circulation, genesis, and vaccination strategies in Egypt. In addition, we analyze representative Egyptian IBV strains from an evolutionary perspective based on available data of their S1 gene. We also provide insight into the importance of surveillance programs and share our perspectives for better control of IBV circulating in Egypt.

Keywords: chicken; disease control; genetic evolution; infectious bronchitis virus; review; vaccine.

Figure 1

Phylogenetic tree of the nucleotide sequences of full S1 gene of Egyptian IBVs. Phylogenetic analysis was based on genotype classification of the S1 gene [7]. Maximum likelihood calculations were done using the IQTree software under the best fit model (TIM3 + F + I + G4) according to the Bayesian criterion. Egyptian IBVs were colored based on the genotype (purple = GI-1, brown = GI-13, green = GI-16, and red = GI-23). Vaccine strains used in Egypt are shown in the blue box. The strain names, locations, and accession numbers of different lineages are fully described in Valastro et al. 2016 [7].